Position adjustment--- what is it and how do you do it? - NAWCC Forums A watch adjusted to isochronism oscillates the balance wheel at the same rate throughout the specified length of run between windings of the mainspring, regardless of how far in each direction the balance wheel rotates This length of run is typically 30 hours for earlier watches and 42 hours for post World War I watches of better quality
Isochonism vs Isochronal Rates - NAWCC Forums Also, isochronism is an absolute only in the ideal state A timepiece is said to be isochronal when all the preconditions are met (lube, gearing, escapement setup etc) when it's instantaneous rates fall within some limit (defined by manufacture I guess) These instantaneous rates are measured when nearly fully wound and for watches, 24 hours later
A Few Thoughts on Isochronism and a 60 Hour Mainspring Watches are tested for isochronism in the vertical, pendant-up position as that is the position in which they are generally carried, and therefore the position in which isochronism is of most importance, although a nearer approach to true isochronism can usually be obtained with the watch in the horizontal position
adjusted to five positions | NAWCC Forums Andy, To attempt to answer your question Typically when a watch is marked "Adjusted" it implys three positions, temperature and isochronism Although as Kent stated this could also be 5 positions, temperature and isocronism Temperature adjustment can be confirmed by the presence of a bi-metalic ballance
What is a Lossier Terminal Hairspring? | NAWCC Forums Re: What is a The Lossier Inner Terminal Hairspring refers to a hairspring shaped like that on the left in this material catalog image It refers to the precisely formed innermost coil of the hairspring before it is pinned to the hairspring collet The Breguet overcoil found on almost all 20th century American hairsprings was introduced to improve the isochronism of the hairspring Due to the
E. Howard Co. | NAWCC Forums All Howard watch movements were adjusted at least to isochronism (Isochronism is the quality of rate independent of winding state) Apart from a short run of experimental movements at S# 3,201 [4,14], Howard otherwise began marking the level of adjustment on his watches at, or shortly before S# 10,964
Isochronism Adjustment - Waltham Model 1892 AT Co Premier Grade Apparently quite a few Just looking at the 1892 model, the Royal grade was "adjusted" with no mention of isochronism and, surprising to me, even the Riverside grade was only adjusted to 3 positions and not isochronism (per a 1900 Waltham brochure - The Perfected American Watch) The Riverside grade was more highly adjusted later in other sizes
Regulating for Isochronism - NAWCC Forums The breguet overcoil was a very important creation for improving isochronism, but good isochronism can also be achieved with a flat hairspring if the terminal curves are correct The shape is critical for both For example, if the overcoil approaches the staff too closely, the watch will be go faster as the mainspring runs down (short arc)
American PW - What Can Cause Isochronal Errors? | NAWCC Forums The only problem is, though, it shows very poor isochronism If I check it 12 hours after winding, it will have gained about a minute I can see this visually on the timing machine At full wind, it registers about 2 min day fast, and after 24 hours of running, it shows about 2 minutes day slow I've never seen such poor isochronism