The other day I posted about a 910 dress pocket watch from 1923 that I had waiting for attention in my workshop for several years. While researching it I was reminded that I had a 920 in my collection, or was it the 922?
Looking on my blog, I've covered the 922 but not the 920. They are very similar as the 922 replaced the 920 as Hamilton's premier 12 size caliber. It was regarded, at least by Hamilton, as the finest 12 size watch made in America.
The 920 is a marvel to behold in person. The movement is nickel, there are 23 fine ruby jewels set in solid gold settings. The train wheels are solid gold. It was adjusted at the factory to temperature, isochronism, and five positions. It really was the finest workmanship that Hamilton could put out.
My recent focus on pocket watches made me dig out the various examples I have to see what sorts of things I've kept over the years. Sure enough, I do have a 920, as well as the 922 that I posted about back in 2014. Since I haven't covered the 920 yet, I thought it would be a project to take on.
From a collector standpoint, I've failed miserably at record keeping. I have no idea when I bought this or even how much I paid. I do know which examples were family pieces, so at least that part is documented. If I could go back in time and do it all over again, I would keep better records.
Anyway, my project watch caught my attention for a couple of reasons. First, it's a 920 and I've not covered it. Second, it's cased in a rolled gold plate case - which is unheard of for such I fine watch. It would have originally been in a solid gold case or at least a case with heavy enough gold fill that it would be "permanently warranted".
So how did it get into this case?
I have a couple of theories - one of them is the Great Depression. Times were very difficult in the 1930s and it's very possible that the original watch case was sold for it's gold content and recased in whatever the least expensive option was. Another theory is an extension of the first... the original case was scrapped sometime between 1922 and the time I got ahold of it.
I find scrapping watch cases to be very sad - at least for a working and desirable watch. It's happening a lot today thanks to gold prices being ridiculously high. Demand for a watch is less than the demand for gold, I guess, so a lot of cases are being scrapped and movements sold for parts.
It's an interesting dynamic. Models that recently might have been considered pretty common are now becoming scarce. I'm sure more than a few $900 watches have been scrapped for $400 in gold melt, maybe making those $900 watches worth more like $1,200 in the future. Who knows?
When I picked up my project watch out of it's drawer I though it might have been a 917 or other 10-size, based on the case. RGP would certainly have been an option in the 1950s. The case back is unremarkable, other than a couple of minor dents.
The movement inside is in great shape. There are several different bridges and quite a few more screws than in a 910 movement but they are very similar from a geometry standpoint and things like dials and cases are interchangeable. It's really the materials of construction and finish work that made the 920 a masterpiece. Two of the jewels support the "motor barrel" - a unique design where the mainspring and barrel are supported by jeweled setting.
The inside of the case back makes me think this is a generic 12 size case. I do not see any indication that I have ever serviced this watch before. There are quite a few other marks inside though.
Two case screws hold the movement in the case and then the assembly can be pushed out the front of the case. I'll pull the hands and dial next.
The dial side of the main plate looks identical to a 910 movement. I'm sure all of these parts are interchangeable between the two calibers (as well as the 900, and 914).
The first thing I'll remove from the back is the balance and then the pallet fork.
Once the pallet fork is lifted out of the way, any remaining energy in the mainspring will be released. At this point I can start disassembling the rest of the movement, starting with the barrel.
Just the train wheels are remaining. There are three bridges, one for the center wheel and third wheel, one of the fourth wheel (the second hand), and lastly, one for the escape wheel.
Check out the solid gold train wheels - I bet these are pricey today if you had to. make them.
Everything is cleaned and ready to be put pack together.
All four train wheels have to go be in place in order to put the bridges back on.
Next the barrel bridge goes on and then I'll add the jewel that supports the arbor.
Lastly, the keyless works goes in and I can replace the final winding bridge.
Once the pallet fork and it's bridge are installed the movement can be wound up. I'll install it temporarily in the case and use the crown to wind it up.
I carefully drop the balance in place and it starts ticking away with a good motion. Let's see what the timer has to say.
Oof - the beat error is a bit high at 6.2ms. That's an indicator of how well centered the balance is and measures the difference in how much it swings to one side or the other. Ideally it would be zero but I usually draw the line at 3.0ms. as it's a tricky adjustment.
My first attempt gets the beat error to 2.9ms. I should stop here but I'll roll the dice again to see if I can do better.
I got it down to 1.1ms. It's a little wavy though so I may need to tweak the hairspring a little and see if I can get it a little better.
One of the reasons I decided to take on this project is I accidentally dropped the 910 I covered the other day. It slipped out of my hand and landed on the floor - perhaps you heard my cry of anguish as it echoed across the Blue Ridge Mountains of Virginia?
I decided to case the 920 in the green gold filled case that housed the now-damaged 910 movement. It's a much more fitting case than the RGP version. Alas, my previous 910 movement will now be used for parts... sigh. It happens.
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