I am turning 440c parts that have a .08 +/-.002 bore that is .2161 +/-.0004 deep. There is a .031 hole thru at the bottom of the bore.
The finish call out is 16 or better on the bottom bore face. I know 440c sucks and 440f is a great option, only 440f isn't readily available in 5/16 diam.
Currently I am turning these parts on a miyano turning center with Blazer coolant. Using Internal Tool .05x.22 boring bar at 2500rpm .0003ipm.
It is has always been an issue and the problem is intermittent...here in lies the other issue with finish and that it will run smoothly for awhile(200-1000 pcs then just not get finish anymore. Even first cut with a new tool.
Any idea's to get finish would be greatly appreciated.
Thanx