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Post Reply - IBM receiver with flat area |
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Topic - IBM receiver with flat area Posted: Jun 10 2020 at 10:30pm By choprboy |
Putting my home-machinist hat on. The flat spots look to have been made on a horizontal mill with a straight wide milling cutter at a depth close to that of a finished profile. I would suspect that the machining steps to produce to top surface of the receiver would be to:
1) rough mill the top of the block with a straight cutter (making the top surface of the rear sight mount) 2) rough mill toward the rear site mount from either side with a straight cutter 3) finish mill toward the rear sight from either side with a concave cutter (to produce the convex top surface) If the stop point of the #2 roughing pass was set to close to the sight mount, it would cut below the finished profile, leaving a flat spot in the final product. |