MPCNC 4th rotary axis

I’m currently adding a 4th rotary axis to my MPCNC.
I’m going to use GRBL MEGA 5X with TB6600 drivers to control everything.
GRBL GRU seems to be an obvious choice for controlling the drivers.
Has anyone done similar?
Has anyone got and advice to offer

A few around here have done it, but how are you going to make the CAM?

I’ve thought to use DeskProto Multi Axis Edition.
I’m learning this CNC stuff as I go along. I have degrees in engineering but didn’t work much with CNC in my career… I make mistakes and blow control boards up :joy::joy:
What do you think…
I’ve also made a lowrider. I’m using GRBL on a CNC shield on that… Its brilliant. Thank you for your help and designs


Maybe this might help you: ZenziWerken | PoorMans4thAxis


Hello. Just an update on my project…
The firmware is working now. GRBL MEGA 5X controlled by GRBLGRU.
I’ve mounted the MPCNC on a open box section frame. This allows me to place it atop some big timber slabs. Making it very portable.
It also allows me to sit it above the 4th rotary axis assembly. That works really well too. I can now rotary carve at will.
I can post a video of it working somewhere if anyone’s interested


I’m interesting some video and/or pictures.


Yes please!


Did you ever get a chance to post pictures and videos of this? I’m interested in seeing what you came up with.

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Hello. Yes i will post some pictures tomorrow. Im really please with this. Its tight and accurate. Ive made a probe to height map uneven surfaces. With the help of Gaithier Briere on the grbl Mega5x forum i managed to get a laser firing properly.
So i can now 3d rotary carve and burn.
The software to control the board is GRBL GRU. It has presets for both MPCNC and Lowriders.
So far its all good. Ill get some photos up tomorrow



Still needs tidying up but it all works superbly


Ok! Now you have to show it working! Very cool.

Hmmm, i have an uno and cnc shield laying around… might have to see if i can make it work. Would love a rotary axis to make chess pieces. Might have to pick your brain some…

Hi. The UNO will run GRBL 1.1
GRBL 1.2 is needed for true 4 axis work on an Arduino Mega… However… its easy enough to use the X or Y axis to drive the 4th axis.
Great tutorials on 3d carving using 3 and 4 axis CNCs can be seen on the DeskProto U tube channel


So when you did this. Is there a how to on getting all the axis set up and calibrated?
I really want to do this.

Yesterday, Jamie mentioned there is now native support for a rotary axis. Not sure what is involved in getting it working, and you will likely need to “upgrade” your Marlin to a nightly build.

This is what I saw in the config:

So I guess this would make it up to 9 (non-extruder) axes.

I’m not sure why the ‘rotates’ flag matters. If it’s just another axis and you assign the gear ratio in terms of steps-per-unit and velocity in units-per-second, when does it matter if units are degrees or mm? I highly doubt that Marlin is attempting to interpolate straight lines on a SCARA robot for example.