2 steppers on one axis 5i25 - 7i76

There is the hard way and the easy way to control a joint axis.

The hard way is to use the current production branch V 2.7
The easy way is to use the development branch V2.8

Either way, PNCCONF won't be of much help

I think you are doing it the hard way. 2.7 does not include the simplified joint axis code described by CNCzombie.
Version 2.8 contains the joint axis code that simplifies homing etc. and no longer hard codes the joints 0,1,2 to X,Y,Z. Some people will start with a XYZA machine to generate their config in PNCCONF and then manually edit the A axis to become the second Y (eg XYZY).

Also, the GEOMETRY only controls the axes that are displayed on the DROs so it should remain as XYZ

and this suggested line

should be

kinstype=BOTH allows the machine to be changed into joint mode so each joint is controlled independently of the other (which is a horrible idea for a gantry style joint axis). Joint mode might be used in a hexapod or delta machine. We don't want it for a gantry.

I think the bugs have been fixed now but initially, it was possible to move one side of the gantry independently in joint mode so don't tempt fate and enable it.

There you go! Since most of what I have done was copied (barely-understood) and pasted/modified from rodw's posts, I suggest to ignore most of what I wrote and follow the guru.

How do I get 2.8?

CNCZombie wrote: There you go! Since most of what I have done was copied (barely-understood) and pasted/modified from rodw's posts, I suggest to ignore most of what I wrote and follow the guru.

Not sure that I qualify as a guru there are others who I hold in awe. I started with a working config borrowed from another 7i76e and coded everything by hand. This might be your turn to shine CNCZombie

Chadrat, if you have installed from the ISO, it is easy to swap between versions. just by changing some settings in Synaptics.
buildbot.linuxcnc.org/

Other idiots build from source.....

rodw wrote: Other idiots build from source.....

I don't know if I'd call them idiots, masochists maybe but not idiots.

Rodw -I remember now why I initially had my kinstype set to "both". When I was playing with everything during build/setup and doing a lot of config changes and Axis restarts, I'd sometimes get distracted and start jogging the Y before I had homed. The result of that was exactly the kind of gantry racking you warn about -- since for whatever reason, only the first joint in the Y axis responds before homing. This, of course, twists the gantry in very bad ways. I fiound having the UI start up in Joint Mode, makes it visually distinct to me that I'm not homed. If the buttons say 0, 1, 2, 3 it reminds me to home before mashing any +/- buttons.

Do you have any ideas on making both joints respond to the Y button in unhomed mode, or is that not possible?

Thanks