Author Topic: How to repair bent rotary switch shaft?  (Read 3868 times)

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Offline skipjackrc4Topic starter

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How to repair bent rotary switch shaft?
« on: August 26, 2013, 02:40:33 am »
I recently got one of the EDC MV-100 voltage "standards" on eBay.  Unfortunately, the most significant digit's rotary switch has a bent shaft, and refuses to turn more than a couple positions.  The knob was also shattered, but I can replace that easily enough.

Does anyone have an idea on how to repair this?  I have never attempted to straighten a shaft like this out before. 

I have attached a pic of the switch.  I can always buy a replacement 11 position switch, but good ones are expensive and I would rather keep the original one if possible.  Thanks in advance for any advice!
 

Offline skipjackrc4Topic starter

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Re: How to repair bent rotary switch shaft?
« Reply #1 on: August 26, 2013, 02:50:56 am »
Now for the pic...
 

Offline WarSim

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How to repair bent rotary switch shaft?
« Reply #2 on: August 26, 2013, 03:18:41 am »

I recently got one of the EDC MV-100 voltage "standards" on eBay.  Unfortunately, the most significant digit's rotary switch has a bent shaft, and refuses to turn more than a couple positions.  The knob was also shattered, but I can replace that easily enough.

Does anyone have an idea on how to repair this?  I have never attempted to straighten a shaft like this out before. 

I have attached a pic of the switch.  I can always buy a replacement 11 position switch, but good ones are expensive and I would rather keep the original one if possible.  Thanks in advance for any advice!

That switch is built from parts. It can be disassembled and the shaft can be replaced. Some parts snap into seats but can be unseated, but most assembly is via tabs. These days the shafts have gotten more expensive. If too expensive you will have better luck straightening the shaft when removed.
 

Offline lowimpedance

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Re: How to repair bent rotary switch shaft?
« Reply #3 on: August 26, 2013, 03:23:26 am »
 No chance of finding a suitable size switch plate in a surplus junk store (depends on your location i guess) !!. Probably easier than to repair this one.
Who is going to see it when the covers are on and if functionality is restored does it matter if the switch plate is not original.
If not then remove the bent one and attach to a suitable bar of metal, which can be held in a vice. So the threaded portion is supported then use a small- ish adjustable spanner fitted over the bent bit (end on) and try to carefully bend it back to as straight as your going to get it. Use some emery to polish the shaft. Nothing to loose anyway at having a crack at it, good luck.
 Btw the shaft has a clip at the end of the thread section to retain it in the mounting plate, unfortunately here your shaft is bent so removing the shaft to work on it only will not be possible.
The odd multimeter or 2 or 3 or 4...or........can't remember !.
 

Offline free_electron

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Re: How to repair bent rotary switch shaft?
« Reply #4 on: August 26, 2013, 04:54:31 am »
digikey still sells that kind of switch. buy one , rip shaft out, replace.
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Any comments, or points of view expressed, are my own and not endorsed , induced or compensated by my employer(s).
 

Online G7PSK

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Re: How to repair bent rotary switch shaft?
« Reply #5 on: August 27, 2013, 08:12:40 am »
That shaft had quite a bash, if you manage to straighten it or find a replacement you will more than likely find that the bushing itself is also deformed also the outer end of the switch would also have exposed to high forces that will have caused distortion.
But the correct way to straighten a shaft is not by holding in a vise and then bending it with a piece of tube fitted over the end, you should lay it on a hard flat surface and tap the shaft with a soft face hammer at the high point turning the shaft as required to keep the highest point upwards with frequent sighting along the shaft to check for straightness.
 


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