[sdiy] Panels, Transistor replacement for Oberheim Mini-seque ncer

[Simon Gatrall]

>How much space is it common to allow for harware?  I've gone by a 
>rule of adding
>5% of the diameter, if the clearance isn't specified in the 
>technical documents
>for the hardware.
>
>Ryan

Well, like many things, it depends.

In this case it is a matter of both the tolerances on the position 
and the diameter of the holes.  Threads are generally just under the 
nominal size (so if it is listed as a M10, it is maybe 9.98mm in 
diameter, or a 3/8" thread is maybe .373").  The hole positions are 
hard to control if you are drilling by hand, even with a centerpunch 
and a drill press.  Using a milling machine and a center drill first, 
you might achieve good positional tolerances.

If all of your pots and jacks are board mounted, you also have to 
worry about the tolerances of the PCB and your soldering - then you 
have make all of your holes larger (.5mm to 1mm).  If each piece of 
hardware is separate, then you just have to be concerned with 
visually how the holes line up.  The hole diameters only need to be 
slightly larger (on the order of .25mm, or .010").

If you're really seriously designing all this for production, you can 
get into all kinds of statistical games to figure out what sorts of 
tolerances you should use.  It's mind-numbingly boring.

5% is large in general.
-- 
Simon Gatrall
gatrall at pacbell.net