z axis jogging?

[badgersurfer]

I am making items in hardwood that are 50mm x 35mm x 6mm. I generally run the blanks which are on average 200mm long across a planer and then a thicknesser to get my thickness smooth and accurate. The problem with this is that it is time consuming. I found that if I just put the rough blanks in my Stepcraft 420 with a 3mm end mill I can mill off a relatively clean surface with a 50% overlap in seconds. This saves me a lot of time and effort. I then finish with sanding.
I have created a template in Vcarve Pro as follows. Pocket toolpath cutting at a depth of 0.025 mm across the workpiece surface.
At the moment I am rewinding the toolpath file and resetting the tool height to take another .025 cut. What I want to achieve is to be able to jog down 0.025 after each run until the surface or thickness is where I want.
I am obviously not doing this correctly. I assume that if I type in the z axis line .025mm it will move down to the correct amount and then run the toolpath again.
Is this the easiest procedure or is there a button I can customise to jog down .025 just with one click?

[badgersurfer]

AN easy way to do that is to Make teh Z step depth a #var such as #100. Use it as for example

G1 Z#100 F5 ( Lowers Z to the value of #100)

Before you run each pass, From teh MDI line, assign a value to #100 such as

#100 = -.025

Then you run teh program and teh Z will step down to -.025.

IF you need to run it again adjust the value of #100 to a lower depth.

(;-) TP

Thanks, I will have to try and get my head around what you are saying here as I am new to uccnc... As a matter of interest can I utilise e.g. G55 (in it is on the interface to do this.
I notice that by default the program always assigns the G54 button. This seems to take on the Z=0 settings. So I thought that if I assign the G55 button to z -0.025 and then clicked it before I rerun the toolpaths it would do what I wanted, but I don't think it does as when I run the toolpath again it always seems to start at the 0 coords assigned in the vcarve toolpath.
I tried it but when I ran the toolpath in Demo mode it always seems to start at zero and not -.025

[cncdrive]

I assume that your g-code program does not contain any Z movement and is in absolute motion mode G90, if so then there is a simple way to implement what you want is to add a few lines at the end of your code:

G91 (switch to incremental motion mode)
G1 Z-0.025 (move the Z with -0.025 units increment)
G90 (switch back to absolute motion mode)

The code will not work good if your g-code program contains any Z movements, because then the Z will move back to that height when you rerun your g-code.

[spumco]

Is there some reason why you can't just set the step jog value to .025mm (or whatever you want) in the jog panel and then jog down one step before re-running the surfacing program?

If your program doesn't have any Z-moves this should be the 'one button' solution you want.

If it does have Z- commands, then edit the program to end at Z0 and rewind. Then jog one step and re-zero the Z-DRO. Re-run program as many times as you need. If you forget to re-zero after you jog down a step you'll just cut air for one cycle - no crashes.

Maybe I'm overlooking something here.

-S