Combining kinematics

hi, i have built one of these and would like to run it on Klipper.
the PolarBear, Multipurpose Desktop CNC Machine (

i currently have it setup using the coreXZ and the arm moves perfectly but the bed (Y) moves but wants an endstop.

I tried polar and the bed worked fine but the arm didnt.

i have attempted to combine these but its way above my skill, is anyone able to help?


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Interesting. I’m not sure I’ll be able to look at it, but if you attach some info, I may try to take a quick look. Make sure you’re on the latest unmodified Klipper code, setup the printer in corexz config (and verify x and z work), attach the resulting full unmodified klipper log file here, then setup the printer in polar mode (and verify that bed rotation works), and then attach that resulting full unmodified klipper log file here.


so ran the 2 configs again and the corexz was as i previously said but the polar was abit strange
i can get it to home X and Z if i start the arm in the right place and Y doesnt need homing but when i tell it to move Y, X stepper also moves moving the arm up and down

oh and just to make it a little more awkward im running it on a arduino uno with cnc shield

corexz klippy.log (18.3 KB)
polar klippy.log (334.5 KB)

Thanks. I took a quick look, but it’s a little more involved than I originally hoped. (It will require new C kinematics code to calculate the two corexz stepper positions.) I’ll add it to my list of things to look at, but it’s not likely that I’ll get to it in the next few weeks.


just wondering if you have had chance to look at this?
i know its probably now where near your priority list.

thanks John

I have a fork on which I’m implementing polar core-rz kinematics, I can’t seem to figure ouyt the homing sequence though.

@koconnor any chance you have had any thought or ideas on this?

Maybe the Armchair-Engineering guys have a solution? They call it “polarXZ” but it should be polarRZ.