Soundproofing a clock

Hi all,
Slightly OT, but not entirely...
Recently I bought a cool clock on eBay. It's a German "Dehomag" slave
clock, probably dating from WWII. The whole thing is made from 1 mm plate, including the dial, which is made by punching out marks in a white-painted plate and laying a black-painted plate behind. Very cool I thought.
Anyway, my plan is to build a circuit to supply the necessary pulses and install it in my bedroom (I have a nice empty space on the wall). I thought being a stepper motor the mechanism would be relatively quiet, but I was wrong. The rotor does abrupt 180 degree turns every minute and has a ratchet to prevent reverse rotation, giving rise to a nice "kerthunk". It is, I think, a little more than I want to try and sleep through.
The clock is missing the original mechanism cover, so I'm thinking of making a new cover with some soundproofing inside. Ideally the cover would be spun or drawn steel, but I think I'll have to make do with finding a container of some sort and cutting off the bottom (unless anyone has a better idea). There will be about 1/4" of thickness for soundproofing material inside the mechanism case, and perhaps more space outside if necessary. Can anyone think of effective, readily available soundproofing material which doesn't cost a fortune? I'm thinking along the lines of some kind of dense foam rubber or cork, but I can't immediately think of a source.
Here are a couple of pictures of the clock. It's 14" in diameter:
http://www.mythic-beasts.com/~cdt22/dehomag.jpg
http://www.mythic-beasts.com/~cdt22/dehomag_mech.jpg
Best wishes,
Chris
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Another thing...I think this clock could probably benefit from a little lubrication. I recall someone mentioning a thin, synthetic oil which doesn't get more viscous as it evaporates. Is there anything available in small, 3 in 1 sized cans which meets this requirement?
Then I need to decide whether or not to repaint the clock. It was originally black, but I can't decide whether to stick with the grey or not :-).
Chris
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    --I'd argue against any lubrication. I remember a guy who made *really* precice clocks telling me that a good clock should rattle when you shake it; i.e. everything should be loose enough to move freely; if it doesn't you might just have something bound up due to previous owner gunking it up with lube that shouldn't have been there in the first place.
--
"Steamboat Ed" Haas : I'll have the roast duck
Hacking the Trailing Edge! : with the mango salsa...
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steamer wrote:

I know this is common advice with mechanical clocks, as they are finely balanced, but I'm not sure it applies to a clock driven by a stepper motor. To me the gears look like they would appreciate a little oil.
Chris
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Christopher Tidy wrote:

Check online for clock oil at salarose.com or timesavers.com. Frei and Borel is another good online source, but more oriented to the professionals in the field.
The pivots in the plates should get oiled. Any oil or grease on the teeth of the gears will result in erratic behavior over time, as the action of the gears works very well to assist the oil drying and becoming sticky.
Cheers Trevor Jones
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The lead plate seems an interesting idea. You should give it a go.
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Trevor Jones wrote:

The more I read about oiling clocks, the more confusing it is. Surely clean oil, of the appropriate viscosity, replenished periodically, will help to prevent wear to the gear teeth? To me, leaving gears running dry seems quite an unnatural thing to do. Is the problem that most people use the wrong oil and let their clock get dirty (i.e., correct, clean oil is good) or is the brass gear train genuinely better off without lubrication? Obviously I want to do whatever minimises wear to the mechanism.
Chris
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Do NOT oil clock teeth. Oil captures fragments of oxides and metal particles and helps create a wonderfully abrasive slurry that will eat the steel pinions meshing with the brass tooth "laps".
In fact, teeth were lubricated until someone figured things out, likely in the 1700-1800s somewhere.
The only exception is pallet surfaces which contact escape wheel teeth. The tiniest bit of oil works wonders, and makes the difference between a running and a non-running clock. Here, wear isn't the issue, it is friction; other wheel and pinion teeth undergo only minimal friction (mostly rolling contact), which, assuming proper alignment (depthing), shouldn't much impede a clock's running.
/mark
Christopher Tidy wrote:

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Mark wrote:

If I may, Most of the clock movement is not subject to load pressure the lubricant absorbs and in so doing helps prevent metal to metal contact/wear. It's a precise timing issue, (tounge in cheek) not 5:23 gears handling 1000 horsepower through 90 degrees.
So, I think lube would not only affect the timing, but actually add drag to the movement due to the surface/skin effect of fluids.
toosmarttoask
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Christopher Tidy wrote:

If you could keep the gears in a bath, it could work out OK. but anything other than that is just asking for inconsistancy to be added the the mix. Aside from dust issues, the relative motion of the teeth with the pinion is massive compared to the motion of the pivot in the plate. This tends to spread the oil out and allows it to flow to parts of the wheel that it does no good to, namely the sides.
So far that seems to be the general gist of several hundred years of clock history.
If you get a chance to see the amount of filth that builds up on a clock movement even in a so called clean environment you would really be able to see that the gears are better off without any oil on them. The oil serves very well to hold any airborne dust directly in the path where the added friction will do it the least amount of good. While the new synthetics are quite less apt to evaporate, they still work very well at sticking dust down.
There are a lot of clocks out there that are very old, running on their original teeth. They will continue to do so as long as the pivots and plates get their due care and attention, keeping the gears at their proper depth to the pinions, and they don't suffer a catastrophe in the form of a blown up spring or some such.
Cheers Trevor Jones
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Trevor Jones wrote:

An oil bath would make good sense, and make the behaviour of the oil easier to understand, too. Having done a little more research it transpires that the GE Telechron synchronous electric movement had an oil bath (with the motor coils on the outside).
I suspect that inconsistent friction is less of an issue in an electric clock, but I can still see that without a bath the oil will soon spread away from the gear teeth. One chap at alt.horology suggested using a trace of thin grease on the gears as it will stay in place better, but it seems like most people would leave them dry.

I had a look inside a clock I acquired from my grandmother recently (the one with the broken teeth on the drum which I'm trying to repair - so far I haven't found a sheet of brass of the right thickness to cut a wedge from). It has been liberally oiled, probably by my grandfather. There is more grime than I would expect inside a clock with an enclosed case. It doesn't feel especially abrasive, but I guess dirt that is abrasive over many years is hard to feel.

> So far that seems to be the general gist of several hundred years of > clock history.
Indeed. But it seems mighty counter intuitive. I feel like I'm going to have to unlearn the desire to oil things. I wonder if anyone has ever done any experiments regarding clock lubrication and wear? It would be interesting to do a scientific experiment on the subject.
Best wishes,
Chris
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The 'old' way of lubricating mantle and Grandfather clocks was to set a small cup of kerosene inside the case. The vapors gave a very light coating of lubricant that didn't attract dust like heavy oiling does. Clocks lubed in this way ran twenty years or more before needing service. Bugs
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Bugs wrote:

Interesting. I did a search on clock lubrication and found a site which recommends this, and another which says it's bad because it stains the case. Anyhow, I can't do it. The case of my clock is too small to fit a dish inside.
Thanks for all the help.
Best wishes,
Chris
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Christopher Tidy wrote:

I have read part of a study that debuncked that particular method of "lubrication". The findings over a period of several years showed that the dish of kerosene did nothing but make the clock smell. The guy's findings were that under identical conditions, the clocks subject to the kerosene without regular lubricant stopped after a very short period (months) with advanced wear, and that no difference could be seen when the kerosene was added to a properly lubricated clock, other than the odor.
That came from one of the NAWCC publications IIRC.
Cheers Trevor Jones
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Christopher Tidy wrote:

Two organisations worth noting.
The NAWCC, National assn. of Watch and Clock Collectors www.nawcc.org
The BHI, British Horological Institute www.bhi.co.uk
Both have extensive libraries of good technical books. Some of wich refer to studies of just the type you refer to.
I have forund the book written by Laurie Penman to be easy to read and very understandable. In Clock Making and Design, he get right into the math behing pivot sizes, spring rates, and a whole pile of other things that have been found out to be a requirement for a clock that runs well without wrecking itself. Worth a read from the library, in any case.
Cheers Trevor Jones
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Trevor Jones wrote:

Thanks for the recommendation!
Chris
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Trevor Jones wrote:

Today I had an interesting chat with a local clockmaker who seemed very knowledgeable. He confirmed your advice that oil on the gear teeth is a bad thing. I think I have finally banished the desire to oil the teeth, and will stick to oiling the pivots. Thanks for dissuading me!
Chris
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    --OK, got the picture now. I was thinking it was more like my synchronome, which uses a solenoid to push the pendulum...
--
"Steamboat Ed" Haas : I'll have the roast duck
Hacking the Trailing Edge! : with the mango salsa...
  Click to see the full signature.
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Why not replace the drive with a small battery driven movement available in hobby stores. On this side they are about ten dollars with hands. I have adapted hands to keep the original appearance of older clocks.
http://cart.clockparts.com/index.php?cPath 0_21
... unless you want to build circuits. Randy
Hi all,
Slightly OT, but not entirely...
Recently I bought a cool clock on eBay. It's a German "Dehomag" slave clock, probably dating from WWII. The whole thing is made from 1 mm plate, including the dial, which is made by punching out marks in a white-painted plate and laying a black-painted plate behind. Very cool I thought.
Anyway, my plan is to build a circuit to supply the necessary pulses and install it in my bedroom (I have a nice empty space on the wall). I thought being a stepper motor the mechanism would be relatively quiet, but I was wrong. The rotor does abrupt 180 degree turns every minute and has a ratchet to prevent reverse rotation, giving rise to a nice "kerthunk". It is, I think, a little more than I want to try and sleep through.
The clock is missing the original mechanism cover, so I'm thinking of making a new cover with some soundproofing inside. Ideally the cover would be spun or drawn steel, but I think I'll have to make do with finding a container of some sort and cutting off the bottom (unless anyone has a better idea). There will be about 1/4" of thickness for soundproofing material inside the mechanism case, and perhaps more space outside if necessary. Can anyone think of effective, readily available soundproofing material which doesn't cost a fortune? I'm thinking along the lines of some kind of dense foam rubber or cork, but I can't immediately think of a source.
Here are a couple of pictures of the clock. It's 14" in diameter:
http://www.mythic-beasts.com/~cdt22/dehomag.jpg
http://www.mythic-beasts.com/~cdt22/dehomag_mech.jpg
Best wishes,
Chris
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R. Zimmerman wrote:

I know it's an obvious thing to do, but I like building circuits and it destroys the authenticity of quite a collectable clock. I also like the way the hands move once a minute, just like the clocks you see in many large public buildings. I'm also doubtful that your average quartz mechanism would last for long driving those heavy steel hands.
Best wishes,
Chris
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