The config attached is my last know good which Homes all three axis (with a but ...)

(X zero, and Y zero, is front bottom left - when standing in front of the machine , looking at it). 


But ...


if I move the Y axis gantry as a whole , after homing completes, (jogging just 1mm at a time)

the Y1 gantry motor goes 1mm towards the rear of the machine (which is correct)

and

the Y2 gantry motor goes 1mm towards the front of the machine (which is incorrect)

So it just ends up racking the machine in slow motion


I tried very many settings, and eventually lost my way, and ended up relentlessly crashing the Y2 side of the machine


I don't know what settings to try to get the Y2 motor to Jog correctly, without affecting the Homing

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All motors are wired in exactly the same order, from the drivers to the motors

So I tried physically swapping the Y2 dir- and dir+ , but it didn't help the end result any

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I also made a config of just X and Y1 and Y2 (no Z) and NOT as a gantry (but as independent motors)
and was therefore able to bypass gantry Homing (as without homing, the gantry won't move)
each motor ran in the correct direction, when independently jogging a few mm at a time 
(testing that there wasn't a physical problem with either the wiring or with the motor drivers) 

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I also found that by making another test config using mesaCT, a with and without, a y2 reverse direction tick, it added two fields
STEP_INVERT= False
DIR_INVERT = True
I only tried the "DIR_INVERT = True" on the Y2 joint which didn't help either

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To recap

I have been able to make the homing of all three axis Home (although the signs still make no sense to me)

I have been able to test the x and y1 and y2 motors working in their correct jogging direction (when not in a gantry mode, and not homed)

I am unable to make the machine do BOTH things (Home AND then Jog the Y axis gantry with Y1 and Y2 in sync together, so gantry doesn't rack)

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My "process" for testing positive and negative homing values 

Start by setting the Y axis gantry of the machine to 25mm (width of a ruler) , so both Y1 and Y2 motors 
Have the same distance to travel, from their respective proximity sensors to the steel it senses against (so the Y axis gantry always starts from a known position)
Set all the signs of the values to positive on both y1 and y2 joints (in Geany)
Switch the power on to machine , and mesa cards
Wait for notification that ethernet is connected 
Launch LinuxCNC
Select the config
Estop off, machine on
Home all
Watch which direction the gantry begins to move on both Y1 (left side) and Y2 (right side)
If it goes in the wrong direction , change the sign  
Repeat for each of the 4 iterations of homing one axis

The attached file , Homes as the photos show. (But Y2 jogs in the opposite direction)

Just incase there is some random element to this somewhere , I re-ran this Homing configuration successfully, ten times in a row. 

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