Can't remove pot - broken thread

[koen]

One of the volume pots in my 5E3 is sitting slightly loose in the chassis. So I tried to tighthen the nut, but it just keeps making turns without moving - seems like a broken thread. So I then tried to remove it, but I cannot get a good grip on it, again it just turns.

Any suggestions how to use some force to get the nut removed, so I can replace the pot? Without damaging much else in the amp, of course

[Enzo]

You have a stripped thread. You already know that.

Try:
On the inside, get a large flat screwdriver between the body of the pot and the panel. As you turn the nut on the outside to loosen, pry with the screwdriver to put pressure on the pot away from the panel. With luck, the nut will catch on the edge of the remaining threads and start to back out.

Got a Dremel? Use a cutoff wheel to cut the nut in two.


Much harder, but if you are careful, a hacksaw can cut the nut off.

[koen]

On the inside, get a large flat screwdriver between the body of the pot and the panel. As you turn the nut on the outside to loosen, pry with the screwdriver to put pressure on the pot away from the panel. With luck, the nut will catch on the edge of the remaining threads and start to back out.

That did the trick, thanks!

[koen]

Grrrr - I put back all pots in the chassis, and now they all seem to have broken threads. The nut will turn all the way down, but then just at the moment when it tightens, loose up again. For now I keep them just at that point, I hope they won't rattle loose and still give provide enough contact of the pot bodies to the brass plate for efficient grounding. Maybe I have overtightened them before and damaged the threads?

[Gibsonman63]

If you have enough threads left, you may be able to get the right sized washer to put you out on the next thread.

[koen]

Oooh, great idea, I'll get some extra washers.

[J M Fahey]

Now that you are committed to that, go the extra mile and, instead of "flat" washers, try to get the toothed "star" ones, with the teeth pointing inside.
Your pots will *not* turn anymore.
They were standard "in the old days"; today pots do not even have nuts (nor threads)
Oh well.
Edit: they go between the pot body and the chassis, not between nut and chassis.

[koen]

My pots already came with those washers, and they sit between the pot body and the brass plate.

[J M Fahey]

Oh !! , then those nuts were *really* tightened, which was absolutely unnecessary
I *always* avoid overtightening, and use a small drop of clear lacquer to fix nuts against vibration.
In my case, not necessary on pots, because zinc cast nuts become friction-locked against my aluminum panels, but on an iron panel (even worse, stainless steel or a slippery chromed one) or on a "Plexi" (really Polycarbonate) one, chemical fixing is a good precaution.

[koen]

Yeah, I may have overtightened them to insure a good grounding of the pots to the brass plate. Looks good now with the extra washers, except one pot, so may need to get some additional washers. Playing tonight, so we'll see how it goes.

BTW, do people put a regular washer between the brassplate and the chassis?, Or just between the chassis and the nut?

[Gibsonman63]

Just between the faceplate and the nut.

[dchang0]

Your original problem is very common--many pots "run out of threading" towards the body of the pot. You probably went past the threading by overtightening. Washers fix this easily.