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Old 16th Nov 2019, 5:06 pm   #1
stevehertz
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Default Splined pot shaft extender wanted

I need a pot shaft extender that will fit over a splined pot shaft at one end and the other end doesn't really matter too much, it can be plain whatever. It needs to be at least an inch long. Thanks.

NB, some Japanese hifi units this type of extension rod to - for example - connect a front mounted control knob to a pot or variable cap at the back of the set.
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Old 16th Nov 2019, 5:52 pm   #2
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Default Re: Splined pot shaft extender wanted

I’ve used a plastic wall plug that was a very tight fit and warmed it with a heat gun and it pushed easily over the splines and was firm after it cooled.
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Old 16th Nov 2019, 6:06 pm   #3
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Default Re: Splined pot shaft extender wanted

I've considered all kinds of Heath Robinson fixes, but without writing reams to explain the lack of space, access, concentricity issues, blah, blah, etc etc, the component as described is what will do the job. Cheers!
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Old 17th Nov 2019, 10:42 am   #4
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Default Re: Splined pot shaft extender wanted

What about filing a peg on a 1/4" shaft to fit the slot in the splined shaft. then araldite it in . Mick.
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Old 17th Nov 2019, 12:05 pm   #5
David G4EBT
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Default Re: Splined pot shaft extender wanted

I don't know if they're still available, but there used to be shaft extenders. Given that the OD of the splined shaft will most likely be 6mm, the fact that it's splined would be an irrelevance if a 6mm ID extender was available. The grub screws would tighten the extender onto the shaft just as well as if the shaft wasn't splined.

Not much of a task for a friendly model engineer if you know one!
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Old 17th Nov 2019, 12:35 pm   #6
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Default Re: Splined pot shaft extender wanted

These are a good option. It pays to use 24 hr epoxy resin on the hole and on the spines before you tighten the two grub screws.

Generally for this its important to cut a small rectangle of aluminum to match the gap between the two halves of the spline, to fill that gap, or compression by one or other of the grub screws can push the two halves of the splined shaft together:

https://www.ebay.com/itm/ARC-5-RECEI...kAAOSw8cNUTq1i
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Old 17th Nov 2019, 1:11 pm   #7
pbengtech
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Default Re: Splined pot shaft extender wanted

Hi Steve,
You know a friendly model engineer, me!
Regards,
Phil b
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Old 17th Nov 2019, 3:43 pm   #8
stevehertz
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Default Re: Splined pot shaft extender wanted

Quote:
Originally Posted by Argus25 View Post
These are a good option. It pays to use 24 hr epoxy resin on the hole and on the spines before you tighten the two grub screws.

Generally for this its important to cut a small rectangle of aluminum to match the gap between the two halves of the spline, to fill that gap, or compression by one or other of the grub screws can push the two halves of the splined shaft together:

https://www.ebay.com/itm/ARC-5-RECEI...kAAOSw8cNUTq1i
Yes a standard pot extender would work - and I'm open to offers or links - but I don't want to pay over 20 for one plus maybe import duties, VAT and (sometimes) so called handling costs to buy one from the US.

I agree about the shim, because if not fitted the two halves of the splined shaft may be squeezed in differently and the shaft at the control end would then move in a non-concentric fashion. And in my case the knob sits in a snug circular hollow; it needs to turn true.

Cheers.
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Old 17th Nov 2019, 3:44 pm   #9
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Default Re: Splined pot shaft extender wanted

Quote:
Originally Posted by David G4EBT View Post
I don't know if they're still available, but there used to be shaft extenders. Given that the OD of the splined shaft will most likely be 6mm, the fact that it's splined would be an irrelevance if a 6mm ID extender was available. The grub screws would tighten the extender onto the shaft just as well as if the shaft wasn't splined.

Not much of a task for a friendly model engineer if you know one!
Thanks David. If anyone can provide links or has a 'standard' (non-splined) pot shaft extender to sell, please let me know. Thanks.
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Old 17th Nov 2019, 3:45 pm   #10
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Default Re: Splined pot shaft extender wanted

Quote:
Originally Posted by pbengtech View Post
Hi Steve,
You know a friendly model engineer, me!
Regards,
Phil b
Hi Phil,

I'm certainly going to bear that in mind, thanks so much!

Steve
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Old 17th Nov 2019, 3:55 pm   #11
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Default Re: Splined pot shaft extender wanted

Quote:
Originally Posted by vinrads View Post
What about filing a peg on a 1/4" shaft to fit the slot in the splined shaft. then araldite it in . Mick.
Yes that's an option I saw on a Youtube video. Tricky to do though because as I explain above, the shaft has to run true to the pot or the control knob will rotate off centre and catch on the front panel that it sits 'inside', in a circular hollow. A hand filing job would be very tricky - especially as the 'tongue' was getting thinner. Machining much less of a problem. See photo.
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Old 17th Nov 2019, 4:22 pm   #12
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Default Re: Splined pot shaft extender wanted

For further clarification, here are photos of the original pot (no splines), and the replacement one with splines that I need to extend the shaft of.

The general dimensions and form of the Bourns replacement are close enough for me to be able to work with, it's just the shaft length that's too short.
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Old 17th Nov 2019, 5:18 pm   #13
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Default Re: Splined pot shaft extender wanted

These any use? Pm your address and I'll pop em in the post tomorrow
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Old 17th Nov 2019, 6:56 pm   #14
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Default Re: Splined pot shaft extender wanted

Quote:
Originally Posted by cliff2903 View Post
These any use? Pm your address and I'll pop em in the post tomorrow
PM sent.
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