Rotary broaching question

M

Maplehead

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Hi All

I have scoured the Internet for a .25” 18 teeth rotary broach for making guitar knobs with no luck. So I got to thinking.
Can I use a .25” hex broach, (six teeth), and then turn it for six more teeth and then turn a last time for the last six teeth, to make 18?
I would set up the knob on a rotary table so that I could make the proper amount of degrees turn for the second and third half-a-dozen teeth after the initial 6 are cut.
Having a custom broach made would cost me a small fortune so I can’t go there.
 
I just looked up the pot shafts and I’m thinking my idea won’t work because the shaft diameters are actually .236”. So in that case the .25” hex broach would probably be too big.
Bummer. To make the inner serrations for my brass knobs would cost me an initial investment of about $1000. Not gonna happen
 
Ha! I’m back in the running. .236” is 6mm. Light dawned on me. 6mm hex broaches exist.
 
Yeah, make it your self.
get some 5/16 (or what ever is needed) drill rod, with your rotary table machine 18 tiny groves in it after turning it to the proper diameter and taper, Heat it cherry red, quench in oil, soak it for 1/2 an hour in the oven at 500º and let it cool down. go to town, make enough to sell to your competitors.
 
T Bredehoft said:
Yeah, make it your self.
get some 5/16 (or what ever is needed) drill rod, with your rotary table machine 18 tiny groves in it after turning it to the proper diameter and taper, Heat it cherry red, quench in oil, soak it for 1/2 an hour in the oven at 500º and let it cool down. go to town, make enough to sell to your competitors.
Click to expand...
Hi Tom
What bit would make those teeth grooves for me?
 
a 10 - 24 tap, any tap with all but one tooth removed. O1 steel is as easy to work unannealed as 1018.
 
Maplehead said:
I only have a micro mill and lathe so I highly doubt that would be doable for me with tooling steel.
Click to expand...
Curious how you intend to use a rotary broach with a micro mill or lathe?
 
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