rotary broaching

[David Taylor 4Participant @davidtaylor4]

I made up the Hemmingway rotary broach kit and it works well using a male broach. Reading the proprietary manufacturers literature they claim that a female broach can be made using the male .

I tried this and the result did work but of course it lacks clearance and is a tough go in use.

Any ideas how to give clearance in a female broach with out using a file?

[David Taylor 4Participant @davidtaylor4]

extrernal

[not done it yetParticipant @notdoneityet]

Make it with a slightly over-sized male broach?

[Martin KyteParticipant @martinkyte99762]

Posted by not done it yet on 28/01/2020 07:13:17:

Make it with a slightly over-sized male broach?

That only gives you a larger sized, straight sided broach with no clearence. A rotary broach wobbles (which is why it's sometimes called a wobble broach so for a female broach the hole down the middle needs to open up to give clearence. Hence the OP's question.

I don't know the answer because I would use a file. Possibly using a male broach to create the initial hole so NDIY is not entirely on another planet.

regards Martin

[David Taylor 4Participant @davidtaylor4]

One attempt I made was to mount the broach on the top slide . I set the top slide over at 1.5 degrees and feed into the female blank. I thought it might give some clearance but it was not obvious that it did.

Filing clearance in a .06"A/F hex hole is not easy.

The attraction of the rotary broach was to produce small hexagons for which bar stock is no longer available and avoid setting up the mill with dividing head.

[Grindstone CowboyParticipant @grindstonecowboy]

I'm not entirely sure I understand the female broach part, but could you grind relief with a Dremel or die-grinder?

[Howard LewisParticipant @howardlewis46836]

Surely, if you use a male wobble broach to produce a hole, the male broach will have clearance, and cut easily, but the hole will have parallel sides, so that there is no clearance for a cutting edge?

To provide clearance behind the cutting edge, the female broach would need to have the cutting edge as the smallest dimension, with a hole behind it to allow the swarf to fall away.

Howard

.

[old martParticipant @oldmart]

If you are lucky enough to have a mill and rotary table, why would you ever need a female broach?

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