Dave:
You are cutting a bore no island,yes?
Does D2 not do G76?
One line will do the whole job. Includes arc in and arc out on the finished profile...will cut to depth the lot....
If you drill a big pilot hole G76 will account for that as well and only cut the remaining material....
Does the cutter comp automatically.program to the size of the hole needed so no math required...just a "D" value in your case. Need larger tool (dia/length) However you will still get tool out cut marks
no matter what size tool you run when doing straight depth moves at size.....All machines will....Gotta approach and depart from the finished surface with feed moving away from the surface....
Cheers Ross
Ross, actually, I’m making a big split collet: 3 ⅜” OD and 80mm ID, so I can fit a Bridgeport Quillmaster to the Deckel.
Since you, Rich, 13engines, and colt45 all asked about use of cutter comp, I went back and reread the D2 Operator’s Manual about compensation on the contour. I could be using G41 to cut the outside of the bushing, and G42 to cut the inside. Or as you suggest, G76 (and G75), which have the advantage of doing the downfeed and the final cut.
OK, got it. What was missing here for me is the need to consider cutter path entering and leaving a cut. i.e. I knew it was possible, saw the examples in the manual, but never understood the need for it. Using a long cutter really amplified the problem, so even the most dense of students might learn...
Thanks for your help, even Emmanuel.
I should mention a couple of things: cutter RPM is limited to 2500 RPM because at 3150 (fastest speed) the spindle howls like a banshee, while 2500 is nice and quiet.
I had a couple of assumptions that some of you called into question: one, I thought a 2-flute end mill would be an excellent tool for a plunge cut, much better than a twist drill. It generated spiral chips like a drill and the plunge cut did not seem to be the cause of the overruns. Second, I thought that a slow feed rate would compensate for the long, fishing rod of a cutter. However, point taken, I will use a ⅝” cutter for the next iteration.
-Dave