Mounting potentiometer in project box...

[Hippogriff]

I wonder if folk could tell me how they usually go about mounting potentiometers so that the things are relatively hardy (can take a bit of punishment without moving or rotating) and the gap between the level of the dial exit and the bottom of the actual knob isn't too much.

I have this potentiometer, I have it doing what I want it to do in my circuit with a PIC, and I'm now wondering about mounting it. Obviously it has a nut and washer, I am assuming they go on the outside of the mounting surface. However, it also has a metal protrusion which I am assuming is to go in some kind of cut-out in the mounting surface to help stop the potentiometer itself rotating, instead of just the dial.

**broken link removed**

At the moment, I have drill bits, but I don't have a tool for cutting out a square hole for this, I guess it could be any round hole and some glue at the end of the day. Same old story, this new hobby, a black hole for money; I keep finding new bits I 'need'...

Is this the right way to go about it? I push the potentiometer's dial through a hole I've made, I create a separate 'guide' hole or recess for this metal protrusion to go into, I use the nut and washer to lock the potentiometer down in the outside, then I put the knob onto the dial... even then I'm thinking there'll be quite a big gap between the mounting surface and the bottom of the rubber knob.

I'm not going about it the wrong way, am I?

 

[blueroomelectronics]

Round holes are just fine.

 

[cr0sh]

If it isn't critical that the pot not rotate, you should be able to snap the tab off with a pair of pliers (or file it off)...

 

[#12]

You are allowed to saw some of the shaft off with a hacksaw.

I make the side hole by drilling 2 or 3 holes and connect them by hogging the bit or using tiny files.

 

[Reloadron]

I just drill a round hole for the shank (shaft) diameter and a smaller tiny round hole for the index tab.

Ron

 

[KeepItSimpleStupid]

I'll add something basically to make it pretty. An internal tooth lockwasher is sometimes used against the inside panel and a second nut on the outside flush with the threaded section. It's not as foolproof as the two hole method, but it's still something to consider. The lockwasher used is strictly an electronic part. It's thin an flat. Very thin washers are used as well to prevent marring the external surface.

 

[PatM]

I use the nut and washer to lock the potentiometer down in the outside, then I put the knob onto the dial... even then I'm thinking there'll be quite a big gap between the mounting surface and the bottom of the rubber knob.

I'm not going about it the wrong way, am I?

You could add another nut to go inside the cabinet - used to adjust how far the shaft protrudes.
The 2 nuts and lockwasher could be adjusted for knob clearance.
Some shafts come slotted so a ring with short protrusion can be added so knob will not turn.

 

[Hippogriff]

Thanks for that - I was thinking of a second nut on the inside... one that still allows the 'index tab' (new term for me) to hold the thing firmly in place. I hadn't thought about hacking some of the shaft off... believe it or not, I don't yet have a vice(!), and I'm guessing it's not a job I should undertake using just my hands.

 

[Nigel Goodwin]

Thanks for that - I was thinking of a second nut on the inside... one that still allows the 'index tab' (new term for me) to hold the thing firmly in place. I hadn't thought about hacking some of the shaft off... believe it or not, I don't yet have a vice(!), and I'm guessing it's not a job I should undertake using just my hands.

In the past I commonly used to cut plastic shafts with my side cutters - but a junior hacksaw is nicer - you really need a vice though, or some way of restraining it (clamp the shaft not the pot).

EDIT:

Just noticed, you live in Sheffield, if any city is the "home of the vice" it must be Sheffield

Not far away from me either, in fact my wife has gone to Sheffield today.

 

[KeepItSimpleStupid]

Here's a pic of the washers typically used: Amazon.com: 1/4 Internal Tooth Lock Washer (10 pieces): Home Improvement