Hi everyone. I've been setting up my k40 with the cohesion3d board and I'm

Hi everyone. I’ve been setting up my k40 with the cohesion3d board and I’m playing with grbl-lpc. Does anyone know how to setup the steps/mm for the a axis (rotation)? I do have the latest 4 axis version.

Quick note, @cprezzi last said that the endstop pinout is different for the 4 axis compile vs. the regular build for C3D.

Also if you want to try with smoothie, there’s a wealth of info in @Jim_Fong youtube vid description here: https://www.youtube.com/watch?v=UoGlDKjPGSE

Grbl-lpc does 4 axis rotary now??? Looks like I will be doing a test very soon…

It does. I did a quick test today but as I haven’t finished my rotary axis build I could only look at a pretty stepper motor attached to it’s own driver turn a piece of sticky tape :grinning:

@Jeff_Lamb Just send $$ to get all the params. :wink:
A axis is following XYZ, so $103 for steps/mm, $113 for max rate, $123 for accelleration, $133 for max travel and $143 for stepper current (if i2c available).

@cprezzi Is Ray correct with regards to the pin assignments being different? I hadnt tried homing and dont want to send the gantry clattering against the stop.

@Jeff_Lamb Yes, the 4 axes bin uses the endstop pins 1.24 for X, 1.27 for Y, 1.29 for Z and 1.28 for A, which are x-, y+, z+ and z- on a Smoothieboard or Cohesion Remix.
The C3D Mini uses 1.24, 1.26 and 1.28 for the endstops, so the 4 axes bin will not work. Would need to compile a special version.

@cprezzi Ok, thanks for the info. When I get my axis finished I’ll check it out again.

LW’s CAM assumes $103 is set to steps/deg, which makes $113 deg/s and $123 deg/s^2.

I’ve finally got my rotary axis finished and it seems to work (mechanically at least) - Is there anywhere I can download a 4 axis version of grbl-lpc for the C3D board? If not, is there some simple instructions so I can build it myself? Thanks.

That YouTube vid description above ^^ and also check @Jim_Fong latest posts.

@raykholo Thanks very much - I had missed that post!. :slight_smile:

cpu_map.h is where the endstop configuration is. I just finished compiling cprezzi “more-axis” branch and changed the endstop to match C3D board. I won’t be able to test until later.

@Jim_Fong In the more-axis branch I have moved all the cpu and pin repated stuff to cpu_map.h and all machine presets to presets.h. This way, the user only has to activate the prepared defines for his board and machine in config.h.

I’m not yet happy with the define BOARD_C3D for disabling I2C current chip and probably will rename it.

@Jeff_Lamb To compile your own version of grbl-LPC you have to install make and the ARM Embedded Toolchain. The links are on https://github.com/cprezzi/grbl-LPC.

@cprezzi thanks for the work on making this happen.

@Jim_Fong Very welcome!
What do you think, would you be able to write a wiki page (for github) on how to setup and compile grbl-LPC?
That would help many people to start with grbl-LPC.

@cprezzi I’ll do a complete write up on how to setup and run on the laser. I actually haven’t run grbl-lpc on the laser yet. I’ve been stress testing it on my corexy test machine and very happy with the performance as compared to original grbl. The atmega was step rate limited.

Still testing Smoothie rotary so once that is done, I’ll flash the board with grbl-lpc.

@Jim_Fong Cool!