Getting the Finishing Cut to Start where the Roughing Cut Left Off

[MarkDarby]

Hi All,
I'm back in my shop today for the first time in a few weeks. I am still new to the CNC world and am using VCarve Desktop 12. I am using an end mill for the roughing cut and a tapered ball nose for the finishing cut. As I start the finishing cut, I see where its cutting a lot of "air" -- starting as if I had not done a roughing cut. How do you get the finishing cut to start where the roughing cut left off?

Thanks in advance,
Mark

 

[riggsp]

Hard to tell without seeing what you are trying to do...there is a "box" in the roughing setup that lets you put in the amount left for the finishing pass.

 

[mkepke]

Yeah, it's hard to troubleshoot without seeing what the actual problem is. You mentioned 'starting to cut a lot of air' - are you saying the 3D finishing pass *never* goes deep enough to smooth the 3D roughing pass? Or only that it *starts* cutting air, but *eventually* goes on to finish-cut the rough pass?

I think you can create the latter condition by picking the right (or wrong) combination of 3d model boundary options between the rough and finish passes.

In any event, you should be able to see if your toolpaths are behaving as expected via the simulation. If that looks right, but it doesn't match what the machine is actually cutting, I'd say you have a set up problem, like the Z-axis wasn't re-zeroed properly with the ballnose bit.

-Mark