Re: [Emc-users] Brushless Servo Selection?
Dave, I'm not sure that all of you guys on this list are aware of the fact that the US has introduced metric units since a long time. In 1866 Congress voted for the metric system, and in 1894 again administration passed bills in that direction. Only in 1975, President Gerald Ford signed the Metric Conversion Act which, however, nobody seems to take notice of. People just didn't want or were too lazy. Nowadays, the US together with other important countries as Liberia and Birma are the only ones not using the metric system in the world (look at the world map at http://de.wikipedia.org/wiki/Metrisches_Einheitensystem). Regards Peter dave schrieb: Some places decided that they could increase the effective price by 10-20% by going metric because the customer wasn't smart enough to do the conversion. Ha! That crashed quickly. So much for greed. I do believe that if we (US) had used metric on signs for the interstate hwy system and provided incentives for selling gasoline and diesel using liters we'd be metric today. Instead we have a mixed system where international companies, eg. aerospace and automotive are metric and almost everything else is english/imperial. I once had a GM manufactured car that was part metric and part english; now that was a pain. Logic and politics are rarely in the same room. Dave -- Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Brushless Servo Selection?
On 06/16/2012 09:41 AM, gene heskett wrote: On Saturday, June 16, 2012 12:31:47 PM Peter Blodow did opine: Dave, funny thing is that European lathes in those days you were describing, many still working today, were equipped with inch lead screws, so that in order to cut mm threads they have to use a 127 teeth gear in the gear case to drive the lead screw. This way, our industry wanted to become compatible with the British and American manufacturers for export And although we are using metric units here in Germany since the late 1880ies, we still buy heating and water pipes, fittings etc. in inch measures. When I sometimes bring my timber to be cut to our local sawmill, I specify 3/4 inch or one inch boards to be made out of it, although they will be measured as 20 or 25 mm boards. By the way, how come that in this mailing list everybody speaks in inches - you were writing about the metric revolution? Peter Peter, I was all on that hay ride for as long as it lasted. But when the gas stations that first put in pumps that measured liters made note that their monthly usage pumped into the customers tanks dropped to 10% because folks would just drive on down the street where they could buy gas by the gallon, a unit they had used all their lives, that effect brought the metric conversion of the US to a screeching halt. The rest of the system did go metric, but that today is entirely the effect of all the manufacturing having been exported. Had they put dual displays in the gas pumps for a few years, so folks could see at a glance what they were paying, they might have been able to let the gallons displays gradually fail, but some numbed nuts bean counter apparently wouldn't consider that idea. Instead, we took very careful aim and shot ourselves in both feet. I suspect real estate was also to be a holdout, hell, nobody around here has a clue what a hectar is, not even me. Dave schrieb: I was in engineering college from 76 to 81 and remember some discussion about this. Fortunately there was not too much to discuss as they had already decided that SI was the way to go and we had recently selected new books. At the same time the metric revolution was in full swing and they were changing out all of their machine tools in the school shop so they would all be metric. They were removing manual machines that were setup in inches and replacing them with machines setup in millimeters. Many of the machines were old so I was happy to see them go and be replaced with new machines. The school was very unique in that they encouraged students to use the machines and the facilities after hours. They had a shop supervisor who was paid to stay late most weekday nights. Even the garage was available, so we could put our cars on the lifts to do repairs and modifications. When I wasn't chasing girls, I lived at school. :-) Dave Some places decided that they could increase the effective price by 10-20% by going metric because the customer wasn't smart enough to do the conversion. Ha! That crashed quickly. So much for greed. I do believe that if we (US) had used metric on signs for the interstate hwy system and provided incentives for selling gasoline and diesel using liters we'd be metric today. Instead we have a mixed system where international companies, eg. aerospace and automotive are metric and almost everything else is english/imperial. I once had a GM manufactured car that was part metric and part english; now that was a pain. Logic and politics are rarely in the same room. Dave -- Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users Cheers, Gene -- Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Brushless Servo Selection?
On 06/16/2012 12:52 PM, Kent A. Reed wrote: On 6/16/2012 2:54 PM, andy pugh wrote: On 16 June 2012 18:48, Davee...@dc9.tzo.com wrote: I suspect real estate was also to be a holdout, hell, nobody around here has a clue what a hectar is, not even me. I think that Hectars are english also, as well as fathoms, etc. No, the Hectare is metric. An Are is an area 1km x 1km. A Hectare is 1/100 of that. So, a hectare is the area of a square 100m on a side. (1 million square metres to the Are, 10,000m^2 to the hectare.) Real estate is all about land records. Even in the relatively young US, land records now stretch back 300 years. No way anybody is going to be in a hurry to convert them to some newfangled system of units. GPS is no panacea. Almost no one's land deed, and certainly not mine, is described in terms that are easily confirmed by GPS survey, and even if I resurveyed my property I'd have to convince all my adjoining neighbors to go along as well as the county-record office before I could use the new measures in a sale of my property. Taint a cheap proposition even if everyone is being reasonable about it, and how often are people reasonable about land? Things are changing in land management , more because of the spread of GIS than anything else, but they are changing very slowly considering the technologies involved were settled decades ago. Standards, including units of measure, are intimately tied to commerce; hence my former employer, NIST, nee NBS, is in the US Department of Commerce. There have been least three official attempts at metrification in the USA in my lifetime, several of which NBS played a role in. None really took root (I exclude engineers and scientists) although many items on the shelves of stores I frequent are now marked in both English and metric units. Simplistically, I think it's because export of goods and services accounts for little more than 10 percent of our gross domestic product. That's a little tail on a big dog. This is a people problem that is not unique to the US. Look at the UK. Even though export accounts for some 30 percent of its GDP I know from firsthand experience that there is still a sizable resistance to SI. In neither the US nor the UK has legislation and its implementing regulations been completely successful. Lots of trade will give those who have the ability to change a monetary incentive to do so and lots of time will allow those who can't change to die away. Standards are intimately tied to agreements as well. http://en.wikipedia.org/wiki/Kilogram gives a nice sampling of the work that has been going into reaching international agreement on the redefinition of the kilogram. Regards, Kent I've had some discussions with county people about gps. Apparently in the Eastern states agreement is pretty good. A park district just acquired land adjacent to ours on Anderson Is. (south puget sound). The property line moved 6 to 10 feet east and this was supposedly done with high accuracy gps. There is a well established reference point less than a mi (as the crow flies) from the survey area so they had something decent to tie in to. I had to laugh at a friend of mine (his business was Ag) who was visiting relatives in Austria. I ask how he did with the metric system and he replied, Not bad ... as soon as I figured out that a Kg of cabbage was about this much (using hands to explain) I was OK. Dave -- Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users -- Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Brushless Servo Selection?
On 06/16/2012 03:21 PM, andy pugh wrote: On 16 June 2012 21:25, Peter Blodowp.blo...@dreki.de wrote: Except that hecto and centi are _not_ prefixes in the SI system. Yes they are. Hekto-, deka-, deci- and centi- (100, 10, 1/10, 1/100 rsp.) are the only ones with the decimal exponents not being multiples of three, Wikipedia seems to agree. I was certainly taught that it was improper to use those prefixes though. Usage really depends on the field. I routinely used Kg, g., mg, ug. for weight and L, mL, uL for volumes. However, take a look at your latest blood chemistry. Units like mg/dL, U/L (units/liter), mmol/L., are routinely used: and then it gets worse K/uL (white blood cells), M/uL (red blood cells), fL (mean cell volume), pg ( no volume given), % (hematocrit), Change those units and you will confuse every medical doctor out there...not something you want to do. Dave -- Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Brushless Servo Selection?
Trying to get this thread back on topic since it was hijacked by the metric system. To run one of these Keling motors how big would the motor cabling need to be? Will it have to be rated for 30 amps? That’s pretty big wire. Or would it only need to be rated for the continual current? Are there any other inexpensive brushless motor options, preferably higher voltage/lower current? -- P. Graham Dunn Phone: 330-828-2105 E-mail: to...@pgrahamdunn.com 630 Henry St. Dalton, OH 44618 www.pgrahamdunn.com -Original Message- From: Kirk Wallace [mailto:kwall...@wallacecompany.com] Sent: Friday, June 15, 2012 1:41 PM To: Enhanced Machine Controller (EMC) Subject: Re: [Emc-users] Brushless Servo Selection? On Fri, 2012-06-15 at 10:53 +0100, andy pugh wrote: On 15 June 2012 06:58, Viesturs Lācis viesturs.la...@gmail.com wrote: Unfortunately it requires relatively larger power supply with higher current output. This is a problem with motors like the Keling ones, with a 48V rated voltage. It is far simpler to make a 300V PSU than a 48V one. Simply rectifying mains voltage into a big capacitor makes a PSU that the 8i20 is happy with. Those Keling motors have a 500V / 1 min rating. I don't know if that meas that they can run indefinitley on a 300V PWM (with a 48V average or not). In the US I suppose a rectified-mains PSU would be around 150V which sounds more reasonable. (only 3x rated voltage, and it is conventional to run steppers at that sort of overvoltage) 48 Volts or rather -48 Volts DC is common for telephone equipment, so there may be cheap supplies available, if one knows where to look. Building an Antek supply shouldn't be too expensive, but I haven't checked prices recently. http://www.antekinc.com/index.php http://www.antekinc.com/gview.php One could make a transformer for the needed voltage, like these guys did. http://mackys.livejournal.com/838591.html Brushed motors (and drives) might be cheaper and universal motors are usually wound for mains voltage. If they can be modified for permanent magnets, universal motors could be handy. http://www.supermagnetman.net/index.php?cPath=37page=3 For most of us, brushes wear well enough to not be a maintenance problem. Scrap yards should have a large supply of vacuum cleaner motors from people that don't know how to replace a rubber belt. Another thing I haven't had time to look into is using a Delon doubler when one needs higher voltage than what is at hand. http://en.wikipedia.org/wiki/File:Bridge_voltage_doubler.svg http://en.wikipedia.org/wiki/Voltage_doubler -- Kirk Wallace http://www.wallacecompany.com/machine_shop/ http://www.wallacecompany.com/E45/index.html California, USA -- Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Brushless Servo Selection?
Todd Zuercher wrote: Trying to get this thread back on topic since it was hijacked by the metric system. To run one of these Keling motors how big would the motor cabling need to be? Will it have to be rated for 30 amps? That’s pretty big wire. Or would it only need to be rated for the continual current? Yes, just the continuous current should be fine. Where are you going to get a 30A motor drive? Are there any other inexpensive brushless motor options, preferably higher voltage/lower current? IMTT USA has some nice 85mm motors made by Wantai. They have a rear shaft, but it is taken up by their Hall sensor. If you removed that and used a 6-channel encoder, or put the encoder somewhere else on the machine, these work fine. They sell them for use on pumps, but I have verified they work well in positioning applications, too. Jon -- Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Brushless Servo Selection?
I think I have found the motors I would like to use. http://www.ebay.com/itm/ElectroCraft-XBR-2910-Nema34-Brushless-AC-Servo- Motors-w-Encoders-CNC-/221048834843?pt=LH_DefaultDomain_0hash=item33778 98b1b Now I need to figure out what drives I would like to use and the power supply. How much would a 4 axis setup from Pico Systems run? Todd Zuercher P. Graham Dunn Inc. 630 Henry Street Dalton, Ohio 44618 Phone: (330)828-2105ext. 2031 -- P. Graham Dunn Phone: 330-828-2105 E-mail: to...@pgrahamdunn.com 630 Henry St. Dalton, OH 44618 www.pgrahamdunn.com -- Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Brushless Servo Selection?
On 18 June 2012 22:51, Todd Zuercher to...@pgrahamdunn.com wrote: I think I have found the motors I would like to use. http://www.ebay.com/itm/ElectroCraft-XBR-2910-Nema34-Brushless-AC-Servo- Motors-w-Encoders-CNC-/221048834843?pt=LH_DefaultDomain_0hash=item33778 98b1b Do you have a spec? Torque / voltage / current? -- atp If you can't fix it, you don't own it. http://www.ifixit.com/Manifesto -- Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Brushless Servo Selection?
Todd Zuercher wrote: I think I have found the motors I would like to use. http://www.ebay.com/itm/ElectroCraft-XBR-2910-Nema34-Brushless-AC-Servo- Motors-w-Encoders-CNC-/221048834843?pt=LH_DefaultDomain_0hash=item33778 98b1b Now I need to figure out what drives I would like to use and the power supply. How much would a 4 axis setup from Pico Systems run? What is the voltage rating of these motors? If they are high-voltage motors, then running them on my drives will force you to reduced speeds (0which may turn out OK). If they are rated for up to 120 V AC, then you can get full speed out of them. So, you'd need a universal PWM controller, $250. The drives are $150 per axis. That is most of it. You can add a power switch and braking module for $50, and a spindle DAC to control a spindle drive, also $50. Are you going to the CNC Workshop in Ann Arbor later this week? Jon -- Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Brushless Servo Selection?
On 17 June 2012 09:09, Steve Blackmore st...@pilotltd.net wrote: Pipe threads are Imperial Units - BSP (British Standard Pipe) and have a Whitworth thread form. Whitworth thread has a 55 degree thread angle. This is better than a 60 degree angle, but harder to draw. (Whitworth calculated that 55 degrees gave the best combination of clamping force and self-locking) Most of the world's thread standards compromise to make things easier for the draughtsman and tool grinder. BA threads are 47.5 degrees. I don't know why. However BA is interesting as the sizes are mathematically derived on a series of equations. http://en.wikipedia.org/wiki/British_Association_screw_threads -- atp If you can't fix it, you don't own it. http://www.ifixit.com/Manifesto -- Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Brushless Servo Selection?
On 6/16/2012 2:54 PM, andy pugh wrote: On 16 June 2012 18:48, Davee...@dc9.tzo.com wrote: I suspect real estate was also to be a holdout, hell, nobody around here has a clue what a hectar is, not even me. I think that Hectars are english also, as well as fathoms, etc. No, the Hectare is metric. An Are is an area 1km x 1km. A Hectare is 1/100 of that. So, a hectare is the area of a square 100m on a side. (1 million square metres to the Are, 10,000m^2 to the hectare.) A metric unit of square measure, equal to 100 ares (2.471 acres or 10,000 square meters). Well obviously I didn't know what a Hectare was. Ironically my house lot is very close to a Hectare at 2.4 acres (in flyover country), so now I know I can relate to a Hectare. :-) Dave -- Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Brushless Servo Selection?
On Sunday, June 17, 2012 02:01:11 PM Dave did opine: On 6/16/2012 2:54 PM, andy pugh wrote: On 16 June 2012 18:48, Davee...@dc9.tzo.com wrote: I suspect real estate was also to be a holdout, hell, nobody around here has a clue what a hectar is, not even me. I think that Hectars are english also, as well as fathoms, etc. No, the Hectare is metric. An Are is an area 1km x 1km. A Hectare is 1/100 of that. So, a hectare is the area of a square 100m on a side. (1 million square metres to the Are, 10,000m^2 to the hectare.) A metric unit of square measure, equal to 100 ares (2.471 acres or 10,000 square meters). Well obviously I didn't know what a Hectare was. Ironically my house lot is very close to a Hectare at 2.4 acres (in flyover country), so now I know I can relate to a Hectare. :-) You've got lots of room for more roofing then. I'm about out. :( Dave -- Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users Cheers, Gene -- There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order. -Ed Howdershelt (Author) My web page: http://coyoteden.dyndns-free.com:85/gene How much of their influence on you is a result of your influence on them? -- Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Brushless Servo Selection?
Andy, way back in my school time, curriculum makers detected that mass and force are different things. Before, forces were expressed in mass units, i.e., kilogramms (greek: chilioi = thousand, gramma = weight), and sometimes called kilogrammforce, which gives roughly identical figures for computations as long as we are on earth. To signify the difference, though, these force units were then called kiloponds (abbreviated kp, latin: pondus = weight). To comply with international SI units, they abandoned this unit soon (right after I had to learn it in school) and introduced the Newton as the official unit of force. Using Newton's law, it is defined by the force that is needed to accelerate one kilogram of mass from zero to the speed of one meter per second during one second (1 m / s / s) and as such independent of local gravity. Using the average gravity constant of our planet, it turns out that one Newton is approx. 1/10 of a kilopond or kilogrammforce (exactly 1 N = 1 / 9.81 kp = 0.102 kp). Newton himself never explained the difference between heavy mass and inertia of mass. For engineering purposes, and to maintain the same figures and values they were used to, the old mechanical engineers used metric prefixes and made up the DekaNewton = ten Newtons, abreviated DN (greek: deka = ten, abbrev. D ). One DekaNewton = 1.02 kp, so, for the time being, they could keep using those old handbooks and their figures of material properties. It was, though, easy to confuse with the abbreviation for nominal diameter, DN, so this was not successful on the long run. To express angular momentum, we have to multiply force by the length of the lever, i.e. one meter. So we arrive at the unit DNm = 10 Nm ^= 1 kpm, and the world is in almost perfect order again. So far, this was all based on the kilogramm-meter-second system (KMS). In physics, they used another widely used system which gave handier figures for small scale considerations, the gramm - centimeter - second system (CGS). In this system, the unit of force is one dyn = 1 gramm divided by 1 cm / s / s. 1 N = 100 000 dyn, 1 Nm = 100 000 dyn m, 1 dyn = 1/100 000 N. The world was a hundred thousand times smaller. So, to make a long story short, I think your unit of kdm could mean a thousand dyn times meter, extremely unusual in technology and engineering science: 1 kdm = 1000 x 1/100 000 Nm = 1/100 Nm. Easy to confuse this dyn unit with dezi- = 1/10! Now, your dad must have a pretty old car since this cgs system was abandoned in 1978. Are you sure that the above explanation is right, or is it rather the kiloDekaNewtonMeter? What is the value on that rating plate? Best regards from Peter Blodow andy pugh schrieb: On 16 June 2012 00:37, N. Christopher Perry n_christopher_pe...@me.com wrote: There are about 1.3 Nm to a ft-lb. Which would reduce confusion no end, except motor manufacturers want bigger numbers, so like to use oz-inch in the US. There was a similar tendency in the metric world, but it seems to have passed. You do occasionally see motors with peculiar units, my dad has one with (I think) kilo-dyne-metres on the rating plate. (that's about 100 x Nm, ie 1 kdm = 0.01Nm) -- Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Brushless Servo Selection?
On 16 June 2012 08:22, Peter Blodow p.blo...@dreki.de wrote: Now, your dad must have a pretty old car since this cgs system was abandoned in 1978. Are you sure that the above explanation is right, or is it rather the kiloDekaNewtonMeter? Thinking back, it was actuality the rating of the variable-speed gearbox that was attached to the motor. And we didn't get much further than realising that the whole motor/gearbox assembly was too feeble for our requirements. -- atp If you can't fix it, you don't own it. http://www.ifixit.com/Manifesto -- Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Brushless Servo Selection?
I was in engineering college from 76 to 81 and remember some discussion about this. Fortunately there was not too much to discuss as they had already decided that SI was the way to go and we had recently selected new books. At the same time the metric revolution was in full swing and they were changing out all of their machine tools in the school shop so they would all be metric. They were removing manual machines that were setup in inches and replacing them with machines setup in millimeters. Many of the machines were old so I was happy to see them go and be replaced with new machines. The school was very unique in that they encouraged students to use the machines and the facilities after hours. They had a shop supervisor who was paid to stay late most weekday nights. Even the garage was available, so we could put our cars on the lifts to do repairs and modifications. When I wasn't chasing girls, I lived at school. :-) Dave On 6/16/2012 3:22 AM, Peter Blodow wrote: Andy, way back in my school time, curriculum makers detected that mass and force are different things. Before, forces were expressed in mass units, i.e., kilogramms (greek: chilioi = thousand, gramma = weight), and sometimes called kilogrammforce, which gives roughly identical figures for computations as long as we are on earth. To signify the difference, though, these force units were then called kiloponds (abbreviated kp, latin: pondus = weight). To comply with international SI units, they abandoned this unit soon (right after I had to learn it in school) and introduced the Newton as the official unit of force. Using Newton's law, it is defined by the force that is needed to accelerate one kilogram of mass from zero to the speed of one meter per second during one second (1 m / s / s) and as such independent of local gravity. Using the average gravity constant of our planet, it turns out that one Newton is approx. 1/10 of a kilopond or kilogrammforce (exactly 1 N = 1 / 9.81 kp = 0.102 kp). Newton himself never explained the difference between heavy mass and inertia of mass. For engineering purposes, and to maintain the same figures and values they were used to, the old mechanical engineers used metric prefixes and made up the DekaNewton = ten Newtons, abreviated DN (greek: deka = ten, abbrev. D ). One DekaNewton = 1.02 kp, so, for the time being, they could keep using those old handbooks and their figures of material properties. It was, though, easy to confuse with the abbreviation for nominal diameter, DN, so this was not successful on the long run. To express angular momentum, we have to multiply force by the length of the lever, i.e. one meter. So we arrive at the unit DNm = 10 Nm ^= 1 kpm, and the world is in almost perfect order again. So far, this was all based on the kilogramm-meter-second system (KMS). In physics, they used another widely used system which gave handier figures for small scale considerations, the gramm - centimeter - second system (CGS). In this system, the unit of force is one dyn = 1 gramm divided by 1 cm / s / s. 1 N = 100 000 dyn, 1 Nm = 100 000 dyn m, 1 dyn = 1/100 000 N. The world was a hundred thousand times smaller. So, to make a long story short, I think your unit of kdm could mean a thousand dyn times meter, extremely unusual in technology and engineering science: 1 kdm = 1000 x 1/100 000 Nm = 1/100 Nm. Easy to confuse this dyn unit with dezi- = 1/10! Now, your dad must have a pretty old car since this cgs system was abandoned in 1978. Are you sure that the above explanation is right, or is it rather the kiloDekaNewtonMeter? What is the value on that rating plate? Best regards from Peter Blodow andy pugh schrieb: On 16 June 2012 00:37, N. Christopher Perryn_christopher_pe...@me.com wrote: There are about 1.3 Nm to a ft-lb. Which would reduce confusion no end, except motor manufacturers want bigger numbers, so like to use oz-inch in the US. There was a similar tendency in the metric world, but it seems to have passed. You do occasionally see motors with peculiar units, my dad has one with (I think) kilo-dyne-metres on the rating plate. (that's about 100 x Nm, ie 1 kdm = 0.01Nm) -- Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users -- Live Security Virtual Conference Exclusive live event will cover all
Re: [Emc-users] Brushless Servo Selection?
On Sat, Jun 16, 2012 at 9:31 AM, Dave e...@dc9.tzo.com wrote: The school was very unique in that they encouraged students to use the machines and the facilities after hours. They had a shop supervisor who was paid to stay late most weekday nights. Even the garage was available, so we could put our cars on the lifts to do repairs and modifications. When I wasn't chasing girls, I lived at school. :-) Dave I expect those days are over everywhere now due to a tragic accident where a Yale student had a fatal incident involving long hair and a lathe. Around here, students have full access to a very nice shop, but they have to have a funding source to use it. Deep pockets aren't a funding source, they have to be spending money from a school budget. After the Yale incident, they required us to tell the safety office about any rotating machinery we had in our labs. I'm pretty disappointed about this whole situation, a mechanical engineering school of any merit should have student shops. Eric -- Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Brushless Servo Selection?
On 16 June 2012 14:46, Eric Keller eekel...@psu.edu wrote: a mechanical engineering school of any merit should have student shops. We had a machine shop course as part of my Physics degree. The theory was that we were likely to be having experimental rigs built, and having some concept of machinability would be handy. -- atp If you can't fix it, you don't own it. http://www.ifixit.com/Manifesto -- Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Brushless Servo Selection?
On 16 June 2012 08:22, Peter Blodow p.blo...@dreki.de wrote: To express angular momentum, we have to multiply force by the length of the lever, i.e. one meter. So we arrive at the unit DNm = 10 Nm ^= 1 kpm, and the world is in almost perfect order again. There is a similar situation with the engine controllers I work on, where there is a tendency to use heck Pascals (hPa) which are coincidentally almost exactly the same as millibars. I do think that this is purely a happy coincidence, as the Pascal depends purely on the definitions of the kilogram and meter, with no reference to atmospheric constants. I think that the kg to Newton correspondence (9.81) might be less accidental, being vaguely linked to the original definition of the meter as the length of a seconds pendulum -- atp If you can't fix it, you don't own it. http://www.ifixit.com/Manifesto -- Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Brushless Servo Selection?
On 15 June 2012 18:40, Kirk Wallace kwall...@wallacecompany.com wrote: 48 Volts or rather -48 Volts DC is common for telephone equipment, so there may be cheap supplies available, if one knows where to look. Very cheap indeed are these fruit machine power supplies: http://www.ebay.co.uk/itm/261031048815 With 10A at 50V they look like a potentially very useful CNC supply. -- atp If you can't fix it, you don't own it. http://www.ifixit.com/Manifesto -- Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Brushless Servo Selection?
On 6/16/2012 11:02 AM, andy pugh wrote: On 15 June 2012 18:40, Kirk Wallacekwall...@wallacecompany.com wrote: 48 Volts or rather -48 Volts DC is common for telephone equipment, so there may be cheap supplies available, if one knows where to look. Very cheap indeed are these fruit machine power supplies: http://www.ebay.co.uk/itm/261031048815 With 10A at 50V they look like a potentially very useful CNC supply. Fruit machines?? What is a fruit machine? Do you know what we call them in the US? Dave -- Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Brushless Servo Selection?
On 6/16/2012 9:46 AM, Eric Keller wrote: On Sat, Jun 16, 2012 at 9:31 AM, Davee...@dc9.tzo.com wrote: The school was very unique in that they encouraged students to use the machines and the facilities after hours. They had a shop supervisor who was paid to stay late most weekday nights. Even the garage was available, so we could put our cars on the lifts to do repairs and modifications. When I wasn't chasing girls, I lived at school. :-) Dave I expect those days are over everywhere now due to a tragic accident where a Yale student had a fatal incident involving long hair and a lathe. Around here, students have full access to a very nice shop, but they have to have a funding source to use it. Deep pockets aren't a funding source, they have to be spending money from a school budget. After the Yale incident, they required us to tell the safety office about any rotating machinery we had in our labs. I'm pretty disappointed about this whole situation, a mechanical engineering school of any merit should have student shops. Eric -- Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users When I was in school they were pushing really hard to get women into the program plus back in those days some of the guys had fairly long hair also (even I had a lot more hair then than I do now!) Shop safety was very important. If you didn't have safety classes and your hair tied back they wouldn't let you close to the machines. We had to check in with the guy running the shop at the time to get cutters, bits, etc. Ties (we actually wore them sometimes) were not allowed around machines. The unfortunate fact is that stuff happens, and people sometimes die. They will get over that, but it might take a while unfortunately. Administrators seem to think that they can eliminate any chance of people getting hurt - but it is not possible. Machinery can be dangerous.I've been around a few industrial accidents where people have been killed. In hindsight they are always preventable. But people sometimes do the wrong things. a mechanical engineering school of any merit should have student shops. I agree. If they eliminate it and another school does not, then they will be at a disadvantage. Dave -- Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Brushless Servo Selection?
Fruit machines?? What is a fruit machine? Do you know what we call them in the US? Dave Slot Machine or One arm bandit I think. Fruit machine is from graphics commonly used on the rotating drums. I note the supplies are multi-output switchers. The cross-regulation between different outputs might be a problem John Prentice -- Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Brushless Servo Selection?
Andy, 1 Pa = 1 N/sq. meter, a very impractical unit. Therefore, the bar as the most commonly used pressure unit of today, not a SI unit, is only accepted as an exception to be near the previously used atmosphere = 1 kp/sq.cm. 1 hPa (hectoPascal) = 100 Pa (greek: hekaton = hundred). The heck with it. 1 bar = 100 000 Pa = 1.02 kp/sq.cm, so 1 mbar = 1.02 hPa. The lenght of a 1 meter pendulum giving exactly one second is about 0.994 m, a bare coincidence. The meter was first defined as 1/40 000 of the earth's circumference and later on by the length of the platimum-iridium specimen in Paris. The factor of 9.81 is owed to the earth's a acceleration of a falling piece of mass measured to be g = 9.81 m/s squared, purely accidental. Greetings Peter andy pugh schrieb: There is a similar situation with the engine controllers I work on, where there is a tendency to use heck Pascals (hPa) which are coincidentally almost exactly the same as millibars. I do think that this is purely a happy coincidence, as the Pascal depends purely on the definitions of the kilogram and meter, with no reference to atmospheric constants. I think that the kg to Newton correspondence (9.81) might be less accidental, being vaguely linked to the original definition of the meter as the length of a seconds pendulum -- Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Brushless Servo Selection?
Dave, funny thing is that European lathes in those days you were describing, many still working today, were equipped with inch lead screws, so that in order to cut mm threads they have to use a 127 teeth gear in the gear case to drive the lead screw. This way, our industry wanted to become compatible with the British and American manufacturers for export And although we are using metric units here in Germany since the late 1880ies, we still buy heating and water pipes, fittings etc. in inch measures. When I sometimes bring my timber to be cut to our local sawmill, I specify 3/4 inch or one inch boards to be made out of it, although they will be measured as 20 or 25 mm boards. By the way, how come that in this mailing list everybody speaks in inches - you were writing about the metric revolution? Peter Dave schrieb: I was in engineering college from 76 to 81 and remember some discussion about this. Fortunately there was not too much to discuss as they had already decided that SI was the way to go and we had recently selected new books. At the same time the metric revolution was in full swing and they were changing out all of their machine tools in the school shop so they would all be metric. They were removing manual machines that were setup in inches and replacing them with machines setup in millimeters. Many of the machines were old so I was happy to see them go and be replaced with new machines. The school was very unique in that they encouraged students to use the machines and the facilities after hours. They had a shop supervisor who was paid to stay late most weekday nights. Even the garage was available, so we could put our cars on the lifts to do repairs and modifications. When I wasn't chasing girls, I lived at school. :-) Dave -- Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Brushless Servo Selection?
On Saturday, June 16, 2012 12:14:55 PM Eric Keller did opine: On Sat, Jun 16, 2012 at 9:31 AM, Dave e...@dc9.tzo.com wrote: The school was very unique in that they encouraged students to use the machines and the facilities after hours. They had a shop supervisor who was paid to stay late most weekday nights. Even the garage was available, so we could put our cars on the lifts to do repairs and modifications. When I wasn't chasing girls, I lived at school. :-) Dave I expect those days are over everywhere now due to a tragic accident where a Yale student had a fatal incident involving long hair and a lathe. Around here, students have full access to a very nice shop, but they have to have a funding source to use it. Deep pockets aren't a funding source, they have to be spending money from a school budget. After the Yale incident, they required us to tell the safety office about any rotating machinery we had in our labs. I'm pretty disappointed about this whole situation, a mechanical engineering school of any merit should have student shops. Eric When will the friggin lawyers understand that you can't save stupid from himself? -- Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users Cheers, Gene -- There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order. -Ed Howdershelt (Author) My web page: http://coyoteden.dyndns-free.com:85/gene Platonic Shadow: A nonsexual friendship with a member of the opposite sex. -- Douglas Coupland, Generation X: Tales for an Accelerated Culture -- Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Brushless Servo Selection?
You can't save anybody from himself, but I understand that nobody will be made responsible for the stupid killing themselves. This is the consequence of today's holy law that nowadays nothing can happen without someone being responsible (even if nobody really is). Makes a lot of money for the lawyers. Peter gene heskett schrieb: On Saturday, June 16, 2012 12:14:55 PM Eric Keller did opine: When will the friggin lawyers understand that you can't save stupid from himself? -- Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Brushless Servo Selection?
On Saturday, June 16, 2012 12:27:40 PM andy pugh did opine: On 15 June 2012 18:40, Kirk Wallace kwall...@wallacecompany.com wrote: 48 Volts or rather -48 Volts DC is common for telephone equipment, so there may be cheap supplies available, if one knows where to look. Very cheap indeed are these fruit machine power supplies: http://www.ebay.co.uk/itm/261031048815 With 10A at 50V they look like a potentially very useful CNC supply. 20 UKP + 12 ukp postage? Needs 230 vac? I think I'll pass. Cheers, Gene -- There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order. -Ed Howdershelt (Author) My web page: http://coyoteden.dyndns-free.com:85/gene audophile, n: Someone who listens to the equipment instead of the music. -- Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Brushless Servo Selection?
On 16 June 2012 17:01, Peter Blodow p.blo...@dreki.de wrote: Andy, 1 Pa = 1 N/sq. meter, a very impractical unit. I know this stuff, I have a physics degree. In fact many years ago the NPL invited me along to a colloquium discussing how best to re-define the kilogram. (Because it is currently based on a lump of platinum-iridium, not on any portable physical constants. In fact the master kilogram and the sub-standards are all drifting in different directions, and that is causing some concern. I think the current plan is to use a perfect sphere of silicon, and then relate the kg back to the meter (which can be re-built from the wavelength of a particular light source). The NPL were looking at using a rotating Watt Balance at the time) -- atp If you can't fix it, you don't own it. http://www.ifixit.com/Manifesto -- Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Brushless Servo Selection?
By the way, how come that in this mailing list everybody speaks in inches - you were writing about the metric revolution? That is the really goofy thing.. the end result was that we are now about half and half, english and metric. After the big metric push back in the late 70's, the car companies went fully metric by about the mid to late 80's, but many US made goods are still english. In my tool chest I have a full set of english and metric sockets which gets quite bulky. The said, if I want to buy english nuts and bolts, I can buy them by them in bulk pound (weight measure) in grades 2-8 at a local tractor/farm equipment supply store. If I want to buy metric bolts and nuts locally I have to either buy them from an industrial supply store (limited hours) or buy them one at a time at a price which can be 3-4 times the bulk price of similar english fasteners. So the use of english fasteners in the US is reinforced by the availability of cheap and available english fasteners. Ironically most of those fasteners are made in Asia or China. The metric system has some issues.. Buying a 2x4 which is 10 feet long and specifying that in millimeters seems crazy. Pipe fittings would be ok for diameter but if I want to but a piece of 2 pipe which is 21 feet long, specifying 51 mm in diameter and 6.x meters long seems totally counter intuitive. I guess the advantage is that fractions become non-existent which would be a big improvement. Dave On 6/16/2012 12:13 PM, Peter Blodow wrote: Dave, funny thing is that European lathes in those days you were describing, many still working today, were equipped with inch lead screws, so that in order to cut mm threads they have to use a 127 teeth gear in the gear case to drive the lead screw. This way, our industry wanted to become compatible with the British and American manufacturers for export And although we are using metric units here in Germany since the late 1880ies, we still buy heating and water pipes, fittings etc. in inch measures. When I sometimes bring my timber to be cut to our local sawmill, I specify 3/4 inch or one inch boards to be made out of it, although they will be measured as 20 or 25 mm boards. By the way, how come that in this mailing list everybody speaks in inches - you were writing about the metric revolution? Peter Dave schrieb: I was in engineering college from 76 to 81 and remember some discussion about this. Fortunately there was not too much to discuss as they had already decided that SI was the way to go and we had recently selected new books. At the same time the metric revolution was in full swing and they were changing out all of their machine tools in the school shop so they would all be metric. They were removing manual machines that were setup in inches and replacing them with machines setup in millimeters. Many of the machines were old so I was happy to see them go and be replaced with new machines. The school was very unique in that they encouraged students to use the machines and the facilities after hours. They had a shop supervisor who was paid to stay late most weekday nights. Even the garage was available, so we could put our cars on the lifts to do repairs and modifications. When I wasn't chasing girls, I lived at school. :-) Dave -- Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users -- Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Brushless Servo Selection?
On Saturday, June 16, 2012 12:31:47 PM Peter Blodow did opine: Dave, funny thing is that European lathes in those days you were describing, many still working today, were equipped with inch lead screws, so that in order to cut mm threads they have to use a 127 teeth gear in the gear case to drive the lead screw. This way, our industry wanted to become compatible with the British and American manufacturers for export And although we are using metric units here in Germany since the late 1880ies, we still buy heating and water pipes, fittings etc. in inch measures. When I sometimes bring my timber to be cut to our local sawmill, I specify 3/4 inch or one inch boards to be made out of it, although they will be measured as 20 or 25 mm boards. By the way, how come that in this mailing list everybody speaks in inches - you were writing about the metric revolution? Peter Peter, I was all on that hay ride for as long as it lasted. But when the gas stations that first put in pumps that measured liters made note that their monthly usage pumped into the customers tanks dropped to 10% because folks would just drive on down the street where they could buy gas by the gallon, a unit they had used all their lives, that effect brought the metric conversion of the US to a screeching halt. The rest of the system did go metric, but that today is entirely the effect of all the manufacturing having been exported. Had they put dual displays in the gas pumps for a few years, so folks could see at a glance what they were paying, they might have been able to let the gallons displays gradually fail, but some numbed nuts bean counter apparently wouldn't consider that idea. Instead, we took very careful aim and shot ourselves in both feet. I suspect real estate was also to be a holdout, hell, nobody around here has a clue what a hectar is, not even me. Dave schrieb: I was in engineering college from 76 to 81 and remember some discussion about this. Fortunately there was not too much to discuss as they had already decided that SI was the way to go and we had recently selected new books. At the same time the metric revolution was in full swing and they were changing out all of their machine tools in the school shop so they would all be metric. They were removing manual machines that were setup in inches and replacing them with machines setup in millimeters. Many of the machines were old so I was happy to see them go and be replaced with new machines. The school was very unique in that they encouraged students to use the machines and the facilities after hours. They had a shop supervisor who was paid to stay late most weekday nights. Even the garage was available, so we could put our cars on the lifts to do repairs and modifications. When I wasn't chasing girls, I lived at school. :-) Dave -- Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users Cheers, Gene -- There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order. -Ed Howdershelt (Author) My web page: http://coyoteden.dyndns-free.com:85/gene A diplomatic husband said to his wife, How do you expect me to remember your birthday when you never look any older? -- Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Brushless Servo Selection?
On 6/16/2012 12:16 PM, gene heskett wrote: On Saturday, June 16, 2012 12:14:55 PM Eric Keller did opine: On Sat, Jun 16, 2012 at 9:31 AM, Davee...@dc9.tzo.com wrote: The school was very unique in that they encouraged students to use the machines and the facilities after hours. They had a shop supervisor who was paid to stay late most weekday nights. Even the garage was available, so we could put our cars on the lifts to do repairs and modifications. When I wasn't chasing girls, I lived at school. :-) Dave I expect those days are over everywhere now due to a tragic accident where a Yale student had a fatal incident involving long hair and a lathe. Around here, students have full access to a very nice shop, but they have to have a funding source to use it. Deep pockets aren't a funding source, they have to be spending money from a school budget. After the Yale incident, they required us to tell the safety office about any rotating machinery we had in our labs. I'm pretty disappointed about this whole situation, a mechanical engineering school of any merit should have student shops. Eric When will the friggin lawyers understand that you can't save stupid from himself? They already understand that. But since they can still make loads of $ from idiots doing stupid things, why stop? Remember the lady that sued McDonalds for having the coffee too hot! Now all of our McDonalds coffee is just above cool. :-( And the women and the lawyers made some serious cash. Dave -- Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Brushless Servo Selection?
Peter Blodow wrote: By the way, how come that in this mailing list everybody speaks in inches - you were writing about the metric revolution? Well, in the US, the metric revolution came and went. Certain industries (aircraft manufacturing and auto manufacturing) have gone totally metric, but must other stuff has not. We had traffic signs in km and km/h for a while, but then they all got pulled out and we went back to miles and MPH. They are only somewhat teaching our kids the metric system, at least until high school chemistry and physics classes. Even our Chinese-liaison PCB manufacturer wants the design files in inch units, they then convert to mm before sending the designs to China for manufacturing. When my boss designs some scientific apparatus in mm and hands the drawing to our shop, they dutifully convert the whole drawing to inches before making the parts. Thanks goodness the local hardware store has a rack of boxes of metric fasteners, so when I need something I can get them. Jon -- Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Brushless Servo Selection?
Gene They solved the litres issue in the UK but making it illegal to sell most things in anything but metric units. However we still measure distance in miles, so what units should we be working out our fuel economy? Miles per litre? At least we can still buy beer in pints ( 20oz ones of course :-) ) Mike On 16 Jun 2012, at 17:41, gene heskett ghesk...@wdtv.com wrote: Peter, I was all on that hay ride for as long as it lasted. But when the gas stations that first put in pumps that measured liters made note that their monthly usage pumped into the customers tanks dropped to 10% because folks would just drive on down the street where they could buy gas by the gallon, a unit they had used all their lives, that effect brought the metric conversion of the US to a screeching halt. The rest of the system did go metric, but that today is entirely the effect of all the manufacturing having been exported. Had they put dual displays in the gas pumps for a few years, so folks could see at a glance what they were paying, they might have been able to let the gallons displays gradually fail, but some numbed nuts bean counter apparently wouldn't consider that idea. Instead, we took very careful aim and shot ourselves in both feet. I suspect real estate was also to be a holdout, hell, nobody around here has a clue what a hectar is, not even me. -- Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Brushless Servo Selection?
On 16 June 2012 18:05, Jon Elson el...@pico-systems.com wrote: Well, in the US, the metric revolution came and went. Certain industries (aircraft manufacturing and auto manufacturing) have gone totally metric Not entirely. Part of our ECU code is being written by Ford in the USA, to plug into the code written in France, the UK and Germany by the supplier and the designer. Imagine my annoyance to find that the very first thing that the US code did was convert the incoming temperature signal to Fahrenheit, then convert it back again at the output port. Considering that the numbers are all scaled representations of the real values as 16-bit ints this makes absolutely no sense whatsoever. -- atp If you can't fix it, you don't own it. http://www.ifixit.com/Manifesto -- Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Brushless Servo Selection?
I suspect real estate was also to be a holdout, hell, nobody around here has a clue what a hectar is, not even me. I think that Hectars are english also, as well as fathoms, etc. You need to get your head wrapped around square meters. (Good luck with that!) I don't have a meter stick, but I have several yard sticks. So how can you estimate realestate in square meters if you don't even have a meter stick?? But I have two feet and my shoes are right at 13 inches.. so if I walk toe to toe . ;-) (I do that more than I care to admit.) Dave On 6/16/2012 12:41 PM, gene heskett wrote: On Saturday, June 16, 2012 12:31:47 PM Peter Blodow did opine: Dave, funny thing is that European lathes in those days you were describing, many still working today, were equipped with inch lead screws, so that in order to cut mm threads they have to use a 127 teeth gear in the gear case to drive the lead screw. This way, our industry wanted to become compatible with the British and American manufacturers for export And although we are using metric units here in Germany since the late 1880ies, we still buy heating and water pipes, fittings etc. in inch measures. When I sometimes bring my timber to be cut to our local sawmill, I specify 3/4 inch or one inch boards to be made out of it, although they will be measured as 20 or 25 mm boards. By the way, how come that in this mailing list everybody speaks in inches - you were writing about the metric revolution? Peter Peter, I was all on that hay ride for as long as it lasted. But when the gas stations that first put in pumps that measured liters made note that their monthly usage pumped into the customers tanks dropped to 10% because folks would just drive on down the street where they could buy gas by the gallon, a unit they had used all their lives, that effect brought the metric conversion of the US to a screeching halt. The rest of the system did go metric, but that today is entirely the effect of all the manufacturing having been exported. Had they put dual displays in the gas pumps for a few years, so folks could see at a glance what they were paying, they might have been able to let the gallons displays gradually fail, but some numbed nuts bean counter apparently wouldn't consider that idea. Instead, we took very careful aim and shot ourselves in both feet. I suspect real estate was also to be a holdout, hell, nobody around here has a clue what a hectar is, not even me. Dave schrieb: I was in engineering college from 76 to 81 and remember some discussion about this. Fortunately there was not too much to discuss as they had already decided that SI was the way to go and we had recently selected new books. At the same time the metric revolution was in full swing and they were changing out all of their machine tools in the school shop so they would all be metric. They were removing manual machines that were setup in inches and replacing them with machines setup in millimeters. Many of the machines were old so I was happy to see them go and be replaced with new machines. The school was very unique in that they encouraged students to use the machines and the facilities after hours. They had a shop supervisor who was paid to stay late most weekday nights. Even the garage was available, so we could put our cars on the lifts to do repairs and modifications. When I wasn't chasing girls, I lived at school. :-) Dave -- Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users Cheers, Gene -- Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Brushless Servo Selection?
I remember Italy was km/hr years ago. I thought the UK was in km/hr also. So at this point, I guess it is a safe bet that the UK will not be going to the Euro anytime soon? ;-) Dave On 6/16/2012 1:08 PM, Mike Bennett wrote: Gene They solved the litres issue in the UK but making it illegal to sell most things in anything but metric units. However we still measure distance in miles, so what units should we be working out our fuel economy? Miles per litre? At least we can still buy beer in pints ( 20oz ones of course :-) ) Mike On 16 Jun 2012, at 17:41, gene heskettghesk...@wdtv.com wrote: Peter, I was all on that hay ride for as long as it lasted. But when the gas stations that first put in pumps that measured liters made note that their monthly usage pumped into the customers tanks dropped to 10% because folks would just drive on down the street where they could buy gas by the gallon, a unit they had used all their lives, that effect brought the metric conversion of the US to a screeching halt. The rest of the system did go metric, but that today is entirely the effect of all the manufacturing having been exported. Had they put dual displays in the gas pumps for a few years, so folks could see at a glance what they were paying, they might have been able to let the gallons displays gradually fail, but some numbed nuts bean counter apparently wouldn't consider that idea. Instead, we took very careful aim and shot ourselves in both feet. I suspect real estate was also to be a holdout, hell, nobody around here has a clue what a hectar is, not even me. -- Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users -- Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Brushless Servo Selection?
On 6/16/2012 1:45 PM, andy pugh wrote: On 16 June 2012 18:05, Jon Elsonel...@pico-systems.com wrote: Well, in the US, the metric revolution came and went. Certain industries (aircraft manufacturing and auto manufacturing) have gone totally metric Not entirely. Part of our ECU code is being written by Ford in the USA, to plug into the code written in France, the UK and Germany by the supplier and the designer. Imagine my annoyance to find that the very first thing that the US code did was convert the incoming temperature signal to Fahrenheit, then convert it back again at the output port. Considering that the numbers are all scaled representations of the real values as 16-bit ints this makes absolutely no sense whatsoever. That is really funny. The problem is that us Americans can't think in anything but Fahrenheit! ;-) Dave -- Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Brushless Servo Selection?
On 16 June 2012 18:48, Dave e...@dc9.tzo.com wrote: I suspect real estate was also to be a holdout, hell, nobody around here has a clue what a hectar is, not even me. I think that Hectars are english also, as well as fathoms, etc. No, the Hectare is metric. An Are is an area 1km x 1km. A Hectare is 1/100 of that. So, a hectare is the area of a square 100m on a side. (1 million square metres to the Are, 10,000m^2 to the hectare.) -- atp If you can't fix it, you don't own it. http://www.ifixit.com/Manifesto -- Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Brushless Servo Selection?
2012/6/16 andy pugh bodge...@gmail.com: On 16 June 2012 18:48, Dave e...@dc9.tzo.com wrote: I suspect real estate was also to be a holdout, hell, nobody around here has a clue what a hectar is, not even me. I think that Hectars are english also, as well as fathoms, etc. No, the Hectare is metric. An Are is an area 1km x 1km. A Hectare is 1/100 of that. So, a hectare is the area of a square 100m on a side. (1 million square metres to the Are, 10,000m^2 to the hectare.) 1/100 is centi - centimeter is 1/100 of meter. Hectolitre is 100 litres, so I guess hectare is 100 ares, which means that 1 is area of 10x10 m. -- Viesturs If you can't fix it, you don't own it. http://www.ifixit.com/Manifesto -- Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Brushless Servo Selection?
2012/6/16 John Prentice j...@castlewd.freeserve.co.uk: Fruit machines?? What is a fruit machine? Do you know what we call them in the US? Dave Slot Machine or One arm bandit I think. The same that look like Mach3 :)) -- Viesturs If you can't fix it, you don't own it. http://www.ifixit.com/Manifesto -- Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Brushless Servo Selection?
On 16 June 2012 20:02, Viesturs Lācis viesturs.la...@gmail.com wrote: 1/100 is centi - centimeter is 1/100 of meter. Hectolitre is 100 litres, so I guess hectare is 100 ares, which means that 1 is area of 10x10 m. You are quite right, I don't know how I got that wrong. Except that hecto and centi are _not_ prefixes in the SI system. -- atp If you can't fix it, you don't own it. http://www.ifixit.com/Manifesto -- Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Brushless Servo Selection?
I know this stuff, I have a physics degree. Sorry, didn't mean to insult you. In fact many years ago the NPL invited me along to a colloquium discussing how best to re-define the kilogram. (Because it is currently based on a lump of platinum-iridium, not on any portable physical constants. In fact the master kilogram and the sub-standards are all drifting in different directions, and that is causing some concern. I think the current plan is to use a perfect sphere of silicon, ...which my collegues at the PTB (German Federal Physical-Technologiocal Institute) at Braunschweig have been doing for the last, say, 15 years. Filing single atoms from a sphere, puuuh... Peter -- Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Brushless Servo Selection?
On 6/16/2012 2:54 PM, andy pugh wrote: On 16 June 2012 18:48, Dave e...@dc9.tzo.com wrote: I suspect real estate was also to be a holdout, hell, nobody around here has a clue what a hectar is, not even me. I think that Hectars are english also, as well as fathoms, etc. No, the Hectare is metric. An Are is an area 1km x 1km. A Hectare is 1/100 of that. So, a hectare is the area of a square 100m on a side. (1 million square metres to the Are, 10,000m^2 to the hectare.) Real estate is all about land records. Even in the relatively young US, land records now stretch back 300 years. No way anybody is going to be in a hurry to convert them to some newfangled system of units. GPS is no panacea. Almost no one's land deed, and certainly not mine, is described in terms that are easily confirmed by GPS survey, and even if I resurveyed my property I'd have to convince all my adjoining neighbors to go along as well as the county-record office before I could use the new measures in a sale of my property. Taint a cheap proposition even if everyone is being reasonable about it, and how often are people reasonable about land? Things are changing in land management , more because of the spread of GIS than anything else, but they are changing very slowly considering the technologies involved were settled decades ago. Standards, including units of measure, are intimately tied to commerce; hence my former employer, NIST, nee NBS, is in the US Department of Commerce. There have been least three official attempts at metrification in the USA in my lifetime, several of which NBS played a role in. None really took root (I exclude engineers and scientists) although many items on the shelves of stores I frequent are now marked in both English and metric units. Simplistically, I think it's because export of goods and services accounts for little more than 10 percent of our gross domestic product. That's a little tail on a big dog. This is a people problem that is not unique to the US. Look at the UK. Even though export accounts for some 30 percent of its GDP I know from firsthand experience that there is still a sizable resistance to SI. In neither the US nor the UK has legislation and its implementing regulations been completely successful. Lots of trade will give those who have the ability to change a monetary incentive to do so and lots of time will allow those who can't change to die away. Standards are intimately tied to agreements as well. http://en.wikipedia.org/wiki/Kilogram gives a nice sampling of the work that has been going into reaching international agreement on the redefinition of the kilogram. Regards, Kent -- Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Brushless Servo Selection?
andy pugh schrieb: You are quite right, I don't know how I got that wrong. Except that hecto and centi are _not_ prefixes in the SI system. Yes they are. Hekto-, deka-, deci- and centi- (100, 10, 1/10, 1/100 rsp.) are the only ones with the decimal exponents not being multiples of three, but just the same widely used whenever SI-units are used at all, probably the most frequently used ones of all of them. Example: women's clothes are measured in cm, beer barrels and all beer production are measured in hectoliters. Want more? Peter. -- Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Brushless Servo Selection?
On 16 June 2012 21:25, Peter Blodow p.blo...@dreki.de wrote: Except that hecto and centi are _not_ prefixes in the SI system. Yes they are. Hekto-, deka-, deci- and centi- (100, 10, 1/10, 1/100 rsp.) are the only ones with the decimal exponents not being multiples of three, Wikipedia seems to agree. I was certainly taught that it was improper to use those prefixes though. -- atp If you can't fix it, you don't own it. http://www.ifixit.com/Manifesto -- Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Brushless Servo Selection?
Viesturs, don't confuse US and British units although they are both called imperial units (since when do Americans care about emperors?) - they are not necessarily the same as you come to details. Screws can be a lot different, for example. I have an old English combined circular wood saw and table router with thread holes in the table where US screws don't fit. British imperial gallons are different from US gallons. Furthermore, there are American metric screws that won't fit into European nuts of the same specifications because the radii of the thread's edges are different - it's all a whole mess as long as there are no efforts of unification. In this respect, we are living in an era not much different from the middle ages because every country wants to protect their products from other manufacturers instead of making joint efforts to compete only in quality and price of the optimal products. British pipe threads are based on inch standard and compatible with all other countries' pipes and fittings, imperial or not. Peter Viesturs La-cis schrieb: 2012/6/16 andy pugh bodge...@gmail.com: You are quite right, I don't know how I got that wrong. Except that hecto and centi are _not_ prefixes in the SI system. Could be, I do not know for sure... BTW the metric vs imperial systems and UK being somewhere inbetween (litres from metric system and miles from imperial), I just remembered one interesting moment from a metrology class: In whole mainland Europe screw threads are metric, pipe threads are in imperial units. Which does not make much of a sense to me, why would they be separated, but then professor mentioned that pipe threads in UK are not imperial (I _think_ that screw threads are imperial in UK)... So I think that pipe thread in UK has to be metric, which makes me think that English people are doing this on purpose :)) -- Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Brushless Servo Selection?
On Saturday, June 16, 2012 06:44:09 PM Dave did opine: I suspect real estate was also to be a holdout, hell, nobody around here has a clue what a hectar is, not even me. I think that Hectars are english also, as well as fathoms, etc. You need to get your head wrapped around square meters. (Good luck with that!) I don't have a meter stick, but I have several yard sticks. So how can you estimate realestate in square meters if you don't even have a meter stick?? But I have two feet and my shoes are right at 13 inches.. so if I walk toe to toe . ;-) (I do that more than I care to admit.) And in my prime, my pace even for my short legs, often put me at 91 or 92 paces from end zone to end zone of a football field. But not recently, the hip joints out voted me. Dave On 6/16/2012 12:41 PM, gene heskett wrote: On Saturday, June 16, 2012 12:31:47 PM Peter Blodow did opine: Dave, funny thing is that European lathes in those days you were describing, many still working today, were equipped with inch lead screws, so that in order to cut mm threads they have to use a 127 teeth gear in the gear case to drive the lead screw. This way, our industry wanted to become compatible with the British and American manufacturers for export And although we are using metric units here in Germany since the late 1880ies, we still buy heating and water pipes, fittings etc. in inch measures. When I sometimes bring my timber to be cut to our local sawmill, I specify 3/4 inch or one inch boards to be made out of it, although they will be measured as 20 or 25 mm boards. By the way, how come that in this mailing list everybody speaks in inches - you were writing about the metric revolution? Peter Peter, I was all on that hay ride for as long as it lasted. But when the gas stations that first put in pumps that measured liters made note that their monthly usage pumped into the customers tanks dropped to 10% because folks would just drive on down the street where they could buy gas by the gallon, a unit they had used all their lives, that effect brought the metric conversion of the US to a screeching halt. The rest of the system did go metric, but that today is entirely the effect of all the manufacturing having been exported. Had they put dual displays in the gas pumps for a few years, so folks could see at a glance what they were paying, they might have been able to let the gallons displays gradually fail, but some numbed nuts bean counter apparently wouldn't consider that idea. Instead, we took very careful aim and shot ourselves in both feet. I suspect real estate was also to be a holdout, hell, nobody around here has a clue what a hectar is, not even me. Dave schrieb: I was in engineering college from 76 to 81 and remember some discussion about this. Fortunately there was not too much to discuss as they had already decided that SI was the way to go and we had recently selected new books. At the same time the metric revolution was in full swing and they were changing out all of their machine tools in the school shop so they would all be metric. They were removing manual machines that were setup in inches and replacing them with machines setup in millimeters. Many of the machines were old so I was happy to see them go and be replaced with new machines. The school was very unique in that they encouraged students to use the machines and the facilities after hours. They had a shop supervisor who was paid to stay late most weekday nights. Even the garage was available, so we could put our cars on the lifts to do repairs and modifications. When I wasn't chasing girls, I lived at school. :-) Dave - --- -- Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users Cheers, Gene -- Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users Cheers, Gene -- There are four
Re: [Emc-users] Brushless Servo Selection?
On Saturday, June 16, 2012 06:46:59 PM andy pugh did opine: On 16 June 2012 18:48, Dave e...@dc9.tzo.com wrote: I suspect real estate was also to be a holdout, hell, nobody around here has a clue what a hectar is, not even me. I think that Hectars are english also, as well as fathoms, etc. No, the Hectare is metric. An Are is an area 1km x 1km. A Hectare is 1/100 of that. So, a hectare is the area of a square 100m on a side. (1 million square metres to the Are, 10,000m^2 to the hectare.) I hope you aren't having a snap quiz on this tomorrow. Cause I likely won't remember it even that long. :( Cheers, Gene -- There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order. -Ed Howdershelt (Author) My web page: http://coyoteden.dyndns-free.com:85/gene Q: How many IBM 370's does it take to execute a job? A: Four, three to hold it down, and one to rip its head off. -- Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Brushless Servo Selection?
2012/6/13 Todd Zuercher to...@pgrahamdunn.com: I was thinking of picking up some AMC servo drives off ebay (BE12A6 drives seem to be cheep and plentiful there). Mesa 8i20 is cheaper, do not know about Pico drives. And paired with KL34BLS-98 ($134/pcs) servo motor it should be a good match: motor has peak current of 33A (and more than 4Nm torque there): http://kelinginc.net/34BLMotor.pdf The drive will handle up to 30A. What do others think of this combination? I was thinking about using them this way. Unfortunately it requires relatively larger power supply with higher current output. OTOH I suspect that commanded acceleration limits will have impact on how much torque is drawn from motor and thus how much current will it need. But that is just my own speculation... What would be a good motor for this and where to buy them? (Max RPM will be less than 1500 without changing gearing, with 1000 being more realistic.) I think that with servos You can easily expect much higher RPM. That Keling, for example, is rated for 3000 RPM. How high of a resolution encoder will I need? I think that generally it would be - the more resolution, the easier tuning and better positional accuracy. The card that counts those pulses is the limiting factor. If the motor can do 3000 RPM = 50 rps, then 1024 cpr encoder will give 4096 ppr = 204800 pps. That is not even close to those few MHz counting rates I have seen for FPGA cards. Short of cobbling together all this stuff for a closed loop system, I am also considering buying a 4 axis servo system from DMM-Tech (costs about $1700) and running Linuxcnc open loop. (probably still use the 5i25 for hardware step generation). And for LinuxCNC You still would have the same open-loop step-dir system... IMHO doing it that way loses at least 75% of the reason, why would one better use servos instead of steppers. 1700$? 4 Keling motors would be 536 $, 4 8i20s would be 960 $ = 1496 $ total... Add the cost of wiring and it would be somewhere there. The whole difference is in the degree of control You have. -- Viesturs If you can't fix it, you don't own it. http://www.ifixit.com/Manifesto -- Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Brushless Servo Selection?
On 15 June 2012 06:58, Viesturs Lācis viesturs.la...@gmail.com wrote: Unfortunately it requires relatively larger power supply with higher current output. This is a problem with motors like the Keling ones, with a 48V rated voltage. It is far simpler to make a 300V PSU than a 48V one. Simply rectifying mains voltage into a big capacitor makes a PSU that the 8i20 is happy with. Those Keling motors have a 500V / 1 min rating. I don't know if that meas that they can run indefinitley on a 300V PWM (with a 48V average or not). In the US I suppose a rectified-mains PSU would be around 150V which sounds more reasonable. (only 3x rated voltage, and it is conventional to run steppers at that sort of overvoltage) -- atp If you can't fix it, you don't own it. http://www.ifixit.com/Manifesto -- Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Brushless Servo Selection?
That is what I was thinking, the existing motors are quite old and are probably not as strong as they should be either, so if I am buying new drives and motors anyway, I thought switching to servos would be a good idea, especially since I would need to get some sort of hardware step generation to make use of a microstepping drive. Todd Zuercher P. Graham Dunn Inc. 630 Henry Street Dalton, Ohio 44618 Phone: (330)828-2105ext. 2031 -- P. Graham Dunn Phone: 330-828-2105 E-mail: to...@pgrahamdunn.com 630 Henry St. Dalton, OH 44618 www.pgrahamdunn.com -Original Message- From: Jon Elson [mailto:el...@pico-systems.com] Sent: Thursday, June 14, 2012 10:33 PM To: Enhanced Machine Controller (EMC) Subject: Re: [Emc-users] Brushless Servo Selection? cogoman wrote: 450 Oz-in. steppers are pretty hefty devices. I followed the link to the Keling website, and the heftiest motor they listed was a maximum of 6.3N.m, which I assume (correct me if I'm wrong) means Newton-Meters. The conversion calculator I used gave me 56 inch pounds, a little more than a tenth of the torque your steppers should be able to put out. If you get outright stalls with 450 inch pounds, you will more often get outright stalls with 56 inch pounds. If you are missing steps, it's probably not the motors' faults. Something else is probably at work here. Thats inch-POUNDS! 16 times inch-Ounces. 56 In-Lb is 896 Oz-In, so you have made a mistake. Also, steppers, ESPECIALLY with non-microstepping drives, are susceptible to timing variations and resonance issues. If you used a hardware step pulse generator and microstepping drives such as the Gecko 201 or 203 drive, you probably would get rid of the errors. At 1000 RPM, all reasonable steppers have lost significant torque from their holding torque rating. But, for peace of mind, and since you would need to replace the drives anyway to go with microstepping ones, you might as well go the servo route. It isn't that much more expensive. Jon -- Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Brushless Servo Selection?
On Fri, 2012-06-15 at 10:53 +0100, andy pugh wrote: On 15 June 2012 06:58, Viesturs Lācis viesturs.la...@gmail.com wrote: Unfortunately it requires relatively larger power supply with higher current output. This is a problem with motors like the Keling ones, with a 48V rated voltage. It is far simpler to make a 300V PSU than a 48V one. Simply rectifying mains voltage into a big capacitor makes a PSU that the 8i20 is happy with. Those Keling motors have a 500V / 1 min rating. I don't know if that meas that they can run indefinitley on a 300V PWM (with a 48V average or not). In the US I suppose a rectified-mains PSU would be around 150V which sounds more reasonable. (only 3x rated voltage, and it is conventional to run steppers at that sort of overvoltage) 48 Volts or rather -48 Volts DC is common for telephone equipment, so there may be cheap supplies available, if one knows where to look. Building an Antek supply shouldn't be too expensive, but I haven't checked prices recently. http://www.antekinc.com/index.php http://www.antekinc.com/gview.php One could make a transformer for the needed voltage, like these guys did. http://mackys.livejournal.com/838591.html Brushed motors (and drives) might be cheaper and universal motors are usually wound for mains voltage. If they can be modified for permanent magnets, universal motors could be handy. http://www.supermagnetman.net/index.php?cPath=37page=3 For most of us, brushes wear well enough to not be a maintenance problem. Scrap yards should have a large supply of vacuum cleaner motors from people that don't know how to replace a rubber belt. Another thing I haven't had time to look into is using a Delon doubler when one needs higher voltage than what is at hand. http://en.wikipedia.org/wiki/File:Bridge_voltage_doubler.svg http://en.wikipedia.org/wiki/Voltage_doubler -- Kirk Wallace http://www.wallacecompany.com/machine_shop/ http://www.wallacecompany.com/E45/index.html California, USA -- Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Brushless Servo Selection?
2012/6/15 andy pugh bodge...@gmail.com: On 15 June 2012 06:58, Viesturs Lācis viesturs.la...@gmail.com wrote: Unfortunately it requires relatively larger power supply with higher current output. This is a problem with motors like the Keling ones, with a 48V rated voltage. It is far simpler to make a 300V PSU than a 48V one. Simply rectifying mains voltage into a big capacitor makes a PSU that the 8i20 is happy with. Yes, I even have servos with 330V rated voltage, but they are too small current-wise for 8i20. Those Keling motors have a 500V / 1 min rating. I don't know if that meas that they can run indefinitley on a 300V PWM (with a 48V average or not). In the US I suppose a rectified-mains PSU would be around 150V which sounds more reasonable. Hmm, this sounds tempting, I can get 1 kW transformer not very expensive with something like 42 VAC output, rectifying that will give something close to 60 VDC... What are the risks, when brushless servos are ran on overvoltage supply? Will they just be warming, which I think is tolerable or is it a nice way to damage them? 3x rated voltage, and it is conventional to run steppers at that sort of overvoltage Those Nema 23 steppers that I have used are rated at 5,46 VDC for with windings connected in series for bipolar drive, I am running them with 28 VDC in one machine and 48 VDC in welding robot, so that is getting close to 10x overvoltage. But what about brushless servos? Has anyone tried that and gained some experience to share? -- Viesturs If you can't fix it, you don't own it. http://www.ifixit.com/Manifesto -- Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Brushless Servo Selection?
Am 15.06.2012 19:58, schrieb Viesturs Lācis: 2012/6/15 Kirk Wallace kwall...@wallacecompany.com: Building an Antek supply shouldn't be too expensive, but I haven't checked prices recently. http://www.antekinc.com/index.php http://www.antekinc.com/gview.php Thanks for the links! 155$ is little more that I would like, especially if it is a shipment from US - add 22% VAT and also shipping cost... But I still got interested to find out, so I looked at this one: http://www.antekinc.com/details.php?p=146 It is rated for 23,4 A and has 4 outputs. A noob question: Is it meant to be able to handle 23,4 A on each of the 4 outputs at the same time? The datasheet shows that it has two 32V and one 18V and one 12V output (Makes in total 4). On each of the 32V lines you can have up to 23.4A and both other 2A. Ciao, Rainer -- Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Brushless Servo Selection?
On 15 June 2012 18:40, Kirk Wallace kwall...@wallacecompany.com wrote: Another thing I haven't had time to look into is using a Delon doubler when one needs higher voltage than what is at hand. http://en.wikipedia.org/wiki/File:Bridge_voltage_doubler.svg http://en.wikipedia.org/wiki/Voltage_doubler Yes, I built a doubler (the aim was to connect it to an Arduino and IRAMS module to make a step-up 3-phase fixed-frequency drive to run the motor in my milling machine. I looked at the dot-board in front of me, with 730V DC on it and got scared, and didn't pursue the idea any further. -- atp If you can't fix it, you don't own it. http://www.ifixit.com/Manifesto -- Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Brushless Servo Selection?
On 06/14/2012 10:33 PM, Jon Elson wrote: Thats inch-POUNDS! 16 times inch-Ounces. 56 In-Lb is 896 Oz-In, so you have made a mistake. Also, steppers, ESPECIALLY Thanks. I don't have an intuitive feeling for N-m measures, so for quite a while I have been making this mistake in my head. I had wondered why the motors Keling sells were so popular, but so weak. Now I know better. 8-) -- Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Brushless Servo Selection?
On 15 June 2012 23:40, cogoman cogo...@optimum.net wrote: Thanks. I don't have an intuitive feeling for N-m measures, As a comparison, the triple stack NEMA 23 steppers are up to 3Nm. -- atp If you can't fix it, you don't own it. http://www.ifixit.com/Manifesto -- Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Brushless Servo Selection?
There are about 1.3 Nm to a ft-lb. N. Christopher Perry On Jun 15, 2012, at 18:40, cogoman cogo...@optimum.net wrote: On 06/14/2012 10:33 PM, Jon Elson wrote: Thats inch-POUNDS! 16 times inch-Ounces. 56 In-Lb is 896 Oz-In, so you have made a mistake. Also, steppers, ESPECIALLY Thanks. I don't have an intuitive feeling for N-m measures, so for quite a while I have been making this mistake in my head. I had wondered why the motors Keling sells were so popular, but so weak. Now I know better. 8-) -- Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users -- Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Brushless Servo Selection?
On 16 June 2012 00:37, N. Christopher Perry n_christopher_pe...@me.com wrote: There are about 1.3 Nm to a ft-lb. Which would reduce confusion no end, except motor manufacturers want bigger numbers, so like to use oz-inch in the US. There was a similar tendency in the metric world, but it seems to have passed. You do occasionally see motors with peculiar units, my dad has one with (I think) kilo-dyne-metres on the rating plate. (that's about 100 x Nm, ie 1 kdm = 0.01Nm) -- atp If you can't fix it, you don't own it. http://www.ifixit.com/Manifesto -- Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Brushless Servo Selection?
On 15.06.12 10:40, Kirk Wallace wrote: On Fri, 2012-06-15 at 10:53 +0100, andy pugh wrote: This is a problem with motors like the Keling ones, with a 48V rated voltage. It is far simpler to make a 300V PSU than a 48V one. Simply rectifying mains voltage into a big capacitor makes a PSU that the 8i20 is happy with. ... 48 Volts or rather -48 Volts DC is common for telephone equipment, so there may be cheap supplies available, if one knows where to look. Have to concur, and yes, being in the right place at the right time is what secured one for me. There is a bonus though, voltage-wise. The -48 Volts DC in telephone exchanges comes from big battery banks, so the power supplies are usually hefty battery chargers, and will put out at least 60v to boost charge the batteries. The small one (2x2x1 ft) I collared does 65v (Boost), 54v (Float2), and 52.8v (Float1) at 20A. The only thing is there won't be filter caps in there, I expect. The SMPS designs produced by the hardware-only team, during my several decades in telecoms transmission systems design, had to cope with the 65v for a limited time, and the float voltage indefinitely. I don't know how hot the charger would get after an extended time on Boost at 20A, e.g. if it were used for a 1.3 kW spindle supply. Erik -- Wisdom is one of the few things that looks bigger the further away it is. - Terry Pratchett, _Witches Abroad_ -- Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
[Emc-users] Brushless Servo Selection?
I am thinking about trying to upgrade some old routers from steppers to servos. I am seeking advice on a good and inexpensive BLDC motor to use. The steppers on them now are NEMA 34 with a 3/8 shaft, rated at 7amp and 450 oz-in. and are half stepping from an old Anaheim Automation unipolar bi-level drive. We are tired of lost and missed steps not to mention outright stalls ruining pieces. I was thinking of picking up some AMC servo drives off ebay (BE12A6 drives seem to be cheep and plentiful there). And run about a 400W motor of some sort. I think I would like to use a Mesa 5i25 for controlling it all (is that a good choice?). What daughter card(s) for the 5i25 would be best? (I will need 4 axes XYZW) What would be a good motor for this and where to buy them? (Max RPM will be less than 1500 without changing gearing, with 1000 being more realistic.) How high of a resolution encoder will I need? Short of cobbling together all this stuff for a closed loop system, I am also considering buying a 4 axis servo system from DMM-Tech (costs about $1700) and running Linuxcnc open loop. (probably still use the 5i25 for hardware step generation). Todd Zuercher P. Graham Dunn Inc. http://www.pgrahamdunn.com/index.php 630 Henry Street Dalton, Ohio 44618 Phone: (330)828-2105ext. 2031 -- P. Graham Dunn Phone: 330-828-2105 E-mail: to...@pgrahamdunn.com 630 Henry St. Dalton, OH 44618 www.pgrahamdunn.com -- Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Brushless Servo Selection?
On 13 June 2012 16:48, Todd Zuercher to...@pgrahamdunn.com wrote: I was thinking of picking up some AMC servo drives off ebay (BE12A6 drives seem to be cheep and plentiful there). And run about a 400W motor of some sort. I think I would like to use a Mesa 5i25 for controlling it all (is that a good choice?). Both Pico and Mesa do brushless motor drives that integrate well with their controller cards. That probably makes more sense than buying a smart drive and ignoring the smartness. Mesa have a bit of a gap between the 250W 7i39 (which connects to the 50-way header on the 5i20, 5i23, 5i22 or 7i43 boards) and the 8i20 (2.2kW) which connects via Smart-serial. You can connect 2x 7i39 to each connector on a 5i23, for example, for a total of 6 motors. A 5i25 with the correct firmware could control 16 8i20 drives. The Pico brushless servo amp is also a bit oversized for the motors you are suggesting (120V, 20A), but is somewhat cheaper than the Mesa 8i20. Keling seem to have a fair range of motors in a directly compatible size to your existing steppers: http://www.kelinginc.net/DCBrushlessMotor.html There is a HAL component that can handle any combination of motor output and amplifier input. -- atp If you can't fix it, you don't own it. http://www.ifixit.com/Manifesto -- Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Brushless Servo Selection?
cogoman wrote: 450 Oz-in. steppers are pretty hefty devices. I followed the link to the Keling website, and the heftiest motor they listed was a maximum of 6.3N.m, which I assume (correct me if I'm wrong) means Newton-Meters. The conversion calculator I used gave me 56 inch pounds, a little more than a tenth of the torque your steppers should be able to put out. If you get outright stalls with 450 inch pounds, you will more often get outright stalls with 56 inch pounds. If you are missing steps, it's probably not the motors' faults. Something else is probably at work here. Thats inch-POUNDS! 16 times inch-Ounces. 56 In-Lb is 896 Oz-In, so you have made a mistake. Also, steppers, ESPECIALLY with non-microstepping drives, are susceptible to timing variations and resonance issues. If you used a hardware step pulse generator and microstepping drives such as the Gecko 201 or 203 drive, you probably would get rid of the errors. At 1000 RPM, all reasonable steppers have lost significant torque from their holding torque rating. But, for peace of mind, and since you would need to replace the drives anyway to go with microstepping ones, you might as well go the servo route. It isn't that much more expensive. Jon -- Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
