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The Separation of Static and Dynamic Beat

From The American Horologist magazine, July, 1944

The Separation of Static and Dynamic Beat
By Emanuel Seibel

To begin with, we are speaking of a good grade of watch in good mechanical condition.

What is good mechanical condition, you may ask.

First, it must be clean. Then we must have positive train freedom, but this freedom must be correct, not because pivots are sloppy but endshakes and sideshakes must be correct; these pivots must be well polished. Wheels must be absolutely round. Barrel arbor must fit as snugly as possible without bind. Center wheel must be upright; all wheel teeth straight without burs; pinions polished so that all frictions are reduced to a minimum.

Then your escapement must be set up as light as possible with safety.

Drops equal, lock and slide as light as you can make it, draw positive.

Roller jewel properly fit to fork slot and your guard sure, and the closer you can make pallet and balance shakes alike, the better you are off.

Now we are ready for poise. Most watchmakers poise to a square that is four points,-some to eight points or a double square. First, the balance must be absolutely true, round and flat. Before we attempt for poise, if the watch has the original staff in it, it should not require much, if any, poising; if a staff is being replaced, and old staff is turned out of wheel and properly staked fast, it should not need any, or very little, but poised it must be.

When you are satisfied it is as close to poised as it can be ,gotten, you have your static poise, or poise in rest.

Now, you put on your hairspring and your static poise is disturbed because your collet, to begin with, is not poised in itself and cannot be, for it has a slot in it, and if it is not a proper fit to Hairspring shoulder and is forced on staff, it is spread and the condition is aggravated. 

The spring, which is spiral, cannot be poised. Remember, the wheel itself is in poise at rest, but the complete assembly of wheel and spring has disturbed this static poise and we must get this assembly in dynamic poise (that is, in poise under power, or in motion). This is where the Watchmaster comes in.

Now, remember, the Watchmaster will not do it, and cannot do it. It can only indicate the trouble; and how you may correct it, is in your ability to interpret the readings of your Watchmaster and make the indicated adjustments.

Your balance under motion to function properly must have a turn and a quarter of vibration and we find that unless the hairspring is properly centered, positively true in round and flat and the pinning point correct so that it developes correctly, and breathes as it were, equally in all directions, you have unequal pushes and pulls in the spring, which disturb the rate and beat of your watch.

Just because your fork and roller are absolutely in line and in the absolute middle of the bankings, does not indicate that it is in beat, for the relationship of your pallets and roller may look correct in static condition, but when power is applied, your balance may pull to one side or the other and not start, and until you get this relationship of pallets to roller correct, it will not pull equally to either side and start. When this is correct, a watch in good mechanical condition will start off at the first twist of the crown. 

After a balance has been poised on a poising tool, equally weighted at every degree of the circle, balancing perfectly in all positions around the axis that balance is in "Static Poise" or in a state of equilibrium. (See Page No.6 in the Book. "12 Thousand Hours").

Counter poise, in the "Static Sphere" means you actually take off or add weight.

The average watchmaker will use four corners, or one square when poising a balance. The more critical workman will use eight corners or two squares. (See Drawing at Top).

It is true that often in poising a balance you start with the screws that are too far in to the center, and when you do this the balance will be under-compensated; naturally if you start with the screws that are too far away from center the balance will then be over-compensated. You must have compensation in "Static poise" or balance that will match as near as possible, the ability of hairspring in "Dynamic Poise", after you have this combination you never destroy static poise by moving or changing screws. 

After hairspring and collet have been added, and placed in watch, we then have the "Moving Element", when this, takes motion we are then concerned with "Dynamic poise".
(See Page No. 6 in the Book. "12 Thousand Hours").

Counter poise, in the "Dynamic Sphere" means, control of equilibrium in motion, and the control of this force is attained by changing the level of hairspring and push and pull under dynamic power. (See Page No.7 in the Book. "12 Thousand Hours").

Take a look at simple drawing at top. First we use the "Static Poise" and accept it as being correct. Then we check the watch on the Watchmaster. In motion we see the rate is good in all positions except P. R. & P. 1. Records show P. R. 5 Sec. slow and P. L. 5 Sec. fast. We instantly know that the "Push & Pull" of hairspring are not equal at these positions, where the "Push" develops towards the rim more than the "Pull", at that position the watch will run slow. Naturally at opposite position the watch will run fast. You simply cause the hairspring to have same ability in both positions. You do this with "Dynamic" counter-poise and NOT by changing screws and distorting your already correct 'static' counterpoise. 

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