pic: Team 3647: Gearbox

[artdutra04]

Originally Posted by Mk.32

We don't have hex borching [wish we did] so just using an set screw on a flat on the shaft was fast and easy. Also since this is mostly a low load application the set screw will be fine.

It sounds like you have access to a decent assortment of machine shop tools. If you have access to a surface grinder, a lathe, a Dremel, and an old worm out HSS end mill you can make your own hex broach. Here's how you can make a 1/2" hex broach:

1. Acquire a few inches of 1" or larger hex stock. Drill and ream a 5/8" hole through it, and add a set screw hole.
2. Take an old 5/8" HSS end mill. Cut off the flutes. Mount the shank into the hex tool holder above with about 1" sticking out.
3. Clamp down the hex stock onto the table of the surface grinder.
4. Take a light pass on the surface grinder.
5. Rotate the hex stock to the next face.
6. Repeat steps 3-5 until you have ground the end mill shank into a 1/2" hex profile.
7. Mount the end mill shank into a lathe with the hex profile facing outwards.
8. Put a cutoff tool in your Dremel tool. Turn on the lathe and Dremel, and hold the Dremel tool perpendicular to the lathe. The objective here is to cut a concave dimple with sharp edges into the hex profile.
9. Congrats, you now have a cheap hex broach that will work in soft materials like aluminum or plastic.

You can substitute in different sizes above to make 3/8", 7/16" or other size broaches.