Mini Boring Bar CHNC I

[BulletHead]

I'm trying to machine a bullet shaped cavity about .224" wide by .350" deep. My boring bar is .077" wide but hits the opposite side of the cut as the lathe backs off after roughing cuts. I'm starting with a .080" through hole. I'm using a Hardinge CHNC I with a 810T controller.

The lathe wants to move away from the cut ~.073" on the X axis and back out but there isn't that much room in there especially since cavity gets more narrow at its max depth. Is there some trick to get it to back away from the cut only 0.001" instead? I edited the tool dimensions but it doesn't seem to change how much it backs off the cut before going for the next pass.

The only alternative I can come up with is to manually program each of the roughing passes but I'm only taking about .002" per pass and that could be something like 50 passes. These little boring bars are $20 a pop so I'm reluctant to try anything too fancy

 

[TimD]

I'm not familiar with that control but I would assume that there is a parameter somewhere you could adjust. Can you program it in straight G code? That way get to control all of the movements without messing with parameters.

 

[GarlicDude]

If I understand your problem, what I've done is to grind a 45 deg angle on the front edge of boring bar, leaving just a small flat area on the front edge.