Rotary Image distorted - steps per rev tests perfect

60 watt laser with an omTech 4 wheel 360 degree rotary. The rotary is setup and correctly testing in the rotary setup tool - steps per rotation, roller diameter and circumference all set - and tests correctly. When engraving tumbler the image is distorted. When I frame an image it appears correct, I have taped off the cup and measured the dimensions out and it frames exactly. However, when I run the job the image is always distorted (squished) as if the steps per rotation were way off or the rotary was not enabled. Any thing further to try?

I don’t know how you set it up, so I can’t help much for what you did.

I’m suspicious when the test works in the gui, but the art isn’t doing what you asked.

What are you values, in the laser window, for Start From and Job Origin?

Might want to post the .lbrn2 file so we can look …


Start from ‘User Origin’. laser head set to top lip of tumbler. Job Origin is right center. Image is circle logo that I have attached.
rycon_Logo.lbrn2 (82.1 KB)

This is how it cuts.

You set up the mug with head over the lip and press origin?

Why do you mention circumference? It’s not needed for wheeled rotaries, only good to know for layout purposes…

When you press test, does the drive wheel on the rotary make one complete turn and back?


Yes - question 1- laser at mug head at lip and press origin, Yes - question 2- Wasn’t sure if circumference made a difference on the test so I set it and as I stated the Rotary Set up test is good, i.e. one full rotation to start mark and back to start mark correctly - it took a few ties to get the steps per rotation correct.

How could this be wrong?

It’s on the placard of the motor driver…

Where did you get steps/rotation?

Here is the basic setup… is this the procedure you used?


Turns out is was all caused by slippage on the drive wheels. There was a light coating of oil on the rubber drive wheels that was causing the issue. All good after a cleaning with alcohol.
Thanks for all input,

Glad you figured it out… the advantage of a chuck rotary is you can spin it back and forth and still have alignment… with a wheeled variety, you’re stuck with a much less reliable drive mechanism… rubber + gravity to object…

I have a PiBurn 3, it has an extra arm to put pressure inside the object…

It’s almost impossible to get a vector engrave with it, even with low acceleration values.

Have fun…


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