d'Arsonval Meter Repair

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Paul Hovnanian P.E. 16 years ago

I'm putting a Weston wattmeter back together and I've run into a bit of a puzzle.

The repair involved freeing the moving coil/pointer shaft and gently moving it aside in order to fasten a few turns of the current coil (stator) down. I managed to do all that without pulling the moving coil out of the core, which would have involved disconnecting its (very tiny) wiring.

Now, I've got to put the shaft back. In order to do so, I've got to set the bottom point into its bearing (similar to a watch jewel) and get the whole assembly to hold still while I align the top bearing and screw its adjustment down. But due to the coil spring and wires, the shaft keeps jumping out of the bottom bearing. Its so small that its difficult to feel when the bottom bearing is seated (the change in shaft position is barely perceptible when it drops in. And the bottom bearing is located deep inside the stator core, so I don't can't see it to line things up.

Any ideas how to hold all this junk in alignment while I reassemble it?

Paul Hovnanian mailto:Paul@Hovnanian.com ------------------------------------------------------------------ In theory, practice and theory are the same, but in practice they are different -- Larry McVoy

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Dave M 16 years ago

I would use a small chunk of Silly Putty to do stuff like that. While I've never tried to overhaul a meter movement as you are doing, I think it might do the trick. Silly Putty is pliable and sticky enough to easily grab the moving parts and hold them in place, while being cohesive enough that none of the stuff will be left on the parts when you are finished. Dollar stores still carry it; I have an "egg" in my toolbox now.

David masondg44 at comcast dot net

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N_Cook 16 years ago

If you succeed, please post back here. That's one of those jobs over the decades i'd like to have reason to have a go at. A company in Totton, Hampshire , UK now called (probably not doing that sort of stuff these days)

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maybe just the same address, used to be called Totton Test Instruments used to do those sort of jobs all the time. Other initially daunting ones I've had a go at are rewinding magneto coils and guitar pick-up

-- Diverse Devices, Southampton, England electronic hints and repair briefs , schematics/manuals list on

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N_Cook 16 years ago

I'd not forseen that problem in such cases, seeing just the fine and laquered-in wire on the frame, counting-off and rewind and problems removing and resetting phosphor bronze hair-spring/s without upsetting them.

For the spindle reseating . Can you drill out a piece of wooden dowel (as non ferrous),an axial hole the diameter of the spindle, friction-fit slide over the open end of the spindle and give you some more positional positivity to replace. If still awkward then maybe a fine rigid wire in the dowel, felt into place in the jewel bearing, dowel clamped off /glued to some temporary scaffold that you can slide the dowel in and out in an alignment . Remove the wire and replace with the movement spidle and lower the dowel and spindle into place, gently

-- Diverse Devices, Southampton, England electronic hints and repair briefs , schematics/manuals list on

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tnom 16 years ago

? Can you put one drop of melted wax onto one end of the shaft? Melt it away when done?

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David Nebenzahl 16 years ago

On 10/29/2009 6:58 AM snipped-for-privacy@mucks.net spake thus:

Far too messy, I'm guessing, and risk of damage from whatever heat source you'd have to use.

Who needs a junta or a dictatorship when you have a Congress blowing Wall Street, using the media as a condom? - harvested from Usenet

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Baron 16 years ago

Have you tried using paper shims to support the rotor whilst you fix the top bearing ?

Best Regards: Baron.

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d'Arsonval Meter Repair

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