How to match herringbone gears?

[Grue]

I made two herringbone gears with the same helix, but different number of teeth. Unfortunately, they don't match. How to calculate helix pitch properly to match two gears?



Word size of OS: 64-bit
Word size of FreeCAD: 64-bit
Version: 0.16.6703 (Git)
Build type: None
Branch: releases/FreeCAD-0-16
Hash: 2ce5c8d2e3020d05005ed71f710e09e9aa561f40
Python version: 2.7.6
Qt version: 4.8.6
Coin version: 4.0.0a
OCC version: 6.8.0.oce-0.17

[ickby]

To get the same gradient in movement direction of the helix I think you must scale the radius and pitch in an equal manner. This means if you halfe your radius you also need to half your pitch etc.

[A_3]

Check your gear dimension calculation, maybe something is missing.

[Mongrel_Shark]

Shouldn't those gears be the same thickness?

[mario52]

hi
see here tandwiel.info

mario

[looo]

I use this to compute the helix:

Code: Select all

angle=height * tan(beta) * gear_radius
auxspine = makeHelix(height * 2 * pi / abs(angle), height, 10., 0, bool(angle < 0))

beta is the angle of the cutting rack rotation.

[Gentlemanrider]

Just scale the helix pitch proportional to the teeth number