# Tutorial: How to model involute gears in SolidWorks and show design intent.

In this tutorial I am going to show how to design involute gears from scratch without using fancy mathematics or built-in functionality. I use SolidWorks but you should be able to use just about any CAD program.

The model from this tutorial is found here:
Involute Gear Design from Scratch

Hi Daniel,

Another good question. Sorry for not having spotted it until now. I had to dig deep to come up with the explanation. The value is obviously correct, since the gears that you design with the method mesh perfectly. If you had used a different value, the cogs would be too thin or too thick.

The explanation is that in order to mesh perfectly, the gap between two teeth need to be identical to the width of a tooth: Think of gear racks that can be considered gears with infinite radius. When two identical gear racks are held against each other all teeth will contact at the same time (in theory anyway). So the angle between two teeth are double the angle between the contact points on the pitch circle and the centerline for a tooth is exactly in the middle because of symmetry, which is half of the angle between the contact points or a quarter of the angle of a cog. Q.E.D.

Hope this makes sense?

perfect tutorial

very nice tutorial....thank you

Bravo Steen

Excellent tutorial! Thanks for taking the time to do it

Mr. Winther I touch solidwork for very first time. After your step by step tutorial I create my gear and move it. My shape of tooth is just according 1/4 of tooth angle and became. Your explanation is excellent. Thank you very much.

I am fishing. Grabcad on my ipad is not liking my comment. You did a great job on this tutorial.

how did you calculate the winding spiral I have always been trying to figure out how that is done

Really great Tutorial Steen. Thanks for taking the time to put it together.

You're welcome Dave. Glad you liked it and thanks for your comment :-)

Really appreciate the effort put in to making this tutorial,only recently started using Solidworks so looking for as much input as possible.Thanks Steen great tutorial!

How to mesh three gears?Can we do it using Move component>Physical Dynamics. I tried but failed.

You're welcome John :-)

thanx sir thanx a lot

Hallo Steen,

Thanks for the tutorial ferry nice.
Ben

How did you define that the centerline of the gear cog in step 22 is offset one quarter of the angle for a cog?

Excellent... But in the end if you add a constraint of gear it spins better