How to increment a parameter in G-code

[Involute]

I'm a G-code newbie and can't figure out how to increment a parameter with it. E.g., I'd like to use the expression #1 = #1 + .001 (i.e. increment parameter 1 by .001), but Mach won't accept it, and the manual even says you can only have a real number on the right side of the =, nothing else (e.g. no expressions). I've posted this question on the Mach forum and can't get a straight answer (e.g. someone suggested I get a copy of Alibre and MeshCAD ???). Is something like this possible? Again, I'm a newbie, but it's pretty surprising if it isn't. Thanks.

Involute

[cncwhiz]

Are you sure that you are talking gcode or macro? You need to talk to someone who does macro programming.

[micsit1]

#1=-0.5
#2=0
G21 G40 G80 G90 G00
Z2
G1 F30
Z[#2]
G4 P1000 (Dwell 1 sec)

(Calling sub O124)
M98 P124 Q5 (Repeat 5 times)
#2=0
G00 Z[#2+2]
Z[#2]
M30 (end program)


O124 (this is a sub)
G1 Z[#2] F30
#2=[#2+#1] (Step decrease Z by value of #1 i.e. 0.5)
G4 P1000
M99


You could also do it with incremental G91

Michel

[Involute]

Thanks, Michel. I'd just figured out my problem was not enclosing the assignment expression in brackets. Now my G-code runs like a charm.

Involute