3 flute End Mills, how do you measure Dia.

[Gerry Sweetland]

The past year that I have been the owner of the 770 mill I have always bought 4 flute end mills. I have been thinking about buying some 3 flute to try out. I almost always machine aluminum and from what I can gather reading here 3 flute is a good way to go. I always measure a new 4 flute (or 2 flute) with a dial caliper just to check dia. They always measure what the manufacturer say the are, no problem so far but I am planning on finding some one locally who can sharpen some of my older tools and I just wondered how one would measure a 3 flute if had those sharpened in the future.
Thanks,
Gerry

[Wog]

V-anvil micrometer

[txcncman]

Just because you measure the diameter of any end mill does not mean it will cut to that size. It also depends on your tool holder and run out. The closest you will get to the actual cutting size is plunge cut into a piece of material and measure the resulting hole size.

The tool and cutter grinders I use let me know what size and reground tools are. Maybe you should ask yours to do the same.

[beanbag]

Use an edge finder to zero the spindle to the vise jaws. Then mount the end mill and move it close to the vise jaw, plus a piece of paper with known thickness.

[Gerry Sweetland]

Thanks fellas,
Gerry