My Clock Build Project Thread

devils4ever said:
I was getting a lot feedback that brass is better and that the aluminum needs to be anodized.
Click to expand...
Somehow I get the feeling that you lost sight that the journey is what it's all about and not the destination....
Anodizing is just another skill/experience to try. And, to me, it sounds more pleasant than hardening each tooth on the wheels.

But to each his own. The timepiece is still going to be spectacular in your home.
 
It's a good decision even if painful. Anodizing hardens the surface, but brass has some self-lubrication qualities and won't gall the way aluminum will. It's not about hardness. I think malleability might be the key characteristic, but that's more intuition and experience than factual knowledge on my part.

Tangential story: Back in the deeps of time, I was a trained as a bicycle mechanic. When I built conventional spoked wheels (which is pretty much all we had in those days), I used brass spoke nipples on the steel spokes. (The nipples were plated with nickel, but the threads cut through the plating.) Sometimes, the steel spoke would corrode and lock up in the nipple, causing the flats on the nipple to round over under the spoke wrench. But that could usually be avoided with just a drop of penetrating oil before disassembling the wheel. I was one who never cut spokes--used spokes were already fully stress-relieved and proven and I reused them.

But I build wheels very tightly--about two-thirds of the yield strength--the greatest tension of a spoke is when the wheel is not carrying a load, and the spoke delivers strength to support an external load only by giving up static tension. (This is a controversial topic, but I'm an engineer and studied this matter with the authority on the topic, who was a mechanical engineer and well-known if unconventional bicycle parts designer.) Turning nipples with spokes at a high percentage of their yield strength puts a lot of stress on those nipple threads. I never stripped the threads on brass spokes, or saw a spoke fail from fatigue, even if I destroyed the nipple trying to get it off a corroded spoke.

Aluminum nipples, on the other hand, would fret and gall terribly on the spokes if made as tight as needed, and they suffered from fatigue failures, too.

Most clocks have been made with brass wheels running on steel pinions, and steel arbors/pins in brass plate holes or bronze pressed-in bushings. Brass or bronze against steel is an excellent combination for avoiding galling. Clocks are very thinly lubricated, and the gear teeth generally won't be lubricated at all. Forces can be high on clocks--the driving weights on a tall-case clock movement often weight 20 or 30 pounds and the tooth bearing surfaces are tiny. Lubricant attracts grit and clocks are absolutely allergic to grit. Brass's resistance to galling is a good thing.

Rick "loves everything about brass except the price tag" Denney
 
Great information.

I'm trying to determine the thickness for the plates, but I'm not sure. I'm thinking it needs to be thinner than 1/4". My wheels are 1/4" and the pinions are 3/8".

Also, I might decide to use bushings in the plate instead of having the arbors run in the plate itself.
 
You must log in or register to reply here.
Back
Top