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Laser cut gear size limits?

Mitchell Terry
asked this on October 08, 2011 17:52

Im currently working on a project where size and weight are critical.

Using laser cut acrylic or delrin (or any other materials you would recommend), Any tips on the smallest size one could make a relatively smooth and functioning gear?

 

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Josh Judkins
Ponoko

Hi Mitchell!

I couldn't tell you specifically how small a gear you could create, but I can provide some context.

The laser burns away an amount of material when it cuts - this can vary, but a good starting reference point is 0.2mm. This will limit how small the narrowest or shortest gear teeth would want to be.

Beyond that, I'd say your best bet would be to make some test gears on a P1 sheet and see how small they can go and still work.

Any advice from other gear-makers would be most appreciated!

October 10, 2011 14:21
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Zach Bean
Check Answer

I've done some testing with laser-cutting gears out of the bamboo.  The smallest gear I made was an 11-tooth gear with a pitch radius of about 0.195".  I don't know if you're using the Inkscape gear plugin to draw your gears, but if you are, this corresponds to a circular pitch of 10px.

Unfortunately, I didn't try anything any smaller.  For the purposes of my project, I'm now wishing I had -- when I first got my test sheet back, I thought the result was "I can make gears arbitrarily small."  But now that I've taken the step of "assembling" my project in SketchUp, I'm finding it hard to squeeze everything into the size I want.

Also, bamboo was the only material I tried.  I considered acrylic, but I was nervous that it might melt too much on the edges for the tiny gears to mesh well. I don't have any practical reason to think that, I just didn't want to chance it since wood works just as well for my purposes.  If anyone else out there has done any tests, I'd love to hear the results.

October 17, 2011 21:15
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Josh Judkins
Ponoko

Thanks for following up on this with your results Zach! I hope the project is working out well, and we look forward to hearing what others have found when making small gears.

Cheers!

October 18, 2011 06:33
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Zach Bean

Well, it's been nearly a year, and I'm now working on version 2 of my gear project. I'm planning to try to make some even smaller gears, and to that end I've ordered a new set of tests.  This time, I'm using 3.0mm acrylic as the material.  I haven't gotten the results yet (I only just ordered them) but when they come in I'll post details here for anyone else who's interested in laser-cut gears.  In the meantime, if anyone's interested in trying their own gears in a different material, I've shared my design file in my showroom at http://www.ponoko.com/showroom/forty2

 

If you do make some new test gears, please come back and let us know how they turn out!

September 03, 2012 22:06
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Catherine Field-Dodgson
Ponoko

Thanks Zach - we look forward to seeing photos of your latest designs, and would be keen to see other community members' gear designs if they feel like sharing their results as well :-)

September 04, 2012 01:31