Gruen Caliber 335 Schematics

Schematics for the Caliber 335 Movement

Finally! Real engineering schematics for Gruen watch parts. Of course these had to exist, but as far as I know, none other than one for a stem have been published.

Background on this find

I think there is a wave of newly discovered Gruen material that is going to be uncovered over the next few years. The generation of past employees from Gruen is leaving this world, and leaving behind possessions that have been stashed in garages and attics all over the country. The caches of Gruen goodies are being found. When they are, the Internet thankfully shows that there is a community of Gruen collectors and researchers that value every small bit of Gruen history uncovered. As a result of this visibility, a number of Gruen artifacts have made their way to me. I will, of course, be making this material available to everyone via this site.

Documents with detailed technical information on Gruen watches and movements are rare, so I was elated to receive a number of these for the caliber 335 movement. The reason it is the 335 movement is quite simple. It is one of the few movements made here in the US so documents related to it will be located here. Ernest Duebendorfer was a Gruen employee working in the Norwood facility in the early 1950s. His son Dave Duebendorfer was very kind and provided the material his father saved. Thanks to Dave we have a candid, insider's view of the Gruen company. This material is particularly valuable because it is unfiltered. We can hear the Gruen story without the Gruen Company filter.

So, enjoy the first of many upcoming posts of this newly unearthed Gruen history.

The schematics

The 335 plate schematics

These schematics, drafted in 1949, show just how incredibly precise each and every part of a Gruen watch was designed and manufactured.  The recesses on these plates were held to within .0004 inches. Using the age-old human hair comparison, a human hair is .001 inches.  What I have yet to locate are the specifications for the plate that has the serial number stamped on it. More schematics have yet to be examined so perhaps one is in the remaining material. These are a very small portion of the schematics that were supplied.

The 335 cannon pinion schematics

These were larger schematics so I wasn't able to scan the full pages. The important bits are there. These show the multiple stages a cannon pinion went through when it was manufactured. There is also a list of the tools used.