SOUTH BEND LATHE MODEL 9C ( 1937-1940 ) 80/63 METRIC TRANSLATION RING GEAR

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This is a Metric Translation gear for cutting metric threads on an imperial leadscrew lathe, designed specifically for a South Bend lathe model 9C. The teeth have a 14.5-degree pressure angle, and the gear boasts a DP of 18. Its module is 1.411. The 63-tooth ring features a designed inside diameter of 75mm but actually measures about 74.4mm due to manufacturing tolerances. In contrast, the 80-tooth ring has a designed inside diameter of 100mm, which ends up being around 99.3mm after production. To accommodate the difference in size between these two rings, I have included a 1mm step, resulting in a gap that is 3/8" wide plus an additional 1mm. The 80-tooth ring itself measures 3/8" wide, matching the standard width of South Bend gears. When it comes to selecting translation gears for this application, space constraints often play a deciding factor, although other considerations may also come into play. Among the common options I am familiar with, two sets stand out: the 127-tooth ring paired with a 100-tooth ring and the 80-tooth ring paired with a 63-tooth ring. The former combination yields perfectly generated pitches without any errors, whereas the latter produces an error of approximately 0.0125%. Another option, the 47-tooth ring paired with a 37-tooth ring, results in an error of -0.0212%. Print Settings: Rafts: No Supports: No Resolution: I utilized a 0.3 resolution. Infill: The infill density is set to 100%. Notes: The center of the gear was crafted from hardwood due to availability, but alternative materials such as form board or marine ply would likely be more suitable options. When preparing the wooden center, it's essential to ensure that it runs true before applying super glue. This involves turning the timber so that the ABS ring just fits snugly over it, allowing for a secure and smooth attachment process.