Pots won't fit through rear routed bass


New member
I'm working on building a rear route '54 style P bass. I had read somewhere that long shaft pots are needed, so I ordered this:https://guitarelectronics.com/cts-250k-audio-taper-pro-guitar-pot-w-long-brass-shaft/
but when I tried to put it in, it wouldn't fit through the holes in the body.

I thought that the longer shafts might have been the problem, so I ordered this: https://guitarelectronics.com/cts-250k-audio-taper-pro-guitar-pot-w-brass-shaft/ and just received it tonight, but unfortunately it also doesn't fit through the body.

Could anyone point me to pots that have fit through a rear route bass body. I'm assuming the holes are the same size no matter what the instrument, but I just have no idea where to look. Do the ones Warmoth sell fit through, or do you really need longer shafts?
Generally for rear rout bodies a long shaft pot would usually be used. But it seems your question is more about the diameter of the pot and holes in the body.

Volume and tone control holes are 3/8" in diameter. This size fits most volume, tone, and blend pots. Warmoth sells CTS pots which as I recall are also 3/8" in shaft diameter. The pots you linked to also are 3/8" shaft diameter. Note not all pots have the same diameter.

Therefore if you have a finished body it is possible there is a degree of paint built up inside the holes. The solution is to take a reamer or similar tool to clean out the hole. I am assuming you may not have one so a workable solution is to take some coarser grit sandpaper wrapped around something like a pencil and use that as a rotational tool to clean out the inside of the hole. A similar method is also used to tuner holes when needed.

Good luck...
I read your post several times and I think that stratamania is right:  You have finish build-up inside your holes preventing the pot to go through them. 

Is this correct?

Assuming it is, the solution is to remove that finish.  There are several methods from the sandpaper around a dowel method, reamer, or stepper bit (which is what I typically use, although you really need to watch it with this method; any carelessness with chip the finish).  I would not recommend using a twist drill bit, as that will chip your finish for sure.

Good luck and let us know how it worked out.
I agree, it's probably finish build up. I finish exclusively with oil, and I don't bother wiping down the interior surfaces, so there's buildup.

Tung oil has essentially zero chance of chipping, I clear the finish with a sharp carving knife, I'd feel comfortable doing that with a lacquer also, however, I'd also lightly chamfer the top edge of the holes (covered by a nut+washer anyway). I would always chamfer holes in lacquer / poly finish, because they're strong enough to lift if caught as you push through.

Thanks everyone,

The sandpaper and pencil did the trick. Now my only issue is the pickup won't fit the cavity. May have to sand that one out too.