[Peteuk]

We do a lot of high speed face milling, removing a lot of material in small Z increments. Currently I programmed a sub program with the X and Y movements, but manually input each drop in Z, so it looks like:

G00 Z1.0
M98 P4000
G00 Z0.950
M98 P4000
G00 Z0.900

etc etc...

Is there a simple line I can add to increment Z from a start position until it reaches zero?

I'm pretty new to this, so all help gratefully received.

Pete.

[CadCamSam]

You are thinking backwards. Z should be your concern and then have your macro repeat as many times as it needs to get to the top of the stock.
So, to take off .25 stock at .05doc:

G90 G0 Z.3
G1 Z.25 F25.

M98 P1000 L5
O1000(SUB)
G1 G91 Z-.05 F25.
XY WHATEVER
M99