The helical gear formulas are given below for Diametral pitch (DP). To model the gear follow the same procedure explained for Module gear type.

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Transverse diametral pitch = No. of teeth / Pitch diameter

Normal diametral pitch = Transverse diametral pitch / COS (Helix angle)

Transverse pressure angle = ATAN ((TAN (Normal pressure angle)) / (COS (Helix angle)))

Normal circular tooth thickness = 1.5708 / Normal diametral pitch

Addendum = 1 / Normal diametral pitch

Outer diameter = Pitch diameter + (2 * Addendum)

Whole depth = (2.2 / Normal diametral pitch) + 0.002

Base diameter = Pitch diameter * COS (Transverse pressure angle)

Root diameter = Outer diameter - (2 * Whole depth)

Transverse circular tooth thickness = 1.5708 / Transverse diametral pitch

Lead = Pi * Pitch diameter / TAN (Helix angle)

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Transverse diametral pitch = No. of teeth / Pitch diameter

Normal diametral pitch = Transverse diametral pitch / COS (Helix angle)

Transverse pressure angle = ATAN ((TAN (Normal pressure angle)) / (COS (Helix angle)))

Normal circular tooth thickness = 1.5708 / Normal diametral pitch

Addendum = 1 / Normal diametral pitch

Outer diameter = Pitch diameter + (2 * Addendum)

Whole depth = (2.2 / Normal diametral pitch) + 0.002

Base diameter = Pitch diameter * COS (Transverse pressure angle)

Root diameter = Outer diameter -

Transverse circular tooth thickness = 1.5708 / Transverse diametral pitch

Lead = Pi * Pitch diameter / TAN (Helix angle)