I'm trying to make a little gear cutter arbor and the cap needs to have a broached recess for the mating key. I've started broaching on the lathe with a piece of 1/4" hss but can already see that this is not going to be successful. I knew it would be difficult but I thought I would give it a try anyhow. I've broached keyways in aluminum before but they were smaller and not blind holes. I milled out the arbor on the lathe successfully but this cap appears to be beyond my capabilities. Any ideas?