Precision Engineering Specifications
This is a newly machined, high-precision 47/37 transposing gear set designed to convert an Imperial 8 TPI lead screw to cut metric threads. The system yields an incredibly low thread lead/crest error of only 0.02% (approximately 0.0025 inches over a one-foot threaded rod). Unlike massive traditional 127-tooth conversion gears, this compact compound gear design is under 3 inches in diameter. This allows you to close your factory flip-out gear cover completely without modification or interference.
Manufactured specifically for the South Bend 9-inch Model A Lathe with a quick-change gearbox, these parts will also cleanly interface with South Bend 10K models. Every gear is meticulously sliced to an accurate 18 Diametrical Pitch (18 DP) out of rugged, aircraft-grade 6061 billet aluminum. The kit comes complete with a custom-machined installation bolt, mounting bushing, and an Oilite bronze sleeve bushing pressed inside the compound cluster.
By pairing this transposing set with your lathe's stock 20-tooth stud gear, standard 40-tooth gear, and the included 56-tooth screw gear, you can cut all standard international threads along with many specialty fine pitches simply by swapping stud configurations and choosing the targeted gearbox tumbler levers.
Supported ISO Metric Thread Pitches
The set natively supports cutting the following pitches (mm):
0.20mm, 0.25mm, 0.30mm, 0.35mm, 0.40mm, 0.45mm, 0.50mm, 0.60mm, 0.70mm, 0.75mm, 0.80mm, 1.00mm, 1.25mm, 1.50mm, 1.75mm, 2.00mm, 2.50mm, 3.00mm, 3.50mm, 4.00mm, 4.50mm, 5.00mm, 5.50mm, 6.00mm
Documentation & Reference Charts
Every set includes a physical configuration spreadsheet detailing the exact stud gear configurations and quick-change gearbox slider placements. You can also view or download a digital copy of the reference guide here:
9Ametric.transposing.gear.chart.pdf.
If you have any engineering questions or need advice regarding compatibility with your machine, email us directly at kane@monroelawncare.com. If you need reference pictures showing how the gears mesh on a live 9A bracket, we are happy to send those over as well.
