Spur Gear Full Depth Tooth Calculations

Basic Rack Of The 14.5° Full Depth Involute System

Basic Rack Of The 20° Full Depth Involute System

To Find	Diametral Pitch Known	Circular Pitch Known
Addendum	=1 / Diametral Pitch	=0.3183 X Circular Pitch
Minimum Dedendum	=1.157 / Diametral Pitch	=0.3683 X Circular Pitch
Working Depth	=2 / Diametral Pitch	=0.6366 X Circular Pitch
Minimum Total Depth	=2.157 / Diametral Pitch	=0.6866 X Circular Pitch
Basic Tooth Thickness On Pitch Line	=1.5708 / Diametral Pitch	=0.5 X Circular Pitch
Minimum Clearance	=0.157 / Diametral Pitch	=0.05 X Circular Pitch

Note: Radius of Fillet = 1-1/3 X Clearance for 14-1/2° full depth tooth and 1-1/2 X Clearance for 20° full depth tooth.

Note: The term Diametral Pitch is used up to 1 DP inclusive and the term Circular Pitch is used for 3 inches circular pitch and over. A suitable working tolerance should be considered in connection with all minimum recommendations. Minimum clearance between the top of the gear tooth and the bottom of the mating gear is specified as “minimum” so as to allow for necessary cutter clearance for all methods of producing gears.

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