Broach Info For The Beginner

[Pmedic828]

I would like some replies to explain what is meant by a collared and non collared broach? Also, when you purchase a set of broaches, I understand that there is different sizes to fit into various diameters for the shafts and also different thicknesses of the broaches themselves - to cut deeper, you add a shim. This I understand. The question is what is an "A" broach, "B" broach, "C" broach, etc and how do they differ? I am a beginning machininst that has limited experience with seeing a broach used and no one to ask my questions to locally - that's why I got my friends on this site - ya'll have been most helpful on everything else I asked so I am looking forward to learning something new tomorrow with all the replies I will receive. Thanks guys and gals in advance!

 

[Bob Korves]

"A" broaches need to be used with A bushings. B with B, and C with C. Not too difficult. Often the shim set comes with the broach, which makes depth of cut easy. I have only ever had the broach, have to make my own bushing and shims, and calculate how many passes with what thickness shims will be needed. Requires measuring the depth of cut to check on the progress as well. Go to the Dumont site and read the information they have there. It is pretty straightforward. Read the safety info as well. You can get hurt easily if you do not understand the issues and what to look for.

 

[Wreck™Wreck]

In push broaches the body width determines the broach size designation, the body is larger then the cutting width.
A collared broach bushing has a flange at the top so that it may not pass through the hole and thus is supported from the top. I have never used a push broach above 2" that had a collar, these are supported by the press platen and may be supplied with up to 3 shims in order to reach the correct depth which requires pushing it through the hole 3 times which is time consuming.

A pull broach can be long enough to go to depth in one pass, at the shop where I work we have a Morrison Keyseater which is a completely different animal it is a simple shaper intended for internal keyways but the setup is cumbersome, I could push broach a single 1/4" keyway into a 1 1/2" bore much faster then setting up the keyseater.