The carriage in the lathe is moved a considerable distance when cutting screw threads of very large lead.
The impact? A massive amount of stress is imposed on the gear mechanism.
To overcome this, you can implement these four strategies.
1. Direct Drive to the leadscrew: This way, the power is applied directly to the leadscrew.
2. Special Leadscrew: Some lathes are equipped quick change mechanism, with a special leadscrew to cut long leads.
3. Speed Reducing Faceplate: The speed reducing faceplate transmits motion through the headstock to the work, thus driving through a planetary gear train which reduces the work speed by 6 times. This is an incredible reduction.
4. Special Drive from the Cone Pulley: On some special lathes, by using special gears, the leadscrew can be driven from the gear of the cone pulley. By using the cone gear as the ‘driver,’ the stress and fatigue on the gears is reduced substantially.