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Knurling tool iirc from my high school machine shop class.

https://www.amazon.com/knurling-tool/s?ie=UTF8&page=1&rh=i%3Aaps%2Ck%3Aknurling%20tool

Bob

You are welcome. The Wolfman DE head takes #10X32 threaded handles just like any 3 piece vintage Gillette DE in case you ever consider getting one.

Bob

From what I have read, you are pretty safe using #10-32 threads for a DE razor handle. There is a metric thread too that is similar M5X0.8.
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