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Pot shaft size.

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Pot shaft size.

Postby Elephone » Sun Mar 22, 2020 12:33 am

Hi. Does anyone know if 5.9mm pot shaft size is also referred to as 6mm, or are the sizes that precise? Most eBay results don't include all the information about sizes.

I'm looking for Pots with '24 fine spline 5.9mm shafts'. Are these for Gibson pots? It doesn't matter, but I need them to go in a Fender. I presume the mismatches are to do with USA not using metric?

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Re: Pot shaft size.

Postby Martin Walker » Sun Mar 22, 2020 12:59 am

I strongly suspect that 5.9mm and 6mm are one and the same, especially when splines are involved.

Pot knobs designed for splined shafts are all friction-fit, so I doubt that 0.1mm is going to make any practical difference anyway.


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Re: Pot shaft size.

Postby Sam Spoons » Sun Mar 22, 2020 1:24 am

More crucial is the number of splines, US and Far East used to have different standards (despite Japan still using imperial for a long while).
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Re: Pot shaft size.

Postby Elephone » Sun Mar 22, 2020 2:17 am

Sam Spoons wrote:More crucial is the number of splines, US and Far East used to have different standards (despite Japan still using imperial for a long while).

Thanks. Yes, most don't mention if they're 18 or 24 spline pots. When they're talking about 'knurled' pots, do they mean splined then? Round shafts must be the ones that require a grub screw. The information on it is quite confusing, especially when people refuse to include numbers in metric. It could also be the case that the knobs I bought are just not molded accurately, but are meant to fit standard CTS pots used by Fender. I found this info:

The Alpha pots that are usually put into guitars have a split shaft with 18 vertical splines (ridges) on it. The shaft is 6mm / 0.236" in diameter.

CTS use two different sized shafts, both of which are found in Fender guitars. Their split shaft pot is mostly found in Strats; it has 24 splines and a diameter of 5.95 mm / 0.235".

CTS also do a solid shaft pot: it has smooth sides and a diameter of 6.35 mm / 1/4".
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Re: Pot shaft size.

Postby Wonks » Sun Mar 22, 2020 7:34 am

'Knurled' knobs refer to the shape of the knob itself. The standard Telecaster control knob is a knurled knob.

US Tele knobs are also normally fitted onto solid shaft pots with a 1/4" diameter (6.25mm). Mexican/Japanese Teles may have the same or may have push-fit knobs that fit on a 6mm splined shaft.

With splined shafts, even if you do get the correct number of splines, I've found that for Gibson style knobs, there is a big difference in how well they fit on the shaft. There seems to be two depths to the splined hole, and the short holed ones are only suitable for pots with a very short splined section, otherwise the knob sits a long way from the body, with the fixing nut and washer on clear display.

I've had the above situation on a 2018 Gibson Les Paul, and had to replace the factory supplied knobs with aftermarket ones to get them to fit well. Even then, it's often been a matter of trial and error.

I do deplore the lack of spline information for pots. Also the lack of info on the mounting thread diameter. It's not rocket science for the retailers to put this info on and it's so helpful. Otherwise you've often got to try and count the splines from a small picture, which may not be possible.
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