Re: [Emc-users] Just curious, backing off of limit switch
Add a spring to your contact, to give it a degree of compression. - Original Message - On Wednesday 23 January 2013 21:02:47 Stephen Dubovsky did opine: Message additions Copyright Wednesday 23 January 2013 by Gene Heskett Gene, Nowhere does it specify in the graphic that the two HAVE to be separate. The drawing is arbitrary/universal and just showing which edges are used on which steps. If you set the SEARCH_VEL reasonably high enough the machine must over travel the switch due to deceleration. Have you tried setting your search velocity high enough that the over travel is greater than your backlash compensation? Stephen No I haven't Stephan, because its backed up against the end of the workpiece in the chuck in normal use, is a solid black of alu with a sheet of double sided pcb materiel glued to the right face for the contact. If I hit it that hard and fast I would be crushing the pcb material. So my initial search is at about 2/min, with a final search vel of about .2/minute. Repeatability is someplace in the 4th digit to the right of the decimal point even with 23 thou of backlash. So we aren't talking about a switch at all, but a contact with hysteresis of perhaps .0001 max. That backlash is going away, I now have a 16mmx5mmx675mm ball screw laying on a chair cushion and am milling the rest of the parts to install it as I sit here yakking. And wonder of wonders, we actually have enough snow to turn the ground white! We are about 40 of rain or equ behind since last spring. On Wed, Jan 23, 2013 at 4:11 PM, Gene Heskett ghesk...@wdtv.com wrote: On Wednesday 23 January 2013 15:59:55 Bruce Klawiter did opine: Message additions Copyright Wednesday 23 January 2013 by Gene Heskett I am curious, how does LinuxCNC back off of a limit switch? I have a bridgeport with hand wheels so it is easy for me, just wondering how this is done on the big machines. Bruce As shown in the gfx on the wiki under homing, there is an implicit assumption that it is a mechanical switch, with a bit of hysteresis space between the close and the open going the other way. It's fairly well explained, but the lack of hysteresis in an electrical contact such as I am using, means I cannot set my backlashes for total compensations, because the backlash takeup move may reopen the contact, and its a show stopper error if the switch is already open when the backup move starts. I have x home working about 90% of the time by setting backlash to half a thou in the .ini file for x on my lathe, and around 3 thou less than real on my old sloppy z. When x works, it does all the motions in just a few milliseconds once the initial contact has been made. The old Z was the same except for the 300 milliseconds the backlash moves of 20 thou take. -- Master Visual Studio, SharePoint, SQL, ASP.NET, C# 2012, HTML5, CSS, MVC, Windows 8 Apps, JavaScript and much more. Keep your skills current with LearnDevNow - 3,200 step-by-step video tutorials by Microsoft MVPs and experts. ON SALE this month only -- learn more at: http://p.sf.net/sfu/learnnow-d2d ___ 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 Onward through the fog. I was taught to respect my elders, but its getting harder and harder to find any... -- Master Visual Studio, SharePoint, SQL, ASP.NET, C# 2012, HTML5, CSS, MVC, Windows 8 Apps, JavaScript and much more. Keep your skills current with LearnDevNow - 3,200 step-by-step video tutorials by Microsoft MVPs and experts. ON SALE this month only -- learn more at: http://p.sf.net/sfu/learnnow-d2d ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users -- Todd Zuercher mailto:zuerc...@embarqmail.com -- Master Visual Studio, SharePoint, SQL, ASP.NET, C# 2012, HTML5, CSS, MVC, Windows 8 Apps, JavaScript and much more. Keep your skills current with LearnDevNow - 3,200 step-by-step video tutorials by Microsoft MVPs and experts. ON SALE this month only -- learn more at: http://p.sf.net/sfu/learnnow-d2d ___ Emc-users mailing list Emc-users@lists.sourceforge.net
Re: [Emc-users] Just curious, backing off of limit switch
On Thursday 24 January 2013 11:05:42 Todd Zuercher did opine: Message additions Copyright Thursday 24 January 2013 by Gene Heskett Add a spring to your contact, to give it a degree of compression. I did, in a previous design, mount the pcb on grommets so there was room for crush. but found it near impossible to get a consistent spring back. Or if off center, a consistent restoration to level. a 4 grommet mount would have solved that, but the frame of that gage didn't have room. So I wound up insulating the pcb being carved in a pocket of micarta, and g38.2'd the pcb I was carving, which worked very well indeed. Like T. Edisons his light bulb, he found 10,000 ways it didn't work. All my current problems regarding this would go away if the switch hysteresis backup move would just do another 5 thou of back away anyway if it found the switch open when it checked instead of freezing in place and fussing with a big red error advisory because the switch was found to be already open as it started the back away move. HINT, HINT. IMO, the only error here is in the assumption that the home switch is mechanical, with several tens of thousandths on an inch, or in metric, possibly a whole mm of hysteresis. Perhaps even a per axis keyword to make it work either way? Would seem to give maximum flexibility at any rate. - Original Message - On Wednesday 23 January 2013 21:02:47 Stephen Dubovsky did opine: Message additions Copyright Wednesday 23 January 2013 by Gene Heskett Gene, Nowhere does it specify in the graphic that the two HAVE to be separate. The drawing is arbitrary/universal and just showing which edges are used on which steps. If you set the SEARCH_VEL reasonably high enough the machine must over travel the switch due to deceleration. Have you tried setting your search velocity high enough that the over travel is greater than your backlash compensation? Stephen No I haven't Stephan, because its backed up against the end of the workpiece in the chuck in normal use, is a solid black of alu with a sheet of double sided pcb materiel glued to the right face for the contact. If I hit it that hard and fast I would be crushing the pcb material. So my initial search is at about 2/min, with a final search vel of about .2/minute. Repeatability is someplace in the 4th digit to the right of the decimal point even with 23 thou of backlash. So we aren't talking about a switch at all, but a contact with hysteresis of perhaps .0001 max. That backlash is going away, I now have a 16mmx5mmx675mm ball screw laying on a chair cushion and am milling the rest of the parts to install it as I sit here yakking. And wonder of wonders, we actually have enough snow to turn the ground white! We are about 40 of rain or equ behind since last spring. Got about 3, DW staying home I guess. Had Dr's apt this morning. On Wed, Jan 23, 2013 at 4:11 PM, Gene Heskett ghesk...@wdtv.com wrote: On Wednesday 23 January 2013 15:59:55 Bruce Klawiter did opine: Message additions Copyright Wednesday 23 January 2013 by Gene Heskett I am curious, how does LinuxCNC back off of a limit switch? I have a bridgeport with hand wheels so it is easy for me, just wondering how this is done on the big machines. Bruce As shown in the gfx on the wiki under homing, there is an implicit assumption that it is a mechanical switch, with a bit of hysteresis space between the close and the open going the other way. It's fairly well explained, but the lack of hysteresis in an electrical contact such as I am using, means I cannot set my backlashes for total compensations, because the backlash takeup move may reopen the contact, and its a show stopper error if the switch is already open when the backup move starts. I have x home working about 90% of the time by setting backlash to half a thou in the .ini file for x on my lathe, and around 3 thou less than real on my old sloppy z. When x works, it does all the motions in just a few milliseconds once the initial contact has been made. The old Z was the same except for the 300 milliseconds the backlash moves of 20 thou take. -- -- -- Master Visual Studio, SharePoint, SQL, ASP.NET, C# 2012, HTML5, CSS, MVC, Windows 8 Apps, JavaScript and much more. Keep your skills current with LearnDevNow - 3,200 step-by-step video tutorials by Microsoft MVPs and experts. ON SALE this month only -- learn more at: http://p.sf.net/sfu/learnnow-d2d ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users Cheers, Gene 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:
Re: [Emc-users] Just curious, backing off of limit switch
On 24 January 2013 16:27, Gene Heskett ghesk...@wdtv.com wrote: All my current problems regarding this would go away if the switch hysteresis backup move would just do another 5 thou of back away anyway if it found the switch open when it checked instead of freezing in place and fussing with a big red error advisory because the switch was found to be already open as it started the back away move. I have a feeling that the issue here is that you are using a touch probe as a home switch. Use a probe routine to measure tool length, not a homing routine. -- atp If you can't fix it, you don't own it. http://www.ifixit.com/Manifesto -- Master Visual Studio, SharePoint, SQL, ASP.NET, C# 2012, HTML5, CSS, MVC, Windows 8 Apps, JavaScript and much more. Keep your skills current with LearnDevNow - 3,200 step-by-step video tutorials by Microsoft MVPs and experts. ON SALE this month only -- learn more at: http://p.sf.net/sfu/learnnow-d2d ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Just curious, backing off of limit switch
Gene; Am not anywhere close my machine right now, so no code, but IIRC when using a touch probe, I did indeed find sometimes that an error would crop up on backing away. Two items, from memory: 1) updated LinuxCNC; this was spring 2012; 2) when I thought I had found the surface, I pushed my way into it by a tiny bit, to ensure that the probe had *really* found the edge. (say, 1 thou or so) #2, above, especially, cleared up my touch probe routines. Hope this helps in some way. John A. Stewart -- Master Visual Studio, SharePoint, SQL, ASP.NET, C# 2012, HTML5, CSS, MVC, Windows 8 Apps, JavaScript and much more. Keep your skills current with LearnDevNow - 3,200 step-by-step video tutorials by Microsoft MVPs and experts. ON SALE this month only -- learn more at: http://p.sf.net/sfu/learnnow-d2d ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
[Emc-users] Just curious, backing off of limit switch
On 24 January 2013 18:27, Gene Heskett ghesk...@wdtv.com wrote: On Thursday 24 January 2013 11:05:42 Todd Zuercher did opine: Message additions Copyright Thursday 24 January 2013 by Gene Heskett Add a spring to your contact, to give it a degree of compression. I did, in a previous design, mount the pcb on grommets so there was room for crush. but found it near impossible to get a consistent spring back. Or if off center, a consistent restoration to level. a 4 grommet mount would have solved that, but the frame of that gage didn't have room. So I wound up insulating the pcb being carved in a pocket of micarta, and g38.2'd the pcb I was carving, which worked very well indeed. Like T. Edisons his light bulb, he found 10,000 ways it didn't work. All my current problems regarding this would go away if the switch hysteresis backup move would just do another 5 thou of back away anyway if it found the switch open when it checked instead of freezing in place and fussing with a big red error advisory because the switch was found to be already open as it started the back away move. HINT, HINT. IMO, the only error here is in the assumption that the home switch is mechanical, with several tens of thousandths on an inch, or in metric, possibly a whole mm of hysteresis. Perhaps even a per axis keyword to make it work either way? Would seem to give maximum flexibility at any rate. How about using a proper travel limit switch. The contact operates well within the first mm, and then you can press it a further 5mm or so with no ill effect. And on release the hysterisis is very short... http://www.galco.com/buy/Eaton-Cutler-Hammer/E47BMS04 http://www.galco.com/buy/NTE-Electronics/54-438-BP Regards Roland -- Master Visual Studio, SharePoint, SQL, ASP.NET, C# 2012, HTML5, CSS, MVC, Windows 8 Apps, JavaScript and much more. Keep your skills current with LearnDevNow - 3,200 step-by-step video tutorials by Microsoft MVPs and experts. ON SALE this month only -- learn more at: http://p.sf.net/sfu/learnnow-d2d ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Just curious, backing off of limit switch
On Thursday 24 January 2013 12:42:26 andy pugh did opine: Message additions Copyright Thursday 24 January 2013 by Gene Heskett On 24 January 2013 16:27, Gene Heskett ghesk...@wdtv.com wrote: All my current problems regarding this would go away if the switch hysteresis backup move would just do another 5 thou of back away anyway if it found the switch open when it checked instead of freezing in place and fussing with a big red error advisory because the switch was found to be already open as it started the back away move. I have a feeling that the issue here is that you are using a touch probe as a home switch. Use a probe routine to measure tool length, not a homing routine. However, this way, if I ever get the x offset correct (that is being a Cast Iron Bitch because the .ini files homes offsets are in radius mode even if the lathe is running in diameter mode, THEN I can write all the gcode in absolute values such that Z0.000 is the end of the workpiece sticking out of the chuck. Right now, I am working on putting a ball screw in the Z axis so its apart and I can't play, but the concept sure seems like it should be consistently workable to me. Ditto for using a boring bar or internal threading tool, swing the backside contact into position and measure. But home can't do that because there is no q d way to reverse the motions for a backside search. So that will probably wind up needing a G38.2 in the code itself, to set G55 at the proper X offset and run the target code to bore a hole, or thread it, in the G55 co-ordinate system. I'll probably be able to figure it out eventually, and may even wind up asking dumber questions yet. OTOH, if I have to ask the question, how does that reflect on the state of the docs? 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 You cannot propel yourself forward by patting yourself on the back. I was taught to respect my elders, but its getting harder and harder to find any... -- Master Visual Studio, SharePoint, SQL, ASP.NET, C# 2012, HTML5, CSS, MVC, Windows 8 Apps, JavaScript and much more. Keep your skills current with LearnDevNow - 3,200 step-by-step video tutorials by Microsoft MVPs and experts. ON SALE this month only -- learn more at: http://p.sf.net/sfu/learnnow-d2d ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Just curious, backing off of limit switch
On Thursday 24 January 2013 13:03:26 John Stewart did opine: Message additions Copyright Thursday 24 January 2013 by Gene Heskett Gene; Am not anywhere close my machine right now, so no code, but IIRC when using a touch probe, I did indeed find sometimes that an error would crop up on backing away. Two items, from memory: 1) updated LinuxCNC; this was spring 2012; 2) when I thought I had found the surface, I pushed my way into it by a tiny bit, to ensure that the probe had *really* found the edge. (say, 1 thou or so) #2, above, especially, cleared up my touch probe routines. Hope this helps in some way. It may, and in fact I have been considering adding cycles to the debounce routine that is in that path, just to achieve a similar effect. Can't do very much delay though, the copper on the pcb isn't thick enough to take a heck of a lot of that. I am not doing visible damage to it ATM unless I miss handle the gage in placing it on, or taking it off the ways. I need to slap another shelf up on the bottom of the 2x4's that are holding the lathes major tools above it now which should help keep the gage clean(er). Its set at 4 ATM, see man 9 debounce, and when it errors I can see the led on the C1G flickering half heartedly 90% of the time. When I get it back together with the ball screw we'll do further adjusting I'm sure. John A. Stewart -- Master Visual Studio, SharePoint, SQL, ASP.NET, C# 2012, HTML5, CSS, MVC, Windows 8 Apps, JavaScript and much more. Keep your skills current with LearnDevNow - 3,200 step-by-step video tutorials by Microsoft MVPs and experts. ON SALE this month only -- learn more at: http://p.sf.net/sfu/learnnow-d2d ___ 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 It's not that I'm afraid to die. I just don't want to be there when it happens. -- Woody Allen I was taught to respect my elders, but its getting harder and harder to find any... -- Master Visual Studio, SharePoint, SQL, ASP.NET, C# 2012, HTML5, CSS, MVC, Windows 8 Apps, JavaScript and much more. Keep your skills current with LearnDevNow - 3,200 step-by-step video tutorials by Microsoft MVPs and experts. ON SALE this month only -- learn more at: http://p.sf.net/sfu/learnnow-d2d ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Just curious, backing off of limit switch
On Thursday 24 January 2013 13:15:06 Roland Jollivet did opine: Message additions Copyright Thursday 24 January 2013 by Gene Heskett On 24 January 2013 18:27, Gene Heskett ghesk...@wdtv.com wrote: On Thursday 24 January 2013 11:05:42 Todd Zuercher did opine: Message additions Copyright Thursday 24 January 2013 by Gene Heskett Add a spring to your contact, to give it a degree of compression. I did, in a previous design, mount the pcb on grommets so there was room for crush. but found it near impossible to get a consistent spring back. Or if off center, a consistent restoration to level. a 4 grommet mount would have solved that, but the frame of that gage didn't have room. So I wound up insulating the pcb being carved in a pocket of micarta, and g38.2'd the pcb I was carving, which worked very well indeed. Like T. Edisons his light bulb, he found 10,000 ways it didn't work. All my current problems regarding this would go away if the switch hysteresis backup move would just do another 5 thou of back away anyway if it found the switch open when it checked instead of freezing in place and fussing with a big red error advisory because the switch was found to be already open as it started the back away move. HINT, HINT. IMO, the only error here is in the assumption that the home switch is mechanical, with several tens of thousandths on an inch, or in metric, possibly a whole mm of hysteresis. Perhaps even a per axis keyword to make it work either way? Would seem to give maximum flexibility at any rate. How about using a proper travel limit switch. The contact operates well within the first mm, and then you can press it a further 5mm or so with no ill effect. And on release the hysterisis is very short... http://www.galco.com/buy/Eaton-Cutler-Hammer/E47BMS04 http://www.galco.com/buy/NTE-Electronics/54-438-BP Regards Roland I don't understand why the pressure to use a sloppy microswitch here, when the electrical contact can and is within .0005 repeatable. All this cut, measure, set touch off, try again is a kludge, why not calibrate it dead on? 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 Be careful! UGLY strikes 9 out of 10! I was taught to respect my elders, but its getting harder and harder to find any... -- Master Visual Studio, SharePoint, SQL, ASP.NET, C# 2012, HTML5, CSS, MVC, Windows 8 Apps, JavaScript and much more. Keep your skills current with LearnDevNow - 3,200 step-by-step video tutorials by Microsoft MVPs and experts. ON SALE this month only -- learn more at: http://p.sf.net/sfu/learnnow-d2d ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Just curious, backing off of limit switch
On Thu, 2013-01-24 at 18:51 +0200, Roland Jollivet wrote: On 24 January 2013 18:27, Gene Heskett ghesk...@wdtv.com wrote: On Thursday 24 January 2013 11:05:42 Todd Zuercher did opine: Message additions Copyright Thursday 24 January 2013 by Gene Heskett Add a spring to your contact, to give it a degree of compression. I did, in a previous design, mount the pcb on grommets so there was room for crush. but found it near impossible to get a consistent spring back. Or if off center, a consistent restoration to level. a 4 grommet mount would have solved that, but the frame of that gage didn't have room. So I wound up insulating the pcb being carved in a pocket of micarta, and g38.2'd the pcb I was carving, which worked very well indeed. Like T. Edisons his light bulb, he found 10,000 ways it didn't work. All my current problems regarding this would go away if the switch hysteresis backup move would just do another 5 thou of back away anyway if it found the switch open when it checked instead of freezing in place and fussing with a big red error advisory because the switch was found to be already open as it started the back away move. HINT, HINT. IMO, the only error here is in the assumption that the home switch is mechanical, with several tens of thousandths on an inch, or in metric, possibly a whole mm of hysteresis. Perhaps even a per axis keyword to make it work either way? Would seem to give maximum flexibility at any rate. How about using a proper travel limit switch. The contact operates well within the first mm, and then you can press it a further 5mm or so with no ill effect. And on release the hysterisis is very short... http://www.galco.com/buy/Eaton-Cutler-Hammer/E47BMS04 http://www.galco.com/buy/NTE-Electronics/54-438-BP Regards Roland Hi all, As Gene would say there are many ways to skin this cat. a. manually run the carriage up against a stop and press home for that axis. Depending on the springiness of the mechanics probably good to about a thou. b. use a home switch with a cam actuator i.e. ramp the switch on which guarantees it will stay closed with over-travel. Then you can either back off until it opens and use that as home or better yet back off to the index pulse. The homing method should match the repeatability of the machine. Like so many things measuring to .0001 isn't very valuable if the machine will only hold a thou. On my cinci I give up a couple of inches to have a homing setup that is easy. Someday I'm going to fix that. HTH Dave -- Master Visual Studio, SharePoint, SQL, ASP.NET, C# 2012, HTML5, CSS, MVC, Windows 8 Apps, JavaScript and much more. Keep your skills current with LearnDevNow - 3,200 step-by-step video tutorials by Microsoft MVPs and experts. ON SALE this month only -- learn more at: http://p.sf.net/sfu/learnnow-d2d ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users -- Master Visual Studio, SharePoint, SQL, ASP.NET, C# 2012, HTML5, CSS, MVC, Windows 8 Apps, JavaScript and much more. Keep your skills current with LearnDevNow - 3,200 step-by-step video tutorials by Microsoft MVPs and experts. ON SALE this month only -- learn more at: http://p.sf.net/sfu/learnnow-d2d ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
