Quote Originally Posted by Metalmuncher View Post
Well, shucks. It doesn't sound too conducive to working in a mini mill then, unless one had a power feed Z axis, which I do not. I'm glad to learn this before I actually got to thinking about making one. Hmm. So this is something like how a hammer drill works, except the hammering is vertical. If one were dead set on trying this in an import mini-mill, I wonder if a setup with springs pulling (or pushing, if compression springs were used) downward on the mill head would work? They could be attached after the tool is set up and touching the piece being broached, and then cranked down with an adjustment similar to the spring that regulates the downward force on a horizontal metal cutting bandsaw (a crank and screw affair) to provide adequate feed pressure. Just an idea.
I 've never seen a spring forced feed set up like you are describing but it might if there was sufficient spring pressure You would probably be about as well off trying to 2 hand one of the handles but what is really needed is an incremental direct feed system like mounting a worm wheel where the handles are and dog clutching it so you can use it when needed a simple hand wheel on the worm will do the trick
Also making worms and worm gears are not outside of the capacity for mini lathes or mini mills they just take a few homemade tools to be able to make them.one can always go the easy route and use all thread for the worm and a tap of the same size for the cutter to make the gear .