I have never seen anything like it, but my impression is of a scale for weighing something very small and it appears like over to the right on the horizontal meter is where it can be zeroed. I must admit to being completely stumped! But I also think the picture is likely the back of whatever this device is.
Lindell
Posts: 10553 | Location: Northeastern Ohio in the USA | Registered: November 19, 2002
David has it. I'm sure he meant balance screw weight scale. This device is sensitive enough to measure the weight of an individual balance screw. Where the slot is on the right side is a small cup with a hole in the bottom of it. The balance screw is placed in the cup with the threaded part thru the hole. The slider on the top is then moved to the left until the cup comes back up to the original starting position. You read the number on the scale and then match a screw to that number. It is also important to know the starting weight of your balance wheel...assuming that it is vibrated correctly to begin with. You can't simply add and subtract weight to poise the balance without maintaining the same weight of the entire balance wheel.
Posts: 1078 | Location: Ticonderoga, New York USA | Registered: March 01, 2008
Hey Roger, Your last sentence about maintaining the same weight of the balance wheel is a little confusing. I thought the purpose of the weights was to time the watch. Such as adding weight to slow it down or removing weight to speed it up. Either way the total weight of the balance wheel will be changed.
Posts: 475 | Location: Gainesville, Florida in the USA | Registered: January 22, 2009
The old fashioned way of doing the same thing is to use a piece of mainspring straightened out and balanced on a knife edge pivot. The straightened mainspring is then trimed until equilibrium is obtained. The balance screws which you are working on are then placed on oposite ends of the mainspring.
Regards, John
Posts: 299 | Location: Mount Brydges, Ontario, Canada | Registered: November 10, 2005
Yes, you are correct that adding or subtracting weight speeds up or slows down the watch and the overall weight of the balance is changed. If you note in my previous post I stated that the starting weight of the balance is important assuming that the balance assembly is vibrated correctly to begin with. This means 18,000 oscillations per hour. (Most of the time.) When you add or subtract weight you are attempting to bring the balance as close to that 18,000 number as possible. That allows small adjustment afterward to be made with the regulator. If you add or subtract weight to get there and you don't have the exact amount of change on opposite sides of the balance, then the balance is now out of poise which means accuracy in positions is compromised. Now a watch with timing screws makes life a lot easier. The weight of the balance is not being changed. By turning the timing screw out you place more weight on the outer perimeter of the balance assembly and slow down the balance. Turn it in and it speeds up. Theoretically poising does not change. I find it fascinating how all this was done with such great accuracy so long ago when so many factors enter into fine watch timing.
Posts: 1078 | Location: Ticonderoga, New York USA | Registered: March 01, 2008
