Log/Lin Pots

[Retired]

Hi,

Thanks Refugee. I spent hours browsing the web during my pot track making project and never did find any clue as to how the tracks were made hence I started from scratch coming up with my own method by trial and error.

It is possible the tracks were made as a flat strip and then formed into a curve but what I found out was that the Tufnol (Paxolin) is actually impossible to bend into a curve and for it to retain the curve unless a lot of heat was applied and the Tufnol strip required bending around a former.

There are different types of Tufnol and I've used two of them these being "Whale" and "Carp". The Whale Tufnol is brilliant for use in making bearings and sliding guides: I turned two lathe head-stock bearings to a very high degree of accuracy from Whale Tufnol. The Carp Tufnol is for use in electrical work due to it's extremely high insulation properties but Carp is very hard and brittle even when new. I believe Whale is cloth based whilst Carp is paper based? Tufnol is expensive material to buy but is still readily available.

I would be very interested to learn how the manufacturers did actually make the pot tracks; it's possible the strips were formed first then a special winding machine employed to add the resistance wire?

What is strange though is that whilst these pots must have been made by the million and possibly still are no one member from two radio related forums could enlighten me as to how they were made?

For my part I found the whole project to be fascinating and at times highly frustrating but what a learning curve it turned out to be; as with many of my projects I learnt lots of new things keeping my head and hands active; repetition bores me so I'm always interested in looking for new adventures.

Kind regards, Col.