Just ran a small part at 2IPM acceleration and 10IPM speed. No change. I am going to put a link to a couple pics shortly.

IF you have changed out teh drives and motors and cables with no change then I would suspect the Smooth stepper acting up. DO you have a spare to test ?

NOW the odd part is IF it skews but yet returns back to exactly zero  

(;-) TP

No. I will have to wait to order one on Monday. I am suspecting the SS as well.

I just ran a test of circles and squares graduating outward from a center point at 800IPM cutting speed and .125 deep in MDF in one pass. My Acceleration was set to 60 IPM and velocity set at 1800IPM. The rapid was set to 1400IPM fixed. I made the machine travel to the end of the X and Y axis in the part file with a G0 move and then did a rapid reposition to the center of a 12" by 12" by 3/4 scrap I wanted to test on. The cuts came out glass smooth without a flaw in the circles or squares and not a bit of jitter in the machine. I pushed it real hard and no missed steps...

I am so confused. If it can do that then why is it doing what it is on relief cuts? I am going to go with the Ethernet SmoothStepper next week and see if this resolves the issue. I used one on a friends upgrade and was super pleased. Maybe this is the issue.

PROBLEM SOLVED. You were right in that is was SmoothStepper related.

I share this in hopes it helps anyone who may be using SS and having scaling or resolution issues.

The one thing I did not check is on the SS plugin config page; the controller and pulse frequency settings. For some reason they were all way too high. I did the math and set them to values that met my needs and the problem vanished. I am not too sure why this would have caused the issue and I hope someone can chime in and explain but I do know it fixed the problem.

To confirm this was the issue I put the settings back to the larger values and the problem happened again. I tuned them again to the proper values and ran the test again with no issue.

Thanks so much for helping to figure this out. The machine is running great and I am getting very fast speeds and excellent cuts on both standard and 3D models!