Marconi knobs crushing brass potentiometer extensions - how to strengthen?

[abeLovesDIY]

I'm rehousing a pair of PM100 channels. One of the mid EQ pots broke and needed replacing. With the center taps these have, this was not easy but I found one (this had glue on it).


Original pots:


I tried adding these brass shaft extensions with glue:

But that isn't working, and the knob just crushes the brass fitting - any tips for making this fit better?

 

[ruffrecords]

The root cause of the problem looks to me like the pot spindles are splined which means they are really meant to use push on splined knobs. If you want to use Marconi knobs, or any grub screw type for that matter, you probably need to fill the gap between the two spline halves with something solid. Maybe cut some small pieces of aluminium or fill the fap with epoxy.

Cheers

Ian

 

[thomasdf]

I second that ! On most pro builds using these, there is a little aluminium piece cut to dimension slid into the knob shaft, preventing it from crushing under the set screw pressure.