Dual Z issue with tandem Z: wiring seems fine, but no movement

Hello all! As you know I am really new to LinuxCNC. I'm running a LowRider v3 (mostly printed CNC) for plasma — QtPlasmaC.

I have wiring all testing OK, both from MESA 7i96s to the stepper drivers, and from the drivers to the steppers themselves.

All joints home except tandem Z.

If I swap the Z2 wiring onto the 7i96s sockets for Z1, then Z2 wiring works fine and the Z2 motor works great. If I swap Z1 (which works fine on the primary Z sockets) over to tandem Z sockets, Z1 stops working.

As is typical with LowRider, I have 5 steppers: X, Y1, Y2, Z1, Z2.

In my INI file, for homing, I have:

X:
[JOINT_0]
HOME_SEQUENCE = 1

Y1:
[JOINT_1]
HOME_SEQUENCE = -2

Y2:
[JOINT_2]
HOME_SEQUENCE = -2

Z1:
[JOINT_3]
HOME_SEQUENCE = -0

Z2:
[JOINT_4]
HOME_SEQUENCE = -0

Here are my INI and HAL files.

Any chance you all can spot something I'm missing?

Thanks again for being awesome.

 

Will give that a try! Thank you! Will report back.

Your reply said "both X" but there is only one X stepper. I'm assuming that won't matter.

Hey, that was the ticket! The first suggestion you made did the trick! You are the man! Thank you!

I thought the first non-negative joint needed to be a 0, then sequential. eg X = 0, Y=Y2 = -1, Z=Z2= -2
Just play with the order to see if you can home Z first in case it collides with something

Thanks! I'm reading up now on this at:

linuxcnc.org/docs/html/config/ini-homing.html#_home_sequence

I will get my head around it so I get the machine axes homing in the right order of priority!

I'm not sure if you will be able to get the Z to home before the X given the behaviour I see on my gantry machine becasue of the multiple joint axes.

The LowRider v3 is made to do Z homing to Z max, and I am setup for that. My unstudied knee-jerk thought is that Z should be homed upwards first, which should make sure that X and Y movements with the plasma torch will be well above anything laying on the table. Does this sound right to you?