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Post by Richard on Mar 19, 2021 17:03:06 GMT 12
Id be interested in ways of doing this? I have a chassis I'm restoring that needs a new Volume Pot, the shaft needs to be 75mm long.
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Post by dada on Mar 19, 2021 19:03:03 GMT 12
One way is a brass tube over the original and extended shaft, pinned though but now perhaps roughened and superglued in place would be easier. Plastic shafts now seem common. Cheers, DC
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redxm
Society Members
Posts: 20
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Post by redxm on Mar 19, 2021 19:17:02 GMT 12
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Steve
Society Members
vintageradio.co.nz
Posts: 727
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Post by Steve on Mar 21, 2021 13:03:07 GMT 12
A while back I bought some vintage brass shaft extenders which I put somewhere 'safe' at the time... they are still there, nice and safe (from me)... one day I will find them 
They look like this (but brass):
There are also these from Jaycar as pointed out above:
But I wonder how these would hold up over time with only one grub screw per shaft-end - I'd be worried they would come loose particularly with a longer extension rod
Cheers, Steve
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Post by Richard on Mar 22, 2021 19:20:40 GMT 12
I'm going to try using the jaycar coupler first, I might have to file a flat spot on the shafts, so I don't get slippage?
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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.
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Post by Richard on Mar 23, 2021 7:53:03 GMT 12
Hi Peter, where have you sourced the right diameter copper tubing?
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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.
Peter W
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Post by Richard on Mar 28, 2021 13:18:16 GMT 12
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.
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Post by Peter Walsham on Mar 28, 2021 16:46:42 GMT 12
That would be right. The Jaycar ones are 6mm ID (probably designed for robotics), but imperial 1/4" pot shafts are close to 6.35mm in diameter. Great that you've had success anyway.
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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. KandS metals price list.pdf (110.68 KB) |
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Post by Richard on Apr 14, 2021 16:10:56 GMT 12
Thanks James
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