It's All In The Choice of Endmill

It's All In The Choice of End Mill

I mentioned a few days ago the inability to take big cuts when milling, even with this new, rather powerful drill press vise that I was using. I had an inspiration, while driving back from Bend.

Until now, I was using a 3/4" diameter, 1 1/2" long two flute roughing mill to do the coarse excavation. Partly this was because a two flute mill is considered the better choice for aluminum and plastic, and partly because the diameter let me do a 1.5" wide section in just over two passes. The more I tried to visualize the method by which a two flute mill cuts, the more I began to wonder if a mill with more cutting surfaces might do to job better--like fine teeth on a saw blade work better on a hard surface than coarse teeth.

Sure enough, I pulled out a 3/8" diameter, four flute end mill called a "rougher"--and discovered that I could mill a .192" deep section in Delrin without any fighting at all. I can't take out as wide of a section at once, but being able to cut this deeply means one vertical movement, and then several passes to cut the 1.5" x .210" section. I suspect also that a larger diameter four flute end mill might also work just as well, and with less passes.