Plomb WWII Dating and Proto LA Characteristics
On 12/2 we kicked off a study attempting to determine the meaning of the infamous 2 letter codes on Plomb tools. In just under 2 days, we believe we've solved the mystery.
First, these appear to only be present on tools made between 1941 (after the start of U.S. involvement in WWII) and the emergance of the Pebble background tools in 1945. We have not found any tools with the Los Angeles stamp that posess the 2 letter codes. Rather, all Los Angeles stamped tools have the conventional number-letter code if a code exists. Virtually all tools stamped with the 2 letter codes end with A through E. There do exist exceptions, such as this Plomb 4751 1/4" Drive Ratchet posessing an NR code and a few Drive Tool Accessories not yet loaded into this database.
Study Update 8/22/2016. I was contacted by a gentleman with pictures of a wrench branded Plomb - Made In U.S.A. and stamped with code 2B in parenthesis. We are seeking more examples of a second digit "B" code and consider this wrench possible evidence that the 2 letter system may have started later than December of 1941.
--- We have broken the code. If we discount the "NR" code as a whole different meaning (we believe it represents something different because you will see some examples with both a date code and the NR code), an oddball "single X" and oddball "single O" stamp, it appears the second letter in the codes follows a pattern of A, B, C, D, and E stampings. Note that tools branded WF for the Wright Field contract have been found with multiple single letter codes including G, O, Q, R, and X. The meaning of these codes is not yet known.
Early on we theorized that the letter stamps could represent wartime only produced tools. Supporting this theory is the fact that most tools are stamped B, C, or D while A and E are less common second letter stamps. If we assign 1941 to A, 1945 to E, and the B, C, D accordingly, that trend would make sense based on the U.S. involvement periods in WWII. As of now, we are assuming the first letter of the Letter-Letter codes represent a production month. There were still the traditional Number-Letter codes before the U.S. involvement in the war in 1941, as well as in 1945, but we have found no examples of 1942, 1943 or 1944 Number-Letter codes. We have also uploaded examples of 1945 Number-Letter coded tools and it appears 1945 is the final year for date coding of any style until the 1970's. An interesting and ironic twist to this theory is that if any tools exist with a 2 letter code for 1941, it would be stamped with the code "LA." We do not currently have any examples of an "LA" date stamp.
We also took notice of tools stamped "War Finish." All current examples end with the C code, indicating they were made in 1943 only. If anyone has a "War Finish" example (NOT WF) with a 2 letter stamp not ending in C, please let us know.
In addition to the 2-letter codes, we also determined that Plomb transitioned from "Made in U.S.A." to "MFD. U.S.A." in early 1947. Combine all aforementioned identification with current knowledge and we can now very accurately date tools from the beginning of 1927 up through the Proto changeover in 1950. Our next focus with regards to Plomb will be dating tools between 1950 and 1976, when the date coding system resumed.
Proto LA Era - 1950 to 1956
For combination wrenches, at least 2 distinct styles were used during this period. First, the pebble field and information are all stamped on the same side of the shank, where the box offset is facing up, as in this example. We believe this style to represent only the first 1 or 2 years of production. Reasoning: 1. This is the same manner in which the immediately prior transition style combination wrenches were stamped. 2. This style appears to be comparatively scarcer than the next style.
The second style is stamped with only the Pebble field sizes on the shank where the box offset is facing up, and the model number, PROTO Los Angeles, MFD USA is stamped on the opposing shank, as in this example. We submit that this style was produced for the majority of the Proto LA time period as they appear to be much more prevalant amongst our inventory.
DOE / DBE Style Wrenches
All normal offset DBE wrenches were stamped with both the pebble field and brand/model stamp on the same side of the shank, where the larger size box offset is pointing up and on the viewer's left, as in this example. Deep offset DBE wrenches did not include the pebble field size stamps.
All DOE wrenches were stamped with both the pebble field and brand/model stamp on the same side of the shank, where the larger opening is on the viewers left, and offset pointed toward the viewer, as in this example.
We have found only one style of stamping for Proto LA era sockets. Some breaker bars and ratchets retained their full pebble field from the Plomb and Transition era for at least the beginning of this timeframe. Specialty wrenches, such as tappets and other wrenches appear to have never received a "pebble field" stamp and retained all size, model, etc. information on one side of the shank, leaving the opposing side blank.