My J&W Tolley had one hammer missing. Got a matched pair with the right throw, need to fit them. Is there any trick to getting the geometry of the square hole right? I have one of the old hammers but there is no easy way to trace that geometry. So far I have just drilled a hole a tad under the correct diameter. Now I need to square the holes. And one more question, should one anneal the hammers to make it easier to file them? Right now they are pretty tough.

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