Author Topic: Pot and Switch heights off for mounting.  (Read 270 times)

aviherman5

Pot and Switch heights off for mounting.
« on: September 19, 2021, 12:40:41 AM »
All all,

I have a project where I want to mount 16mm right angle pots and an on-off-on 3pdt toggle switch (MTS-303) to the board, but the heights are off and that makes housing the pedal extremely difficult.  :'(

Any tips? Thanks!

anotherjim

Re: Pot and Switch heights off for mounting.
« Reply #1 on: September 19, 2021, 03:58:59 AM »
A common issue. You can't make the pots go lower, easier to raise the switch. Use solid wire to extend the switch lugs. Fit the switch to the enclosure - you should have 2 nuts on it so you can set the bush to just have enough thread showing to hold the switch with the top nut. Fit the pcb in with pots soldered up and guide the switch wires into the pcb as you go. When happy solder the switch wires and trim.
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GGBB

Re: Pot and Switch heights off for mounting.
« Reply #2 on: September 19, 2021, 08:10:48 AM »
It depends on which pots but I'll assume something like an Alpha RV16AF.

3PDT toggle switch body height's are usually a bit taller than the pot leg length. If you include the lower nut and lock washer, the difference is a couple of millimetres. Either way, you need to extend the pots somehow. The easiest way is to extend the lugs as Jim described (but on the pots not the switch). You might also be able to get them height aligned if you mount the switch without the lower nut, and add a washer to the pot (I use an M7 lock washer). That should get you close enough so that the pot lugs are through the board and can be soldered properly but maybe not quite all the way in. Just make sure you have clearance between the pot body and any solder joints below it on the PCB.

Mount all the hardware to the enclosure (or build a template from 1/8" hardboard or similar) and then solder. If the switch is shorter (which is the case with SPDT and DPDT toggles) solder the switch first before mounting. This is so that everything is sitting where it should be and the positions don't shift (and stress the joints) when you do the final assembly.

When it's the other way around (SPDT and DPDT toggles shorter than pot) I use the toggle's bottom nut to bring the overall height to the same as the pot plus a lock washer. I solder the switch first, then mount the pots in a template and attach board and solder. For final assembly, after tightening pots, I adjust the lower nut of the switch until it is just snug, and then tighten the top nut.

I prefer to use pots with lugs rather than the right-angle PCB mount ones. I use solid core wire for leads, and this lets me adjust the height as desired.
« Last Edit: September 19, 2021, 08:12:56 AM by GGBB »
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ElectricDruid

Re: Pot and Switch heights off for mounting.
« Reply #3 on: September 19, 2021, 12:24:10 PM »
I used Alpha RV16AF right angle pots on my FilterFX PCB along with PCB mounting Salecom T-series switches. There was some tiny difference in height (9.8mm vs 10mm or something - I'd have to look it up) but it was close enough for rock'n'roll.

https://www.salecom.com/en/category/Miniature-Toggle-Switches/Toggle-Switches_T80-T.html

This is a very wide range with many options, but various common members of the group can often be found at your favourite reseller, even if that means you don't get to choose long toggle/short toggle or flat lever/round lever or whatever.
The close match in height was one substantial reason for choosing these switches in particular.