Grid rows engrave offset from above row when using rotary

50w blue/white Chinese laser with Ruida controller…

I’m trying to use a rotary to engrave a 10x10 material test array/grid on a tumbler/cup. It looks good in the Lightburn preview, but engraves each row offset by about 1/3 of a column compared to the row above it.

I don’t know what I’m doing wrong because I’ve spent half a day trying every setting I can find. At this point I can’t find anything I haven’t tried so I’m just trying stuff again. ANY suggestions would be appreciated.

Is this a new rotary you having issues with.?

If so, how did you set it up?

If not, what has changed and how?

Can you show (photo) or describe how it setup on your machine… a link to the rotary would be nice…


To save time i dropped the test grid with filled boxes and changed to lines. I also adjusted the steps/rotation. I did two test patterns and thought i had the problem solved but once i changed the boxes from lines to fill everything seems to have randomly moved around.

It looks like it’s slipping on the rotary…

Did you make any change to the controller settings when you switched to the rotary other than the rotary enable.?

Why? Once set you should be golden and no need to ‘fiddle’ with it.

What procedure did you use to set this up?


The rotary came with the used laser, or should I say previously purchased laser, I don’t think the guy had a full hour on the machine. We have played with doing a beer glass once before and it worked fine, but it was just a simple image we engraved and we had stretched it 20% to get it to come out about right (according to things we read on the facebook groups). This is the first time I’ve really played with it.

I can’t find the rotary online, except in this thread…
It’s a 200 step motor. The dip switches on the driver are set to 2000 pulses/rev. Motor gear has 20 splines and the roller gear has 32 spines. According to my math, that puts one revaluation at 3200 pulses. Does that sound correct? At 3200 my 1" wide grid comes out exactly 1" wide.

I added a layer of friction tape to the rollers and adjusted the dia. in Lightburn. But the grid was still engraving with the bottom row not not spaced correctly. I changed the settings to engrave all shapes at once and it seams to be working perfectly. I added a box around the grid with the same dimensions as the outside edges of the grid. I wanted to see if it is getting off as it runs, but when it finished filling the grid it came back and cut the outside box dead on the edges of the grid.

So, barring more problems when I start running more complicated designs, I think it’s working now??? But should I have to use the engrave all shapes at once option or is that just a band-aid that won’t always work?

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Oh yeah, here’s a picture. Notice how the bottom grid and top grid have the bottom row compressed compared to the other two? That bottom left box is where it starts, it does the first row then comes back for the 2nd row then 3rd. But it offsets that bottom row! Setting it to fill all shapes at once gave me the middle grid, which is white because I turned the power down as well.

How is the rotary setup?

Screenshot from 2022-04-05 10-11-46

Which diameter did you change ‘roller’ or ‘object’, how much, why?

What kind of speeds/accelerations are you running? You are obviously aware of the issue…


I changed the roller dia because the friction tape increased the dia. The calipers were reading about .97" without the tape and 1.100 with the tape.

Now I’m just wondering if it’s normal to have to use the "fill all shapes together " setting when using a rotary, or am i going to still have issues when i do more complicated files?

I can’t see how you are actually doing the machine.

Vector cuts are tougher because there is a tendency to ‘out’ accelerate the grip on the mug, as you have obviously experienced.

I usually ‘scan’ the image, rotating the cup as slow as possible with the X axis doing the moving. Here is how it’s setup. The X axes does most of the moving.

All this is going to cause is a very slight change in the width of the image. Probably undetectable with your eye.

Once set, you should be good…

I’ve reduced most of the speeds, but you pay for it in time to get to speed. Don’t use any of the X acceleration values…

Good luck


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I don’t know that I ever knew what the problem was. I just kept tinkering with everything I could think of that might have somehow be causing the issue. Reading your post last night gave me a couple of ‘lightbulb’ moments, and I think I have a decent grasp on the situation now.

I’m so used to trying to make everything I can vector lines to speed up the process and save the machine from all the many extra direction changes you get by when you fill a line rather than cut a line, for lack of better terminology. It makes total sense, after reading your last post, that I would want to scan the entire image and not have any vectors.

Also, I played with slowing my layer speeds down because I’ve recently tightened a belt that was keeping me from running over 100mm/s or I’d get farther and farther off the longer the laser ran on a file. So I wanted to make sure that wasn’t an issue again. But I never thought about the acceleration speed, or even how to change it. So THANK YOU for that tip!

I think I’m good to go now. I’ll know for sure tomorrow when more cups get delivered.

Thanks again!

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I’ve tried and have had some success with vectors, but everything has to be slowed down.

This is one of my videos from the past of a cup in the PiBurn rotary doing vectors. some of the issues are pretty obvious… the main one… how ‘slow’ it’s running…

My power levels were about bottomed out…

Good luck


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