parallel flute end mills

What are these used for? Why not helical?

Best as doorstop for a very small door....

I bought one, years ago, and found it totally useless.

Regards, Frank

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(a) According to this supplier:

"For tight tolerance slots and keyways."

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(b) Because helical ones don't do that very well.

I find them ideal on brass and gun metal

Roy

If you are doing any maching using the edges on the end of the cutter, the helix angle will be related to the material it's intended for. So aluminium would require a fast helix, copper and brass a slow (or parallel) helix and you can even buy a reverse helix. I suspect the latter is actually best used for thin sheet material, as it will push the work against the table.

Of course, you could have a parallel flute cutter with any kind of cutting angle if you are mainly cutting radially and I expect you can get different combinations of helix angle and cutting angle according to both material and type of cut. But one advantage of the spiral is a smoother cutting force which is presumably why parallel edged cutters are best used for light finishing cuts.

Murray

I made an 'emergency' slot drill from silver steel to the 'LBSC' design. Mill away two sides then file relief on the edges and ends. Harden and stone an edge. To my amazement, it worked, and also worked well for light facing cuts using the end.

Neil