Metamec Electric Clock stalling

[SteveSmit]

Hey folks,

I've been given an electric clock by Metamec, a fairly standard-for-the-era looking oak mantle clock. Looks to be about 1970s. I gingerly powered it up, and the second hand moved for a few seconds but kept halting, and then wouldn't move again. I could hear movement inside, but wasn't seeing any on the hands. So I figured I'd take it to bits and have a look.

Turns out the synchronous motor itself (a self-starter with a rather crafty auto-correct mechanism for if it starts backwards, lovely to see working), is working fine. Unfortunately, most of the gears in there are plastic, white perhaps nylon looking stuff, and the one that takes the power from the motor (via a metal worm gear) seems to have bit the dust, and been ground away by the rotating of the worm gear against it.

Doesn't look too healthy.
A better view.
Top view.

I'm not holding much hope out, but is there anything I can do to...I don't know build that gear back up again with something? You know, something along the line of dipping the teeth in some sort of thin expoy to give them a bit more of something for the worm to grab. Or am I chasing my tail with this?

It's a shame because it's a nice looking little clock when it's together, I've got a bit of a soft spot for synchronous clocks so it'd be nice to see it running again.

Any help would be very much appreciated.

Steve.

[julie_m]

Could these sort of parts be made using a 3D printer?

I certainly wouldn't buy a 3D printer just to make one clock gear wheel; but if you can find somebody who has one, or maybe a mini CNC lathe, it might be worth a try.

[Mike Phelan]

Steve,

It looks as if you might be able to save it by reversing the pinion?

I'm assuming the pinion and wheel are one piece so you'd have to separate them by using something like a piercing saw.

The usual reason for this happening is that someone has put oil here - that plus the dust make a good grinding compound!

[Nicklyons2]

May I suggest if that part really has 'had it' try the following. Using a v, sharp craft knife or similar, neatly cut around the base of the small section so as to separate it from the lower larger wheel. If you can then 'waggle' the small cog up and off the shaft - dab of Araldite (or similar) on the shaft - tip the worn cog over ( so that the bit which was unworn at the bottom is now at the top) and slide it back down the shaft toward the large diameter cog. And hopefully, when the Araldite has set it should stay put.

P.S.
Looks like Mike bet me to it!

[David G4EBT]

Some Metamecs seem to be being 'restored' by having the electric movement replaced by a quartz one. It won't look the same because like fake Rolex watches, the second hand won't 'sweep' - it will tick.

I suppose some might argue that such conversions are akin to removing a valve chassis in a vintage radio and replacing it with a transistorised one, (as Bush did when they brought out the TR82!).

But as well as giving the clock a new lease of life, replacing the movements in this way seems not to detract from the value of the clock. Leastways, not as far as this one is concerned, with a £195.99 price tag.

I does also have the advantage of not needing mains, so can be moved around the room on a whim from one place to another:

https://www.etsy.com/uk/listing/1243...yle?ref=market

(Most Metamecs seem to be on offer for £15.00 - £20).

I'm not suggesting the Steve does this - I'm sure he'll wish to get the clock working again, and that was the intention of his post, but it's a solution if it can't in the end be restored to function reliably.

[andrewn]

I also had a Metamec clock with the same movement. The drive gear was chewed up in the same way because the worm gear wasn't making good contact. Both metal and plastic parts were worn out so I had to replace the movement with a quartz type. Sweep movements are available on the internet and only cost me £6. I was able to choose hands that were almost identical to the originals.
When I dismantled the clock I found that underneath the metal face was another unpainted face. I decided to paint the raised numbers and second divisions and now have more modern looking clock. It was a shame I couldn't repair the original movement but I'm pleased with the end result and it was fun to do.

[Nickthedentist]

If the worst happens and you're forced to fit a quartz movement with a "silent", sweep seconds hand, then do preserve the original hands at all costs - they can be fitted to the new movement with a bit of ingenuity.

Sadly, I fear that buying a similar clock to canibalise would prove fruitless as they're all probably similarly worn by now. But I could be wrong of course.

[julie_m]

It would definitely be worth keeping the original movement, if you do this, in case you ever do manage to find a way to replicate the gear wheel. I searched on YouTube and soon found videos showing a design of clock where almost all the parts -- barring the screws that hold it together, metal shafts and the weight that powers the clock -- were made by 3D printing, plus some videos of small parts being made on a CNC lathe.

EDIT: Crossed with Nickthedentist.

[Mike Phelan]

I have agree with AJS and Nick, I fear. For me, it's no longer a clock, just a case.
Just about passable if the movement is kept, I suppose.

All mechanical parts can be made at home; though a clock made in the 20th C hasn't any great value at the moment, many clocks in Victorian times were scrapped but now would be worth thousands.

[nutteronthebus]

Hi I have 2 Ferranti movements from syncro clocks ( I removed tham and put in Quartz movements) and you are more than welcome to them if you think they may help either pickup or cover postage costs

Dave

[Nickthedentist]

Ferranti movements are very reliable and easy to service. Go for it!

[SteveSmit]

Thanks for all the excellent suggestions folks.

I'll see if I can flip that gear over to begin with and see how I go on with that. I'll be sure to get hold of some of those sweeping quartz movements too. That'd be a last resort to be honest, but, call me nuts, I wouldn't mind swapping some modern ticking quartz movements for those sweeping hand ones. I do prefer their look.

Also nutteronthebus, yeah I would be very interested in acquiring those movements. Just PM me as to the various details and I'll see you right. Glossop must be the thick end of fifty miles from here, and considering I just potter about on a 125cc motorbike, I think postage would be the preferable solution!

Thanks again everyone, that's some great help.

Just one final thing, is there anything specific I should be searching for (manufacturer for instance) when I search for those swept hand movements. It does strike me a little as something that could be easily mistaken when buying - it's not as if you can see that particular characteristic on a photograph.

Cheers,
Steve.

[Mike Phelan]

Steve,

Good - you're saving them!
Most of the synchro clocks you find will be Smiths; occasionally you might get Ferranti, TMC (Temco), Metamec, Warren or Hammond.
They are all much of a muchness.
The main failures will be the stator coil but we've a couple of memers here who can rewind them.
They will all need dismantling and cleaning properly and you will need some clock oil.
Sometimes rotors lost their magnetism but that's quite unusual.
As you're only at Glossop you can whizz over Woodhead pass and pop in here if you're stuck - PM me.

Like I said, swapping with a quartz is a bit like sticking a Superdrug radio in a DAC90 and calling it a vintage radio. Chacun à son goût, I suppose.

[mark_in_manc]

Hi Folks

Coincidentally, I've just had one of these apart. Mine has the same problem. The motor shaft has a deep brass worm on it, which makes a reliable deep mesh with the steel worm wheel which bears on it. This deep mesh is just as well, because the shaft on which the worm wheel sits is held on two bent pieces of brass, the holes in which have worn very, very oval. This means the (second, steel) worm at the other end of this shaft makes a really iffy mesh with the nylon pinion on which it bears - which is now a bit chewy, just as shown in the pictures above.

All may not be lost, however - although the nylon pinions don't look great, the one above, like mine, is not even close to 'stripped'. On mine, if I push the worm shaft perhaps 0.5mm back across its now oval bearing hole towards the pinion which is meant to engage, then motion resumes. This means I need to make something to permanently take the place of the screwdriver blade which I have been using to try this out. There's room to attach a small brass plate alongside the existing tab which forms the bearing; I have some small BA taps and screws; and if I'm lucky and I make it fairly thin, I may be able to bend it to get the right degree of backlash between the gears (I'm pretty sure I won't be accurate enough first time!).

Steve - I'd really like to hear if your holes have gone oval too!

{Edit to add some measurements, using small number drills as feeler gauges. I can get a No.66 alongside the shaft through the oval bearing hole at the motor end - about 0.85mm play - and a No.73 at the problematic other end - about 0.6mm play}.

[Mike Phelan]

Sounds like a good temporary fix, Mark. Let us know if you sort it; same applies to Steve.

[mark_in_manc]

OK...my method works, and I didn't even break any taps or drill bits . In the end I fixed both ends of the shaft with the (grey nylon, not steel) worm and worm wheel.

I'll try to add some pictures later. I guess the repair is kind-of a bodge (a horological bodge, as opposed to a horrible bodge), but it has come together quite tidily. The brass strip I used to make the repair pieces which force the shaft to run in its original position as opposed to at the 'worn' side of the oval bearings, is a little thicker than the original tab, so hopefully we should be good for another 35-40 years of continuous running before these need replacement.
cheers
Mark

[mark_in_manc]

Here are some photos.

1) Original bearing fault at worm end of grey plastic shaft; fault similar to OP
2) Bearing fault at the other end of this shaft, at worm-wheel driven by worm on motor shaft
3) Nylon pinion - OK, mine is not as chewy as that in the OP!
4) Shaft out...actual steel shafts are in two pieces which push into the ends. I decided to place extra brass inside the original bearing at the first end, so filed a little off the end of the grey plastic piece at the worm end to maintain end-float.
5) Aligning new piece with saw/file slot in it, alongside oval bearing, using 1.5mm drill in place of grey plastic gear and shafts.

[mark_in_manc]

and finally:

1) Tapping a hole to 10BA. OK, it's thin brass, but I was very pleased with myself that I broke neither drill nor tap!
2) Starting to shape the repair piece - you can see how it sorts out the ovality.
3) Gear in place.
4) Doing the same thing at the motor end of the shaft.

So now we can tell the time like it's 1979 - at least we can when I replace the broken 8" glass. One final one in all its orange plastic beauty when I work out whether to find some 2mm glass and try to cut it in a circle, or to use the 1mm transparent plastic I found on the way home from the school run.

[Mike Phelan]

Sounds like a good result, Mark. You ought to be able to get a glass disc of the right thickness somewhere locally.

For the oval pivot holes, I'd have just done the same as on any clock with that problem; opened out the hole and fitted a bush - either ready-made one or turned one up.

A surprising amount of wear in a relatively new clock.

[mark_in_manc]

Mike

Would you simply drill out the ovality?

It seemed to me this would mean the bush would locate somewhere in the middle of the oval; as opposed to concentric with where the centre of the bearing was originally, where it could maintain a correct mesh. I then started to think about ways of making a hole which don't follow a pilot which is already there - small slot drills or perhaps an end mill, for instance.

The other idea I had was to turn a bush with the hole eccentric to the OD (pack the jaws), which one might then rotate until a good mesh was achieved and fix in place with a dab or epoxy. It would be rather fiddly, but perhaps possible.