Rotary framing does not return to origin

Working with a new Thunder Laser w/ Ruida controller trying to calibrate steps/rev under tightly controlled conditions, I discovered that if you frame a rectangle about the height size of the circumference of the object, the origin doesn’t return exactly to the starting point. Without touching anything, a few more framing operations reveals that the origin drifts. Steps/rev, diameters of drive wheels, etc. have no effect on remedying this issue. It should be noted that the object is a perfect cylinder, no tapers. The rotary device is new, solid, nothing appears to be slipping or unusual noises. The belt drive and pulleys are ribbed.

Any help with this issue would be most appreciated.


Have a read through the posts below and let us know the results, and we can go from there.

Sorry, the posts do not address the problem. Ignoring the actual steps/rev number, I expect the framing function to return to exact center each time. It’s as if Lightburn is counting steps differently depending on direction, hence the drift.

On my setup, this problem has always been caused by too high acceleration on the axis. Have you tried the same test with accel and speed really slow to see if you see the same problem? You can work the numbers back up from there. It’s never really the top speed, but the accel generally.



Thanks for the suggestion. I will see what I can do to adjust the acceleration value on the rotary axis and report back.

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I made adjustments to the acceleration and maximum speed values and the problem persisted. During all of my testing, I noticed that the rotary device drive wheels appeared not perfectly aligned with the idler wheels (almost imperceptible). I took the object off of the rotary device and marked the pulley of the stepper motor and selected that point as my new origin. Framing this point multiple times showed that the stepper pulley returned to it’s starting point perfectly each time. So, my issue all along was mechanical instead of software related. I have a new issue to address but at least I know where the problem lies.

Thank you for offering this update and glad to hear you are sorted. :slight_smile:

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