7/8" diameter A-2 (not heat-treated yet). I need to put holes with a square bottom that are .122" diameter +/-.002" x .134" deep. I tried just plunging with a 4 flute carbide .120" diameter end mill and holes came out about .144". So I had a #39 (.0995") carbide drill and pre-drilled it .130" dp., then used a 3mm (.118") carbide 4 flute end mill and the holes are still .138". How can I put blind, square bottom holes to size? I would think a reamer would leave a little chamfer at the bottom and I can't have that. It needs to be square. Ideas??
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