The fabrication of knobs.


If you are busy with a project you want your tuning capacitor/regeneration/volume knob looks like
it is old and looks good on your radio. You can go search radiomarkets for your knob and perhaps
you will find more then one of the same,..or you don`t find what you want.
Why not make these yourself.

You need:
Poly resin by Hobby Time
Silicon Kautshuck RTV-NV by Hobby Time.
(also others manufacture the above)
and a original you refabricate.

The original mother knob I made myself using the cover of a limonade bottle and piece of wood.
The wood piece is made taper using a hand drill and a hand file. The limonade cover is glued
on top of it, and you see the result in the following picture.

  


Limonade bottle cover


With a piece of wood glued underneath it and painted.


Silicon Kautshuck mold of knob.


And the result of a finished knob.

The mold is made using a piece of PVC tubing, put some silicone in it at the bottom, then put in the original knob, and fill the tube
completely with the silicone. Let the silicone harden overnight. Take a sharp knife and cut out the top of the mold. Take the original
knob out of the mold.
Then mix the resin with some black paint (resin is transparant) till you get the color you want. Next mix the resin with the hardener.
Pour the resin into the mold,.....slowly,..you do not want air bubbles trapped into the resin.
Let it harden overnight and then take out the knob.

I made a 6mm hole in the middle using a lathe. I gleud a 8mm piece of hexagon in it with a 6mm hole in it to
fit the shaft of the capacitor,...sideways I also drilled a hole,...also through the brass,..made some thread in it so
I can put a small screw in it to fasten it onto the shaft.

This way you also can replicate knobs you already have.

There is a long complete desciption of this procedure on "jogis Röhrenbude" at the link "Formteile - selbstgegossen"
the description is in German.


 

Good luck.



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