4th axis for grbl Mega

[dguerizec]

Hello,

I'm currently in the process of building a 4th axis for my OX CNC, and I needed to have a cheap controller for it.
I've being using grbl for about a year now, so that seemed the easiest way.
I quickly tested grbl-Mega, it worked for 3 axis, then I found an old grbl port for 6 axis, and I adapted it on grbl-Mega.
On the sender part, I also adapted bCNC to handle the A axis (control & DRO by now). You can check my repo, I guess it's the easiest way to test this pull request.

I have one question though, in the last commit I've extended the ijk array to match the size of xyz, because it's used as a temporary storage for XYZ (and A...) but that seems wrong to me.
Wouldn't it be better to use a stack allocated array for this temp storage, or is there any reason we want to save stack space ?

[juri74]

any news about 4th axis implementation?
thanks

[LETARTARE]

You can watch ici

[T-Kuhn]

Is there any plan for a merge of this?
Or maybe more to the point: What was the reason for not merging this?
I saw chemnit talk about how the mega-grbl will support the 4th. axis on this issue
grbl#1001
and that's the reason I came here.

Let me add that I imagine chemnit to be a quite busy individual. I am not trying to push any work. Just wondering.

Will definetely give this a try. Thanks for all the work on both grbl and this 4th. axis implementation!

[jflapao]

Hello, I'm try find a grbl with 4 axis to mod my mpcnc.
I use bcnc to send g-codes to my arduino uno with grbl 1.1 and CNC Shield 3.0, but I want to add a lathe to the mpcnc, I have tryed change the Y axis to use the lathe, but I have to change the step/min to, If we use a arduino mega with the ramp's 1.4 we have allredy 5 axis with pinouts maped, and we can add 3 more on the aux2. If possible we can use multi pourpose machine where we use the 3 standard axis XYZ, plus a 4 one that can be a A one to the lathe using the extruder 0, and use the extruder 1 for future 5 axis head with B axis rotation. I planed make a 5 axis home made CNC. but I'm still need a extra axis for the lathe that I can go for it on the aux 2 of the ramps. so can you please remap the axis pinount to the ramps 1.4?

[fra589]

@jflapao Hi,
You can find my 5 axis Grbl (X, Y, Z, A & B) version for Mega + Ramps here : https://github.com/fra589/grbl-Mega-5X
Hope this help you...

[jflapao]

@fra589 Hello,
Thanks a lots for the replay, but I can't upload to arduino mega, give me a erro that can't find the grbl.h, but all the files ar in the same folder that the .ino file, i don't understand, becouse the mpcnc firmware, is identical file estruture and don't give me errors can you please explai me how can i upload the firmware to the mega

[fra589]

@jflapao Hi,
Do you apply the standard method to compile and upload Grbl ? The process is described in the Grbl Wiki : https://github.com/gnea/grbl/wiki/Compiling-Grbl
Perhaps it's not the same method than mpcnc firmware...
You can also see other method for flashing here : https://github.com/gnea/grbl/wiki/Flashing-Grbl-to-an-Arduino
Personally, I do not use the Arduino IDE to develop the 5-axis Grbl. Grbl does not use Arduino libraries to perform better and better manage CPU functions and optimize memory. I program under Linux, I compile with avr-gcc and I use avrdude for upload to arduino mega.