Re: [Emc-users] Closed loop stepping system
On 13 April 2013 23:32, Gene Heskett ghesk...@wdtv.com wrote: Old but properly made: http://www.ebay.co.uk/itm/Harrison-Milling-Machine-Vertical-attachment-and-clutch-/121092566051 Gentlemen, I recently bought a machine similar to that one, at scrap value. The rubber bellows for the knee screw is replaced in the picture. http://forumbilder.se/CDVO4/fras It has no power feed whatsoever but is not much worn and feels very sound. It is meant to be converted to LinuxCNC as a hobby project. I have not made anything this big before, wondering what drive torque on the feed screws to aim for? -- Precog is a next-generation analytics platform capable of advanced analytics on semi-structured data. The platform includes APIs for building apps and a phenomenal toolset for data science. Developers can use our toolset for easy data analysis visualization. Get a free account! http://www2.precog.com/precogplatform/slashdotnewsletter ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Closed loop stepping system
On 14 April 2013 11:20, Lars Andersson l...@larsandersson.com wrote: http://forumbilder.se/CDVO4/fras It has no power feed whatsoever but is not much worn and feels very sound. It is meant to be converted to LinuxCNC as a hobby project. I have not made anything this big before, wondering what drive torque on the feed screws to aim for? I am using 750W servos with a 2Nm (7Nm peak) rating, with a 4:1 belt ratio, and it seems to be about right. I don't think I would want to go any lower on the Z, though it is rather more than necessary on the Y. I had to convert the Z to ball screw, the torque was inadequate with the original leadscrew. So if you want to keep the Z as it is, then you would need more. I went for a rotating-nut arrangement on the Z to keep the motor inside the machine. It isn't clear if you have access to that area in yours. -- atp If you can't fix it, you don't own it. http://www.ifixit.com/Manifesto -- Precog is a next-generation analytics platform capable of advanced analytics on semi-structured data. The platform includes APIs for building apps and a phenomenal toolset for data science. Developers can use our toolset for easy data analysis visualization. Get a free account! http://www2.precog.com/precogplatform/slashdotnewsletter ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Closed loop stepping system
i used 1600 oz in steppers pn my mill and am looking for more but still need ballscrews and i want to try some way friction reduction. i get 60 ipm wuth a @200 lb table, i havent powered the knee yet just the spindle head i will need ballscrew for the z and am planning to coumterbalace the knee . my drives will handle 80 volts and im currently at 48 i plan to step this up soon On Sun, Apr 14, 2013 at 6:20 AM, Lars Andersson l...@larsandersson.comwrote: On 13 April 2013 23:32, Gene Heskett ghesk...@wdtv.com wrote: Old but properly made: http://www.ebay.co.uk/itm/Harrison-Milling-Machine-Vertical-attachment-and-clutch-/121092566051 Gentlemen, I recently bought a machine similar to that one, at scrap value. The rubber bellows for the knee screw is replaced in the picture. http://forumbilder.se/CDVO4/fras It has no power feed whatsoever but is not much worn and feels very sound. It is meant to be converted to LinuxCNC as a hobby project. I have not made anything this big before, wondering what drive torque on the feed screws to aim for? -- Precog is a next-generation analytics platform capable of advanced analytics on semi-structured data. The platform includes APIs for building apps and a phenomenal toolset for data science. Developers can use our toolset for easy data analysis visualization. Get a free account! http://www2.precog.com/precogplatform/slashdotnewsletter ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users -- jeremy youngs -- Precog is a next-generation analytics platform capable of advanced analytics on semi-structured data. The platform includes APIs for building apps and a phenomenal toolset for data science. Developers can use our toolset for easy data analysis visualization. Get a free account! http://www2.precog.com/precogplatform/slashdotnewsletter ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Closed loop stepping system
On 13 April 2013 04:11, Jon Elson el...@pico-systems.com wrote: On my mini-mill, I mounted the spindle encoder outside the head, see the last picture here : http://pico-systems.com/minimill.html An alternative: https://plus.google.com/photos/108164504656404380542/albums/5747722155741347649/5866287005551819154?banner=pwa -- atp If you can't fix it, you don't own it. http://www.ifixit.com/Manifesto -- Precog is a next-generation analytics platform capable of advanced analytics on semi-structured data. The platform includes APIs for building apps and a phenomenal toolset for data science. Developers can use our toolset for easy data analysis visualization. Get a free account! http://www2.precog.com/precogplatform/slashdotnewsletter ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Closed loop stepping system
On Saturday 13 April 2013 09:59:47 andy pugh did opine: On 13 April 2013 04:11, Jon Elson el...@pico-systems.com wrote: On my mini-mill, I mounted the spindle encoder outside the head, see the last picture here : http://pico-systems.com/minimill.html An alternative: https://plus.google.com/photos/108164504656404380542/albums/574772215574 1347649/5866287005551819154?banner=pwa The bearing nut that is retaining that disk in the same manner I did use to put one on the lathe, is below those nylon gears in the micro head. The amount of shaft sticking up isn't sufficient to allow anything above it. The draw bolts shoulder bottom is actually about 3/16 below the top of the gearbox cover. The nose of the spindle sticking out of the bottom is only a fat CM long, and has the 6mm hole pair for sticking a tommy bar in to hold it while the draw bolt is tightened or loosened in it, so theres little if any usable room there either. All of the ~10 CM above the spindles top bearing is occupied by the two drive gears, and the shift gears on their countershaft occupy the space between them. About the only way would be an extension, pin locked to the spindle, to bring it above the upper cover. That would involve making new draw bolts another inch longer. Which wouldn't be a bad idea as the #2 collets I have now are bored an oversized 3/8-18, and the bolt I got from Chris that fits them, is probably a good 10 thou undersized. I am amazed that I haven't stripped the 1/4 collet, its very poorly fitted and to reliably hold a 1/4 mill, it has to be pulled at least 3/4 turn past tight. The only OEM #2 spud that actually fits that spindle is the one on the drill chuck that came with it. That uses the OEM metric draw bolt, which goes from loose to plenty tight in about 30 degrees rotation of the draw bolt. IOW, all of the US made after-market stuff is very sloppily built. But if tightened enough, it gets the job done. All the more reason to go get a G0704. I've put enough sheckles in this sows ear of a mill. 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 is up! My views http://www.armchairpatriot.com/What%20Has%20America%20Become.shtml Men are those creatures with two legs and eight hands. -- Jayne Mansfield A pen in the hand of this president is far more dangerous than a gun in the hands of 200 million law-abiding citizens. -- Precog is a next-generation analytics platform capable of advanced analytics on semi-structured data. The platform includes APIs for building apps and a phenomenal toolset for data science. Developers can use our toolset for easy data analysis visualization. Get a free account! http://www2.precog.com/precogplatform/slashdotnewsletter ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Closed loop stepping system
On 13 April 2013 15:33, Gene Heskett ghesk...@wdtv.com wrote: The bearing nut that is retaining that disk in the same manner I did use to put one on the lathe, is below those nylon gears in the micro head. The amount of shaft sticking up isn't sufficient to allow anything above it. The draw bolts shoulder bottom is actually about 3/16 below the top of the gearbox cover. This is the case with mine too, that encoder disc is actually a very thin-walled top-hat. All the more reason to go get a G0704. I've put enough sheckles in this sows ear of a mill. I reached the same conclusion. But I decided if I was going to upgrade I was going to get something made in Yorkshire, not China. -- atp If you can't fix it, you don't own it. http://www.ifixit.com/Manifesto -- Precog is a next-generation analytics platform capable of advanced analytics on semi-structured data. The platform includes APIs for building apps and a phenomenal toolset for data science. Developers can use our toolset for easy data analysis visualization. Get a free account! http://www2.precog.com/precogplatform/slashdotnewsletter ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Closed loop stepping system
I reached the same conclusion. But I decided if I was going to upgrade I was going to get something made in Yorkshire, not China. me likes me some empirialism :) thats why i converted a 1947 matson, but it is large :) On Sat, Apr 13, 2013 at 4:40 PM, andy pugh bodge...@gmail.com wrote: On 13 April 2013 15:33, Gene Heskett ghesk...@wdtv.com wrote: The bearing nut that is retaining that disk in the same manner I did use to put one on the lathe, is below those nylon gears in the micro head. The amount of shaft sticking up isn't sufficient to allow anything above it. The draw bolts shoulder bottom is actually about 3/16 below the top of the gearbox cover. This is the case with mine too, that encoder disc is actually a very thin-walled top-hat. All the more reason to go get a G0704. I've put enough sheckles in this sows ear of a mill. I reached the same conclusion. But I decided if I was going to upgrade I was going to get something made in Yorkshire, not China. -- atp If you can't fix it, you don't own it. http://www.ifixit.com/Manifesto -- Precog is a next-generation analytics platform capable of advanced analytics on semi-structured data. The platform includes APIs for building apps and a phenomenal toolset for data science. Developers can use our toolset for easy data analysis visualization. Get a free account! http://www2.precog.com/precogplatform/slashdotnewsletter ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users -- jeremy youngs -- Precog is a next-generation analytics platform capable of advanced analytics on semi-structured data. The platform includes APIs for building apps and a phenomenal toolset for data science. Developers can use our toolset for easy data analysis visualization. Get a free account! http://www2.precog.com/precogplatform/slashdotnewsletter ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Closed loop stepping system
Gene Heskett wrote: Of which, this toy has none. All nylon. For your encoder hanging outboard, is is a problem to access the drawbolt for tool changing? Not at all! You do have to be careful with wrenches not to not break the pulleys, but there is a big preload nut for the spindle bearings that sits above the top of the head, I just glued a bored-out pulley to it. That turned out to be too fragile, so I put a piece of PC board stock under the nut and glued the pulley to that, figuring a glass-epoxy board would be good for adhering more epoxy to, and it has held for years. So, the pulley is close, but not actually in the way at all, at least on my machine, which I think is identical to the X2. Jon -- Precog is a next-generation analytics platform capable of advanced analytics on semi-structured data. The platform includes APIs for building apps and a phenomenal toolset for data science. Developers can use our toolset for easy data analysis visualization. Get a free account! http://www2.precog.com/precogplatform/slashdotnewsletter ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Closed loop stepping system
On Saturday 13 April 2013 18:31:16 andy pugh did opine: On 13 April 2013 15:33, Gene Heskett ghesk...@wdtv.com wrote: The bearing nut that is retaining that disk in the same manner I did use to put one on the lathe, is below those nylon gears in the micro head. The amount of shaft sticking up isn't sufficient to allow anything above it. The draw bolts shoulder bottom is actually about 3/16 below the top of the gearbox cover. This is the case with mine too, that encoder disc is actually a very thin-walled top-hat. I did not see that in the pix. I'll go back and look again. All the more reason to go get a G0704. I've put enough sheckles in this sows ear of a mill. I reached the same conclusion. But I decided if I was going to upgrade I was going to get something made in Yorkshire, not China. Link to candidate? 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 is up! My views http://www.armchairpatriot.com/What%20Has%20America%20Become.shtml I want to see people using Perl to glue things together creatively, not just technically but also socially. -- Larry Wall in 199702111730.jaa28...@wall.org A pen in the hand of this president is far more dangerous than a gun in the hands of 200 million law-abiding citizens. -- Precog is a next-generation analytics platform capable of advanced analytics on semi-structured data. The platform includes APIs for building apps and a phenomenal toolset for data science. Developers can use our toolset for easy data analysis visualization. Get a free account! http://www2.precog.com/precogplatform/slashdotnewsletter ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Closed loop stepping system
On Saturday 13 April 2013 18:34:55 Jon Elson did opine: Gene Heskett wrote: Of which, this toy has none. All nylon. For your encoder hanging outboard, is is a problem to access the drawbolt for tool changing? Not at all! You do have to be careful with wrenches not to not break the pulleys, but there is a big preload nut for the spindle bearings that sits above the top of the head, I just glued a bored-out pulley to it. That turned out to be too fragile, so I put a piece of PC board stock under the nut and glued the pulley to that, figuring a glass-epoxy board would be good for adhering more epoxy to, and it has held for years. So, the pulley is close, but not actually in the way at all, at least on my machine, which I think is identical to the X2. Jon The X1 (Micro-Mill) however, is a different critter. -- Precog is a next-generation analytics platform capable of advanced analytics on semi-structured data. The platform includes APIs for building apps and a phenomenal toolset for data science. Developers can use our toolset for easy data analysis visualization. Get a free account! http://www2.precog.com/precogplatform/slashdotnewsletter ___ 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 is up! My views http://www.armchairpatriot.com/What%20Has%20America%20Become.shtml I want to see people using Perl to glue things together creatively, not just technically but also socially. -- Larry Wall in 199702111730.jaa28...@wall.org A pen in the hand of this president is far more dangerous than a gun in the hands of 200 million law-abiding citizens. -- Precog is a next-generation analytics platform capable of advanced analytics on semi-structured data. The platform includes APIs for building apps and a phenomenal toolset for data science. Developers can use our toolset for easy data analysis visualization. Get a free account! http://www2.precog.com/precogplatform/slashdotnewsletter ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Closed loop stepping system
Gene Heskett wrote: Humm, now that you mention that, I read something similar on the net a few years agom from somebody at Gecko. Could have been the same person I'd have to assume. Mariss is the designer and owner of Gecko, and an awesome engineer. Which is 17 amps more than my lathe spindle has. I wonder if that could make me a REAL variable speed spindle. This one runs out of steam when the steel is above 5/8 in diameter. Supposedly a 250 watt motor, older 7zx12. I'd like to take it up to shaving 1.75 to 2 stock. Could that reverse w/o needing to toggle a 4pdt relay? Yes. I use one of my servo amps to run the spindle of my minimill, and it does reversing under computer control when rigid tapping. If you have some kind of spindle speed sensing or spindle encoder, then you could have closed- loop spindle speed control. Jon -- Precog is a next-generation analytics platform capable of advanced analytics on semi-structured data. The platform includes APIs for building apps and a phenomenal toolset for data science. Developers can use our toolset for easy data analysis visualization. Get a free account! http://www2.precog.com/precogplatform/slashdotnewsletter ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Closed loop stepping system
On Friday 12 April 2013 13:36:59 Jon Elson did opine: Gene Heskett wrote: Humm, now that you mention that, I read something similar on the net a few years agom from somebody at Gecko. Could have been the same person I'd have to assume. Mariss is the designer and owner of Gecko, and an awesome engineer. Which is 17 amps more than my lathe spindle has. I wonder if that could make me a REAL variable speed spindle. This one runs out of steam when the steel is above 5/8 in diameter. Supposedly a 250 watt motor, older 7zx12. I'd like to take it up to shaving 1.75 to 2 stock. Could that reverse w/o needing to toggle a 4pdt relay? Yes. I use one of my servo amps to run the spindle of my minimill, and it does reversing under computer control when rigid tapping. If you have some kind of spindle speed sensing or spindle encoder, then you could have closed- loop spindle speed control. Jon I don't have that on the mill, very limited space to install, and a very dirty environment inside the gear case. Lots of flying grease. Which doesn't help, and may hinder because grease deteriorates some plastics, I've lost the hubs out of 2 of those nylon gears now. Just one of the reasons why that mill may yet get replaced to a grizzly go704. -- Precog is a next-generation analytics platform capable of advanced analytics on semi-structured data. The platform includes APIs for building apps and a phenomenal toolset for data science. Developers can use our toolset for easy data analysis visualization. Get a free account! http://www2.precog.com/precogplatform/slashdotnewsletter ___ 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 is up! My views http://www.armchairpatriot.com/What%20Has%20America%20Become.shtml To Perl, or not to Perl, that is the kvetching. -- Larry Wall in 199801200310.taa11...@wall.org A pen in the hand of this president is far more dangerous than a gun in the hands of 200 million law-abiding citizens. -- Precog is a next-generation analytics platform capable of advanced analytics on semi-structured data. The platform includes APIs for building apps and a phenomenal toolset for data science. Developers can use our toolset for easy data analysis visualization. Get a free account! http://www2.precog.com/precogplatform/slashdotnewsletter ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Closed loop stepping system
On 12 April 2013 18:40, Gene Heskett ghesk...@wdtv.com wrote: I don't have that on the mill, very limited space to install, and a very dirty environment inside the gear case. Lots of flying grease. Which doesn't help, and may hinder because grease deteriorates some plastics, I've lost the hubs out of 2 of those nylon gears now. Steel replacements exist: http://www.littlemachineshop.com/products/product_view.php?ProductID=3453category= -- atp If you can't fix it, you don't own it. http://www.ifixit.com/Manifesto -- Precog is a next-generation analytics platform capable of advanced analytics on semi-structured data. The platform includes APIs for building apps and a phenomenal toolset for data science. Developers can use our toolset for easy data analysis visualization. Get a free account! http://www2.precog.com/precogplatform/slashdotnewsletter ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Closed loop stepping system
On Friday 12 April 2013 14:43:55 andy pugh did opine: On 12 April 2013 18:40, Gene Heskett ghesk...@wdtv.com wrote: I don't have that on the mill, very limited space to install, and a very dirty environment inside the gear case. Lots of flying grease. Which doesn't help, and may hinder because grease deteriorates some plastics, I've lost the hubs out of 2 of those nylon gears now. Steel replacements exist: http://www.littlemachineshop.com/products/product_view.php?ProductID=345 3category= That is for the next bigger mill, this things original carcass was the micro-mill from Harbor Freight. I have talked about that with Chris at LMS, and it for sure doesn't fit my head. Darnit. 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 is up! My views http://www.armchairpatriot.com/What%20Has%20America%20Become.shtml We cannot do everything at once, but we can do something at once. -- Calvin Coolidge A pen in the hand of this president is far more dangerous than a gun in the hands of 200 million law-abiding citizens. -- Precog is a next-generation analytics platform capable of advanced analytics on semi-structured data. The platform includes APIs for building apps and a phenomenal toolset for data science. Developers can use our toolset for easy data analysis visualization. Get a free account! http://www2.precog.com/precogplatform/slashdotnewsletter ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Closed loop stepping system
On 12 April 2013 19:45, Gene Heskett ghesk...@wdtv.com wrote: Steel replacements exist: http://www.littlemachineshop.com/products/product_view.php?ProductID=345 3category= That is for the next bigger mill, Some of us have hobbing equipment and can make gears. -- atp If you can't fix it, you don't own it. http://www.ifixit.com/Manifesto -- Precog is a next-generation analytics platform capable of advanced analytics on semi-structured data. The platform includes APIs for building apps and a phenomenal toolset for data science. Developers can use our toolset for easy data analysis visualization. Get a free account! http://www2.precog.com/precogplatform/slashdotnewsletter ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Closed loop stepping system
On Friday 12 April 2013 18:45:02 andy pugh did opine: On 12 April 2013 19:45, Gene Heskett ghesk...@wdtv.com wrote: Steel replacements exist: http://www.littlemachineshop.com/products/product_view.php?ProductID= 345 3category= That is for the next bigger mill, Some of us have hobbing equipment and can make gears. Maybe, but thats a lot of work for someone with little return no noise reduction. I've had my name on Chris's list for the belt drive 3 speed conversion, IF the guy that made them 10 years ago ever makes any more of them. OTOH, I just did my taxes today, so a G0704 might follow me home from the Grizzly store in Muncy PA before the summer gets full blown. I am hearing rumors of Dee wanting to go see her sister, near Ithaca NY which will make a good excuse to detour from Williamsport PA on over to Muncy as we go by that neck of the woods going one way or the other. At nominally 400 lbs by the time I throw in some tools, methinks the Toy might be able to handle that. 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 is up! My views http://www.armchairpatriot.com/What%20Has%20America%20Become.shtml The grave's a fine and private place, but none, I think, do there embrace. -- Andrew Marvell A pen in the hand of this president is far more dangerous than a gun in the hands of 200 million law-abiding citizens. -- Precog is a next-generation analytics platform capable of advanced analytics on semi-structured data. The platform includes APIs for building apps and a phenomenal toolset for data science. Developers can use our toolset for easy data analysis visualization. Get a free account! http://www2.precog.com/precogplatform/slashdotnewsletter ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Closed loop stepping system
On 12 April 2013 23:55, Gene Heskett ghesk...@wdtv.com wrote: Some of us have hobbing equipment and can make gears. Maybe, but thats a lot of work for someone with little return no noise reduction. I do it for fun. But you will be appalled at the noise increase. Belt drive probably is the way to go. Did I mention I can make belt pulleys too? http://youtu.be/ltmZrDrt6pQ -- atp If you can't fix it, you don't own it. http://www.ifixit.com/Manifesto -- Precog is a next-generation analytics platform capable of advanced analytics on semi-structured data. The platform includes APIs for building apps and a phenomenal toolset for data science. Developers can use our toolset for easy data analysis visualization. Get a free account! http://www2.precog.com/precogplatform/slashdotnewsletter ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Closed loop stepping system
On Friday 12 April 2013 21:26:22 andy pugh did opine: On 12 April 2013 23:55, Gene Heskett ghesk...@wdtv.com wrote: Some of us have hobbing equipment and can make gears. Maybe, but thats a lot of work for someone with little return no noise reduction. I do it for fun. But you will be appalled at the noise increase. Its quite tiresome to these old ears now, not just the whine, but the rattling too. Belt drive probably is the way to go. Did I mention I can make belt pulleys too? http://youtu.be/ltmZrDrt6pQ I see that. I have an A table and its tailstock, but the tooth would have to be rather laboriously formed by a ball nosed, small mill. And I would have to figure out the initial diameter needed to get x teeth per turn, which in gilmer belting, seems to be pretty critical else the belt would be obviously trying to climb out of the slot near the end of the wrap. I would probably be farther ahead just to order the pulleys, and using a 5mm center hole as a locater, machine the holes to fit the shafting. That also means a sliding mount for the motor so the belt could be flipped from pair to pair. That whole box with its sliding cluster gear setup, needs to go, its way too big now that the controller has been removed and it gets in the way of the A axis, severely restricting table movement because of that in favor of a slightly taller but much more compact direct to the spindle from the motor belted design. One with about 2x the low speed geardown available now, and the same 2x higher on the top end. And my screws are wearing out, just another reason to go get the G0704 put some real screws in it. There are other, heavier and more rigid machines available but that one is by far the most operating volume per dollar spent. 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 is up! My views http://www.armchairpatriot.com/What%20Has%20America%20Become.shtml University politics are vicious precisely because the stakes are so small. -- C. P. Snow A pen in the hand of this president is far more dangerous than a gun in the hands of 200 million law-abiding citizens. -- Precog is a next-generation analytics platform capable of advanced analytics on semi-structured data. The platform includes APIs for building apps and a phenomenal toolset for data science. Developers can use our toolset for easy data analysis visualization. Get a free account! http://www2.precog.com/precogplatform/slashdotnewsletter ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Closed loop stepping system
Gene Heskett wrote: I don't have that on the mill, very limited space to install, and a very dirty environment inside the gear case. Lots of flying grease. Which doesn't help, and may hinder because grease deteriorates some plastics, I've lost the hubs out of 2 of those nylon gears now. Just one of the reasons why that mill may yet get replaced to a grizzly go704. Well, I used some gear tooth sensors that are made to go inside a car transmission, so they are heat and lube-resistant. Of course, they need ferrous gears. On my mini-mill, I mounted the spindle encoder outside the head, see the last picture here : http://pico-systems.com/minimill.html As for the Bridgeport encoder contraption, see http://pico-systems.com/bridge_spindle.html for a description of the gear tooth sensors and how I installed them. Jon -- Precog is a next-generation analytics platform capable of advanced analytics on semi-structured data. The platform includes APIs for building apps and a phenomenal toolset for data science. Developers can use our toolset for easy data analysis visualization. Get a free account! http://www2.precog.com/precogplatform/slashdotnewsletter ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Closed loop stepping system
On Saturday 13 April 2013 00:13:15 Jon Elson did opine: Gene Heskett wrote: I don't have that on the mill, very limited space to install, and a very dirty environment inside the gear case. Lots of flying grease. Which doesn't help, and may hinder because grease deteriorates some plastics, I've lost the hubs out of 2 of those nylon gears now. Just one of the reasons why that mill may yet get replaced to a grizzly go704. Well, I used some gear tooth sensors that are made to go inside a car transmission, so they are heat and lube-resistant. Of course, they need ferrous gears. Of which, this toy has none. All nylon. For your encoder hanging outboard, is is a problem to access the drawbolt for tool changing? On my mini-mill, I mounted the spindle encoder outside the head, see the last picture here : http://pico-systems.com/minimill.html As for the Bridgeport encoder contraption, see http://pico-systems.com/bridge_spindle.html for a description of the gear tooth sensors and how I installed them. Jon 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 is up! My views http://www.armchairpatriot.com/What%20Has%20America%20Become.shtml tmps_base = tmps_max;/* protect our mortal string */ -- Larry Wall in stab.c from the perl source code A pen in the hand of this president is far more dangerous than a gun in the hands of 200 million law-abiding citizens. -- Precog is a next-generation analytics platform capable of advanced analytics on semi-structured data. The platform includes APIs for building apps and a phenomenal toolset for data science. Developers can use our toolset for easy data analysis visualization. Get a free account! http://www2.precog.com/precogplatform/slashdotnewsletter ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Closed loop stepping system
Search for Leadshine closed loop stepper on YouTube. Looks like some very smooth and quiet operation from steppers. -- Precog is a next-generation analytics platform capable of advanced analytics on semi-structured data. The platform includes APIs for building apps and a phenomenal toolset for data science. Developers can use our toolset for easy data analysis visualization. Get a free account! http://www2.precog.com/precogplatform/slashdotnewsletter ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Closed loop stepping system
That's nice presentation, and exactly what I'm looking for to improve my two rotary axes with steppers... Search for Leadshine closed loop stepper on YouTube. Looks like some very smooth and quiet operation from steppers. -- Precog is a next-generation analytics platform capable of advanced analytics on semi-structured data. The platform includes APIs for building apps and a phenomenal toolset for data science. Developers can use our toolset for easy data analysis visualization. Get a free account! http://www2.precog.com/precogplatform/slashdotnewsletter ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Closed loop stepping system
Thanks Gene, this has been a very enriching discussion. No plans still for the Hubles's mirror :). Cheers, Javier On Wed, Apr 10, 2013 at 7:37 PM, Gene Heskett ghesk...@wdtv.com wrote: On Wednesday 10 April 2013 13:01:29 Javier Ros did opine: This system http://www.automationtechnologiesinc .com/products-page/nema23-closed-loop-stepper-motor-system-hybrid-servo- kit/hybrid-servo-drive-kl-5080h Is apparently a stepper motor that is controlled as a brushless. Essentially a stepper is a brushless. This needs a encoder, probably one with a index pulse correctly positioned, so that the electronics can compute the switching accurately. This means, even if the control of the drive looks like a STEP DIR control, internally there are position and current loops, theoretically such a drive could offer, velocity and current control (I've not checked for the above reference). This means essentially that, the motor runs cooler, because only the required intensity is flowing in the motor, and not the maximum required intensity (the one that is controlled with the typical potentiometer in typical stepper drives). This means as well that the motor runs smoother, this must be most noticeable at low velocities, and finally that the positioning can be as precise as the encoder is. I regard of precision, note that a stepper, is not as precise as 3600/steps_per_revolution/microsteps, because microsteps don need to be equally spaced, even steps are not precise due to manufacturing (magnetic field) do not have to be equally spaced. In addition to this forces make that the motor is not centered at the center of the microstep. Let me fine tune this by pointing out that the stepper motor maker can, with access to the maps the controller uses to adjust its currents when microstepping, could be fine tuned such that at light loading, the microsteps can be pretty accurate. This of course means the motor and the controller must be calibrated to each other. That will be the makers job since few if any of us have the tools to do that, and it sure wouldn't be feasible economically for everyone to own their own stuff to do that. More just plain old comment: The noise would likely go down a bit, but since we aren't also throttling the current in many drivers (mine does after about a second of no motion, so mine only heat about 15F when idle), the motor is still going to run hot. The ideal situation would be by adjusting the overall currents to keep the motor within say 20%/microstep of the ideal microstepped position, but again this would require a high precision encoder, or some sort of magnetically detected feedback to detect the error in real time only use enough current to achieve that. But at that point, you may as well spend the money on a servo system, which may well be what this outfit is doing. Net cost will be similar. My current stepper setup, using 425oz motors on the lathe, was just under $100/axis. This is only a 252oz motor and costs USD 210/axis. I can't seem to justify the extra sheckel's for me. In comparison a brushless type encoder based drive for steeper can be as precise as the encoder, you know the actual position with the encoder position, although the position can be different of the commanded position, but you know the difference. The only limitations seem to be related to control at hih rpms, performance degrades in comparison with brushless. I would say that this is related to the higher pole count of the steeper,and the inherent dificulty to stablish intensity at high pole conmutation frecuency due to impedance, something that con be alleviated increaing voltage as much as possible.. In regard to this the error position, it can be even smaller in this brushless system because, as it runs cooler, you can allow for small duration current higher than the nominal. For a steeper you can not surpass the nominal value, not for the motor not for the electronics. Theoretically true. The motor can be banged with considerable overcurrent when it is lightly loaded and essentially exactly in position, but if half s step off or more due to heavy loading, then the rotor's magnetism could be effected, permanently damaging the motor. I've never run a system of this type, but I would love to use one of the MESA cards and brushless firmwares to test a such a setup (I'm interested in current control) if somebody with more experience thinks/knowns this is possible and not too difficult. Just using a double shaft stepper and a cheap encoder. I would love, to identify stepper cogging, and to software compensate for it. A moot point IMO when the gearing is such that 1 microstep is a fraction of a micron without resorting to a doubling of cost per axis. I haven't actually checked, as my step accuracy is the same on both axis's of the lathe, the x is a 2.5mm/turn screw, the z is 5,
Re: [Emc-users] Closed loop stepping system
Gene Heskett wrote: Somebody thinking outside the box, and making perfect sense. The only fly in the soup is the 10,000 step encoder, and servicing it at 200 rpS to get that 12,000 rpms If you run a stepper motor at 12,000 RPM, it will burn up in minutes. You can spin a typical stepper with the spindle motor, and above 1000 RPM it will get very hot with no current at all in the windings. That is all iron loss. 12,000 RPM will require insane voltages be applied to the drive, several hundred Volts. A typical stepper may generate 50 V at 1000 RPM, so that would require a 600 V supply just to equal the back EMF at 12K. Oh, but then cogoman said : the stepper motor could be designed with less steps per rev. Yes, then why make it a stepper at all? How about an 8-pole brushless servo motor? These work GREAT, used by Fanuc since the late 1980's, and now available from many sources. I make affordable servo amps for brushless motors, and have one on my minimill. You do need to get rotor position info from the motor, most small ones have Hall sensors that you connect to the servo amp. I use 500 cycle/rev encoders on mine, that is quite satisfactory. Jon -- Precog is a next-generation analytics platform capable of advanced analytics on semi-structured data. The platform includes APIs for building apps and a phenomenal toolset for data science. Developers can use our toolset for easy data analysis visualization. Get a free account! http://www2.precog.com/precogplatform/slashdotnewsletter ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Closed loop stepping system
On Thu, 11 Apr 2013, Jon Elson wrote: Date: Thu, 11 Apr 2013 11:32:55 -0500 From: Jon Elson el...@pico-systems.com Reply-To: Enhanced Machine Controller (EMC) emc-users@lists.sourceforge.net To: Enhanced Machine Controller (EMC) emc-users@lists.sourceforge.net Subject: Re: [Emc-users] Closed loop stepping system Gene Heskett wrote: Somebody thinking outside the box, and making perfect sense. The only fly in the soup is the 10,000 step encoder, and servicing it at 200 rpS to get that 12,000 rpms If you run a stepper motor at 12,000 RPM, it will burn up in minutes. You can spin a typical stepper with the spindle motor, and above 1000 RPM it will get very hot with no current at all in the windings. That is all iron loss. 12,000 RPM will require insane voltages be applied to the drive, several hundred Volts. A typical stepper may generate 50 V at 1000 RPM, so that would require a 600 V supply just to equal the back EMF at 12K. Oh, but then cogoman said : the stepper motor could be designed with less steps per rev. Yes, then why make it a stepper at all? How about an 8-pole brushless servo motor? These work GREAT, used by Fanuc since the late 1980's, and now available from many sources. I make affordable servo amps for brushless motors, and have one on my minimill. You do need to get rotor position info from the motor, most small ones have Hall sensors that you connect to the servo amp. I use 500 cycle/rev encoders on mine, that is quite satisfactory. Jon The Leadshine closed loop step motors actually do have some advantages. because of the high number of poles (50 typically), when run in step motor mode the torque vs displacement curve is much steeper than a normal brushless motor which allows a clever hack when stationary. When staionary the motor can be run in step motor mode (radial pull vs tangential pull) with reduced current. This eliminates the +- a count or so jitter that full servo systems have when stationary (especially with static load) You still have the torque vs speed limits because of the number of poles and stepmotors even run as servos are not as efficent or as high performance as normal brushless motors but in the size ranges that make sense, closed loop stepper systems are very nice. -- Precog is a next-generation analytics platform capable of advanced analytics on semi-structured data. The platform includes APIs for building apps and a phenomenal toolset for data science. Developers can use our toolset for easy data analysis visualization. Get a free account! http://www2.precog.com/precogplatform/slashdotnewsletter ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users Peter Wallace Mesa Electronics (\__/) (='.'=) This is Bunny. Copy and paste bunny into your ()_() signature to help him gain world domination. -- Precog is a next-generation analytics platform capable of advanced analytics on semi-structured data. The platform includes APIs for building apps and a phenomenal toolset for data science. Developers can use our toolset for easy data analysis visualization. Get a free account! http://www2.precog.com/precogplatform/slashdotnewsletter ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Closed loop stepping system
On Thursday 11 April 2013 22:13:10 Jon Elson did opine: Gene Heskett wrote: Somebody thinking outside the box, and making perfect sense. The only fly in the soup is the 10,000 step encoder, and servicing it at 200 rpS to get that 12,000 rpms If you run a stepper motor at 12,000 RPM, it will burn up in minutes. You can spin a typical stepper with the spindle motor, and above 1000 RPM it will get very hot with no current at all in the windings. That is all iron loss. 12,000 RPM will require insane voltages be applied to the drive, several hundred Volts. A typical stepper may generate 50 V at 1000 RPM, so that would require a 600 V supply just to equal the back EMF at 12K. And I never considered the iron loses Jon, but you are dead on. Oh, but then cogoman said : the stepper motor could be designed with less steps per rev. Yes, then why make it a stepper at all? How about an 8-pole brushless servo motor? These work GREAT, used by Fanuc since the late 1980's, and now available from many sources. I make affordable servo amps for brushless motors, and have one on my minimill. You do need to get rotor position info from the motor, most small ones have Hall sensors that you connect to the servo amp. I use 500 cycle/rev encoders on mine, that is quite satisfactory. Jon That also makes great sense as long as its economical enough to do. 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 is up! My views http://www.armchairpatriot.com/What%20Has%20America%20Become.shtml Evil isn't all bad. A pen in the hand of this president is far more dangerous than a gun in the hands of 200 million law-abiding citizens. -- Precog is a next-generation analytics platform capable of advanced analytics on semi-structured data. The platform includes APIs for building apps and a phenomenal toolset for data science. Developers can use our toolset for easy data analysis visualization. Get a free account! http://www2.precog.com/precogplatform/slashdotnewsletter ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Closed loop stepping system
Gene Heskett wrote: And I never considered the iron loses Jon, but you are dead on. Mariss Freimanis of Gecko describes some torture tests he did years ago and reported this. I make affordable servo amps for brushless motors, and have one on my minimill. You do need to get rotor position info from the motor, most small ones have Hall sensors that you connect to the servo amp. I use 500 cycle/rev encoders on mine, that is quite satisfactory. Jon That also makes great sense as long as its economical enough to do. The Gecko 201 series sells for $114, my brushless servo amp sells for $150, for 20 A at 120 V. Not vastly more expensive than a good stepper drive. Of course you need a PWM generator to run my servo amp, but then you need a hardware step generator to get full performance out of a microstepped stepper motor, too. Jon -- Precog is a next-generation analytics platform capable of advanced analytics on semi-structured data. The platform includes APIs for building apps and a phenomenal toolset for data science. Developers can use our toolset for easy data analysis visualization. Get a free account! http://www2.precog.com/precogplatform/slashdotnewsletter ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Closed loop stepping system
On Friday 12 April 2013 00:56:36 Jon Elson did opine: Gene Heskett wrote: And I never considered the iron loses Jon, but you are dead on. Mariss Freimanis of Gecko describes some torture tests he did years ago and reported this. Humm, now that you mention that, I read something similar on the net a few years agom from somebody at Gecko. Could have been the same person I'd have to assume. I make affordable servo amps for brushless motors, and have one on my minimill. You do need to get rotor position info from the motor, most small ones have Hall sensors that you connect to the servo amp. I use 500 cycle/rev encoders on mine, that is quite satisfactory. Jon That also makes great sense as long as its economical enough to do. The Gecko 201 series sells for $114, my brushless servo amp sells for $150, for 20 A at 120 V. Which is 17 amps more than my lathe spindle has. I wonder if that could make me a REAL variable speed spindle. This one runs out of steam when the steel is above 5/8 in diameter. Supposedly a 250 watt motor, older 7zx12. I'd like to take it up to shaving 1.75 to 2 stock. Could that reverse w/o needing to toggle a 4pdt relay? Not vastly more expensive than a good stepper drive. Of course you need a PWM generator to run my servo amp, but then you need a hardware step generator to get full performance out of a microstepped stepper motor, too. True, if you can find the voltage for the motors. I hate paying 150-200 for a big linear when I can cobble something up out of the surplus catalogs for 1/3rd of that. Unforch, suitable transformers seem to be getting rarer as time goes by. The gears are turning on that spindle idea though. :) Jon 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 is up! My views http://www.armchairpatriot.com/What%20Has%20America%20Become.shtml If you can, help others. If you can't, at least don't hurt others. -- the Dalai Lama A pen in the hand of this president is far more dangerous than a gun in the hands of 200 million law-abiding citizens. -- Precog is a next-generation analytics platform capable of advanced analytics on semi-structured data. The platform includes APIs for building apps and a phenomenal toolset for data science. Developers can use our toolset for easy data analysis visualization. Get a free account! http://www2.precog.com/precogplatform/slashdotnewsletter ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Closed loop stepping system
This system http://www.automationtechnologiesinc .com/products-page/nema23-closed-loop-stepper-motor-system-hybrid-servo-kit/hybrid-servo-drive-kl-5080h Is apparently a stepper motor that is controlled as a brushless. Essentially a stepper is a brushless. This needs a encoder, probably one with a index pulse correctly positioned, so that the electronics can compute the switching accurately. This means, even if the control of the drive looks like a STEP DIR control, internally there are position and current loops, theoretically such a drive could offer, velocity and current control (I've not checked for the above reference). This means essentially that, the motor runs cooler, because only the required intensity is flowing in the motor, and not the maximum required intensity (the one that is controlled with the typical potentiometer in typical stepper drives). This means as well that the motor runs smoother, this must be most noticeable at low velocities, and finally that the positioning can be as precise as the encoder is. I regard of precision, note that a stepper, is not as precise as 3600/steps_per_revolution/microsteps, because microsteps don need to be equally spaced, even steps are not precise due to manufacturing (magnetic field) do not have to be equally spaced. In addition to this forces make that the motor is not centered at the center of the microstep. In comparison a brushless type encoder based drive for steeper can be as precise as the encoder, you know the actual position with the encoder position, although the position can be different of the commanded position, but you know the difference. The only limitations seem to be related to control at hih rpms, performance degrades in comparison with brushless. I would say that this is related to the higher pole count of the steeper,and the inherent dificulty to stablish intensity at high pole conmutation frecuency due to impedance, something that con be alleviated increaing voltage as much as possible.. In regard to this the error position, it can be even smaller in this brushless system because, as it runs cooler, you can allow for small duration current higher than the nominal. For a steeper you can not surpass the nominal value, not for the motor not for the electronics. I've never run a system of this type, but I would love to use one of the MESA cards and brushless firmwares to test a such a setup (I'm interested in current control) if somebody with more experience thinks/knowns this is possible and not too difficult. Just using a double shaft stepper and a cheap encoder. I would love, to identify stepper cogging, and to software compensate for it. This said, if the proposed system works as theoretically expected, it looks to me it has a pretty reasonable price. Regard, Javier On Wed, Apr 10, 2013 at 6:45 AM, Viesturs Lācis viesturs.la...@gmail.comwrote: 2013/4/10 Tomaz T. tomaz_...@hotmail.com The whole point is that I don't have any feedback from steppers at this stage, and as I said, the cheapest solution would be to simply change the existing one with the one with closed loop future (and also drivers). So the basic idea might be to use In-Position signal (output) from stepper driver and when this goes fault, it triggers following error in linuxcnc. Could this work? So why don't You put encoders on stepper motors and link encoder position to axis.n.motor-pos-fb pin and let LinuxCNC track actual motor position and it definitely will trigger following error, once it has been reached. This way there are no fancy stepper drives and motors are required. Anyone using this stepper system from kelinginc? http://www.automationtechnologiesinc.com/products-page/nema23-closed-loop-stepper-motor-system-hybrid-servo-kit/hybrid-servo-drive-kl-5080h No tuning of feedback loop? Well, then I do not see, how does this system achieve its goal and correct for motor's position error. -- Viesturs If you can't fix it, you don't own it. http://www.ifixit.com/Manifesto -- Precog is a next-generation analytics platform capable of advanced analytics on semi-structured data. The platform includes APIs for building apps and a phenomenal toolset for data science. Developers can use our toolset for easy data analysis visualization. Get a free account! http://www2.precog.com/precogplatform/slashdotnewsletter ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users -- Precog is a next-generation analytics platform capable of advanced analytics on semi-structured data. The platform includes APIs for building apps and a phenomenal toolset for data science. Developers can use our toolset for easy data analysis visualization. Get a free account!
Re: [Emc-users] Closed loop stepping system
On 10 April 2013 12:18, Javier Ros j...@unavarra.es wrote: Is apparently a stepper motor that is controlled as a brushless. Essentially a stepper is a brushless. This needs a encoder, probably one with a index pulse correctly positioned, so that the electronics can compute the switching accurately. The Mesa 7i32 does this too. Note that this is _not_ a Hostmot2 device, it needs to be controlled by SoftDMC and there is (As far as I know) no official LinuxCNC support, though there is a component http://wiki.linuxcnc.org/cgi-bin/wiki.pl?ContributedComponents#Mesa_7i32_micro_stepping_motor_driver -- atp If you can't fix it, you don't own it. http://www.ifixit.com/Manifesto -- Precog is a next-generation analytics platform capable of advanced analytics on semi-structured data. The platform includes APIs for building apps and a phenomenal toolset for data science. Developers can use our toolset for easy data analysis visualization. Get a free account! http://www2.precog.com/precogplatform/slashdotnewsletter ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Closed loop stepping system
On Wednesday 10 April 2013 13:01:29 Javier Ros did opine: This system http://www.automationtechnologiesinc .com/products-page/nema23-closed-loop-stepper-motor-system-hybrid-servo- kit/hybrid-servo-drive-kl-5080h Is apparently a stepper motor that is controlled as a brushless. Essentially a stepper is a brushless. This needs a encoder, probably one with a index pulse correctly positioned, so that the electronics can compute the switching accurately. This means, even if the control of the drive looks like a STEP DIR control, internally there are position and current loops, theoretically such a drive could offer, velocity and current control (I've not checked for the above reference). This means essentially that, the motor runs cooler, because only the required intensity is flowing in the motor, and not the maximum required intensity (the one that is controlled with the typical potentiometer in typical stepper drives). This means as well that the motor runs smoother, this must be most noticeable at low velocities, and finally that the positioning can be as precise as the encoder is. I regard of precision, note that a stepper, is not as precise as 3600/steps_per_revolution/microsteps, because microsteps don need to be equally spaced, even steps are not precise due to manufacturing (magnetic field) do not have to be equally spaced. In addition to this forces make that the motor is not centered at the center of the microstep. Let me fine tune this by pointing out that the stepper motor maker can, with access to the maps the controller uses to adjust its currents when microstepping, could be fine tuned such that at light loading, the microsteps can be pretty accurate. This of course means the motor and the controller must be calibrated to each other. That will be the makers job since few if any of us have the tools to do that, and it sure wouldn't be feasible economically for everyone to own their own stuff to do that. More just plain old comment: The noise would likely go down a bit, but since we aren't also throttling the current in many drivers (mine does after about a second of no motion, so mine only heat about 15F when idle), the motor is still going to run hot. The ideal situation would be by adjusting the overall currents to keep the motor within say 20%/microstep of the ideal microstepped position, but again this would require a high precision encoder, or some sort of magnetically detected feedback to detect the error in real time only use enough current to achieve that. But at that point, you may as well spend the money on a servo system, which may well be what this outfit is doing. Net cost will be similar. My current stepper setup, using 425oz motors on the lathe, was just under $100/axis. This is only a 252oz motor and costs USD 210/axis. I can't seem to justify the extra sheckel's for me. In comparison a brushless type encoder based drive for steeper can be as precise as the encoder, you know the actual position with the encoder position, although the position can be different of the commanded position, but you know the difference. The only limitations seem to be related to control at hih rpms, performance degrades in comparison with brushless. I would say that this is related to the higher pole count of the steeper,and the inherent dificulty to stablish intensity at high pole conmutation frecuency due to impedance, something that con be alleviated increaing voltage as much as possible.. In regard to this the error position, it can be even smaller in this brushless system because, as it runs cooler, you can allow for small duration current higher than the nominal. For a steeper you can not surpass the nominal value, not for the motor not for the electronics. Theoretically true. The motor can be banged with considerable overcurrent when it is lightly loaded and essentially exactly in position, but if half s step off or more due to heavy loading, then the rotor's magnetism could be effected, permanently damaging the motor. I've never run a system of this type, but I would love to use one of the MESA cards and brushless firmwares to test a such a setup (I'm interested in current control) if somebody with more experience thinks/knowns this is possible and not too difficult. Just using a double shaft stepper and a cheap encoder. I would love, to identify stepper cogging, and to software compensate for it. A moot point IMO when the gearing is such that 1 microstep is a fraction of a micron without resorting to a doubling of cost per axis. I haven't actually checked, as my step accuracy is the same on both axis's of the lathe, the x is a 2.5mm/turn screw, the z is 5, but the z is also geared down 2/1. On my .0001 dial indicator, I can't see the individual steps. This said, if the proposed system works as theoretically expected, it looks to me it has a pretty reasonable price. Debatable, unless you
Re: [Emc-users] Closed loop stepping system
On 04/10/2013 07:18 AM, Javier Ros wrote: Is apparently a stepper motor that is controlled as a brushless. Essentially a stepper is a brushless. This needs a encoder, probably one with a index pulse correctly positioned, so that the electronics can compute the switching accurately. This means, even if the control of the drive looks like a STEP DIR control, internally there are position and current loops, theoretically such a drive could offer, velocity and current control (I've not checked for the above reference). The only limitations seem to be related to control at hih rpms, performance degrades in comparison with brushless. I would say that this is related to the higher pole count of the steeper, If you were to design one of these from the ground up, since position would be verified from a 10,000 step encoder, and the stepper would be run as a type of servo motor, the stepper driver would function much differently. It would generate commutation from the encoder, then it would drive a current into one coil to draw the motor towards the commanded position. PID would decide how hard to hit the motor by the difference between commanded position and current encoder position. Since this works like a servo and not a stepper with feedback, the stepper motor could be designed with less steps per rev. less steps per revolution would require less soil current reversals, and would allow the motor to step faster. If a 1mH coil standard stepper could be driven to 3000 RPM, one with 100 steps per rev instead of 200 could be driven at 6000 RPM. One with 50 steps per rev could be driven at 12000 RPM. The control circuit would have to do some tricky math to keep cogging to a minimum, but it's likely possible to make a very fast but still accurate stepper system this way. -- Precog is a next-generation analytics platform capable of advanced analytics on semi-structured data. The platform includes APIs for building apps and a phenomenal toolset for data science. Developers can use our toolset for easy data analysis visualization. Get a free account! http://www2.precog.com/precogplatform/slashdotnewsletter ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Closed loop stepping system
On Thursday 11 April 2013 00:58:10 cogoman did opine: On 04/10/2013 07:18 AM, Javier Ros wrote: Is apparently a stepper motor that is controlled as a brushless. Essentially a stepper is a brushless. This needs a encoder, probably one with a index pulse correctly positioned, so that the electronics can compute the switching accurately. This means, even if the control of the drive looks like a STEP DIR control, internally there are position and current loops, theoretically such a drive could offer, velocity and current control (I've not checked for the above reference). The only limitations seem to be related to control at hih rpms, performance degrades in comparison with brushless. I would say that this is related to the higher pole count of the steeper, If you were to design one of these from the ground up, since position would be verified from a 10,000 step encoder, and the stepper would be run as a type of servo motor, the stepper driver would function much differently. It would generate commutation from the encoder, then it would drive a current into one coil to draw the motor towards the commanded position. PID would decide how hard to hit the motor by the difference between commanded position and current encoder position. Since this works like a servo and not a stepper with feedback, the stepper motor could be designed with less steps per rev. less steps per revolution would require less soil current reversals, and would allow the motor to step faster. If a 1mH coil standard stepper could be driven to 3000 RPM, one with 100 steps per rev instead of 200 could be driven at 6000 RPM. One with 50 steps per rev could be driven at 12000 RPM. The control circuit would have to do some tricky math to keep cogging to a minimum, but it's likely possible to make a very fast but still accurate stepper system this way. Somebody thinking outside the box, and making perfect sense. The only fly in the soup is the 10,000 step encoder, and servicing it at 200 rpS to get that 12,000 rpms, which would need to be able, if software, to do the whole control loop at a 2 megacycle rate. The best we've been able to do in software is less than 100 kilohertz at the relatively simple job of just issuing steps to the motor. These atom boards can do 50, but are hugely more comfortable running at about 47 kilohertz. To do the whole control loop at 2 megahertz to get that 12,000 rpm would need dedicated hardware that could do this in much less than .5 microseconds. I won't say its impossible, but I don't believe we have the 'state of the art', nor do we represent a sufficient economic incentive to do that as a chip design. At least not in the next calendar year. 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 is up! My views http://www.armchairpatriot.com/What%20Has%20America%20Become.shtml divorce, n: A change of wife. A pen in the hand of this president is far more dangerous than a gun in the hands of 200 million law-abiding citizens. -- Precog is a next-generation analytics platform capable of advanced analytics on semi-structured data. The platform includes APIs for building apps and a phenomenal toolset for data science. Developers can use our toolset for easy data analysis visualization. Get a free account! http://www2.precog.com/precogplatform/slashdotnewsletter ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
[Emc-users] Closed loop stepping system
Does anyone have any experiences using this this system with linuxcnc? http://www.fastech.co.kr/bbs/eng/product.php?mode=view1uid=1# As far as I understand, there would be only one feedback signal from driver to linuxcnc, telling that stepper is in position or not... In my case might be interesting as I'm already using servos for all linear axis, except rotary axes where I still have steppers, as it is in my case a bit difficult to switch on servos, but with this system I could simply change motors (same size, same specs...), and would also be reliable about accuracy and no loosing steps in any case... -- Precog is a next-generation analytics platform capable of advanced analytics on semi-structured data. The platform includes APIs for building apps and a phenomenal toolset for data science. Developers can use our toolset for easy data analysis visualization. Get a free account! http://www2.precog.com/precogplatform/slashdotnewsletter ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Closed loop stepping system
On 9 April 2013 10:11, Tomaz T. tomaz_...@hotmail.com wrote: http://www.fastech.co.kr/bbs/eng/product.php?mode=view1uid=1# It isn't immediately clear what advantage it gives over normal steppers other than stall-detection. I guess it should also be able to recover from a stall too, so perhaps there would be the option of using adaptive-feed to slow other axes to allow it to catch up. It would be interesting to see how it worked out. -- atp If you can't fix it, you don't own it. http://www.ifixit.com/Manifesto -- Precog is a next-generation analytics platform capable of advanced analytics on semi-structured data. The platform includes APIs for building apps and a phenomenal toolset for data science. Developers can use our toolset for easy data analysis visualization. Get a free account! http://www2.precog.com/precogplatform/slashdotnewsletter ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Closed loop stepping system
The whole point is that I don't have any feedback from steppers at this stage, and as I said, the cheapest solution would be to simply change the existing one with the one with closed loop future (and also drivers). So the basic idea might be to use In-Position signal (output) from stepper driver and when this goes fault, it triggers following error in linuxcnc. Could this work? Anyone using this stepper system from kelinginc? http://www.automationtechnologiesinc.com/products-page/nema23-closed-loop-stepper-motor-system-hybrid-servo-kit/hybrid-servo-drive-kl-5080h It isn't immediately clear what advantage it gives over normal steppers other than stall-detection. I guess it should also be able to recover from a stall too, so perhaps there would be the option of using adaptive-feed to slow other axes to allow it to catch up. It would be interesting to see how it worked out. -- Precog is a next-generation analytics platform capable of advanced analytics on semi-structured data. The platform includes APIs for building apps and a phenomenal toolset for data science. Developers can use our toolset for easy data analysis visualization. Get a free account! http://www2.precog.com/precogplatform/slashdotnewsletter ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Closed loop stepping system
2013/4/10 Tomaz T. tomaz_...@hotmail.com The whole point is that I don't have any feedback from steppers at this stage, and as I said, the cheapest solution would be to simply change the existing one with the one with closed loop future (and also drivers). So the basic idea might be to use In-Position signal (output) from stepper driver and when this goes fault, it triggers following error in linuxcnc. Could this work? So why don't You put encoders on stepper motors and link encoder position to axis.n.motor-pos-fb pin and let LinuxCNC track actual motor position and it definitely will trigger following error, once it has been reached. This way there are no fancy stepper drives and motors are required. Anyone using this stepper system from kelinginc? http://www.automationtechnologiesinc.com/products-page/nema23-closed-loop-stepper-motor-system-hybrid-servo-kit/hybrid-servo-drive-kl-5080h No tuning of feedback loop? Well, then I do not see, how does this system achieve its goal and correct for motor's position error. -- Viesturs If you can't fix it, you don't own it. http://www.ifixit.com/Manifesto -- Precog is a next-generation analytics platform capable of advanced analytics on semi-structured data. The platform includes APIs for building apps and a phenomenal toolset for data science. Developers can use our toolset for easy data analysis visualization. Get a free account! http://www2.precog.com/precogplatform/slashdotnewsletter ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
