[sdiy] Source for dual Concentric shaft pots?

[Paul Perry]

I use a commercial tool (from Farnell) for the single collet knobs that I
used on something that I used to manufacture (the narrow shaft 16 position
encoder for a midi-cv channel selector).

But I expect that you could make your own by finding metal tubing that just
fitted over the shaft, and cutting two notches in the end, so that the
remaining pieces just fit in the spaces in the collet retainer.
(If you are good at model train engineering, that is.. I know some of you
are..)

With a single collet, I have had success with a "snakes eye" bit. Won't work
on the one in the pic, though.

Paul perry Melbourne Autralia

-----Original Message-----
These work on the same principle:
http://www.dompselaar.org/concentric.jpg (from a mixer I'm currently 
scavenging for parts)
As far as I can tell, they're also just two regular knobs with the cap 
missing from the bottom one.
As an aside, does anyone know what kind of tool to use on the screws 
that are inside these knobs?