Keyway for 3/4 shaft ----Arghhhh

[Abner]

Cutting a 3/16 keyway in 3/4" CR shaft steel using an end mill. I keep breaking end mills.

It was recommended in - Machine Shop Trade Secrets to make a hexagonal single flute end mill for this.

McMaster has M2 HHS 3/16 drill rod. Could I cut a piece and grind a 1/2 way through flat and use that instead of the whole hexagonal shape.

Suggestions?

[whoski]

flutes are packing with chips. use cutting oil and compressed air to blow chips out of keyway/flutes.

[Ken_Shea]

Slow the feed down and be sure you have the rotation correct for the cutter.

There are other aspects of end milling a keyway but you have to get past the breakage first.

[lakeside53]

yes, blow out the chips...

[Toolguy]

There are 2 flute endmills with straight flutes made just for cutting keyways.
They work pretty well.

[Ken_Shea]

Not as yet mentioned,
The RPM, cutter material, Carbide or HSS and diameter, # flutes.

Given this, some recommended rpm and feed can be suggested.

[Forrest Addy]

Is it time for my keyseat cutting lecture?

[RB211]

Is it time for my keyseat cutting lecture?

Yes, if not for the OP, for the rest of us

[oldtiffie]

Thanks for the timely offer Forrest

Seems so.

[Ken_Shea]

Is it time for my keyseat cutting lecture?

I vote wait till we get some answers to the end mill breakage. then absolutely