Gap with rotary chuck

do you know why he produces this gap?
the problem this product with the rotary axis.
I have a chuck as a rotary axis.
My engraver is a red and black 100w with a ruida controlor rdc6442s-b (ec).
I replaced the driver and the step motor.
Same problem.
I am using version 9.04.
the problem does not occur each time but less often with RDWork.
I am looking for a solution, do you have an idea?


What does this job look like in the ‘Preview’ window? Are you seeing this gap? Does it happen in the same location each time? And does this happen in the same location when running the job from RDWorks?

I do not see the gap in the window “preview”. when this happens if I do not change anything. it’s always in the same place. that’s why I suspected the engine.

And in RDWorks? Is this gap happening in the same place if you run the job from RDW?

I would say yes. Look, I have another example. it’s still almost at the end.

If this is happening in both LightBurn and RDWorks and not showing in the ‘Preview’ window, that would indicate slippage or a mechanical/hardware issue.

Do you see this happen when running this job as a test on a flat surface, not using your rotary?

no and that’s why I changed the step motor. If I had an idea let me know. meanwhile I will change the cable between the driver and the step motor, to try something. Thanks

Have you checked that 10000 is the correct number of steps for your rotary?

If you do a test with a cardboard tube, for example, and draw two lines that are ‘circumference’ mm apart, do they draw on top of each other?

(I hope the question is clear - if not, I can describe better)

I have the cardboard tubes. I do not really understand what you want me to do with it. can you draw me a picture? I send you the setup of my driver.

The switches show that the motor driver uses 5000 steps per rotation. Is there a pulley or gear reduction between the motor and the rollers? If not, you would need to change that setting from 10000 to 5000 in the software.

In the rotary setup dialog, LightBurn has two values, Object Diameter and Circumference. If you take an object that is 50mm in diameter, the circumference would be 157mm (roughly) - The software will tell you the exact circumference for your object diameter.

If you create a file that is a rectangle whose Y height is exactly the value of the circumference, and you ‘cut’ the rectangle, the top should perfectly meet the bottom (they should touch exactly, no gap between the ends, and no overlap). If the ends don’t meet, or they overlap, either the diameter number is wrong, or the steps per rotation number is wrong.

I just want you to verify that these numbers you have displayed here are correct, because if you’ve never set this up for your rotary or motor driver, they could be wrong, and that could explain this result.

there is actually a reduction pulley between the engine and the chuck. here is the result of the test.


forget the test before my chuck was not squeezing enough.

That looks correct. I would check to make sure that the glass is held properly as well - if it slips on the chuck at all you could get gaps or overlaps. Are you holding it in place with anything sticky, like rubber pads? Glass itself is very slippery and hard to hold securely otherwise.

I will redo tests. yesterday I engraved the logo 8 times on a cardboard tube and no problem. I also added some grounding on the chuck. can also be a pulse of static could blow step to motor. Thanks a lot for your help. I will keep you informed.

Are you holding it in place with anything sticky, like rubber pads?

FWIW, one layer cut from a flat rubber band can be wrapped around the flat section of the teeth of the jaw chuck insert and then tied off on the back side to give the jaw better grip. Since you stretch it thin before tying it off, it is thin enough to not affect most calculations. A thin coat of rubbery plasti-dip or similar is another option.

The problem is that if he had slipped. I had an overlay and not a gap.

hi Oz, I did another test and I still have the same problem. with this logo, he always jumps to the same place. do you want to have the .lbrn file. maybe you could see?


Did you try copying the file over to the machine and running it from there?

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