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.

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23 Answers

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?

 
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Excellent tutorial! Thanks for taking the time to do it

 
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Hallo Steen,

Thanks for the tutorial ferry nice.
Greads from Holland.
Ben

 
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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.

 
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Great answer thanks for your efforts ...

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

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

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

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

 
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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!

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

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

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

 
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It is a detailed tutorial but I'm finding that the model it produces is not robust enough to change the size later. The geometry fails and SW reinstates the previous values. I'm going to start again from the beginning creating each step as a separate sketch, and if I can get it to behave more parametrically I will then maybe set up some variables to change in the part properties. It is a pity there isnt a built-in gear tool in SW as this is taking too much time to create a basic part.

 
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The attached shows how to model a helical involute gear in SolidWorks.
In real manufacturing modeling requires special software because gears are often not pure involute: involute has modifications and the root surface is complex. There is special software to calculate these gear tooth surfaces offered by spiralbevel.com

 
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