Hi all,
The potentiometers I bought for my arduino project each have this little metal spike next to the main shaft which prohibits proper mounting on the metal casing. Instead of embarrassing myself with clumsy descriptions, please have a look at the attached pictures.
I assume the pin is somehow meant to provide fixation for the potentiometer so that it doesn't spin when you turn it's shaft once mounted - which is not bad - but does it require me to drill super precise holes next to each hole for the main shaft? (I probably can't drill that precisely) Or are there specific parts used for this which I am still unaware of? Does anyone have experience with this? What would you do here?
Thank you for your thoughts, I will appreciate every advice!
but does it require me to drill super precise holes next to each hole for the main shaft?
Yes it does.
Not only that but it is a rectangular hole.
What you do is to drill the main hole, slide the pot into it and mark the position of the slot. Either by pressing down and twisting slightly to mark the space or by putting a spot of Prussian blue on the spike to mark the surface.
Then you know where the slot should go drill two 1.5 mm holes at each end and join them with a router or Swiss file.
It is easy enough for plastic and you don’t have to be too precise because the hole is covered by the knob.
Don’t ignore it because it will not mount flat and the mechanical stress will make the pot fail a lot sooner than it otherwise would.
It’s called an anti-rotation tab. A round hole is fine if you use a large enough knob to cover the result. Another option is to just break/cut/grind it off. The metal is die cast zinc, it’s fairly weak as metals go so it should snap right off if you use an appropriately sized pair of pliers.
If the body is diecast, snapping it off with pliers is much the simplest way to remove it. Remember to tighten
the shaft nut very tight if not using the anti-rotation tab and have a large knob on the shaft (typically you need
the anti-rotation tab for large knobs/chicken-head knobs as there is enough leverage to spin the pot and loosen
the nut with time.)
With small collet knobs its less of a problem.
Gorillas (metaphorical or real) will always spin pots of course, you have to use vandal-proof hardware for them!
Looks like there is plenty of room on the inside of the panel, to stick or glue a thick fiber or rubber washer with a slot that mates to the tab, and doesn't let it quite reach the panel itself. Washers that are a lot easier to cut Than the panel is to drill...
From anti-rotation tab noob to pro in such a short time!
Thank you, dear repliers!
I will experiment with the possibilities. It seems to me that leaving the tabs on and drilling extra holes would be most robust and no visual impairment as the knobs will cover the holes. Although, it could turn out to be far too much work. I have 50 potentiometers only on this device. Then I will try out the various washers.
