Hi All,
Happy New Year to all pocket watch lovers out there.
Just in need of a bit of help regarding the correct size key to use for my Waltham 18s PS Bartlett model 1857 dated 1872 KW and KS watch.
The key supplied with the watch is marked with a number 5 which to me seems a bit oversize, especially when adjusting the hands. Could it be the right size but worn through use or is it the wrong size, and needs to be the next size down - not sure how the numbering goes on these keys so any help appreciated.

Cheers Jon

Happy New Year.
is it new reproduction key if yes you will have to file the tip a bit for better fit.
if old you have wrong one.

Thanks Peter - no it`s not a new key, it looks pretty old but is stamped Switzerland on it

The following , with permission, from PocketWatchRepair.com

How to Determine Pocket Watch Winding-Key Size


"What size winding key fits my vintage pocket watch?"

"If you have a key-wind pocket watch and don't have the key to wind it, you'll need to find out what size key you need. To determine what size key is required for winding or setting your vintage pocket watch, you'll need to accurately measure the size of the winding and/or setting square (the square-shaped "shaft" that is either used to wind or set the watch). This measurement must be made accurately, preferably with caliper or micrometer. If you don't know how to find the winding or setting square, you should read our article on how to wind your vintage watch.

Keys (especially modern "reproduction" keys) tend to vary from these precise measurements, so if you think you might need a #5 (for example), you might also want to have a #4 or #6 on hand in case the #5 doesn't quite fit your winding square. Using too large a key will tend to round off the corners on your winding square, and once they are rounded off, you'll no longer be able to wind or set the watch. A key that's too small simply won't fit over the square. The best bet is often to purchase a complete set, as you'll then be able to choose the key(s) that give you the best fit.

Note that key-wind/key-set watches sometimes used the same key for winding and setting, and sometimes used different keys for winding and setting. Be sure to measure both squares if you have a key-wind/key-set watch."

Thanks Lorne
Will get a full set of repro ones thanks

I just bought a reproduction #4 key from eBay for my 1857 Waltham. To set the time, you will need to file the end of the key - they are made with an inside bevel that needs to be removed.

Doug

If by chance you are looking to use vintage keys, keep to American-made.
Cheers,
kh