Setting up a gantry with 4 joints and 3 axes

Just noticed the values in my INI file were different for the two Y joints. They're fixed in the attached file, which still doesn't work.

The first obvious error I see is that the HOME_SEQUENCE = lines for joints 1 and 3 (the Y joints ) should have the same negative number so Linuxcnc knows to home them together as a slaved pair.

So set them to HOME_SEQUENCE = -2

Thanks, Todd. I set HOME_SEQUENCE = -2 on joints 1 and 3 in the INI file, and now when I try to jog the Y axis it says "Homing is REQUIRED to jog requested coordinate because joint (1) in home_sequence is negative (-2)". There is still no option to home the Y axis in the Machine>Homing menu.

Thanks,
Abe

A couple of best practices I'll point out first:

1. I moved the Y-axes together in the INI file so that it's easier to scan for differences between the Y joint configurations. Trust me, you do not want differences there.
2. ALWAYS edit one Y joint and paste it whole-hog into the other Y joint config. If you make a typo and add-in/leave-out a minus sign on a HOME_SEARCH_VEL or SCALE entry (for instance) you would send the two ends of your gantry in conflicting directions. Same thing if you were playing with offsets or home position. One joint stops while the other keeps going. Giving different instructions to the two axes is bad. Groan-screech-pop-zing-cursing bad. Very bad.

As Todd points out, you must make the controller aware that Joints 1 & 3 are designated to a single axis -- and the absolutely unintuitive way that is accomplished is by assigning them both the same negative homing sequence number.

Home All doesn't work?

Ah, so that's what actually links the joints! Yes, counterintuitive for sure. I think my INI (attached) now conforms to these suggestions, and I'm getting the error message I mentioned in my last post, along with there being no option to home the Y axis in Machine>Homing.

Thanks,
Abe