Forcing overcut

[HuFlungDung]

Since I am loathe to clutter my drawings with extra boundaries, or offset profile chains, I have had a fair bit of success using negative amounts in the "amount to leave for finish" field, if I wanted to cut an offset in an exterior profile, that is smaller than the part profile.

I wanted to use Z level roughing because I had some wide zones that needed cleaning up. I planned to have my cutter stay inside all the boundaries, except that in actual fact, by commanding a negative amount for finish, the cutter would trespass the boundary by my specification.

I sketched in a rectangular boundary for the outside of the cut zone, and created a surface between this and the profile chain. Then, I moved that surface to the proper depth. This leaves the original profile chain and rectangular boundaries above the surface to be machined. These are the extents for the machining boundaries.

Okay, if you follow that, then understand that I wanted the cutter to actually cut past the boundary profiles by 1/16 inch, hence using a -.0625" for amount to leave for finish. Logically, this overcut amount will also be applied to the Z depth, but that took me a while to figure out

As usual, I get the warning that I specified a negative amount, but I click ignore, and then I would get a warning that the Z offset was incorrect (because it was also overcutting the depth by 1/16). So, the trick was to specify a "bottom of job" that was 1/16" higher than the actual surface position, then the overcut in depth fell exactly on the surface, and was accepted.

DISCLAIMER The above methods are my own "perversion" of normal methods and do not reflect in any way on the proper use of Onecnc's functions, although there was actually no problem whatsoever in making the procedure work properly, once I understood what I was doing

[wms]

Originally posted by HuFlungDung
DISCLAIMER The above methods are my own "perversion" of normal methods and do not reflect in any way on the proper use of Onecnc's functions, although there was actually no problem whatsoever in making the procedure work properly, once I understood what I was doing

Hu,
You crack me up!

[SRT]

Hu,
What you describe, reminds me of the way that I adjust the wheels on my push lawn mower when I don't want to cut the grass too short.