Post by Peter Walsham on Mar 22, 2021 22:15:00 GMT 12
RS Components also have a shaft coupler available (Part No: 509-793) (see:https://nz.rs-online.com/web/p/trimmer-resistor-mount-adaptors/0509793/?relevancy-data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searchHistory=%7B%22enabled%22%3Atrue%7D) (wow - I didn't realise the URL was this long!). These are made of aluminium, and have two grub screws at each end, with points that dig their way in to a pot shaft. I have used these on many occasions with perfect success without slippage. However, a shallow hole drilled in to the pot. shaft and the extension shaft so the grub screw has something to screw down in to wouldn't be a bad idea. More lately, when I have come across a radio (like a Gulbransen tombstone, with volume & tone control position indicators that are screwed onto their respective pots with collars, and not leaving enough room for an aluminium extension (meaning that the aluminium extension would bind on the radio cabinet holes, without making these bigger) I have used copper tubing in a few cases, as the tubing is made from a thinner material, and I have glued these on to the shafts as required. If they ever need to be removed, applying heat from a heat gun works well to break the epoxy bond - even if the pot. ends up being sacrificed.
Post by Peter Walsham on Mar 27, 2021 8:29:14 GMT 12
Good morning Richard
I had actually answered your question, but I see that it didn't get posted, so here's a second go at it.
I got the copper tube from a heat pump/refrigeration guy that my daughter's 'ex' knows. Unfortunately, things have become very difficult with the 'ex', and I no longer have anything to do with him, so asking for some more is now not possible. However, your local heat pump/refrigeration guy should be in a position to help. The other thought I had was using thin walled 1/4" ID brass tube. I'm guessing that this could be available from a hobby shop.
I ended up using the Jaycar couplers, however I had to hone them out using a 6.5mm drill in the drill press, as the shaft diameter of a potentiometer is more than 6mm. I filed a flat spot on the shafts to help stop slippage.
Post by radioholic on Apr 13, 2021 16:46:07 GMT 12
I finally found the perfect brass tubing for extending a 1/4 inch shaft - it is made by K&S metals (stock no. #8132). This has OD 9/32 inch and wall 0.014 inch which results in ID=6.43mm. It is stocked by some hobby shops in NZ (e.g. Constellation Hobbies) - their price is $8 for a 12 inch piece. I use a 2cm length and epoxy glue.