Balance Screw Washers
American Watchmaker and Jeweler (1892)
All watch adjusters and expert repairers time their watches by the balance screws, without unpinning the hairspring, and have their regulator in the center. After the curve of the hairspring is once correct, it should never be let out or taken up. The portion of the spring where it is pinned is naturally stiffer and often abruptly bent to make the first coil conform to the stud and regulator. In unpinning the spring this curve is necessarily altered and the spring thrown out of the center, the heat and cold adjustment is altered and the isochronal adjustment often entirely destroyed. When a watch has timing or quarter screws and they move in or out friction tight, you can very soon bring your watch to time without molesting the spring and have the regulator in the center, and also poise by these screws. Very often some of these timing screws are so tight that there is danger of twisting them off. You will also find that two-thirds of the watches of the best makes do not have timing screws. In this case time by a pair of screws opposite the balance arms. If it runs too slow lighten an opposite pair of screws (just mentioned) in a split chuck or file in the slot with slotting file. If it runs too fast put a pair of washers under the screws near the balance arms, or four at right angles or more under other screws. Whatever may be required in poising put the required amount on the light side of the balance rim. Do not tamper with an adjusted hair-spring or any other. If you are anxious to do your work quickly and accurately, compare your seconds hand with that of the regulator. See Poising the Balance.
What Has Changed in the Last Century
The 1892 advice assumes a world where nearly every watch had a screwed balance rim and a repairer judged rate by comparing the seconds hand with a regulator clock, adding washers under screws or filing their slots to gain or lose a few seconds a day. Both halves of that world have gone: rate is now read in seconds per day off an electronic timing machine that listens to the escapement and prints a trace in under a minute, and the screwed balance itself has largely vanished, replaced by smooth rims of Glucydur or similar alloy paired with self-compensating Nivarox-type hairsprings, which made the old heat-and-cold adjustment by screw largely unnecessary. Where fine adjustment by inertia survives at the top of the trade it is done on free-sprung balances with a few permanent weights or nuts, not by slipping washers under ordinary rim screws. The quartz watch, from Seiko's Astron of 1969 onward, removed the balance wheel from most wristwatches entirely, and timing washers are now a vintage-restoration supply rather than everyday bench stock.
Written for this edition, 2026.