All about Gruen

[Mr. Bieser]

Ok, why not, let's add to the confusion.
Another unknown caliber and maker without a setting works shot!

This is in a Gruen National 14k 97860.

[Fred]

So this is close enough to mystery #2 for me to speculate that they’re sisters, HC here. Different stud, different balance cock marks, but some sn space to. We know those things changed lots on same calibers from 1902- 1910.

Hey—is anything known about caliber 10XP? Even it’s size?

[Mr. Bieser]

Do look like sisters! Currently off the top of my head I'm only aware of the designation "10X". Which is an Extra Precision caliber.
I assume that's what you are referencing. Does Gruen call it "10XP" somewhere too?
No, I'm not aware of the size.

[Mr. Bieser]

Speaking of XP...just had a light bulb go off about a random caliber...
On seperate forums online, what is identified as caliber 35 is not! Why?
Because theres Gruen documentation that caliber 35 is Extra Precision.

K, just wanted to get that out there, carry on.

[Fred]

Love it! Worthy of looking into. Btw, I think you’re correct on 10X… was also going on memory!

[Dietrich]

This movement appears to be close to my #130504 which is also in a National case and luckily it is engraved with a date: 7-06
So I would date yours to Christmas 1905.

Here my little sister which has the mirrored design and appears to be smaller?

[Fred]

It does look smaller. I do think this 130k is a true Lecoultre ebauche.

Here are three differences. The winding wheel arbor has a bearing not seen in the 2 other unknowns—this cues Lecoultre for me. Also, note the middle bridge extension comes off slightly at an angle, and note a different stud. No, none of this cues a supplier for me—only curiosity.

[Dietrich]

Yes, I noted the differences, but they might be related to the other size. Or as you might be assuming a different maker...

[Mr. Bieser]

"Worthy of looking into." Well already stymied, the 21 & 26 Stand Parts both list cal 35 as 17 jewels and it doesn't appear to be Extra at all...not the first time official Gruen literature doesn't match up. There appears to be a 21 jewel 35 but I suspect it's a whole different caliber designation..Perhaps 35 transitioned to Extra Precision after 1926, dunno, just a theory. But cal 35 is listed in 1937 as Extra Precision as is
10X, 20, 50, 60, 87,and 89.

[Mr. Bieser]

I just want to bring up Gruen supplier Cattin in relation to a couple of these unknowns, he's showing a very similar movement in some of his ads, a 10 Ligne.