Rotary Broach holder

[SteveHGraham]

Your cutter should have relief on the sides. I don't know if there is such a thing as a prefab cutter. I make them on the mill.

Ok. I knew that from having watched videos of them in use. I wasn't sure how you were doing it without cutting any angles on them, as in your earlier post. What angle are you talking about, then, that isn't needed?

The cutter's axis of rotation doesn't have to be at an angle to the cutter holder. With a mill, it's different.

[tornitore45]

O1 is what I have used. Hardened and tempered.

[RSG]

Thanks Tornitore!

[johnfreese]

Rotary broaches usually have the center of rotation 1* offset from the spindle centerline. Tools typically have a 2* per side clearance.

No need to buy the cutters. You can make them from drill rod. Having a tool & cutter grinder makes the job a lot easier.

[SteveHGraham]

I used 1/2" oil-hardening drill rod for my cutters. Something from Enco. I don't recall the exact type.

If you're not afraid to tilt your mill's head, making cutters for hex holes is very easy. Tilt the head several degrees to put relief on the cutter. Put the drill rod in a rotary table, standing up. Cut one side, rotate 60 degrees, cut another side...nothing to it.

[RSG]

I used 1/2" oil-hardening drill rod for my cutters.

If you're not afraid to tilt your mill's head, making cutters for hex holes is very easy.

Thanks Steve, I'm not afraid of tilting the head at all, but I also have a tilting rotary table ,

[4gsr]

I'm a little late to the meeting here. Little Machine Shop used to carry a few rotary broach cutters. I haven't lately. I bought several from them years ago. At the time, they were around $30 a piece. I made a rotary broach fixture to use in the lathe, as mentioned above. For some reason I couldn't get mine to cut into the material I was using, which was 4140HT. Never did go back and try a softer material at the time. KenS.