Numerical: Lead angle of thread, given lead & diameter

Q.  Calculate lead angle of a thread which has mean diameter of 45 mm and lead of 10 mm
- Published on 14 Sep 15

a. 8.5o
b. 4.04o
c. 3.02o
d. None of the above

ANSWER: 4.04o


  • Sravanthi   -Posted on 04 Nov 15
    - Lead angle is the angle made by the helix or thread with a plane which is perpendicular to axis of screw. It is denoted by λ.

    - Lead: The distance between two corresponding points on a helix.

    - Formula used to calculate lead angle is tan λ = l / π dm

    here, l = lead, dm = mean diameter

    Given: Mean diameter (d) = 45 mm, lead (l) = 10 mm

    Formula: tan λ = l / π dm


    Substituting the given values we get,

    tan λ = l / π dm = 10 / (π x 45) = 0.0707

    Therefore, lead angle λ = tan-1 (0.0707) =4.04°

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