Z-Offset for Scribe

Hello all,
I am running QtPlasmaC on 2.9.0 with sheetcam.
I added a pneumatic scribe that is mounted to the Z carriage that when actuated is driven down on a slide - pretty typical.  Everything seems to be working except my slide can't reach the material.  How do I add a Z offset for an engraving/scribing operation?  
This is a problem when scribing is the first operation because Z is high up at Z home-offset.  Whereas if a cut is the first operation, then the next engraving op is actuated from Safe Height rather than Z home-offset.  
I tried adding a Z offset at   T1 P1 X0 Y0 Zx ; scribe   in the tool.tbl to the scribe tool, but it didn't do anything.  It would be awesome to have a field to set the scribe height similar to the probe height. 
Thanks!

The tool table seems an obvious place for this. I'm not sure why it is not working. Maybe take a look at your logs to see if there is something in the tool table LinuxCNC does not like.
Try manually editing your g-code. Look for G43 H0. Change the H parameter to the tool number. For instance if your scriber is tool number 1 you'd have something like this:

N01230 T1 M6
N01240 G43 H1

If that does not work I should be able to modify the post to add an offset.

Daddio wrote:

I tried adding a Z offset at   T1 P1 X0 Y0 Zx ; scribe   in the tool.tbl to the scribe tool, but it didn't do anything. 

You need a G43 to apply the tool offset.

I suspect that is all that is missing.

Hi Les,
I changed:
T1 M6
G43 H0 --> G43 H1
but got the same results, it doesn't grab the z offset.

The intent of the behavior of the scribe is that when it is "armed", the pneumatic cylinder would make the scribe touch the material.  I suppose if moving the scribe's slide closer to the material is not an option, then you could try  Keep Z Motion  for the scribe portion of your cut file.  In this case you might consider providing the coordinates via G53 so that resetting the DRO wont affect where the Z axis is positioned.  

An easy way to set this would be to use a variable:

EDIT: see below for correct code


Where 1.001 is the distance measured from the top limit switch down.  

snowgoer540,
That throws a "bad number format (conversion failed) parsing" error..

I'll try to take a look after work.

does it fail on
or the G53 line I pasted above?

I think this may be wrong (i copy pasted from the qtplasmac manual, but it doesnt match the gcode filter):


EDIT: see below for correct code


You could just use the actual number.  G53 G0 Z-3.500

obviously change -3.500 to suit your needs.

Yeah, something is up with the G53 G0 Z[{AXIS_Z MAX_LIMIT} - 1.001] line.

#<keep-z-motion> = 1 works no problem, same with the G53 G0 Z-3.500 at first test.

I'm basically adding it in as a code snip in sheetcam.

This should work:





3.5 would be whatever you need it to be of course.

Edit:  I should note that I grabbed the original code I posted from the button code section of the QtPlasmaC manual without thinking.  So, that would work for button code, but not for G-Code.  Sorry about that