RD2755

Chauncey Jerome invented a method of making clock gears in 1837 by stamping them out of sheets of brass, so it was done in the past. But today, most gears seem to be made from stronger methods like extrusion or forging. Those methods also don't produce as much scrap metal as stamping (though stamping still wastes less material than milling most of the time). There are in particular a lot of documents about this related to the US Army in the 1970's, '80s, and '90s. They mainly wanted to mass-produce cheaper and stronger gears for tanks and helicopters. The documents are about the die design and computer programs to calculate its dimensions: SPIRAL BEVEL GEAR AND PINION FORGING DEVELOPMENT PROGRAM- February 29, 1972 Precision Forged Spiral Bevel Gears- CAD/CAM Technique Makes It Practical- August/September 1984 Manufacturing of Forged and Extruded Gears- July/August 1990 I also read about thread rolling machines like this planetary thread roller (the fastest kind there is), or the other three kinds: 2-die, 3-die, and flat. They are covered here, or Wikipedia has a diagram of each type of rolling. In theory, gears could be made the same way (now that I think about it, threaded bolts are technically a very heavily angled helical gear), with a gear-shaped die rolling the blank into a gearwheel. For the Lewis Gun and some other WWI weapons, I don't have to wonder: Compilation of sources from WWI-era American Machinist volumes (includes Welin breech manufacturing) From that source, I can go to Volume 48, to Part IV of the Lewis Gun article on pages 581-583 (using the Internet Archive link), for example: Gauges and jigs. Gauges and jigs everywhere. For reference on what the finished receiver of the Lewis Gun looked like, C&Rsenal's teardown has good views of most of its parts. The rest of the Lewis Gun series is like this, and most of the other articles linked in the original post are like this too. In addition Volume 52's article about the Canon de 75's recoil cylinder has been copied and reposted on that forum, with a bunch of typos corrected, images shifted around, metric values added, and links and sources about the operation and background of that recoil system: Canon de 75 mle 1897/ US Model 1897 recoil system function and manufacturing. I'm sure that today a 0.0008" tolerance on a 63" long lapped hole is nothing special, but in 1918 it was the biggest mass production achievement of WWI, believed impossible by the French and anyone else.