All about Gruen

[Fred]

So true! It’s almost impossible to accurately tell size from photos, at least for me.

I was referencing Gruen cal 131, which should be Favre

[Mr. Bieser]

Ok, thanks I know it, I thought you were noting the similarities in connection to the makers. but the manufacturers are different between 130, Favre and likely Robert 620. I'm on a Robert tangent. I'm assuming Robert bc the setting works are like 100, 101 which is Robert. Researching a seperate movement, looks like a 101 relative but I'm not sure what other 8 3/4 ligne there are, not 89's or 100, 101 or 200, or 620 I just think it could be Robert. Gosh what other 8 3/4 ligne are there?

[Fred]

Hmmm, does it happen to have 16j? I know of one from WSC days, but do not have a separate number (it has a 101 stamped dial).

[Mr. Bieser]

This is it. No 15 jewels. 8.75 ligne. Does anyone know what calibre? Can't find visual refererence for this one in any of my books

[Fred]

I have that catalogued as updated 101. I have one with cal number stamped in the boneyard. But my pic leaves me uncertain. I’ll try to find it this evening.

[Mr. Bieser]

Interesting! I do not believe an updated version has been documented, at least publicly.

Note numerous differences between your example and mine, center bridge, being only one.... Must be because mine is OF or...? Hmmm.

Let's look at what Gruen reference shown in 26 and 39 for 100/101 documentation.

101 in 26 parts book.

100/101 in 39 book.

So when was it updated?

[Fred]

Totally missed that yours is OF. That makes yours the first true cal 100 (OF variant) I’ve ever seen. So I cannot say what normal # of adjustments were vs 101. But I would say your middle bridge is identical to those shown in 26 & 39. The change has not been documented to my knowledge: it’s almost too subtle to see!

The change appears to have happened circa 1921. 1922 transitional stamps & “Precision” stamp follow (yours just before the transition, but Precision dial). You’ll note the lower cutaway on middle bridge is the same shape but mine seems to be cut very much deeper & closer to the 2nd wheel jewel recess. Yes, the center wheel hole is slightly different, too, but that’s not as crucial. Look closely at the middle bridge jewels on updated version: they’re smaller! The bridge cutaway is basically identical, but I imagine much more difficult to drill & finish the old bridge with so little metal in between. I’m not savvy enough to tell for sure if the 2nd wheel pivot position has moved slightly higher (=new wheel sizes), but I think so.

[Mr. Bieser]

Ok cool! I'm following but...are you positive?
The caliber *100* shown in 1921 parts is exact same layout as the 101 in 1926... which leaves me some doubt as to mine...
But the 1921 book list 100 as 15 and 17 jewels, so what calibre is 17 jewels?

[Fred]

…are you positive?

On Gruen? Never!

I don’t have the ‘21 book or repairers ref, either. I’ve yet to see a 17J, and I’m still trying to figure out how Cleves et al date this movement launch to 1915. All cased movements I’ve seen with the above layouts are 1920s.

Unless we really want to lean over the skis to get older or find a 17j… I’ve a 16J Gruen WSC, I would call it 626. Except the setting bridge and setting detent are a closer match to 100/101—exactly the same as my 101 I posted above—and the dial back is stamped “101.”
-Was there a separate entry for cals 620-27 in 1921, or were they consolidated with 100-1 based on parts interchangeability? (You will know that, but I don’t)
-Was there an even older version of 100/101 with more generic bridges?

Yeah, I’m only positive that it’s murky waters before 1921. Only seriously cloudy thereafter

[Mr. Bieser]

"On Gruen? Never!"

I know, right? The uncertainty makes it fun.

"Was there a separate entry for cals 620-27 in 1921, or were they consolidated with 100-1 based on parts interchangeability?"

No, not in 1921, just the 100.

But in 1926 there is an entry for 101, and in 1926 supplement B there is a separate entry for 626, 15 and 16 jewels.
Imo, While the setting works are very, *very* close between 101 and 626,side by side on paper there is some slight differences & they aren't an exact match.
Interestingly enough Barnett lists Durowe 552 as being interchangeable with 627.

"Was there an even older version of 100/101 with more generic bridges"

Yes I believe there was, but don't know if it's been shown conclusively.

I'll take the dial off if I have to, to see what we have here with mine.