This guy might be of some help. http://dknob.com/customknob.html It looks like he uses some sort of set screw collar type insert for solid shaft pots and maybe just a nylon insert for split shafts. After a closer look, he says acetal.

Bob

Athena I made these knobs on this guitar using my cnc router and a hand drill. It took me several tries due to not knowing the wood real well and having a not so good cnc machine and spindle. I know I have run out in the spindle and began programming taking that into consideration. Not knowing the wood cost me several attempts at this due to the wood chipping. Once I realised that I had to model the knob again to overcome that aspect of the wood, I then used the cnc to drill and mill the hole in the knob so that I had a tight press fit on the shafts of the pots. I did not have to use screws or inserts. Your results will surly vary due to wood, machine and a world of other reasons!



Try it on some scrap and see what you come up with. Sorry for not having close up photos.

Mike

If you could fixture them accurately you could wax pot shafts and cast epoxy.

We make our own wood knobs and make brass inserts out of tube. I couldn't get a decent finish routing the shape so we do the outside shape on a sander with a fixture.

We also cast our own knobs. Getting the tooling concentric without a lathe is really tough.

The casting idea is interesting. I have an e-pal with a Taig who's a jeweler who does a lot of casting. I'll have to talk to him about the possibility. I have a fourth axis I haven't hooked up yet so I might be able to fake some lathe action if necessary.

I noticed how nice your knobs where last time I was cruising your site. Even your black cast knobs are lovely. I wish I could talk this guy into multiple piece wood knobs. You have such lovely photos on your site. Do you shoot them yourself? I used to be a black background only person, but you've converted me... I love your grey background.

Thanks,
...Athena

I'm trying to understand why you all find it necessary to have an insert in the knob...

I've seen wood knobs go out of round with humidity and get wobbly. I think a stable insert is pretty important.

Stuart, do you find that the epoxy core holds up well long term in a tuner knob application?
That would be a much simpler approach and also the guys mentioned above casting a waxed shaft profile into the wood for a pot knob.

It's not me making the decision. I was just asked to find the suckers.

I talked to my friend about this and he's concerned about slippage and longevity. He does 5-way rotary switches sometimes and I know how tight those are. He doesn't want the knobs eventually slipping on a spirited player at some point in the guitar's future. He does have some pro player customers.

I think he expected I could just order them somewhere online. He has some knobs he got off ebay a long time ago that had these serrated inserts.

...Athena

It's not me making the decision. I was just asked to find the suckers.

I talked to my friend about this and he's concerned about slippage and longevity. He does 5-way rotary switches sometimes and I know how tight those are. He doesn't want the knobs eventually slipping on a spirited player at some point in the guitar's future. He does have some pro player customers.

I think he expected I could just order them somewhere online. He has some knobs he got off ebay a long time ago that had these serrated inserts.

...Athena

I missed the rotary switch part. We have longterm testing results with rotary switches. Unless you use the Stew Mac splined shaft switches you'll need a grub screw. If you're using a grub screw you'll need a brass insert. We tried epoxy and JB weld for molded inserts with grub screws. They eventually stretched and slipped. Look for heavy wall brass tube, threaded inserts and drill them out, bronze bushings etc. What ever you can find locally and cheap. There's not much of a market for $40 knobs so every penny counts. If you have a 3/8" collet on your Taig you could fixture a drill and a reamer in a vise and while you're at it a parting tool held horizontally. Then you could mill solid bar stock by spinning it in the collet and plunging the onto the drill, then the reamer, then a horizontal move to part it off.

Pay attention to the rake angles of your cutting tools when working with brass. It gets really grabby with positive rake tools. Grinding a zero rake onto the tip of your drill and parting tool will make things much smoother and safer. I have the scars to remind me of this.

Ah, Schroeder?

Here's a video of the process. It's pretty cool just from an entertainment standpoint.

http://www.youtube.com/watch?v=wbfXXeiS ... re=related