M Comp table can't be created (Resolved)

[locutus]

Lathe Pro 4.20.1 DMM Dyn4 Servo Drives on a 14x40 Lathe using GS3 VFD
Everything setup and pretty much working without issue.
Can easily run the pawn program with encoder.
Rigid tap, single point threading, CSS, etc all work.
Now I'm looking into lash & axis compensation.
Homing via marks using custom home program - using ZRI pulse only.
Home is currently somewhat in middle of travel.

Trying to press F5 "M COMP" I get the following messages.
"The Z Axis Table cannot be created because of invalid travel limit settings."
"The X Axis Table cannot be created because of invalid travel limit settings."
"There are no axes valid for compensation"

I seem to have what I think are valid travel limits.
CNC12 v. 4.20 coordinates file
Axis Minus Plus Return Return Return Return
Limit Limit #1(G28) #2(G30) #3 #4
Z -20.5000 14.0000 -11.75000 0.00000 0.00000 0.00000
X -2.3750 2.8750 2.00000 0.00000 0.00000 0.00000

Please help me find the error of my ways.

[cncsnw]

You might try changing your homing procedure so that Machine Home (Machine Zero) is at the end of travel on each axis, instead of in the middle.

[locutus]

I did try this. Set to physical max Z+ and X+ instead of approx middle of machine to Machine Coordinate 0.
Software Travel limits are just beyond that so it can park and home on ZRI and also stop before hitting real limits.
There are no home switches. Just park it and home via ZRI.
It made no difference I'm afraid. Still cannot create M Comp table.

[cncsnw]

I should have been more specific: try a configuration where all your axis travel is negative, and the positive limits are both zero.

[locutus]

I see. OK easy enough to just change the positive limits to zero. Shouldn't affect anything other than travel.
I'll give it a go this evening.

[martyscncgarage]

I see. OK easy enough to just change the positive limits to zero. Shouldn't affect anything other than travel.
I'll give it a go this evening.

You really should square away how you home the machine. You can set marks, jog to the marks, and then let the machine move in the - direction until it finds the marker pulses, set home. Set up your soft limits.

Or put mechanical switches on each end of travel, let the machine hit those, then back off and look for the marker pulses then set home CONSISTENTLY.

I don't understand how leadscrew comp is going to do you any good otherwise.

Marty

[locutus]

Thanks very much cncsnw.

Changing the positive limits to zero and homing to one side of the axis does indeed satisfy the prerequisites for M Comp Table creation.
Issue is resolved.