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 Post subject: Re: Production figures for movements?
PostPosted: Thu Jul 26, 2012 5:53 pm 
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Yes, as I recall they do have spiral arms, and of course no adjusting screws on the rim (they are factory-poised by cuts on the underside of the wheel, much like the Hamilton 505).

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 Post subject: Re: Production figures for movements?
PostPosted: Thu Jul 26, 2012 8:02 pm 
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I assume that the 731 is to the 730 what the 736 is to the 735. In other words, the 731's also have screwless balances.


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 Post subject: Re: Production figures for movements?
PostPosted: Mon Jul 30, 2012 12:29 am 
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So, I've been digging into this a bit more and I find a couple of things that raise questions. Wd be great if anyone has any insights into this:

There are discrepancies in the date ranges given on these two resources:


Specifically:

    979: HWI says 1928-1934; VWF says 1927-1930
    986: HWI says 1921-1923; VWF says 1915-1921
    987: HWI says 1926-1948; VWF says 1937-1948
    987E: HWI says 1935-1937; VWF says 1928-1937

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 Post subject: Re: Production figures for movements?
PostPosted: Mon Jul 30, 2012 9:44 am 
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Will is more spot on with his information:

979 (including F variant) = 1928 - 1934
986 = 1915 - 1923 (Marketed in men's watches from 1922)
986 A = 1923 - 1926
987 (including F, E, A & S variants) = 1926 - 1948

The E variant first appeared in 1935.

These are general dates, as movements out of production appeared in watches years later. An example of this is the wartime cushion watch of the 40's, some of which had 986A movements.


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 Post subject: Re: Production figures for movements?
PostPosted: Mon Jul 30, 2012 12:24 pm 
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Just to add my two cents... and based on my understanding (so I could be wrong).

One also needs to remember what the E's, F's and A's represented..., as they help with timeframes a little. The catalogs are suprisingly silent on the movement varieties. I suspect inventory could be used everywhere that way.

The 987 came first in 1926, then the 987F around 1930 (not exactly sure about the year though). The F is for "friction" where the jewels were friction fitted (pressed) into the plates, vs held in with screws. Next came the 987E in 1935. The E is for Elinvar when the new hairspring material came out, otherwise it's just like an F. The 987A was introduced in 1937 and the 987S in 1940. The 987A was the first real design variation of the 987, as it's a lot different than the earlier models - especially in the bridges, setting mechanism and the hairsprings. The S in 987S stands for Sweep second - - and it shares most parts with the 987A.

Technically they're all 987's though and use a lot of the same parts - especially the 987, 987F and 987E.

Putting a 987A in a Cushion seems a bit of a franken to me. But putting a 987F in a cushion is totally fine, IMHO, especially if it's a 2nd generation cushion. Likewise, putting a 987F in an Endicott is a little out of place but a 987E would be fine.

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 Post subject: Re: Production figures for movements?
PostPosted: Mon Jul 30, 2012 1:30 pm 
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From a factory log issued at the beginning of 1958, summarizing production through Dec. 31, 1957:

Quote:
987 produced 1926-1929
987F produced 1929-1935
987E produced 1935-1937 "remarks: Monometallic balance, Elinvar hairspring starting with #4447301, year 1935"
987A produced 1937-1948
987S produced 1940-1948 "remarks: sweep sec. hand"


Individual quantities made were not recorded: "Quantity of 987A includes total for 987, 987F, 987E, and 987A as of Dec. 31, 1946."

The more detailed production logs, listing production by case style and year, make no distinction at all between sub-grades; all are lumped together as 987.

Installing a 987F or E into a 987 case is no problem, but the reverse is not always true. The jewel settings of the 987 make it thicker than later ones. Some later cases were made correspondingly shallower to accommodate the fractionally thinner F and E subgrades. So in some instances, if you put a 987 into a 987F case you'll hear a sickening crunch when you snap the back on. That's the balance pivot snapping off as the case back presses on the jewel............ Been there, done that. Ouch.

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 Post subject: Re: Production figures for movements?
PostPosted: Mon Jul 30, 2012 1:37 pm 
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This summary makes at least passing mention of the F and A grades, but not a word about E.


Attachments:
987.JPG
987.JPG [ 187.14 KiB | Viewed 550 times ]

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 Post subject: Re: Production figures for movements?
PostPosted: Mon Jul 30, 2012 7:46 pm 
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Brilliant stuff. Thank u all.

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