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Find Helix Angle = f(pitch, or height & revolution)

Find Helix Angle = f(pitch, or height & revolution)

Find Helix Angle = f(pitch, or height & revolution)

(OP)
For a milled cutter, I am given the specification of 10 degree helix angel (angle to the axis of the cylinder).
In Solidworks, I can only define the helix in terms of pitch; or height and degrees of revolution.

How can I determine pitch when given the helix angle?

I cannot find the answer in Marks Handbood or Machinery's Handbook, www.eng-tips.com, www.engineers.com

Thanks for any pointers you can give me.
Ken Apacki

RE: Find Helix Angle = f(pitch, or height & revolution)

Hi Ken,
If your cutter diameter = D and your Pitch Angle = A then
the pitch will be;
                    P = Pi * D * Tan(90-A)
If the the cylindrical surface of the cutter is developed or unrolled into the flat then the helix becomes a right angled triangle whose base is the circumference and the height is the pitch.
The helix angle is between the hypotenuse and the height.
Cheers,
Dave

RE: Find Helix Angle = f(pitch, or height & revolution)

p=πDtanα
where D is the diameter at which the angle α is to be measured.

prex

http://www.xcalcs.com
Online tools for structural design

RE: Find Helix Angle = f(pitch, or height & revolution)

The posts by kapitan and prex may seem contradictory, but this is due to nomenclature.  According to ISO 5408, Cylindrical screw threads - Vocabulary, the lead angle ψ is the angle between the inclined thread and a perpendicular plane to the thread axis.  Thus,

P = π · d2 · tan ψ

where

P is thread pitch (assuming a single start thread)
π = 3.141 592 654
d2 is the pitch diameter

prex shows the same equation, with ψ = α

The helix angle is the compliment of the lead angle, so kapitan's equation is correct assuming the terms helix angle and pitch angle are identical.

RE: Find Helix Angle = f(pitch, or height & revolution)

(OP)
Thank you all.
Your answers are very clear and I have my answer.

Strange that I couldn't find this in the mechanical handbooks.

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