[sdiy] Why I was asking about UNEF etc.

[Simon Gatrall]

At 9:45 PM -0400 5/16/03, harrybissell wrote:
>my $.02
>
>The tapped hole in the front panel is prlly fine for 1/4-32 threads...
>
>Aluminum usually taps poorly, so be very careful... a sloppy tap will
>ruin the panel.
>
>If you can fit a jam nut from the back of the panel, that could work 
>as well...
>
>you might try getting knurled round nuts with slots like some 1/8" 
>jacks use...
>or similar dress nuts...
>
>If you do the tapped panel thing... use a good dab of RTV silicone on the back
>of the panel to the pot body... one dab on a side would be fine. 
>This will really
>discourage
>the pot from rotating,
>
>IMHO if you do not use the anti-rotation tab of the pot... it WILL eventually
>start
>to turn. The RTV could help a lot by making the rotation small until you can
>effect
>a repair.
>
>OK that was $.04 worth
>
>H^) harry

Harry's ideas about how to prevent the pot from rotating are good. 
There is however one problem that you (JH) may not have thought of 
until you actually start tapping the panels - if you are doing it by 
hand, it may be difficult to tap the holes normal to the panel.  You 
may end up with your pot shafts coming through the panel at random 
angles.  It's especially difficult as the hole size increases 
relative to the panel thickness.  A thick part with a small whole 
will tend to self-align the tap, but with a thin part with a large 
hole, it is easy to get the threads crooked.  With a 1/4" hole in a 
1/8" panel, you're probably safe, but it could be tricky.  Certainly 
I would try the idea with some scrap before committing to a design 
based on your chosen assembly scheme.  You can also use a drill press 
to hold the tap vertical while you tap the panel (just use the drill 
press to guide the tap, don't turn it on).
-- 
Simon Gatrall
gatrall at pacbell.net