Washers under CTS Strat pots?

scarry67

My partscaster volume knob is sitting proud and when I looked under the pickguard it confirmed there's no washer there. Should there be two (regular flat one plus serrated one) and do they serve function linked to grounding?!

ICBM

There should be a serrated washer on the inside, and sometimes (but not always) a plain washer on the outside under the nut. No plain on the inside even if there isn't on the outside.

The purpose is to lock the pot to the pickguard and stop it working loose. It might marginally improve the ground contact but it should be pretty good anyway - unless the pot is actually loose.

scarry67

Thanks. I got hold of 2 washers which were fractionally too small so I've put in a little rubber washer. Presumably it's safe (if unauthentic)?

ICBM

Safe, but there's a possibility that will break the ground connection. You're now relying on a contact on the very edge of the foil around the hole.

SteveRobinson

If the pot has "medium" length shaft, I always put a nut on first, then the star washer. 

If you need any spare nuts I'd be happy to send you some.

FelineGuitars

I tend to use a second nut at the base of the pot shaft and then the jagged washer leaving just enough room on top for a nut and washer. I also like a clear earth path or bus bar across the back of the pots. Relying on the foil for earh path is a bit hit and miss.

scarry67

Aah, it's clearly more important than I'd thought! Thanks to all. Will get washer that fits...

SteveRobinson

FelineGuitars said:

I also like a clear earth path or bus bar across the back of the pots. Relying on the foil for earth path is a bit hit and miss.

Yes, I usually use thick copper wire from a 1971 Rover P6 high tension battery cable for this, but since refitting our kitchen, the earth wire from left-over 45 amp cooker cable lets me totally over-engineer the earth bus.

scarry67

Anyone know what star washer sizes are e.g. Is M12 12 mm in outer diameter? Need to order one or two...

SteveRobinson

M10 would be best I think. The M size refers to the nominal thread diameter and the pot shaft is 3/8"or 9.5mm.

scarry67

9.5mm looks the one. Ta. 

OilCityPickups

FelineGuitars said:

I tend to use a second nut at the base of the pot shaft and then the jagged washer leaving just enough room on top for a nut and washer. I also like a clear earth path or bus bar across the back of the pots. Relying on the foil for earh path is a bit hit and miss.

We always do the earth bus bar too on our pre-made harnesses, I would never rely on the foil.