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Question Box

From Horology magazine, November, 1938

Question Box

Mainsprings Break

Editor HOROLOGY, 
Dear Sir:
Would you please tell me the cause of a watch mainspring breaking shortly after cleaning the watch? In one watch I cleaned, the spring broke about two hours after assembly.  I usually don't clean the spring, just put in fresh oil. This doesn't happen in very many watches and I thought perhaps the watch had been laid away wound tightly for some time before cleaning, causing it to break when put in use again.

Will you please give your opinion on this?
F. R. C.

Answer: The exact cause of mainspring breakage is not definitely known.  According to one theory it is due to minute imperfections in the steel itself which are introduced during manufacture. We do not believe that the process of cleaning had anything to do with the breaking of the spring. As a matter of fact, mainsprings often break in the packages before they are ever placed in watches.

If you do not clean mainsprings when you take watches apart you are making a grave mistake for it is as essential to clean the barrel and mainspring of a watch as it is the other parts. By handling the springs with reasonable care there should be no undue amount of breakage.

Idler Wheel

Editor Horology,
Dear Sir:
May I submit a question to the Question Box? It concerns the mechanism of a sweep second wrist watch, the type which has a wheel placed above the train bridge, pressed onto a pivot of the third wheel and engages a pinion running through the center wheel staff. The question is, "By what procedure is this wheel removed when taking the watch apart for cleaning?"
F.M.S.

Answer: In a factory, where just one type of movement is handled by an individual a special fixture would be used for this' purpose, but the repairer must be able to handle all makes of watches. A safe and simple method of removing the extra third wheel is to first take off the bridge and wheel. By holding the wheel with one hand and the regular third wheel with the other hand the two can be separated by gently twisting and pulling them apart.

Poising Editor 

Horology 
Dear Sir:
When poising a balance should weight ever be removed from a timing screw? In a 992 Hamilton should the overcoil of the hairspring be below the center wheel? If it is in line with the center wheel will it strike when the mainspring is fully wound?
M.F.C.

Answer: Timing screws should never be filed, turned or otherwise reduced in weight when poising a balance. They are intended only for bringing a watch to time by turning them in or out. If any alterations in weight are necessary to poise a balance, only the other screws should be touched.

The 992 Hamilton movement is designed so that the level of the hairspring is below the center wheel. In fact, unless a watch has been somehow mutilated it does not seem possible that anyone could alter this relation.

Contact Mechanism for Clock 

Editor Horology 
Dear Sir:
I have an old Brown street clock with two dials, the movement of which is worn out. I also have a Seth Thomas No. 70 regulator in my store on which I would like to put a cam and contact mechanism to operate minute impulse secondary clocks behind each dial on the street clock.

Would this affect the timekeeping of my regulator? And how much extra weight would I have to add to the present clock weight to pull the extra load operating the contact cam?

Any advice you have to offer will be appreciated.
Very truly yours,
]. N. B.

Answer: If the contact mechanism is made fairly sensitive it will have very little effect on the rate of your clock. The extra drag will be so little that no addition to the driving force should be necessary. Inasmuch as the contact finger will have to be very light. it will not be able to safely carry sufficient current to operate two large clocks so that it will be advisable to interpose a relay. The cam should be placed on the escape wheel arbor of your regulator and need not be any greater than a half inch in diameter.

The smaller the size of the cam, the less power will be lost in friction. With good workmanship there is even the possibility of securing enough pressure on the contact finger to transmit sufficient current to operate the secondary clocks without a relay. Circuit breakers have been successful applied to watch movements and it is comparatively easy to install one in a large clock.

To prevent sparking and the consequent burning of the contacts a condenser and resistance should be connected to them. 
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