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Old 11th Apr 2013, 10:58 pm   #25
mintras
Retired Dormant Member
 
Join Date: Jun 2012
Location: Manchester, UK.
Posts: 40
Default Re: Copying a control knob by moulding

I thought I would try making some Murphy knobs so I got some white rtv silicone from Fred Aldus £25 kg and a casting kit for another £25. This seems a lot but I am using all the material on other projects.

The Murphy A124 knob came out grand.

I used a spray can plastic top and stuck a cleaned original knob into it pressing the base in place with double sided tape.

Mix the RTV silicone (3% setting agent 97% white stuff), I did spray some silicon oil over the original first but I don't think it needed it. then just pour it in.

8hrs later I had a perfect mold.

I mixed the other material with 50% stone power included in the kit, with some black colour. The result would be very hard to distinguish from an original, after a little polishing.

Used the same mold again for a second knob in dark brown.

This looks and feels like the original.

This was all too easy.

Now All I need is a source for brass inserts, I suppose I could butcher some existing knobs, but I would like to find a source.
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