Machsupport Forum
Mach Discussion => General Mach Discussion => Topic started by: chrisinestes on May 03, 2010, 06:08:17 PM
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It's been a BAD Monday! Yeah, I pretty much just ruined 40 hours of work and $450 in materials with the problem below.
For simplicity, let's say I told my router to route a 32" x 42" rectangle. It routed the (X-Axis) 42" part at 42", but it routed the (Y-Axis) 32" part at 32.25. My artwork was correct. I had no offset for the job related to the material in VCarve Pro (it was all at 0,0). My machine 0,0 point was really at 0,0, with X,Y,& Z at 0,0,0 in Mach 3. I had the correct bit in the machine. This is a new problem, so unless something in Mach 3 changed it's self, my steps per inch should be set correctly. The controller is new to me too. It's a Soigeneris STDR-4C Stepper Drive System. I haven't had any trouble with it before, either.
Come to think of it, it seems a few things have measured differently then it was told to route, but not consistantly, and never enough to ruin any work, and I never spent the time to figure out if it was really happening, or why. The router is clean and lubed, I can't hear or see any jerking with missed stepper steps. There isn't any binding when I move each axis with the power off.
Any ideas on where I should begin to look for this problem?
I will cross-post this in a couple other places, just so as many people can see it as possible.
Thanks!
Chris
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Is this with the parallel port or SmoothStepper?
Have you contacted Jeff at Soigener?
Hood
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I just noticed you posted this here too Chris.
Since I'm not a member of the Vectric forum where he posted it first I'll copy my reply email here as it does contain some good troubleshooting steps.
Hmm…problems like this can be tough as you have to find a way to track the issue to the machine or GCode. Since it sounds like it was consistently scaling everything in the Y-axis, instead of only screwing up one place (hesitating in one place), it is probably not an issue with loosing steps or something mechanical. That would leave a configuration problem (Mach) or a GCode problem.
Is it something you can replicate easily with a simpler drawing? If you start the router at 0,0 and then jog or use the MDI line to move the Y-axis close to the full range of travel does it go the right distance? If you can post the file/gcode on the Vectirc forum I bet they can go through it and see if there is a problem there.
I would probably try testing the router with a very simple gcode program, something that just made it do a series of rectangles and return to 0,0. If it returns to 0,0 then mechanically your probably in good shape and it is more likely a gcode issue.
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Just had another thought. You might check both the X and Y axis for backlash. If you have a lot of backlash you can get interesting results at times. Do you see any stair stepping on areas where you have taken multiple passes to cut all the way through the stock?
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Just had another thought. You might check both the X and Y axis for backlash. If you have a lot of backlash you can get interesting results at times. Do you see any stair stepping on areas where you have taken multiple passes to cut all the way through the stock?
I don't see any stepping on the routed edges. I don't find any backlash greater than about 0.001 in the X & Y axis, and about 0.005 in the Z Axis (which has been there since it was new)
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What are we dealing with here, is it a parallel port system or a SmoothStepper one?
Have you tried doing a single axis move back and forth many times, say 40 or 50 and at the end seeing if the axis is where it started from?
Hood
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What are we dealing with here, is it a parallel port system or a SmoothStepper one?
Have you tried doing a single axis move back and forth many times, say 40 or 50 and at the end seeing if the axis is where it started from?
Hood
It's a smooth stepper. I have a STDR-4C Stepper Drive System from Jeff @ Soigeneris. I did run the Mach 3 Axis calibration utility 10 or so times per axis and it always came back to within 0.001 to 0.002. which is as close as I can measure. I will set up a simple program that will run an axis back and forth 50 ish times and see where it ends up at the end. I just sent my spindle is off to get bearings, so I can't actually route right now.
Thanks!
Chris
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Can you take attach your xml please, may be a problem in it.
Hood
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Can you take attach your xml please, may be a problem in it.
Hood
Sorry, I'm not fully up on the tech speak. I don't know what you're asking for.
Chris
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Ok the xml is the file that has all of your config settings and is a file you should really have backed up just in case things go bad.
The xml will be in the main Mach 3 folder on your drive, if you use the standard mill profile it will be called Mach3Mill.xml if you use a custom profile it will have the name of that custom profile.
To attach to the forum you will need to copy it to your desktop (or some other location) and rename it, suggest you call it chrisinestes.xml You can then use the additional options button on the reply page to attach it.
Hood
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Oh... okay, I know what that is... just didn't know wht it ws called. How do I post it without it taking up so much space here? Or should I just paste it into this window?
Chris
I got it! Here it is.
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Bit curious, your steps per unit seem quite course, how are the axis driven, presume a rack of some sort as you have for example the X axis at 2035 steps per inch and your motors will be 2000 steps per rev so your axis must move almost 1 inch per motor rev
In the SS config I would reduce the Step Frequency to 32KHz for all axis, this probably wont make any difference but you never know. Reason to reduce is with your steps per unit and velocity in motor tuning the fastest axis (Y axis) is only requiring 12KHz.
Hood
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Bit curious, your steps per unit seem quite course, how are the axis driven, presume a rack of some sort as you have for example the X axis at 2035 steps per inch and your motors will be 2000 steps per rev so your axis must move almost 1 inch per motor rev
In the SS config I would reduce the Step Frequency to 32KHz for all axis, this probably wont make any difference but you never know. Reason to reduce is with your steps per unit and velocity in motor tuning the fastest axis (Y axis) is only requiring 12KHz.
Hood
All of the Axis' are driven through a gear & belt system. None are connected 1 to 1 to the steppers. I'll look in to the step frequency thing.
Thanks!
Chris
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Hood, Chris's router is a quite interesting commercial built unit. The X-axis is driven by one humongous 950 oz-in (as I recall) stepper through a belt reduction, sent to both sides of the gantry with a cross shaft which has timing pulleys fixed to the ends that drive fixed (wide) timing belts. It pulls itself along the belt. Consequently the steps/unit is quite low but the big stepper has lots of torque at those low speeds.
Chris says the Y-axis was cutting long, he recalibrated the steps/unit for each axis with the Mach axis calibration tool and it is coming out quite close now. I'm anxious to see how things go when he gets his spindle remounted.
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Sounds interesting and likely accurate enough for a router.
Can a 950 ozin stepper be run from a G540? would have thought the current requirements would have been too much to use the full torque potential of the stepper.
Hood
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Can a 950 ozin stepper be run from a G540? would have thought the current requirements would have been too much to use the full torque potential of the stepper.
That was my first reaction too, when Chris said that Gecko recommended a G540 to him. Then as I researched the original controller/stepper driver he had I realized that the G540 was heaps a lot better then the OEM stuff. As I recall the motor was already wired in series with a resulting current requirement that fell within the G540's range. You cannot get the maximum performance out of the stepper as if you could as if it were wired in parallel with a higher current driver or with a higher driving voltage but it does provide all the power needed for the application.
I just thought the design was interesting and a but unusual, but it seems to work well. Since we typically get all worked up about getting every last drop of performance out of a stepper motor it is kind of interesting to see a design that 'under drives' a large stepper to provide the power needed for the application with a more modest driver.
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Would be good to see some pics of it :)
Hood
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Chris I had a problem on my milling machine with a sudden ambient temperature change a couple of times, don't know if that helps, but I agree that checking your tuning is important, I found that checking on short moves is not as accurate as checking on repeated long moves, I also had a unexplained change in my .xml once and had to use a .xml backup from a couple of days back when things were good. Read your Mach3 manual about .xml's JD
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Hood,
Here's a couple pics of my machine with the covers off the gantry.
(http://i872.photobucket.com/albums/ab289/chrisinestes/XAxisdrive1.jpg)
(http://i872.photobucket.com/albums/ab289/chrisinestes/XAxisDrive3.jpg)