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Cutting a keyway?

718 Views 7 Replies 5 Participants Last post by  hotbarrel
Anyone done this? This is a groove inside a bore that runs parallel to the axis (linear) vs. alond the radius like threads.

The store's keyway broach sets are pricey:

I'm thinking about using a dremel 90-degree cutter head, and mount this along a piece of PVC pipe that is fitted to the ID of the bore, and use a simple routing bit to cut into the material. The PVC would be the "jig" to ensure the router bit stays in the correct location, then just run it up/down the bore of the tube.

If this doesn't work, I'm thinking about cutting a slit down the bore, then putting a shim of some sort down it that will mimic a keyway.

Any other ideas? I don't want to spend a great deal of time building a tool...
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Internal keyways are usually broached. If the torque load is not high you can use a round key(rod) and drill the keyway. What is the bore dia. and what is your application? The other way is to put a round bar in the bore, drill a round hole and then square it up with a file.

Enco sells individual broaches.
Another way is to make a single point tool to mount in your mill. With mill not rotating, use spindle feed to move it up/down and feed part with table feed. Would work like a single tooth broach.
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