[SvdSinner]

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.

[Jim Dawson]

You are going to want to use the side of an endmill so that the transition from 10mm to 4mm has a radius rather than a sharp edge. Now the problem is how to support and index the shaft while machining. For support maybe something like this would work for you https://www.youtube.com/watch?v=zJIs0LihNPQ

Indexing can be done by putting the machined surface against the hard jaw, that will get 2 sides parallel. Then you only need to rotate 90° and do one other side. This could be indexed by aligning one machines side on a parallel.

All of this does mean that you would have to support the armature outside of the vice. V-block maybe?

If you can live with a sharp edge, then it is really easy. Just hang onto the shaft in the vice, use the end of an endmill, and support the armature outside of the vice on a jack screw.

[SvdSinner]

Thanks! I got the first one done without breaking anything :cheers: 5 more to go . . .

[Jim Dawson]

Congratulations! Could you post some pictures of your setup?