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
 

Is this with the parallel port or SmoothStepper?
Have you contacted Jeff at Soigener?
Hood

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.

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?

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)

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

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

Can you take attach your xml please, may be a problem in it.
Hood

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

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