Rotary Broaching a Keyway on the Lathe with simple materials you have in the shop

[JRock]

Is that a turret tool? I think I have a couple of them around, wondering what I'd do with'em. That's great!.
Love to see the guts.

[Crusty]

I think it originally was. They can still be found on Ebay for a reasonable price and it saved me a bunch of work.

It's really dirt simple. I just flycut a 1º off perpendicular surface along the long axis of the tool holder cap flange, then machined a bronze cup bearing with a top flange that fits the tool holder cap bore and a similar looking tool carrier out of steel which fits the cup and is bored to hold the square lathe tool by its corners. The bearing is only as long as the tool holder cap is deep and the tool carrier doesn't quite bottom out in the bearing so that the broaching force is felt by the bearing flange and the carrier flange.

The slickest part of the build for me was chucking the lathe tool in the 4 jaw and then mounting a Dremel with a cutoff wheel onto my tool post and when it was brought edge on against the spinning work it ground a nice hemispherical depression in the end of the lathe tool to provide rake for the cutting edges. It looked like it was done in an actual machine shop.

Good luck in your search for where you put those tool holders.

[JRock]

Very cool. That CutOff wheel is a great idea.
I know exactly, approximately, which pile it's in

[Crusty]

You just think you know which pile. I'd bet a mustard covered donut that it'll eventually be found elsewhere. That's how it goes here - I'm about to order another pair of vice grips because I can't find mine and I've looked everywhere 3 times (everywhere except where they are).

[JRock]

You'll find'em shortly after the new ones arrive!