SOUTH BEND LATHE MODEL 9C ( 1937-1940 ) 127/100 METRIC TRANSLATION RING GEAR by timbologist

Last crawled date: 4 years, 3 months ago

This is a Metric Translation gear for cutting metric threads on an imperial leadscrew lathe this was designed for a South Bend lathe model 9C.
photo is of 80/63 translation gear as I don't think this 127/100 would fit my present set up need to make another banjo to make it fit.
The teeth have 14.5 degree pressure angle
The gear has a DP of 18
The module is 1.411
True involute form
The 127 tooth has an designed inside dia of 165mm but ends up about 164mm
The 100 tooth has a designed inside dia of 127mm but ends up about 126mm
The 100 tooth ring has 1mm step so it give a gap between the gears so it is 3/8" wide + 1mm
The 127 tooth ring is 3/8" wide which is the width of the standard South Bend gears
It's mainly a space problem that dictates which of the translation gears you use, there may be others but these are the common ones that I know of.
The 127/100 metric translation gear which gives no errors in the generated pitches.
The 80/63 gives an error of 0.0125%
The another gear set 47/37 gives an error of -0.0212%