Trying to save some parts that would otherwise be scrap. They’re now 64rc hardness, m1 tool steel, and I’ll be using a 1/4” tialn coated carbide 4 flute thread mill to cut 3/8-16 threads. Currently has a .315” hole that tapers to .313” at full depth (checked with gage pin) thread depth is .75” I’ve only done a little bit of thread milling in my nearly 2 decades of experience, and never on anything nearly this hard. Looking for SFM and chip load suggestions, and should I do multiple passes with light cuts and flood the hole out multiple times (machine is not flood coolant only) or just give ‘er the full send right to the major diameter? Should I climb cut (starting at full depth, work my way out) start to finish? Thanks in advance for any suggestions!

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