In a nutshell, it basically works, but the setup in Lightburn is rather puzzling. For a “roller” type, you’d think it would only require either the diameter or the circumference of the roller to calibrate it. The distance of the surface of whatever object set on the rollers would move the same distance under the laser, regardless of the diameter.
In light burn, there are two parameters in the roller rotary setup. One is “mm per revolution”, and the other is “Roller diameter”. Using a digital caliper, the rollers on the FoxAlien R42 are 26mm in diameter, which equates to a circumference of “131.947”. If I set the “mm per rotation” to 131.947 and the “Roller diameter” to 26mm, the output is way off. It rotates the object way further than it should. I’m using an object with a diameter of 42mm to test with, and it rotates roughly twice as far as it should.
I experimented with the “mm per rotation” value, and if set to 39.70, the engraving comes out spot on. I would think that if the roller diameter is setup correctly, there wouldn’t be a need for the “mm per rotation” parameter. Either value by itself would calibrate the roller movement.
I just spent more than an hour Googling the issue as well as searching the Lightburn forum. The examples I found are for older versions of Lightburn and the parameters in the rotary setup screen vary quite a bit.
Mm per revolution is basically the distance required to rotate the roller one full turn. You still need roller diameter to then determine how much linear travel is made for one rotation.
Thanks! But! Plugging 81.681 into the “mm per rotation” field and 26mm roller diameter, the object rotates way too far. My circumference of “131.947”in the original message is incorrect. That’s the circumference of the smaller oject.
I experimented with two different objects. One is 131mm in circumference. The other is 378. I placed two 5mm horizontal lines on the grid, positioned them 131mm apart vertically, and offset them left/right so that they wouldn’t overlap. Using 39.52 for “mm per rotation” and 26.000mm for “Roller diameter”, the two 5mm lines lined up perfectly. I had to play the Price is Right “Hi/Low” game to get the 39.52 value dialed in. I then did the same thing with the 378mm circumference object, and the lines again lined up perfectly.
I also looked at the pulleys used on the FoxAlien R42 unit. They used the same pulleys on the rollers as they did on the stepper motor, so that should provide a 1 for 1 match on the rotation between all three rollers.
So, I still need an explaination for the “mm per rotation” and “Roller Diameter” fields. In my mind, you should only need one of those values to get the rotation needed to have the image scaled properly on the object. The fact that using “39.52” and “26” just doesn’t make sense.
Did you read through the entirely of the other Topic? It’s explained there.
Roller diameter is pretty straightforward. It’s needed to know the circumference (linear distance) of the roller.
The mm per rotation is needed to understand how to rotate the roller one turn. Don’t think of it as a specific length of travel. The reason this is required as it may take a different input distance to get the roller to turn a full turn depending on multiple factors.
You then need both so that you can determine how much linear travel is happening based on a certain amount that the roller is turned.