Take for example the 1951 Bailey. I was produced for only two years.
The Bailey looks a lot like several different prior models, for example the 1948 Forbes, but there are plenty of others. A lot of times you need to look closely at the dial to narrow down what model it is. For example, is the dial all numerals, numerals and markers, or markers and dots.
The Bailey has a 14K gold filled case, that's a good identification clue to - as other models have 10K gold filled cases.
The 14K gold filled cases with 14/0 movements got the 19 jewel 982 movement. 10K gold filled models got the 17 jewel 980 movement. Solid gold models got the 982M movement.
The dial on the Bailey is sterling silver with a white finish. The dial features 18K solid gold numerals and dots.
I haven't seen too many Baileys in the wild but that doesn't mean it's rare. I did happen upon one recently though and it look ed like it would be a good project. It arrived with a vintage strap that was well worn. I have no idea if it's original or not.
The case back is unengraved and doesn't show too much wear. The crystal is all beat up but the rest seems like all it needs is a good cleaning.
The dial looks very nice too and appears to be original.
Hamilton did a nice job decoratively engraving their movements. That's a sure mark of quality considering the only people who would ever see this side of the movement would be watchmakers. The watch is ticking. That's always a good sign.
Identifying the model is a breeze thanks to the name being stamped into the case back. That's not always the case (pardon the pun) but it's definitely helpful.
A new white alloy mainspring is ready to be inserted into the barrel.
There are three challenges to installing a mainspring. First, you have to make sure you wind it in the right direction. Next, you need to install it in the barrel and get the little tab on the T-end of the spring to catch in the tiny hole in the barrel. Finally you need to get the arbor back into center of the spring and not lose it in the process - as it has a tendency to fly off if you're not super careful.
I'll also prep a new glass crystal for installation after the case gets out of the ultrasonic.
Everything is cleaned and dried and ready for reassembly.
The movement is now ticking away. The motion looks pretty good so it's off to the timer.
Well, the amplitude is good, there's a little noise but the beat error of 9.7ms is way too high.
My first attempt to reduce the beat error is basically a best-guess at which direction to adjust the hairspring. I lowered it to 5.8ms but getting below 3.0 is my objective and the closer to zero the better.
Well, that'll do. It doesn't get much better than this.
Installing the dial and hands is a breeze compared to overhauling the movement. Reassembling it all into the freshly polished case with a new crystal, this watch is looking great, even with it's old strap.
Old straps are interesting but I personally find them to be a little on the nasty side too. They can't be cleaned as well as an old bracelet. So I've outfitted this watch with a fresh Hamilton-branded strap.