Tumbler engraving on rotary is not holding proportion

I have an 80w chinese laser and using a mansfield customs rotary. When burning a 10x10mm square, I get the width at 10, but height at 22mm instead of 10. Another issue when testing the rotary is that it overshoots 360 rotation, but does come back to the exact start. We’ve tried adjusting the steps per rotation from 4100 or 2050 but both yielded the same results.

Wheel diameter are set to 42mm. Cup size for Polar 20oz tumbler is 89mm. Machine 80w red and black, ruida control.

It’s not steps per rotation, it’s just rotation diameter. I forget the correct term, but you have to set a new calibration distance for the rotary. It obviously has a different ratio that your machine, and that’s before you take into account the circumference of what ever you are engraving.

Save / backup your settings, then run a calibration for the rotary. You already have 10mm = 22mm. Some controllers will let you save rotary and non rotary dimensions, others you have to save your settings with and without the rotary and load the appropriate file.Worst case, there’s always pencil and paper…

You have 4 points of gearing:

Just forget the complexity of this because what matters is the steps per rotation and that roller the object is resting on. Steps per rotation and the roller diameter are the two adjustable values to play with to dial in this type of rotary. Independently, neither one of them have to be technically correct. The two values just need to work together to calibrate the movement.

Plug in an accurate diameter for your test object, then go to work with the steps per rotation and roller diameter. (Also make sure you have enabled the rotary in Lightburn AND enabled the rotary on your machine usually by way of a switch that transfers the driver to a panel mounted plug).


Thanks for the feedback! I did a million iterations in this area and nothing changed the results.

uh… not so true for a roller rotary you only have to use the steps / rotation, diameter is only used to determine the amount of space you have on your object, once you have the right number of steps/revolution you never have to touch that again

What is not true? If you’re referring to my post, I advised that he adjust steps per rotation and roller diameter effectively until those values result in a calibrated scale. Once set, those values should never be changed.

Indeed I did not read your post correctly.

Are you sure you have enabled the rotary?

And if the result is 2.2 times as long as your wanted you need to devide your steps through 2.2 and you will be set. If the result does not change I fear you did not enable the rotary (or LB did disable it after a communication error which I noticed today)

Positive, rebooted the machine and mac a few times and double checked to make sure it saved settings and it did. I was able to make the logo, just had to distort the logo in lb to make it work right.

If you have enabled rotary in Lightburn, plugged the rotary into the panel mounted connector on the machine, and toggled the machine’s switch to rotary then the only answer here is to adjust steps per rotation or roller diameter within the rotary setup.

Although the values you have entered were provided by the manufacturer and may even be engraved in the rotary itself, they’re wrong according to your result.

Deeper into the equation, there are other factors that could have changed from those provided specifications e.g., the steppers and stepper driver for your Y axis which then in turn would possibly have changed the dip switch assigned Pulse / Rev on the driver (this completely changing the steps per rotation on the stepper motor on the rotary) OR maybe the motor used on the rotary was changed to a different model.

Dial in the values for steps per rotation and wheel diameter until it is accurate. Just to prove / show the affect of the change to the steps per rotation, go ahead and make a significant change to the current value. Double it or half it. You will see that by adjusting this, the rate at which the rotary spins will change.

@stroonzo I have this EXACT rotary and having a similar issue. Engraved on my rotary it says 4100mm for steps per rotation, however seeing this picture & also the screen from bearded builds who has his at the same 360, Im wondering if that is my issue as well. I am getting 5" engravings on a 3" image.