Online Catalogue last updated 17th of September 2023
You get two books in one, first there is "Manual of Screw Cutting" 4th edition by William Simpson (1887) "containing rules for calculating the change gears on screw-cutting lathes to cut square and angular threads per inch or per pitch, with two or four gears. Also, useful rules for calculating the diameters and speeds of pulleys."
This is the kind of small vest pocket booklet that workers probably carried with them in 1887. People back then often didn't finish grade school. So little books like this helped them calculate the gear ratios they need to cut threads.
Topics include how to cut a thread without reversing or stopping the lathe, how find two gears, how to cut fractional threads, how to measure fractional threads, how to find the set required on a screw cutting tool, how to find the diameters of pulleys, how to prove four gears, strength of tapping holes, how to cut double or treble threads, and more. We enlarged the pages and removed as much of the dirt and water stains as our software would allow. The result is useful, entertaining, and easy to read.
Then in the second part you get "Change-Gears" from the Machinery Magazine in 1935. "Calculating auxiliary change-gears for cutting special threads or pitches not within the range of the regular quick-change gear-box - A method of utilizing various settings of the gear-box to avoid using special auxiliary gears."
You get change gear formulas, examples of calculations, compound gearing for thread cutting, number of threads per inch cut with given combination of change-gears, change-gears for metric pitches using English lead-screw, when the lathe has a metric-lead screw, translating gears for metric pitches, and more.
Code No. 010089, ISBN 155918289X