Minute Shaft Thread Sizes

[gearhead42]

Coming from car hobby where every dimension is documented, I’m trying to adjust to apparent lack of documented specs for restoring mass-produced clocks. In my newness, am I just missing where such documentation is? Having Sessions and Gilbert shop clocks and wanting to replace most commonly damaged/missing pendulum/minute hand nuts, I expected replacements to be fairly easy to find…after all, just about everything (slight hyperbole) uses a #6 key and they’re everywhere. Gingerly tried my Gilbert hand nut (came with clock) on my Sessions (missing nut). Right away could tell was going to cross thread. Managed to find NAWCC post identifying Sessions thread as 2-50. Best I could find for Gilbert was maybe 2-54 and suggestions to re-thread to 2-56. I know sellers offer American hand nut assortments that fit “most” clocks…not very reassuring…if I had taps/dies in that range, or could look up my thread sizes and sellers identified sizes in assortment…done.

Sorry for the rant,
John

[willofiam]

John, I hear you….many times over I have run across nuts and screws that previous “smiths” or owners have just jammed on or in to make work and it can be a pain to rework and make right….I have not taken the time to research or document thread sizes even though sometimes its a battle to get the right one. Even from one style of movement to the next from the same company can have different thread sizes. I have many older movements that are donors for such a task, otherwise…. with a fair assortment of taps and dies new ones are made to match. If you ever find the build sheets, plans or documentation of manufacturers of older American clock movements, with that kind of detailed information it, it would be a fantastic resource. Regardless… you would still have to have in stock the proper taps and dies to make them….having the ability to measure threads would probably be the best idea to prepare and document …The Tran Duy Ly books give some pertinent info on movements but not what your looking for. Have fun. William

[Author]

Posts