Gmoccapy Touch-Off Offsets

3-axis mill with RPi 4B and LC 2.9.3 from Download page, and Gmoccapy 3.4.6 - runs a job fine.

Offset Values:
In Axis, Touch-Off populates with a value generally within 0.001 mm of the value entered
Minor corrections are often successful, but sometimes ignored.

In Gmoccapy, Touch-off x=0, y=0, z=0, G54 populates with a value, like z=0.511.
    - Touch-off often leaves small errors on the DRO, like 0.008 mm.
    - I seem to run in circles trying to get the Offsets Page to agree with the DRO display, the G54 values, and the current position.

Suggestions ?
 

This one time, LinuxCNC started acting super random.

I restarted my PC and everything was fine.

I have no idea why it started acting super wierd.

Perhaps LinuxCNC calculates that your machine is not capable of attaining that level of accuracy.

Like maybe your microstepping moves 0.1mm at a time say, then you can have 0.08 and -.0.02, but nothing in-between

I find it odd that a computer cannot populate a memory location with a value entered.
Goes against 65 years of experience.

The Z0.511 error is actually disconcerting.
I tried increasing the precision value from 3 to 4, still strange results.
Note that the errors are either very small, or only arise when setting the Offsets.

Touch-Offs prior to program Run are good.
But, that means I cannot rely on the Offsets.

Spent some time chasing the mysterious Z-0.511 value.
The value pops up at Homing.
Cleared linuxcnc.var and linuxcnc.var.backup without joy.
Went through all the setup files, until I got to tool.tbl - and there it was, the cutting length of tool T1 = 0.511.
Launched Gm, selected the tool editor, and T1 was 0.511, and ticked as selected.
Cleared the tick and closed/opened Gm - but the 0.511 comes back, with T1 selected in the tool table !!

Found a youtube clip by sliptronic that includes a view of his tool table.
T1 is selected and set to length 0.00.
It could be the default behaviour of Gm is to automatically load T1, then allow for its length in the displayed position.
Edited my tool table to make T1 cut length 0.000.
Now Gm loads with only the minor offset errors (0.008 etc).

Really weird.

Thanks for taking the interest.

Just realized that T1 at 0.000 is sensible.
It is the datum point against which the other tool offset heights are measured.
My previous post used the wrong terminology, not 'cutting length' but 'tip offset'.

I have an edge finder permanently mounted in a NT30 chuck.
I could set all my tool height offsets reference that.
Could be an ideal time to start using my table mounted tool height setter.

I never tripped over this in years of Axis use.
Always just touched-off the actual tool when it was mounted, never used the tool table.
When the mill is next in use, I will check how Axis handles this.

Perhaps try out QtDragon too.

There's a reason AXIS is the default GUI, it's pretty old and stable.

There's been plenty of time for bugs to be fixed.