What can I do here short of resorting to boring? I need to make a counterbore thats already been roughed out about .015 undersize in hardened 4140. The diameter needs to be 1.501 +/-.0005 and it needs to be 2.875 deep. Ive located a fairly new, and rather long, 1 3-flute carbide EM that Im not measuring any taper on, but I cant quite get the hole straight enough to hold this tolerance. Im taking two .003 rough passes at full depth to get to my final size and then five spring passes, but the best I can get it is 1.5014 at the top and 1.5002 at the bottom. For reference, Im using 675 RPM with a feedrate of 3 ipm. Any advice?
Posted on: Wed, 06 Aug 2014 05:43:54 +0000
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