Want to try Rotary Axis, possible to hack together before investing more time?

Hey Everyone,

I’ve had my shapeoko xxl for a few years now and its been amazing. I mostly do wood and plastics so minor deflection and precision have not been issues for me. I’m looking to try rotary milling and was wondering how feasible it would be to add an eBay 4th axis and replace my x axis connection with it.

Would The existing carbide grbl controller board be able to accomodate it? I understand I would need to move over to a different control motion app like ugs. Aside from purchasing the 4th axis/stepper hardware, would there be more I would need?

Thank you very much for the insight and time!


I think, last I read, current board doesn’t have the ability to do 4th axis. Or it could, you’d just have to remove one of the Ystepper motors.
@RichCournoyer did a 4th axis a bit ago, I believe. Let me see if I can dig up the thread on that.

Ah, maybe he didn’t post about it here. I did find some stuff on instagram from him:

Edit 2: Here’s a thread about results from reddit: https://www.reddit.com/r/shapeoko/comments/g7jjtu/4th_axis_shapeoko_mug_drag_engraving/

In that thread

I installed a new 5-Axis GRBL board (computer). At present I’m only using 4. It’s called SuperGerbil. It was a Kickstarter project.

Edit 3: If you’re looking to do multi sided machining, an easier way might be to make a jig. Something similar to this: Community challenge #15, 2019-2020 edition
Or Like in @Vince.Fab post here: Community challenge #11, 2019-2020 edition


A bit of discussion on this at:


Correct, SuperGerbil, running UGS 2.5, and it’s swappable back to Carbide3D GRBL in about 15 min.

PS Currently running Carbide3D’s board/software. Because I’m will be running another one-on-one CC, CM, Fusion360 Class soon to a new Shapeoko Owner.

PS2. Classes are free and open to anybody willing to sit with me for a few days.

PS3: REALLY hoping that @Jorge dreams up a 4-Axis board someday…Because I would be willing to be first in line to test it. (Course that would also mean that Rob would need to write a major upgrade to CM/CC )

On a SIDE note, I also made a 4th-Axis for me ORTUR Laser. LightBurn has a really slick method of unplugging the Y-Axis and converting the code to wrapped text. VERY SLICK.

This was my idea, but it really only allows for simple 2D cutting on round stock. I finally got around to buying a crappy ALIExpress 4th axis to put it into play. I think I bought the 8PDT switches (oh, i couldn’t get them so I bought some 8PDT relays) and I might have a couple of easy drivers from my Arduino days. So, I have everything needed to cobble the monstrosity together now.

Thanks everyone for the wealth of information! I’m looking to get my feet wet first before investing more into a 4th axis and the idea of the rack pinion system is pretty ingenious and doable for me. I’m looking to mainly machine tube/pipe stock like pvc. I think with proper calibration I could get the precision of a setup like this acceptable for my needs. Hopefully I get around to doing this and can post up some results :slight_smile:

So to backtrack a bit and elaborate on the eBay 4th axis stepper idea, I was under the impression that I could disconnect one of the axes (lets say X axis in this case) and literally plug it into the rotary stepper motor. Keeping the carbide Grbl board, I would calibrate the steps so that my circumference of tube stock would match whatever set amount of stepper motor turns. Once that’s been done, I could use whatever software and having a simple 2.5 axis job be “wrapped” around the cylinder. Does this sound feasible?

I’m very thankful for everyone sharing information, as I’ve never seen the rack pinion idea before.

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Sounds feasible to me, as long as you can match the specs of the rotary stepper motor to what the Shapeoko controller can deal with. The main effort would be on the G-code generation side, but Vectric VCarve/Aspire (among other software) has a “rotary toolpath” option for just that usecase, so it might be easy, in fact. I’ll be quite interested to see what you come up with, should you pursue this endeavour :slight_smile:

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