[sdiy] good source of 1/4" shaft couplers that'd work well with pot. shafts?

[anthony]

I want to keep the knobs on the front of a radio I'm turning into an amp, 
but two of them were not originally connected to pots. One was the tuner 
spindle and the other was the mode switch. the shafts are even longer than I 
can buy new (that I've found) and they're splined which I never find new 
except perhaps as OEM replacements.

What would be simpler is just to cut the shafts and couple them with a 
coupler to join the two ends. Already though I forsee a problem with 
run-of-the-mill couplers, like excessive play etc. The really tough part is 
that one of the pots I want to use (an 8 Meg jobby for a tremolo speed 
control) is a very short D-shaft. So what I need is a normal shaft coupler, 
and then a shaft coupler than could accomodate a D-shaft.

Now I have thought of my own homebrew methods of tackling this problem and 
it may be what I have to resort to:

1. Get some clear flexible tubing that will fit snugly on the shafts, boil 
it in waterfor a bit, dry it off put it on the shaft and then soak it in a 
stong solvent like acetone or starter fluid (which has a lot of ether in 
it). The solvent will leech out the plastisizers in the tubing and it wil 
become smaller and much stiffer like lucite. Or avoid smelly nasty solvents 
(which I'm supposed to anyway since I only have 1 kidney that works) and fit 
a piece of brass tubing over the plastic tubing to make it rigid.

2. Use thick-walled lucite tubing and drill 4 small holes for two set screws 
at each end (that number of set screws should keep shaft play well doown. 
For the D-shaft, cut a small length of 1/4" wooden dowel rod, glue it to the 
D-shaft and then proceed as before.

I think I like my second method best. I'm fortunate that I have a lot of 
area that is hidden but accessible for what ever contraption I end up using.

cheers,
aa