Gear Set for 3D Printing

 by Tomdf
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Pictures 12-31-12 307.jpg
What it is
A set of small, matching gears intended for 3D ABS extrusion printing, along with instructions on how to make your gears and gear boxes. After printed gears for my own projects I eventually wound up with this set, that I'm calling "Gear Set 1", and created a reference chart to aid in the pairing of its gears. Gears from this set, printed from ABS on an up!3D printer, have been tested thoughtfully, but I'd wager that they would also work well for laser cutting.

History
Back in the day I had a some Lego Technics that came with a set of plastic gears that I absolutely loved to fiddle with. I spent hours building little contraptions only to tear them apart and build something else. Eventually I left the legos behind and moved on to building things from scratch materials, but I never really had a way to make gears myself and ended up just buying motors with gears already attached.

Fourteen-years later 3D printing becomes something that you can do at home, and with it came the ability to just print out my own gears. Remembering my Lego set, I headed out with the goal of creating my own version that could be mixed and matched for whatever thingamajig I was was working on. It took a lot of software hopping and a lot of test printing, but eventually I was able to make a set of gears tuned for the up!3D.

The Instructable
I've included all of the gear files that I've made in this Instructable along with reference chart you'll need to use them. The gears are made to the absolute smallest size that I was able to print f while still getting something that actually works.

The rest of this Instructable will explain how to generate vector gears, make them into 3D solids, and ultimately, design gear boxes around them.  I must warn you, this method is more convoluted than ideal as it uses a total of four programs to get from vector to dwg, but the end result is worth it in my opinion. It's worth noting that Autodesk Inventor (not Inventor Fusion) can generate 3D gears all by itself. I would have just used that but, well, it had lots of options that I didn't understand.



You can get the DWG and STL files in the ZIP below, or you can download them from thingerverse (www.thingiverse.com/thing:49614)
 
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Step 1: Gear Design Basics

Gear Set 1 -  Specs-2.jpg
It turns out that designing gears can be very complicated as there are dozens of variables that, when perfectly calculated, allow gears to mesh together smoothly with very little friction. Although I like to pretend, I am not a professional engineer and the finer points of gear design are lost on me. For the purpose of these instructions we are not going to worry about all of the variables, as they would likely just hinder the creative process. Cutting these corners will result in a less than optimal gear, but you know, whatever, they work.

To use the gears presented here you only need to concern yourself with a few things:
  1. Center Distance - How far apart the centers of two gears should be in order to mesh properly
  2. Outside Diameter - Outer diameter of the gear, needed for clearance
  3. Pitch Diameter - How far away the gear needs to be from mating gears' Pitch Diameters
The chart above lists the center distances for all of the gear pairs that can be made with the set, by referencing this chart you can easily connect gears to each other and design supports. There is a PDF version of these charts attached to this page.
GrantLevy says: Feb 19, 2013. 8:54 PM
I'd like to generate gears for a clock moon phase dial. Not the usual 59 tooth gear, but using a set of gears that produces a moon dial accurate to the loss of 1 day per 122 years or one that loses only 1 second every 2.82 years (depending on the accuracy of the clock motor that driving it).

I don't own my own 3D printer. Is there a company that I can pay that will print the required gears for me?
Tomdf (author) in reply to GrantLevyFeb 20, 2013. 10:07 AM
There most definitely are:
Shapeways.com
i.materialise.com
ponoko.com
GrantLevy in reply to TomdfFeb 25, 2013. 10:35 PM
Thank you, Tomdf!
jeikmauf13 says: Feb 19, 2013. 5:49 PM
You sir have made my day better. I had never heard of all-silhouettes.com (you forgot a hyphen), but it is awesome!
Tomdf (author) in reply to jeikmauf13Feb 19, 2013. 7:59 PM
They got some really good stuff over there.
Thanks for the heads up on the link, I really butchered it :p
Ralphxyz says: Feb 17, 2013. 7:26 PM
Absolutely fabulous!! What a great introduction to making gears, thank you very much.

Ralph
mrdoug says: Feb 17, 2013. 4:54 PM
I think this is really neat, and I have fiddled around with a gear or two my self on the rare occasion. With a 3d printer the possibilities would be endless, well done.
pfred2 says: Feb 16, 2013. 7:28 PM
I never knew Inkscape could render gears. Thanks for the tip.
Tomdf (author) in reply to pfred2Feb 17, 2013. 12:20 PM
Right, it is kind of a weird thing to be included by default in inkscape.
pfred2 in reply to TomdfFeb 17, 2013. 4:51 PM
Little surprises me in the realm of FOSS anymore. I don't subscribe to the mistaken belief that logic has much to do with anything when it comes to computer science. Us humans still write the programs after all.
MsJaxFla says: Feb 17, 2013. 1:14 PM
Wow, that is just gorgeous. Can I get it rather cheaply as a stencil?
Tomdf (author) in reply to MsJaxFlaFeb 17, 2013. 2:32 PM
Stencil? Hmm, sure, I think I know what your asking for. Is it this? I've also added a vector version to the first step.
gearset 1 - stencil-01.jpg
TheStudio7 says: Feb 17, 2013. 1:20 PM
THIS IS BRILLIANT! Thank you x 10000
liquidhandwash says: Feb 15, 2013. 11:41 PM
thanks for posting that's real cool
Tomdf (author) in reply to liquidhandwashFeb 17, 2013. 12:21 PM
Glad you liked it :)
Phanbury says: Feb 17, 2013. 4:27 AM
Great stuff. Keep it up.
If you do get to making gearboxes that run for long periods then a few odd numbered gears are a good idea. A hunting gear set (uneven ratio) lasts much longer because the same teeth don't continue repeating on the same teeth. And they don't have as many harmonics issues when they go fast.
Tomdf (author) in reply to PhanburyFeb 17, 2013. 12:19 PM
Ah thank you! I was completely obvious to this concept so when I choose the number of teeth I was mainly focused on making the math easy :P
Gear Set 2 will use hunting gears, now that I know what they are.
bajablue says: Feb 16, 2013. 8:44 AM
lol... you lost me at 3D printer, tom! ;-D
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