AnsweredAssumed Answered

How to draw the perfect involute curve (or other recomendation for polymere spur gears)?

Question asked by Mans Collner on Jun 21, 2012
Latest reply on Apr 1, 2014 by Wayne Easton

I've been trying to replace steel spur gears with polymer (most likely Grivory) gears. To do this I would like to send correct 3D-geometry to the toolmakers, wich seems simple for at least the gear contact-surfaces as Solidworks has the Toolbox gears.


However when I spin these toolbox gears they do not seems to match!

In the attached picture you see the gear-profiles at module 1.5 and in the sizes Z=12 mated tangent with a Z=69. When rotaded to the point were the next gear get into contact, thats were I see interference between the two.


1. Can I assume that the Toolbox profiles is incorrect?


2. If so, is there any curve-equations out there that would save me the work of writing my own?


3. Is the traditional involute gearflank the best way to go with polymer gears? I'll try to give these as large base-radius as possible.

We move at very low speed, 38PRM on the small wheel, but on the other hand we have a load that is close to what a GF-plastic gear-tooth this size can handle, it peaks at 66Nm on the large wheel axis.

As we wish to keep down the width close to 30 mm, the small wheel should probably still be steel, but sintered so that we are free in shaping our own profiles. Steel in the small wheel also helps us get a decent milage before fail.