To make a shaft for some surplus DC motors I bought, I need to mill the end of a 10mm round shaft to be a centered 4mmx4mm square shaft. This'll be the smallest piece I've milled, and the first time I've tried to mill an edge that is smaller than some of my end mills. Rather then plowing in blindly and breaking my end-mills willy-nilly, I thought I should ask:

What's the best strategy?
  1. Use the side of an end mill to cut
  2. Use the tip of the end of a 4mm end mill (Size same as width of cutting surface)
  3. Use the tip of a larger end mill, say 8mm
  4. Use the tip of a smaller end mill, say 3mm and make multiple passes




FWIW, surface finish is irrelevant, and accuracy only needs to be +/- .015 inch. My big concern is to not break mills or mangling the end of the shaft.