broaching a keyway

[David Hill 5Participant @davidhill5]

Hi Guys, can I ask a question to the knowledgeable?

I have to cut a 1/4" keyway in a cast iron flywheel. I have the broach but I do not have an arbor press. I do have a fairly hefty mill (Marlow). Would I damage the mill by using it as a press to broach the keyway? I am not sure of the forces involved. Thanks in advance.

[David Hill 5Participant @davidhill5]

[JasonBModerator @jasonb]

Find a friend with a hydraulic press, a 1/4" broach needs a lot of force that the quill won't be upto handling.

I use an old drill press to do upto 1/8" but that's pushing it to it's limits so would not advise going any larger

[old martParticipant @oldmart]

You could try very small increments in depth at each pass, that would reduce the strain on your available machinery. It would mean having the patience and assembling a good stock of shims first.

[Anonymous]

I used my Bridgeport to cut a 1/8" keyway with a broach, and was less than happy. Never used the mill with a broach since. I now have a slotting head on the back of the Bridgeport and a proper arbor press.

Andrew

[David Hill 5Participant @davidhill5]

Thanks Guys, I appreciate your comments and won't abuse my lovely mill……..

David

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