Re: [Emc-users] Trouble with EMC spiral example
Jeffrey Pease wrote: I have no explanation for why this glitch is occurring in these spots, and no real idea how to fix it. Any ideas? My machine is using steppers and lead screws. Running EMC2 on Ubuntu 8.04. Sebastian Kuzminsky wrote: Which version of emc2? EMC2 2.2.8 What hardware is driving your steppers? I'm using the EZ Driver Board from HobbyCNC.com. Perhaps more usefully, this board uses SLA7078MR stepper drivers, datasheet here - http://www.datasheetarchive.com/pdf-datasheets/Datasheets-29/DSA-575103.pdf My board is configured for single stepping on all axes. What config are you using? What are your latency numbers like? 17901 ns latency, measured over almost an hour of messing around on the machine. I have both dirhold and dirstep for each motor set to 37901 based on the tuning info found in Chapter 28 of the Integrator manual. Hope that helps. Sorry, I know this is probably a tough issue to visualize as explained. Any suggestions would be appreciated. Thanks, Jeff Hi EMC, I'm tuning my machine, and I am having some weird problems with the EMC spiral example. This issue is entirely repeatable, and seems to happen without fail regardless of any feed rate, acceleration or speed settings that I have tried. What happens is on a particular place in every arc, the X and Y axis both seem to stutter in the same way - pausing for a second before continuing to finish the arc. This occurs in the area of the arc right before each axis changes direction to start drawing the other half of the arc - so the X axis stutters at 2:30, 3:30, 8:30, and the 9:30 hour positions (the extreme left and right sides of each arc of the spiral) and the Y axis stutters at 12:30, 5:30, 6:30 and 11:30 (the extreme top and bottom of each arc). This strikes me as an unintuitive spot for this stuttering to occur for each axis, since it seems like the actual movement required at these points in each axis is relatively small - once everything speeds up, it seems fine again. I have lubricated all the guide rods and lead screws (thinking it might be some sort of binding issue), but that has not helped. The spiral appears to be perfectly smooth in these areas on the EMC preview, so I don't believe it's a programming issue. I have no explanation for why this glitch is occurring in these spots, and no real idea how to fix it. Any ideas? My machine is using steppers and lead screws. Running EMC2 on Ubuntu 8.04. Thanks, Jeff -- -- ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Trouble with EMC spiral example
Are you using backlash compensation? If so, what is your backlash compensation speed? Les Jeffrey Pease wrote: Hi EMC, I'm tuning my machine, and I am having some weird problems with the EMC spiral example. This issue is entirely repeatable, and seems to happen without fail regardless of any feed rate, acceleration or speed settings that I have tried. What happens is on a particular place in every arc, the X and Y axis both seem to stutter in the same way - pausing for a second before continuing to finish the arc. This occurs in the area of the arc right before each axis changes direction to start drawing the other half of the arc - so the X axis stutters at 2:30, 3:30, 8:30, and the 9:30 hour positions (the extreme left and right sides of each arc of the spiral) and the Y axis stutters at 12:30, 5:30, 6:30 and 11:30 (the extreme top and bottom of each arc). This strikes me as an unintuitive spot for this stuttering to occur for each axis, since it seems like the actual movement required at these points in each axis is relatively small - once everything speeds up, it seems fine again. I have lubricated all the guide rods and lead screws (thinking it might be some sort of binding issue), but that has not helped. The spiral appears to be perfectly smooth in these areas on the EMC preview, so I don't believe it's a programming issue. I have no explanation for why this glitch is occurring in these spots, and no real idea how to fix it. Any ideas? My machine is using steppers and lead screws. Running EMC2 on Ubuntu 8.04. Thanks, Jeff -- ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users -- ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Trouble with EMC spiral example
Les wrote: Are you using backlash compensation? If so, what is your backlash compensation speed? Les No, no backlash compensation (at last not that I know of - I guess it's possible that stepconf snuck something in though). My lead screw nuts are of the anti-backlash variety, so I am not doing anything special for backlash in software. Thanks, Jeff Jeffrey Pease wrote: Hi EMC, I'm tuning my machine, and I am having some weird problems with the EMC spiral example. This issue is entirely repeatable, and seems to happen without fail regardless of any feed rate, acceleration or speed settings that I have tried. What happens is on a particular place in every arc, the X and Y axis both seem to stutter in the same way - pausing for a second before continuing to finish the arc. This occurs in the area of the arc right before each axis changes direction to start drawing the other half of the arc - so the X axis stutters at 2:30, 3:30, 8:30, and the 9:30 hour positions (the extreme left and right sides of each arc of the spiral) and the Y axis stutters at 12:30, 5:30, 6:30 and 11:30 (the extreme top and bottom of each arc). This strikes me as an unintuitive spot for this stuttering to occur for each axis, since it seems like the actual movement required at these points in each axis is relatively small - once everything speeds up, it seems fine again. I have lubricated all the guide rods and lead screws (thinking it might be some sort of binding issue), but that has not helped. The spiral appears to be perfectly smooth in these areas on the EMC preview, so I don't believe it's a programming issue. I have no explanation for why this glitch is occurring in these spots, and no real idea how to fix it. Any ideas? My machine is using steppers and lead screws. Running EMC2 on Ubuntu 8.04. Thanks, Jeff -- ___ Emc-users mailing list emc-us...@... https://lists.sourceforge.net/lists/listinfo/emc-users -- -- ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Trouble with EMC spiral example
steppers do go quiet on spiral as there is little to do in places Dave Caroline -- ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Trouble with EMC spiral example
What is your threading TPI on the lead screws. In addition, have you tried different stepping rates (1/2 or 1/4)? I have the HCNC Pro Rev 1 board (basically the same as yours + Idle Current Control). I currently use 1/2 stepping with 10tpi acme threads and have not noticed any similar issue. As Dave noted, you are approaching the point on the spiral where the movement on a given axis is at a minimum. With the full step and a low thread count, you might be encountering a detent on the motor perhaps? Brian -- ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Trouble with EMC spiral example
Hi Brian, As Dave noted, you are approaching the point on the spiral where the movement on a given axis is at a minimum. With the full step and a low thread count, you might be encountering a detent on the motor perhaps? Bingo, I think that nailed it. I was running 5 tpi lead screws at full step with 200 step/rev motors. I changed each of these to 1/4 step it it seems to run MUCH smoother on the spiral. It seems sort of obvious in hindsight, but it didn't occur to me that any loss of precision from running full step would actually make that perceptible of a difference in the stuff I do with my lowly hobbyist setup. I'm glad I picked the spiral as my test exercise as otherwise I might not have caught this and would have been pretty frustrated when making actual projects requiring any precision, I think. This is my first machine so I'm still getting a feel for the tradeoffs between low and high tpi leadscrews. I'm still running it through its paces, but so far it's a night and day difference. Thanks a lot! Jeff -- ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Trouble with EMC spiral example
Given this is a hobby machine, the 5TPI while sexy could lead to this type of thing. I use 10TPI on a 2'X4' work surface and can get 120IPM but stick to 90ipm due to slop in my machine. If your carving out templates from large sheets of 1/4 MDF or the like, then 5tpi is the way to go, otherwise, its an accuracy and speed versus actual needs. Good luck. -- ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
[Emc-users] Trouble with EMC spiral example
Hi EMC, I'm tuning my machine, and I am having some weird problems with the EMC spiral example. This issue is entirely repeatable, and seems to happen without fail regardless of any feed rate, acceleration or speed settings that I have tried. What happens is on a particular place in every arc, the X and Y axis both seem to stutter in the same way - pausing for a second before continuing to finish the arc. This occurs in the area of the arc right before each axis changes direction to start drawing the other half of the arc - so the X axis stutters at 2:30, 3:30, 8:30, and the 9:30 hour positions (the extreme left and right sides of each arc of the spiral) and the Y axis stutters at 12:30, 5:30, 6:30 and 11:30 (the extreme top and bottom of each arc). This strikes me as an unintuitive spot for this stuttering to occur for each axis, since it seems like the actual movement required at these points in each axis is relatively small - once everything speeds up, it seems fine again. I have lubricated all the guide rods and lead screws (thinking it might be some sort of binding issue), but that has not helped. The spiral appears to be perfectly smooth in these areas on the EMC preview, so I don't believe it's a programming issue. I have no explanation for why this glitch is occurring in these spots, and no real idea how to fix it. Any ideas? My machine is using steppers and lead screws. Running EMC2 on Ubuntu 8.04. Thanks, Jeff -- ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Trouble with EMC spiral example
Jeffrey Pease wrote: I have no explanation for why this glitch is occurring in these spots, and no real idea how to fix it. Any ideas? My machine is using steppers and lead screws. Running EMC2 on Ubuntu 8.04. Which version of emc2? What hardware is driving your steppers? What config are you using? What are your latency numbers like? -- Sebastian Kuzminsky -- ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
