Official Luthiers Forum!

I've made wooden knobs for tube amps, not for guitars...
I haven't seen a broach that would cut the splines into a wood knob. Also, there must be splined 'inserts' available somewhere...
There are a couple of options you could consider-
Buy some mini-knobs that will push on to the splined pot shaft and stick them inside your wood knobs (you may have to turn down the mini-knob...)
Pick pots with round-not splined- shafts and then use setscrew-type knobs

Cheers
John

The rosewood knobs on my last I just friction fit but I would probably go with a set screw next time.

I made wooden knobs once. I used some threaded hardware from Menards, came out okay, but could have been better.
Someone posted this link awhile ago http://www.mcmaster.com/#99362a100/=8ivaxt I guess these are self tapping and small enough for knobs. The only problem with these is it says you need a drive tool http://www.mcmaster.com/#99362a100/=8ivaxt which cost over a hundred bucks. Whether or not you could install these without that expensive tool, I don't know. Search through their catalog and see if something works for ya. This is about the best help I can give.

Maybe instead of having to tap these in you could drill a hole big enough for it to slide in then epoxy them in place. Just a thought.

You could try contacting
http://dknob.com/customknob.html
about getting some inserts, I suppose.
After seeing the pics of his work, I think I'd buy finished knobs from him rather than making my own, though......

John

Filippo,

I make all of my own knobs -

I start with a friction fit for the knurled shaft (typically, if I recall, they are about 0.243" diameter, so I use a 0.240 drill for the hole). Then, I use typically a number 36 or 37 tap drill through the side of the knob. Using the number 37 makes it so that the threads are even deeper and you have more meat for the #6 thread to hit against. Then I press it onto the shaft, and drop the set screw in until snug. Sometimes, I use a bit of white glue to help secure it, sometimes not. Don't overtighten such that you strip out the threads, but you will be fine.

Here is an example from a semi-recent bass.

_________________
www.ziegenfussguitars.com

Some guys use the splined inserts out of cheap plastic knobs, breaking them out then glueing into the wooden knob. Some also drill and install a set screw. Sounds like that should work for a push pull set-up.

i bought some wooden knobs from somewhere.
lmi or stew-mac.
pretty nice.
they have a brass insert,
and a set screw.
you could buy those and split the wood off, if you want some other wood.
i think they come in ind-ros and ebony.

Hey Filippo, if you go the set screw route you might consider using heli-coils in the knob.

_________________
Jim Watts
http://jameswattsguitars.com

Concerning push-pull:

As an engineer, adding brass inserts, helicoils, etc... that is all a very good solution and will only add to the strength of the system, but as a whole, I think they are generally unwarranted.

If you were to buy an ebony knob from stewmac right now, they would be done the same way to which I am referring - a slightly undersized hole for the split shaft knurled pot, with a set screw that engages the pot (generally) below the flare.

With the undersized hole and the knurled shaft, you are more or less forming a custom spline, which is an excellent way to transfer torque - which is limited to the rotary friction in the pot - not that much. And to be fair, the occasional impulse of hitting the end of the pot travel. However, any guitar player who is going to be holding a custom guitar like this knows that cranking the knob past its stops is not going to do anything good - hence such an action could almost be removed from consideration.

the set screw - particularly if it is engaged below the flare at the end of the knurled shaft, both tightens up th e tolerance of the shaft against of the bore - better facilitating torque transfer, but it also provides a positive reaction force against the pull in a push/ pull pot configuration.

All that being said, I have push/pull coil tap configurations on all of my humbucker electrics, and have not ever had a problem - granted my first data point is only 4 years old, but, those are my 0.02 cents.

Stephen

_________________
www.ziegenfussguitars.com

hehe.....out of curiosity I magnified a slotted, splined potentiometer post and found that it has 24 ridges in the circle. After a quick CAD experiment I found that the splined hole could actually be machined into the wood for the knob. It might take a while to cut on the cnc but it certainly will hold without needing an insert.

I'm doin' it!

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I read Emerson on the can. A foolish consistency is the hobgoblin of little minds...true...but a consistent reading of Emerson has its uses nevertheless.

StuMusic

That's a fun thought but I have to make special jaws from the cad file in order to find center hold mine as it cuts the hole. I'd have to design different jaws for yours. My knobs are recessed into a pocket carved into the face of the body. They'll look funky sitting on a flat surface.

Do you have the knobs made already? If not I could maybe do a quick design that would work for you and still fit into my jaws.

Is the pole diameter of your pots .235" like mine?
Split shaft?
24 grooves?

_________________
I read Emerson on the can. A foolish consistency is the hobgoblin of little minds...true...but a consistent reading of Emerson has its uses nevertheless.

StuMusic

I'm not sure that in a push pull situation the spline fit thing would hold up. I can only have .25" depth and still be able to cut the spline groove into the knob. The tiny milling tools have very little depth of cut. With a push pull I expect you'd HAVE to use a set screw.

At any rate....I'd need to know the post width and a few details before making them so the pots have to come first.

I have to design the knob around the pot.

_________________
I read Emerson on the can. A foolish consistency is the hobgoblin of little minds...true...but a consistent reading of Emerson has its uses nevertheless.

StuMusic