All about Gruen

[thesnark]

The most interesting thing about 134929 is that it's not signed Precision on the movement, only the dial. So what does the "extra" reference? Of course it is Extra Precision in some sense of those words, but...

Many high-grade Swiss watches carry the mark "Extra". On some makes at least, it indicates that the watch has spent time with a regluer (proper term for a professional watch adjuster in Switzerland). Often these watches were intended for time trials.

I propose that this is how Gruen used the term as well. It fits with the scarcity of the label on the watches, along with them being scattered in many calibers.

[Mr. Bieser]

"The most interesting thing about 134929 is that it's not signed Precision on the movement, only the dial. So what does the "extra" reference?" Of course it is Extra Precision..."

Possibly...or I suggest it could sometimes reference "Extra Jewels". There is precedent, seen that on a movement before.
I'm also curious where Gruens post-22 Precision in a Diamond revision means Extra? Sounds familiar and correct most of the time but I'd like to find the source on that to see if it applies all the time.
Maybe Extra had slightly different definitions in different time periods for diff movements.

No Precision on dial or movement of 126234, so I can't assume Extra means Extra Precision in this particular case.. though whatever it has Extra of must make it more precise! You got me on that one...

37021772nx67386/gruen-watch-movements-f11/unknown-calibre-and-maker-2-t94.html

I do like yr règleur proposal, could explain a lot, I thought I heard somethin about someone digging deeply into the Gruen bulletins - so if viable no doubt there will be a trace..

[Mr. Bieser]

Moving on, this is sn 134138. Extra on dial only.

[Fred]

Christmas arrived a bit early this year, with a gift of the out of print "Watch Repairers Reference" coming my way (thanks very much!). I have been pouring through it, and I would like to share something. I do not presume this is all proven, but I am laying it out on the table as a possibility.

We know one thing for certain: there are many different Aeby calibers that we may have seen as movements but are not documented or pictured in the later books (1921, 1926, 1926sup, etc). From Charles Cleves' article How to Date Your Gruen Watch (Horological Times, May 1989), we also know: (1) the Gruen service department still had documents that we've never seen for identifying specific Aeby calibers by number--so there's hope(!), and (2) these 1950s letters give us a more complete list of Aeby caliber numbers, grouped by sister calibers (from known calibers, we can presume these pairs show Open Face vs. Hunter).

Let's put our assets together...

1902-10-08 JC ad ("New latest model" sizes) + actual sizes Gruen used, some with spacer rings:

• 16 size (= 19L for Gruen, which is 15.5 size, ~42.86mm)
• 12 size (= 17L for Gruen, which is closer to 10 size, ~38.35mm)
• 0 size (= 13L, ~29.3mm)
• 00 size (aka 2/0 size = 12.75L, ~28.76mm)
• 9L (= 12/0 size, ~20.30mm)

Now, a list of all documented Aeby-era calibers from Gruen letters + publications, grouped as known pairs, with my *proposed* grouping by size. Notes/assumptions:

1. From the calibers listed in later Gruen documents, we know there are two caliber number series for each Men's pocket size: 20 & 50 series are both 16 size/19L; 30 & 60 series are both 12 size/17L (references: 1921catA, 1926catB, 1926supB, 1939 & later mainspring charts, etc.).
2. Since 40 & 70 series appear to possibly fit this same convention (note: no 70 series caliber sizes are documented, that I can find), you will see I group them.
3. This leaves only 80 series, which based on later calibers in this series (see: calibers 87, 89) I propose are the special import Swiss-size ladies calibers.
4. I include known & possible Model pic #s, from 1908 swiss deposit

Key:
BOLD numbers: caliber size + jewel count documented
Unformatted numbers: caliber size documented
ITALIC number: no info documented beyond caliber #

20 & 50 Series - 19L (15.5-16 Size) --> Model pic #1
20-21, 24-25, 50-51, 52-53, 54-55, 56, 57-58

30 & 60 Series - 17L (10-12 Size) --> Model pic #2 & possibly #3
30-31, 34-35, 60-61, 62-63, 64-65

40 & 70 Series - Ladies Size(s), 12L-12.75L-13L (0000-00-0 Size, based on spacer ring used) --> Model pic #4 & possibly #6
45, 75

80 Series - Unknown but possibly Special Swiss ladies sizes, including 9L --> Model pic # 7
80-81, 80B, 82-83, tbd if also 84-85

[Fred]

At risk of overwhelming after my post above, here is the 16 size/19L caliber list + all known info I can find--please, make builds!!

From known calibers, these Aeby movements appear to be the time at which sister caliber pairs begin to *mostly* match later Gruen nomenclature (even = Open Face, odd = Hunter). Recall that Dresden/Glaschutte nomenclature was the other way around.

Key:
BOLD : documented info
BOLD ITALICS: *proposed exception* to info that's documented

16 Size/19L Aeby Caliber Details (Source) --> somewhere in this list must be the "16j Special" seen earlier in thread

• 20-21: 21j, Open Face-Hunter (Cleves, 1921catA, 1926catB)
• 22-23: Missing from all records, gap in numbers supports existance, possible OF-H
• 24-25: probable OF-H (Cleves)
• 50-51: 19j, OF-H* (Cleves, 1921catA specifies only 19j)
• 52-53: 21j, OF-H, EXTRA (Cleves, known ads/movements)
• 54-55: probable OF-H (Cleves)
• 56: 17j, OF --> no sister movement (Cleves, known ads/movements)
• 57-58: probable OF-H** (Cleves)

*Caliber 50--among all Aeby movements ever shown in ads or Gruen literature--is the only one with a picture that does not match the "even cal # = open face, odd caliber # = hunter" nomenclature. Both 1921catA and 1926catB show a Hunter movement on "50" listing. However, I propose that this is an anomaly, with 50 & 51 actually being OF & H, respectively. As supporting evidence, please see cals 870/871 and 802(ss)/803 in those same books, where the wrong configuration is pictured vs. what is known & documented to be actual truth.
**The only likely outliers to this "even/odd" nomenclature might be Calibers 57 & 58, where Caliber 56 being an orphan may have interfered. Having no details of cals 57 & 58 beyond just their numbers, I cannot be certain if this is true.