Re: [Emc-users] Newbie Help Needed - Losing Steps
Emory, I changed the jumpers on my HobbyCNC board. I then recalculated the number of steps to move one unit (one inch or one millimeter) then adjusted the INPUT_SCALE value in the EMC2 ini file to that amount. Basically going from full stepping to 1/4 stepping will quadruple the value for INPUT_SCALE, but if your lead screws are in inches and you are using EMC2 in mm, or vice versa, I would recalculate the INPUT_SCALE value from scratch to avoid any rounding problems. Andy Emory Smith wrote: > Andrew, > What did you do to switch to 1/4 step mode. > Was it within EMC or something on your controller? > Is there a FAQ? > I'd like to try that. > > Thanks, > Emory > > On Tue, Apr 8, 2008 at 8:08 PM, Andrew Ayre <[EMAIL PROTECTED]> wrote: >> John Kasunich wrote: >> > Andrew Ayre wrote: >> >> [EMAIL PROTECTED] wrote: >> >>> --- [EMAIL PROTECTED] wrote: >> >>> >> >>> From: John Kasunich <[EMAIL PROTECTED]> >> >>> To: "Enhanced Machine Controller (EMC)" >> >> >>> Subject: Re: [Emc-users] Newbie Help Needed - Losing Steps >> >>> Date: Sun, 06 Apr 2008 19:46:09 -0400 >> >>> >> >>> Andrew Ayre wrote: >> >>>> Hi, >> >>>> >> >>>> I have a gantry style machine with three axis. The X and Y axis have >> the >> >>>> same motor and the same nut and lead screw on each). I am testing the >> >>>> machine using manually entered commands into AXIS such as: >> >>>> >> >>>>G01 F80 X1 >> >>>>G01 F80 X0 >> >>>> >> >>>> When manipulating one axis at a time (no cutting, just moving around) I >> >>>> have found that I lose steps at different feed rates for each axis. >> >>>> >> >>>>X - lose steps at 148 ipm >> >>>>Y - lose steps at 81 ipm >> >>>> >> >>> All those calculations are for theoretical limits to the step rate. But >> >>> the reason you are losing steps is much less theoretical. You are >> >>> probably running out of torque. When step motors go faster, the amount >> >>> of torque that they can produce drops. When the load needs more torque >> >>> than the motor can make, you lose steps. >> >>> >> >>> It does seem odd that the X can go faster than Y. X has to move more >> >>> weight (I assume that X is the gantry, and Y moves a much smaller weight >> >>> across the gantry). But something is making Y require more torque than >> >>> X, so Y loses steps first. >> >>> >> >>> Regards, >> >>> >> >>> John Kasunich >> >>> >> >>> It looks to me like Andy is using full step motion. Probably what is >> happening is that he's hitting resonant frequencies that are a bit different >> for each axis. The extra weight of X might even work to advantage to help >> it cross that zero torque spot. >> >>> >> >>> Rayh >> >>> >> >> Hi Ray, yes I'm using full stepping. My next step was to switch to 1/4 >> >> or 1/8 microstepping. So could that actually help? I know that the >> >> speeds overall will be reduced of course. >> >> >> > >> > Micro-stepping will lower the theoretical speed, but as you've already >> > calculated, the theoretical speed is pretty fast right now. On the good >> > side, micro-stepping will mostly likely increase the torque somewhat, >> > especially at certain speeds where full-stepping causes resonance and >> > dramatically lowers torque. >> > >> > Regards, >> > >> > John Kasunich >> >> Update - I switched to 1/4 stepping mode. Movement is smoother and >> quieter. The top speed of each axis is now limited by the speed of the >> real time system on my PC, with no stalls. >> >> Thanks for the help. :) >> >> >> Andy >> >> -- >> Andy >> PGP Key ID: 0xDC1B5864 >> >> - >> >> This SF.net email is sponsored by the 2008 JavaOne(SM) Conference >> Don't miss this year's exciting event. There's still time to save $100. >> Use priority code J8TL2D2. >> >> >> http://ad.doubleclick.net/clk;198757673;13503038;p?http://java.sun.com/javaone >> ___ >> Emc-users mailing list >> Emc-users@lists.sourceforge.net >> https://lists.sourceforge.net/lists/listinfo/emc-users >> > > > -- Andy PGP Key ID: 0xDC1B5864 - This SF.net email is sponsored by the 2008 JavaOne(SM) Conference Don't miss this year's exciting event. There's still time to save $100. Use priority code J8TL2D2. http://ad.doubleclick.net/clk;198757673;13503038;p?http://java.sun.com/javaone ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Newbie Help Needed - Losing Steps
On Wed, 2008-04-09 at 08:50 -0700, Andrew Ayre wrote: > [EMAIL PROTECTED] wrote: > > > > --- [EMAIL PROTECTED] wrote: > > > > From: Andrew Ayre <[EMAIL PROTECTED]> > > To: "Enhanced Machine Controller (EMC)" > > Subject: Re: [Emc-users] Newbie Help Needed - Losing Steps > > Date: Tue, 08 Apr 2008 18:08:58 -0700 > > > > Update - I switched to 1/4 stepping mode. Movement is smoother and > > quieter. The top speed of each axis is now limited by the speed of the > > real time system on my PC, with no stalls. > > > > Thanks for the help. :) > > > > Andy > > > > A while back I posted a pic of full step torque that was made for a project > > in India. It showed full step torque drop to near zero at resonant > > frequencies. Glad to hear that the microstepping took care of the problem > > for you. > > > > You can probably tune the loops in EMC and HAL to boost high speed > > performance if you need more than you've got. > > > > Rayh > > Ray, learning how to tune loops sounds intriguing and perhaps > interesting to play with, but it's probably well beyond my abilities. Is > there a tutorial somewhere? > > The speeds I now get for X and Y is 71.4 IPM, which I think is fine for > my small machine (18" x 12"). I'm using a P4 1.6GHz, 512Mb RAM with > Ubuntu Gutsy if anyone is interested. > > Andy > There is good stuff here. http://wiki.linuxcnc.org/cgi-bin/emcinfo.pl?TweakingSoftwareStepGeneration I tend to do what that page recommends one not do. I play some with the base period after I've done the math. Just gradually reducing the period and increasing the max velocity till it breaks. Then back off a bit. Rayh - This SF.net email is sponsored by the 2008 JavaOne(SM) Conference Don't miss this year's exciting event. There's still time to save $100. Use priority code J8TL2D2. http://ad.doubleclick.net/clk;198757673;13503038;p?http://java.sun.com/javaone ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Newbie Help Needed - Losing Steps
Andrew, What did you do to switch to 1/4 step mode. Was it within EMC or something on your controller? Is there a FAQ? I'd like to try that. Thanks, Emory On Tue, Apr 8, 2008 at 8:08 PM, Andrew Ayre <[EMAIL PROTECTED]> wrote: > > John Kasunich wrote: > > Andrew Ayre wrote: > >> [EMAIL PROTECTED] wrote: > >>> --- [EMAIL PROTECTED] wrote: > >>> > >>> From: John Kasunich <[EMAIL PROTECTED]> > >>> To: "Enhanced Machine Controller (EMC)" > >>> Subject: Re: [Emc-users] Newbie Help Needed - Losing Steps > >>> Date: Sun, 06 Apr 2008 19:46:09 -0400 > >>> > >>> Andrew Ayre wrote: > >>>> Hi, > >>>> > >>>> I have a gantry style machine with three axis. The X and Y axis have the > >>>> same motor and the same nut and lead screw on each). I am testing the > >>>> machine using manually entered commands into AXIS such as: > >>>> > >>>>G01 F80 X1 > >>>>G01 F80 X0 > >>>> > >>>> When manipulating one axis at a time (no cutting, just moving around) I > >>>> have found that I lose steps at different feed rates for each axis. > >>>> > >>>>X - lose steps at 148 ipm > >>>>Y - lose steps at 81 ipm > >>>> > >>> All those calculations are for theoretical limits to the step rate. But > >>> the reason you are losing steps is much less theoretical. You are > >>> probably running out of torque. When step motors go faster, the amount > >>> of torque that they can produce drops. When the load needs more torque > >>> than the motor can make, you lose steps. > >>> > >>> It does seem odd that the X can go faster than Y. X has to move more > >>> weight (I assume that X is the gantry, and Y moves a much smaller weight > >>> across the gantry). But something is making Y require more torque than > >>> X, so Y loses steps first. > >>> > >>> Regards, > >>> > >>> John Kasunich > >>> > >>> It looks to me like Andy is using full step motion. Probably what is > happening is that he's hitting resonant frequencies that are a bit different > for each axis. The extra weight of X might even work to advantage to help it > cross that zero torque spot. > >>> > >>> Rayh > >>> > >> Hi Ray, yes I'm using full stepping. My next step was to switch to 1/4 > >> or 1/8 microstepping. So could that actually help? I know that the > >> speeds overall will be reduced of course. > >> > > > > Micro-stepping will lower the theoretical speed, but as you've already > > calculated, the theoretical speed is pretty fast right now. On the good > > side, micro-stepping will mostly likely increase the torque somewhat, > > especially at certain speeds where full-stepping causes resonance and > > dramatically lowers torque. > > > > Regards, > > > > John Kasunich > > Update - I switched to 1/4 stepping mode. Movement is smoother and > quieter. The top speed of each axis is now limited by the speed of the > real time system on my PC, with no stalls. > > Thanks for the help. :) > > > Andy > > -- > Andy > PGP Key ID: 0xDC1B5864 > > - > > This SF.net email is sponsored by the 2008 JavaOne(SM) Conference > Don't miss this year's exciting event. There's still time to save $100. > Use priority code J8TL2D2. > > > http://ad.doubleclick.net/clk;198757673;13503038;p?http://java.sun.com/javaone > ___ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users > -- Emory Smith [EMAIL PROTECTED] Website: http://stratcat50.googlepages.com Band: http://defoliants.googlepages.com Blog: http://stratcat50.blogspot.com/ - This SF.net email is sponsored by the 2008 JavaOne(SM) Conference Don't miss this year's exciting event. There's still time to save $100. Use priority code J8TL2D2. http://ad.doubleclick.net/clk;198757673;13503038;p?http://java.sun.com/javaone ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Newbie Help Needed - Losing Steps
[EMAIL PROTECTED] wrote: > > --- [EMAIL PROTECTED] wrote: > > From: Andrew Ayre <[EMAIL PROTECTED]> > To: "Enhanced Machine Controller (EMC)" > Subject: Re: [Emc-users] Newbie Help Needed - Losing Steps > Date: Tue, 08 Apr 2008 18:08:58 -0700 > > Update - I switched to 1/4 stepping mode. Movement is smoother and > quieter. The top speed of each axis is now limited by the speed of the > real time system on my PC, with no stalls. > > Thanks for the help. :) > > Andy > > A while back I posted a pic of full step torque that was made for a project > in India. It showed full step torque drop to near zero at resonant > frequencies. Glad to hear that the microstepping took care of the problem > for you. > > You can probably tune the loops in EMC and HAL to boost high speed > performance if you need more than you've got. > > Rayh Ray, learning how to tune loops sounds intriguing and perhaps interesting to play with, but it's probably well beyond my abilities. Is there a tutorial somewhere? The speeds I now get for X and Y is 71.4 IPM, which I think is fine for my small machine (18" x 12"). I'm using a P4 1.6GHz, 512Mb RAM with Ubuntu Gutsy if anyone is interested. Andy -- Andy PGP Key ID: 0xDC1B5864 - This SF.net email is sponsored by the 2008 JavaOne(SM) Conference Don't miss this year's exciting event. There's still time to save $100. Use priority code J8TL2D2. http://ad.doubleclick.net/clk;198757673;13503038;p?http://java.sun.com/javaone ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Newbie Help Needed - Losing Steps
--- [EMAIL PROTECTED] wrote: From: Andrew Ayre <[EMAIL PROTECTED]> To: "Enhanced Machine Controller (EMC)" Subject: Re: [Emc-users] Newbie Help Needed - Losing Steps Date: Tue, 08 Apr 2008 18:08:58 -0700 Update - I switched to 1/4 stepping mode. Movement is smoother and quieter. The top speed of each axis is now limited by the speed of the real time system on my PC, with no stalls. Thanks for the help. :) Andy A while back I posted a pic of full step torque that was made for a project in India. It showed full step torque drop to near zero at resonant frequencies. Glad to hear that the microstepping took care of the problem for you. You can probably tune the loops in EMC and HAL to boost high speed performance if you need more than you've got. Rayh - This SF.net email is sponsored by the 2008 JavaOne(SM) Conference Don't miss this year's exciting event. There's still time to save $100. Use priority code J8TL2D2. http://ad.doubleclick.net/clk;198757673;13503038;p?http://java.sun.com/javaone ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Newbie Help Needed - Losing Steps
John Kasunich wrote: > Andrew Ayre wrote: >> [EMAIL PROTECTED] wrote: >>> --- [EMAIL PROTECTED] wrote: >>> >>> From: John Kasunich <[EMAIL PROTECTED]> >>> To: "Enhanced Machine Controller (EMC)" >>> Subject: Re: [Emc-users] Newbie Help Needed - Losing Steps >>> Date: Sun, 06 Apr 2008 19:46:09 -0400 >>> >>> Andrew Ayre wrote: >>>> Hi, >>>> >>>> I have a gantry style machine with three axis. The X and Y axis have the >>>> same motor and the same nut and lead screw on each). I am testing the >>>> machine using manually entered commands into AXIS such as: >>>> >>>>G01 F80 X1 >>>>G01 F80 X0 >>>> >>>> When manipulating one axis at a time (no cutting, just moving around) I >>>> have found that I lose steps at different feed rates for each axis. >>>> >>>>X - lose steps at 148 ipm >>>>Y - lose steps at 81 ipm >>>> >>> All those calculations are for theoretical limits to the step rate. But >>> the reason you are losing steps is much less theoretical. You are >>> probably running out of torque. When step motors go faster, the amount >>> of torque that they can produce drops. When the load needs more torque >>> than the motor can make, you lose steps. >>> >>> It does seem odd that the X can go faster than Y. X has to move more >>> weight (I assume that X is the gantry, and Y moves a much smaller weight >>> across the gantry). But something is making Y require more torque than >>> X, so Y loses steps first. >>> >>> Regards, >>> >>> John Kasunich >>> >>> It looks to me like Andy is using full step motion. Probably what is >>> happening is that he's hitting resonant frequencies that are a bit >>> different for each axis. The extra weight of X might even work to >>> advantage to help it cross that zero torque spot. >>> >>> Rayh >>> >> Hi Ray, yes I'm using full stepping. My next step was to switch to 1/4 >> or 1/8 microstepping. So could that actually help? I know that the >> speeds overall will be reduced of course. >> > > Micro-stepping will lower the theoretical speed, but as you've already > calculated, the theoretical speed is pretty fast right now. On the good > side, micro-stepping will mostly likely increase the torque somewhat, > especially at certain speeds where full-stepping causes resonance and > dramatically lowers torque. > > Regards, > > John Kasunich Update - I switched to 1/4 stepping mode. Movement is smoother and quieter. The top speed of each axis is now limited by the speed of the real time system on my PC, with no stalls. Thanks for the help. :) Andy -- Andy PGP Key ID: 0xDC1B5864 - This SF.net email is sponsored by the 2008 JavaOne(SM) Conference Don't miss this year's exciting event. There's still time to save $100. Use priority code J8TL2D2. http://ad.doubleclick.net/clk;198757673;13503038;p?http://java.sun.com/javaone ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Newbie Help Needed - Losing Steps
John Kasunich wrote: > Andrew Ayre wrote: >> [EMAIL PROTECTED] wrote: >>> --- [EMAIL PROTECTED] wrote: >>> >>> From: John Kasunich <[EMAIL PROTECTED]> >>> To: "Enhanced Machine Controller (EMC)" >>> Subject: Re: [Emc-users] Newbie Help Needed - Losing Steps >>> Date: Sun, 06 Apr 2008 19:46:09 -0400 >>> >>> Andrew Ayre wrote: >>>> Hi, >>>> >>>> I have a gantry style machine with three axis. The X and Y axis have the >>>> same motor and the same nut and lead screw on each). I am testing the >>>> machine using manually entered commands into AXIS such as: >>>> >>>>G01 F80 X1 >>>>G01 F80 X0 >>>> >>>> When manipulating one axis at a time (no cutting, just moving around) I >>>> have found that I lose steps at different feed rates for each axis. >>>> >>>>X - lose steps at 148 ipm >>>>Y - lose steps at 81 ipm >>>> >>> All those calculations are for theoretical limits to the step rate. But >>> the reason you are losing steps is much less theoretical. You are >>> probably running out of torque. When step motors go faster, the amount >>> of torque that they can produce drops. When the load needs more torque >>> than the motor can make, you lose steps. >>> >>> It does seem odd that the X can go faster than Y. X has to move more >>> weight (I assume that X is the gantry, and Y moves a much smaller weight >>> across the gantry). But something is making Y require more torque than >>> X, so Y loses steps first. >>> >>> Regards, >>> >>> John Kasunich >>> >>> It looks to me like Andy is using full step motion. Probably what is >>> happening is that he's hitting resonant frequencies that are a bit >>> different for each axis. The extra weight of X might even work to >>> advantage to help it cross that zero torque spot. >>> >>> Rayh >>> >> Hi Ray, yes I'm using full stepping. My next step was to switch to 1/4 >> or 1/8 microstepping. So could that actually help? I know that the >> speeds overall will be reduced of course. >> > > Micro-stepping will lower the theoretical speed, but as you've already > calculated, the theoretical speed is pretty fast right now. On the good > side, micro-stepping will mostly likely increase the torque somewhat, > especially at certain speeds where full-stepping causes resonance and > dramatically lowers torque. > Thanks for the info. The maker of the machine confirmed that the Y axis typically is slower due to different forces. Now on to 1/4 stepping... Andy -- Andy PGP Key ID: 0xDC1B5864 - This SF.net email is sponsored by the 2008 JavaOne(SM) Conference Register now and save $200. Hurry, offer ends at 11:59 p.m., Monday, April 7! Use priority code J8TLD2. http://ad.doubleclick.net/clk;198757673;13503038;p?http://java.sun.com/javaone ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Newbie Help Needed - Losing Steps
Andrew Ayre wrote: > > [EMAIL PROTECTED] wrote: >> --- [EMAIL PROTECTED] wrote: >> >> From: John Kasunich <[EMAIL PROTECTED]> >> To: "Enhanced Machine Controller (EMC)" >> Subject: Re: [Emc-users] Newbie Help Needed - Losing Steps >> Date: Sun, 06 Apr 2008 19:46:09 -0400 >> >> Andrew Ayre wrote: >>> Hi, >>> >>> I have a gantry style machine with three axis. The X and Y axis have the >>> same motor and the same nut and lead screw on each). I am testing the >>> machine using manually entered commands into AXIS such as: >>> >>>G01 F80 X1 >>>G01 F80 X0 >>> >>> When manipulating one axis at a time (no cutting, just moving around) I >>> have found that I lose steps at different feed rates for each axis. >>> >>>X - lose steps at 148 ipm >>>Y - lose steps at 81 ipm >>> >> All those calculations are for theoretical limits to the step rate. But >> the reason you are losing steps is much less theoretical. You are >> probably running out of torque. When step motors go faster, the amount >> of torque that they can produce drops. When the load needs more torque >> than the motor can make, you lose steps. >> >> It does seem odd that the X can go faster than Y. X has to move more >> weight (I assume that X is the gantry, and Y moves a much smaller weight >> across the gantry). But something is making Y require more torque than >> X, so Y loses steps first. >> >> Regards, >> >> John Kasunich >> >> It looks to me like Andy is using full step motion. Probably what is >> happening is that he's hitting resonant frequencies that are a bit different >> for each axis. The extra weight of X might even work to advantage to help >> it cross that zero torque spot. >> >> Rayh >> > > Hi Ray, yes I'm using full stepping. My next step was to switch to 1/4 > or 1/8 microstepping. So could that actually help? I know that the > speeds overall will be reduced of course. > Micro-stepping will lower the theoretical speed, but as you've already calculated, the theoretical speed is pretty fast right now. On the good side, micro-stepping will mostly likely increase the torque somewhat, especially at certain speeds where full-stepping causes resonance and dramatically lowers torque. Regards, John Kasunich - This SF.net email is sponsored by the 2008 JavaOne(SM) Conference Register now and save $200. Hurry, offer ends at 11:59 p.m., Monday, April 7! Use priority code J8TLD2. http://ad.doubleclick.net/clk;198757673;13503038;p?http://java.sun.com/javaone ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Newbie Help Needed - Losing Steps
[EMAIL PROTECTED] wrote: > > --- [EMAIL PROTECTED] wrote: > > From: John Kasunich <[EMAIL PROTECTED]> > To: "Enhanced Machine Controller (EMC)" > Subject: Re: [Emc-users] Newbie Help Needed - Losing Steps > Date: Sun, 06 Apr 2008 19:46:09 -0400 > > Andrew Ayre wrote: >> Hi, >> >> I have a gantry style machine with three axis. The X and Y axis have the >> same motor and the same nut and lead screw on each). I am testing the >> machine using manually entered commands into AXIS such as: >> >>G01 F80 X1 >>G01 F80 X0 >> >> When manipulating one axis at a time (no cutting, just moving around) I >> have found that I lose steps at different feed rates for each axis. >> >>X - lose steps at 148 ipm >>Y - lose steps at 81 ipm >> > > All those calculations are for theoretical limits to the step rate. But > the reason you are losing steps is much less theoretical. You are > probably running out of torque. When step motors go faster, the amount > of torque that they can produce drops. When the load needs more torque > than the motor can make, you lose steps. > > It does seem odd that the X can go faster than Y. X has to move more > weight (I assume that X is the gantry, and Y moves a much smaller weight > across the gantry). But something is making Y require more torque than > X, so Y loses steps first. > > Regards, > > John Kasunich > > It looks to me like Andy is using full step motion. Probably what is > happening is that he's hitting resonant frequencies that are a bit different > for each axis. The extra weight of X might even work to advantage to help it > cross that zero torque spot. > > Rayh > Hi Ray, yes I'm using full stepping. My next step was to switch to 1/4 or 1/8 microstepping. So could that actually help? I know that the speeds overall will be reduced of course. Andy -- Andy PGP Key ID: 0xDC1B5864 - This SF.net email is sponsored by the 2008 JavaOne(SM) Conference Register now and save $200. Hurry, offer ends at 11:59 p.m., Monday, April 7! Use priority code J8TLD2. http://ad.doubleclick.net/clk;198757673;13503038;p?http://java.sun.com/javaone ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Newbie Help Needed - Losing Steps
John Kasunich wrote: > Andrew Ayre wrote: >> Hi, >> >> I have a gantry style machine with three axis. The X and Y axis have the >> same motor and the same nut and lead screw on each). I am testing the >> machine using manually entered commands into AXIS such as: >> >>G01 F80 X1 >>G01 F80 X0 >> >> When manipulating one axis at a time (no cutting, just moving around) I >> have found that I lose steps at different feed rates for each axis. >> >>X - lose steps at 148 ipm >>Y - lose steps at 81 ipm >> > All those calculations are for theoretical limits to the step rate. But > the reason you are losing steps is much less theoretical. You are > probably running out of torque. When step motors go faster, the amount > of torque that they can produce drops. When the load needs more torque > than the motor can make, you lose steps. > > It does seem odd that the X can go faster than Y. X has to move more > weight (I assume that X is the gantry, and Y moves a much smaller weight > across the gantry). But something is making Y require more torque than > X, so Y loses steps first. > > Regards, > > John Kasunich > Hi John, Thanks. So does it come down to trial and error to find the limits? Yes, X is the gantry and Y is across the gantry. Andy -- Andy PGP Key ID: 0xDC1B5864 - This SF.net email is sponsored by the 2008 JavaOne(SM) Conference Register now and save $200. Hurry, offer ends at 11:59 p.m., Monday, April 7! Use priority code J8TLD2. http://ad.doubleclick.net/clk;198757673;13503038;p?http://java.sun.com/javaone ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Newbie Help Needed - Losing Steps
--- [EMAIL PROTECTED] wrote: From: John Kasunich <[EMAIL PROTECTED]> To: "Enhanced Machine Controller (EMC)" Subject: Re: [Emc-users] Newbie Help Needed - Losing Steps Date: Sun, 06 Apr 2008 19:46:09 -0400 Andrew Ayre wrote: > Hi, > > I have a gantry style machine with three axis. The X and Y axis have the > same motor and the same nut and lead screw on each). I am testing the > machine using manually entered commands into AXIS such as: > >G01 F80 X1 >G01 F80 X0 > > When manipulating one axis at a time (no cutting, just moving around) I > have found that I lose steps at different feed rates for each axis. > >X - lose steps at 148 ipm >Y - lose steps at 81 ipm > > I performed the real time tests on my PC and the theoretical maximum > feed rate for both these axis is 285.72 ipm. > > What factors could stop me from operating the Y axis at the same speed > as the X axis? > > What factors stop me from operating both axis at 285.72 ipm and how do I > adjust the ini file to compensate for those factors? > > Here are my calculations: > > -- > Set BASE_PERIOD to 12us (hold time) + 93us (PC latency) = 105us = 105,000ns > > Therefore maximum step rate is 1 / (2 x 105us) = 1 / 210us = 4,762 steps > per second > > The motor turns 200 steps per revolution. The lead screw is 5 threads > per inch = 0.20in pitch. 0.20in / 200 steps per rev = 0.001in per step. > Therefore 1 / 0.001in = 1000 steps per inch. > Maximum speed is 4762 steps per second / 1000 = 4.762in per second = > 285.72in per minute. > > MAX_VELOCITY and STEPGEN_MAXVEL for the X and Y axis should therefore be > 4.76. > The INPUT_SCALE for the X and Y axis should be 1000. > -- > All those calculations are for theoretical limits to the step rate. But the reason you are losing steps is much less theoretical. You are probably running out of torque. When step motors go faster, the amount of torque that they can produce drops. When the load needs more torque than the motor can make, you lose steps. It does seem odd that the X can go faster than Y. X has to move more weight (I assume that X is the gantry, and Y moves a much smaller weight across the gantry). But something is making Y require more torque than X, so Y loses steps first. Regards, John Kasunich It looks to me like Andy is using full step motion. Probably what is happening is that he's hitting resonant frequencies that are a bit different for each axis. The extra weight of X might even work to advantage to help it cross that zero torque spot. Rayh - This SF.net email is sponsored by the 2008 JavaOne(SM) Conference Register now and save $200. Hurry, offer ends at 11:59 p.m., Monday, April 7! Use priority code J8TLD2. http://ad.doubleclick.net/clk;198757673;13503038;p?http://java.sun.com/javaone ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Newbie Help Needed - Losing Steps
Andrew Ayre wrote: > Hi, > > I have a gantry style machine with three axis. The X and Y axis have the > same motor and the same nut and lead screw on each). I am testing the > machine using manually entered commands into AXIS such as: > >G01 F80 X1 >G01 F80 X0 > > When manipulating one axis at a time (no cutting, just moving around) I > have found that I lose steps at different feed rates for each axis. > >X - lose steps at 148 ipm >Y - lose steps at 81 ipm > > I performed the real time tests on my PC and the theoretical maximum > feed rate for both these axis is 285.72 ipm. > > What factors could stop me from operating the Y axis at the same speed > as the X axis? > > What factors stop me from operating both axis at 285.72 ipm and how do I > adjust the ini file to compensate for those factors? > > Here are my calculations: > > -- > Set BASE_PERIOD to 12us (hold time) + 93us (PC latency) = 105us = 105,000ns > > Therefore maximum step rate is 1 / (2 x 105us) = 1 / 210us = 4,762 steps > per second > > The motor turns 200 steps per revolution. The lead screw is 5 threads > per inch = 0.20in pitch. 0.20in / 200 steps per rev = 0.001in per step. > Therefore 1 / 0.001in = 1000 steps per inch. > Maximum speed is 4762 steps per second / 1000 = 4.762in per second = > 285.72in per minute. > > MAX_VELOCITY and STEPGEN_MAXVEL for the X and Y axis should therefore be > 4.76. > The INPUT_SCALE for the X and Y axis should be 1000. > -- > All those calculations are for theoretical limits to the step rate. But the reason you are losing steps is much less theoretical. You are probably running out of torque. When step motors go faster, the amount of torque that they can produce drops. When the load needs more torque than the motor can make, you lose steps. It does seem odd that the X can go faster than Y. X has to move more weight (I assume that X is the gantry, and Y moves a much smaller weight across the gantry). But something is making Y require more torque than X, so Y loses steps first. Regards, John Kasunich - This SF.net email is sponsored by the 2008 JavaOne(SM) Conference Register now and save $200. Hurry, offer ends at 11:59 p.m., Monday, April 7! Use priority code J8TLD2. http://ad.doubleclick.net/clk;198757673;13503038;p?http://java.sun.com/javaone ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
[Emc-users] Newbie Help Needed - Losing Steps
Hi, I have a gantry style machine with three axis. The X and Y axis have the same motor and the same nut and lead screw on each). I am testing the machine using manually entered commands into AXIS such as: G01 F80 X1 G01 F80 X0 When manipulating one axis at a time (no cutting, just moving around) I have found that I lose steps at different feed rates for each axis. X - lose steps at 148 ipm Y - lose steps at 81 ipm I performed the real time tests on my PC and the theoretical maximum feed rate for both these axis is 285.72 ipm. What factors could stop me from operating the Y axis at the same speed as the X axis? What factors stop me from operating both axis at 285.72 ipm and how do I adjust the ini file to compensate for those factors? Here are my calculations: -- Set BASE_PERIOD to 12us (hold time) + 93us (PC latency) = 105us = 105,000ns Therefore maximum step rate is 1 / (2 x 105us) = 1 / 210us = 4,762 steps per second The motor turns 200 steps per revolution. The lead screw is 5 threads per inch = 0.20in pitch. 0.20in / 200 steps per rev = 0.001in per step. Therefore 1 / 0.001in = 1000 steps per inch. Maximum speed is 4762 steps per second / 1000 = 4.762in per second = 285.72in per minute. MAX_VELOCITY and STEPGEN_MAXVEL for the X and Y axis should therefore be 4.76. The INPUT_SCALE for the X and Y axis should be 1000. -- thanks, Andy -- Andy PGP Key ID: 0xDC1B5864 - This SF.net email is sponsored by the 2008 JavaOne(SM) Conference Register now and save $200. Hurry, offer ends at 11:59 p.m., Monday, April 7! Use priority code J8TLD2. http://ad.doubleclick.net/clk;198757673;13503038;p?http://java.sun.com/javaone ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
