Worm Gear or Threaded Rod Drive
A worm gear is a form of threaded rod that has more precision threads, both in form and pattern. This type of gearing allows for perpendicular conversion of force to either move another shaft through a gear, lever w/ nut, or sliding shaft w/ nut. Due to the threading to gear conversion, the driving force must be from the worm gear or threaded rod.
If a low cost threaded rod from a hardware store is going to be used you must consider a few factors. Weight, steel rod is heavy and weight needs to be considered. Thread count per inch needs to match the pitch or thread count of the converting contact device whether it be a gear or nut. Thread surfaces need to be even, clean, and free from burrs and other deformations that can cause snagging. The rod also needs to be as straight as possible. This type can be used for hobbyist grade projects due to cheap costs, but would not be considered in commercial applications due to quality.
Safety needs to be considered to warn of possible intrusion or binding which could case damages to either the unit or other objects, or worst humans. Limit switches should be used to identify when the travel is at the maximum positions in both directions. Encoders can be used to identify movement and speed.
Use of threaded rod or worm gear with a spur or helical gear:
Good for converting from one angle to another.
