Rotary broaching

[Maplehead]

Hi All

I’m looking into broaching my guitar knobs as I don’t like the plastic inserts I purchased. (They’re too long and they don’t stick with the glue.)
A big standard on the guitar world for volume/tone knobs is the posts on the potentiometers are 18 tooth serrated at .236” wide. I cannot find the inner serration broach for this standard anywhere. So I’m wondering, would the inner serrations be made by using a hex broach and then just turning the broach to create additional grooves?
Very nube onn this so I don’t know at all about broaching. As always, any and all help is greatly appreciated.

 

[Frank Ford]

As a rule, you'd use an internal broach that has the same profile as the splined shaft. For just a few parts, you could set up an indexing head or rotary table on the mill and broach each "tooth" separately with a single point tool, plunging with the quill.

It would not be cheap, but Slater and other suppliers can make the necessary broaching tools to whatever profile you want.

 

[Asm109]

.236 is 6 mm so maybe searching for a 6 mm serrated broach will yield results.