It is not an uncommon occurrence for machines or their components to fail, and gear trains are no exception. Gear failure produces undesirable results for the machines in which they operate. This is no different in rotary tools where failures include broken or worn parts, low tool life, damage to the machine, excessive vibration and noise.

It is a problem with undesirable noise that Cooper Power Tools, manufacturers of D.C. electric and pneumatic industrial power tools, has encountered and desires to be investigated and solved, as their customers find this noise to be undesirable.

This thesis discusses the approach and method that was used to solve the noise problem at Cooper Power Tools and design better gears. The gears were analyzed to check if they met certain fundamental requirements and contact ratio and specific sliding calculations were done to see if they satisfied standard criteria. Some of these values were found to be in error and were corrected during the redesign of the tools using computational software programs as well as hand calculations; thus, creating a better gear design that reduces vibration and noise, and increases the life of the tool.