Friday, May 25, 2012

Oh Hamilton 917s

I am back on the watch making and decided to revisit some movements that I have had in my inventory with various ailments that I finally got around to fixing. The Hamilton 917 movement is turning into my favorite movement (until I get my hands on a 921, 923, or 945 that is) and I got a few movements backup and running. One was missing the roller jewel (or impulse pin, depending on who you ask), another with a broken mainspring, and the last was a purchase off of ebay as a broken movement but otherwise looked like it had all of it's parts.

The first issue with the roller jewel was solved when I finally located and purchase a tool specifically designed to holder the roller table and to apply heat radially from the tool. The tool is called the combination tool because well, it is a combination of various jewel application to a watch as can be seen in a vintage manual for the tool;

The combination tool is setup so that the slots at the jaw will hold the roller table securely while I heat the tail end with an oil lamp (or in my case, a butane mini torch is what I had on hand) and heat the roller table through the tool until it is hot enough to melt a small flake of shellac that will hold the roller jewel.

I would have loved to of taken pictures during the process but it was a rather annoyingly two handed process where I nearly lost a roller jewel (for a 10 size Hamilton, they are .39mm wide and needless to say tiny.) The reason I nearly lost the first jewel was that I was not aware that I should not of have tried picking it up with tweezers...well not directly. The jewel is not only tiny but is slippery and a shaped like the letter 'D', and if I were to pick it up with the tweezers with too much tension, it goes flying...(lay down a ton of white paper on your desk, it is how I was able to locate it the first time I launched it). The trick is to lick the tip of the tweezers and the jewel will appear to just stick to it like ferrous alloy to a magnet. Once you have that going, heat the combination tool's long arm and drop a flake of shellac on the 'D' shaped receiving hole on the roller table, wait for the shellac to melt a bit and lay the jewel in and take the heat away. You have maybe twenty seconds before the shellac sets to where you can still re-position the jewel for a good fit and after that, this process all over again. For those that are wondering, no, I did not get it right on the first try.

With the first of the three Hamilton 917s fixed, moving on to the next one which has a broken mainspring, which is evident when winding and no tension ever holds. I have another junker 917 I bought at a yard sale for it's parts and time to swap out the mainspring. This process is really straight forward and once done, the movement runs beautifully. Since I was going to take it apart to service anyway, I went the extra step and cut down the base plate diameter for a future PAM homage build with this movement. There is already an excellent tutorial by Nightwatch at his blog here that covers in detail not only the plate size reduction but an entire 917 disassembly. I strongly recommend this tutorial to anyone who wants to get in to working on the 917.

A few shots of the cut down plate 917;

Onto the third one, the ebay chance purchase. These purchases can go a lot of different ways and the one thing I hope it is not is that it is missing the roller jewel like the first one in this article was. Usually I can ask enough questions to the seller to sort out issues like a broken staff but no way to tell if the roller jewel isn't there without looking. The only possible tell is if the watch winds but does not tick and this symptom can be caused by many things. Well, it turns out it was a really simple problem in the end, the stem was snapped off inside the movement. I took apart the movement, cleaned and oiled and re-assembled, stuck a stem from a another 917 to see if it would work about that, it runs well.

A close up where you can see the snapped stem;

Well, as for the three Hamilton 917s, two are spoken for, if you are interested in the third to be turned into a watch, please get a hold of me to reserve it.

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