After my father in law died I inherited some heavy duty cutting tools, about 15 or so of various size from <1" to over 2". He used these when he worked at Northrup sometime between 1950 and 1980. I can't quite figure out what they are. My first thought was a hole saw for metal or wood. They don't seem sharp enough for wood. I tried one on a 1/8" thick piece of mild steel and it seemed to be working at first (slow speed + cutting oil), but then just got too hot and stopped cutting 1/16" in. Anyone in the woodworking collective have any ideas?

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