Does steps per rotation change from part to part?

I’ve been getting inconsistency with results on rotary projects. The culprit appears to be (or my ability to influence the end result is through) the steps per rotation. I originally thought this was a constant value that never needed to be modified once set and changing the diameter entry in the rotary was the way to influence it. I’ve been speaking with Omtech support and they advise that it might change depending on sizes. To me this just isn’t sitting well. I’ve read conversations that advise one single value is all that is needed.

Is there anyone out there that regularly has to calibrate their steps per rotation before each time you use it? Typing that out seems even more nuts now that I say it. The only way I can do this is to apply some tape to the cup or whatever and measure that the dimensions line up properly before each time!? Something seems fishy.

please just give a yes or no if you have a sec

I should mention, I say lately, but I’ve barely used my rotary since purchasing. It isn’t necessarily something that just started…

mm per rotation should stay the same. It is the steps needed to complete one revolution of the rotary device. Diameter of object doesn’t matter.

However, what I do change is the “Object Diameter” or “Circumference”. That number needs to change according to the diameter of the item being lasered.


Thanks for this Tim, I kind of figured. Wonder if anyone else has had this problem. I swear something is wrong with the controller. I burned these two sides the other day on an engraved cup, doing nothing other than flipping the cup and framing it. Obviously something going wrong.

Would love to hear if anyone has in fact seen this before.

I have always needed to change the steps using a roller rotary for different size objects. I just do a quick check with some tape and 2 lines 80mm apart. Line up the laser to one of the lines then use the move window to move the rotary 80mm and if it stops on the second line it’s good.

This is just my experience. Others say it shouldn’t change but they don’t have the rotary I have.

I always change the object diameter as stated above but it doesn’t seem to work with a rotary for me.

Craig Bondy


Jeff, can I ask what rotary unit you use? Thanks for the input, it helps me with this

This is the proper setup for a rotary…

It’s digital to the stepper motor drivers and they should also produce a digital step rate.

If set for so many steps/rotation, it means the motor will rotate one complete turn for that many steps… This does not change… it should always turn one complete rotation… that’s how come digit stuff works or fails miserably…

Using a chuck type, where the chuck is directly driven by the stepper motor, if one rotates properly so will the connected chuck…

What can add a slightly analog variable to the system is a pulley/gear ratio and for a wheel type the driving wheel diameter. There are these pulley/gear drives some chuck types, but they are in all wheel or roller type that I’ve seen…

With a wheel type, you need the ratio X steps/rotation on the motor driver for the Lightburn gui along with the driving wheel diameter.

I’ve used this on both of these setups on my rotaries for my co2 and fiber… they don’t seem to exhibit anything really unusual…

I have a PiBurn 3 and an M80 chuck type that I got with the fiber… I have interchanged them with the above changes to steps/rotation and they seem to be fine.

It would be nice to know if you are using a chuck or wheel type rotary… When discussing these the best is to have a link so we can see what you have…

How can this possibly occur?

The math says no… poor setup maybe…?

Even more likely, with a chuck, is precise diameter measurement…

Other things can influence rotation… if you need to move the rotary a certain amount and the turns out to 2.3343 steps… it’s not going to happen… you will probably get 2 steps as it can only step not portions of a step…

@Thelaserjacks your mug appears to be slipping… Why too large of an error for what I’ve been talking about… even with a chuck… that’s excessive.

That’s what I get when I move an object too fast, it slips on the wheel/roller… if you have a chuck we have to look elsewhere…


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I used to use a rotary from Mansfield customs. My steps per rotation were roughly 5300. Depending on the cup diameter I would adjust +/- 150 to get the exact size I needed. I’m now using a chuck style and the software calculates this now.

I didn’t read your entire post and if all you did was flip the cup and it came out different I would suspect slipping as @jkwilborn stated.

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Jack I understand what you are thinking but the image I’m getting on other attempts is the same thing, only everything seems more compressed as well.

It is a roller version.

I’ve actually got a really good guy helping me through this now.

The crashing into the side of the machine is what has me most concerned now, however I haven’t really used it much since the reset either…


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