Rotary Broach

[silverhawk]

I contemplating this project I am left with one question. Why does the broach need to rotate? I understand that this engages each tooth separately. But if I put the punch in a press and forced it into the work each tooth should see the same cutting force? Yes it would take more overall force but wouldn't the cutting force on each part of the tool be the same?
Robert

You don't "need" to rotate it. What the rotating does is apply the cutting edge to one corner at a time instead of all surfaces at once. Usually, a regular broach has reliefs cut into it so you don't end up with long chips. If you just press it through, you will need more reliefs, as the one long chip has no where to go.

Rotary broaching is great for blind holes, but through holes you can use regular broaches. You can't use regular broaches on blind holes.