Polytone pot knobs question

[Dutchbopper]

As you can see from the pic I need a few new pot knobs for my Polytone amp. Does anybody know the diameter of the pot shaft as used on the pots so I can order some online? I do not have a caliper ...

TIA,

DB

[jazzmus]

T18, split shaft.
Heres a original looking option -
Sifam – Thonk – DIY Synthesizer Kits & Components

[Dutchbopper]

T18, split shaft.
Heres a original looking option -
Sifam – Thonk – DIY Synthesizer Kits & Components

Thanks so much. What exactly does T18 stand for? Does the split shaft make any difference? Are all T18 knobs designed to fit 6mm shafts?

DB

[jazzmus]

Thanks so much. What exactly does T18 stand for? Does the split shaft make any difference? Are all T18 knobs designed to fit 6mm shafts?

DB

DB, your are welcome.
18T means 18... Teeth, for splined shafts/axles, look at the pot shaft, see the splines/ridges/teeth.
The shaft is split to keep the fit tight since theres no “mechanical” force to hold it.

fwiw. I just tried a couple generic 18T brand x, y and z knobs on both a 70’s and 80’ s polytone to make sure im not just assuming, they fit just fine.
if in doubt just count the splines/teeth on the axle.

Knobs for smooth smooth axles ( 6 and 6.35mm) have grub screws to keep them in place, you Can use that too, 6.35mm will move a little of center radius, remedy with a piece of heatshrink on the pot shaft.
I hope it makes sense, otherwise just ask.

[Dutchbopper]

DB, your are welcome.
18T means 18... Teeth, for splined shafts/axles, look at the pot shaft, see the splines/ridges/teeth.
The shaft is split to keep the fit tight since theres no “mechanical” force to hold it.

fwiw. I just tried a couple generic 18T brand x, y and z knobs on both a 70’s and 80’ s polytone to make sure im not just assuming, they fit just fine.
if in doubt just count the splines/teeth on the axle.

Knobs for smooth smooth axles ( 6 and 6.35mm) have grub screws to keep them in place, you Can use that too, 6.35mm will move a little of center radius, remedy with a piece of heatshrink on the pot shaft.
I hope it makes sense, otherwise just ask.

Most helpful. Thanks once again!

DB

[Dutchbopper]

DB, your are welcome.
18T means 18... Teeth, for splined shafts/axles, look at the pot shaft, see the splines/ridges/teeth.
The shaft is split to keep the fit tight since theres no “mechanical” force to hold it.

fwiw. I just tried a couple generic 18T brand x, y and z knobs on both a 70’s and 80’ s polytone to make sure im not just assuming, they fit just fine.
if in doubt just count the splines/teeth on the axle.

Knobs for smooth smooth axles ( 6 and 6.35mm) have grub screws to keep them in place, you Can use that too, 6.35mm will move a little of center radius, remedy with a piece of heatshrink on the pot shaft.
I hope it makes sense, otherwise just ask.

Would these fit in your opinion? The ad does not state they are 18T. But they are 6 mm.

DB

[jazzmus]

Opinions are like...
but old fashioned logic, on picture 6 you see the teeth, T18 is often refered to as “just” 6mm by some sellers, to geeks the correct description would be T18 - as “6mm” could be a smooth shaft.
The picture shows T18.
I would guess from intuition and the pictures that they fit, yes.