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potentiometers: How thick is the enclosure allowed to be, how can I fix them inside the enclosure? Answered

So in a nutshell: I'm following an instructable where potentiometers are used which i was never working with before. Those potentiometers are covered with some potentiometer-knobs which are between the enclosure and the potentiometers.
And now I have some questions ... a) how do I fix / secure the potentiometers inside the enclosure so they don't move when I turn them, but the potentiometer-knobs do, and b) how thick is the enclosure allowed to be when I use 500K, 5% tolerance potentiometers? This is so frustratingly confusing.



Best Answer 6 years ago

A link to the instructable you're following and pictures of your pots will go a long way to getting an answer.

a) With out knowing what your pots look like, sometimes there are threads around the base of the shaft that you thread a nut onto once the shaft of the pot is sticking through the enclosure. Other pots have mounting holes in the body that you thread a screw in to through the enclosure.

b) I don't really understand the question. The thickness of the enclosure has no effect, as long as the shaft sticks out enough for the knob to spin freely.

To a): By "pots" you mean the potentiometers or the knobs for them? Either case, here are the links.
The instructable ( I use the same pontentiometers ):

The knobs:

To b): Well, ehm... I am pretty confused, so don't expect sense-making-questions, since I am not even sure if there IS a problem. Anyway, so.
As shown in one of the pictures in the instructable, the pontentiometers just got nudged through the holes, but if my hole is, lets say, 1 cm thick, then I might have the problem that the long "beam" of the potentiometer, where the knob is attached to, is too deep into the enclosure. Perhaps I am completely wrong, since I can only imagine it right now, but I need to know about that before I buy everything, including the enclosure and the potentiometers. I hope this one made more sense than the question before. :P

If your enclosure is 1cm thick you need a pot with >1cm of threaded area to protrude through the enclosure to allow the nut to grab.

Hmm, makes a lot of sense now, yet more when I take a look at bwrussell's drawing of it.

...and linked is JUST the knob, NOT the pot.

I actually DID linked the pot itself. Let me quote myself.
"The instructable ( I use the same pontentiometers ):"

Same pontentiometers == same as in the instructable which has pictures of it.
But thanks for giving me a trip back to the instructable - I'd actually buy a bit different ones. Ones like these: http://tinyurl.com/d5pwukd ( and yes, onces again, the german ebay. Sorry 'bout that. )

Pot is just a contraction of potentiometer.

Attached is a close up of the pot showing the threads and the nut. To install: Take the nut off the threads, put the pot through the hole in the enclosure (The hole needs to be just bigger than the threads), thread the nut back on to the pot from the outside of the enclosure. Also notice the little tab on the left edge of the pot, that needs to be removed or you need to clear a small pocket for it to go into. It helps prevent the pot from rotating when you turn it.

When you install the pot it needs to get pushed all the way against the inside of the enclosure. If the shaft of the pot is sticking to far out once you install the knobs you can just cut or grind the end of the shaft off until you have the length you need. The thickness of your enclosure must be thinner than the length of threads on the pot so the nut has something to grab.

pot.jpgpot install.jpg

Reckon on a maximum panel of about 6mm 1/4"


a) Most pots will have a threaded portion where the shaft enters the body of the pot. There should be a nut with the pot which threads onto this part of the shaft. Drill a hole the size of the threaded part, pass the shaft through, and tighten the nut on the other side. This could work loose over time, so some pots have a peg that also protrudes through the case. You will have to drill a smaller hole in the enclosure next to the hole for the shaft to allow this peg to pass through.

b)The physical size of the pot won't really depend on its resistnace value. You will have to measure whatever pot you obtain to see how much clearance will be needed inside the enslosure.

Most pots come with shafts that are much longer than needed, and they will likely have to be trimmed to the proper lenght so that your shaft isn't poking 2 inches through your enclosure. You will have to cut the shaft to size such that it bottoms out inside whatever knob you use, while not protuding too far through the case.

Knobs typically have a single set screw that tightens them down onto the pot shaft. Some pots have a flat spot on the shafts for the set screw to tighten down on, so that the knob doesn't work loose and just turn around on the shaft.

All the specifics of clearance and lenght will depend on your actual pot.