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Looking for a Gear Set for 3D printing

A little over a decade ago I spent a large amount of time playing with lego technics. These mechanical legos had a set of gears with them that you could arrange in infinite variations and I loved them (still do.) What I would really like is file with a standard set of small gears that I could easily place into a 3D model and design around just like building something out of technics. The difference being that I get to design the parts connecting the gears instead of using lego bricks. These gears would ideally range in size from 5mm to 30mm diameter and would ultimately be used to make 8 inch or smaller robot things.

Now, the obvious solution is to just make them, Inventor has a generator and they can be drawn in almost any program. The thing is that, well, it is over my head. I've used a lot of Sketchup, but am just getting into Inventor and 123D. Also, it turns out gears are incredibly complicated. I've looked at the diagrams and between the pitch diameters and diameter pitches and pressure angles I get lost, I'm not even sure where to start.

On top of that, in my research I haven't found any kind of standard like there are with screws and electrical components; one can't just call the robot store and say "gimme some A5 gears good sir."

So my questions are:
1. Is there a simple standard for gears? Specifically small plastic gears like those found in toys and clocks.

2. Do you have any advice on how I could go about creating my own "standard" set of small gears, like most important factors or common pitfalls, a magic button?

3. Am I going about this in a weird, round-about, wrong way? I'm learning as I go with 3D modeling/printing and I often fall down rabbit holes, this may be one. How would a professional engineer who is designing a toy go about choosing or creating his gears?

Thanks in advance for any insight you can lend.

These are the lego technic gears that are so dear to my heart

Picture of Looking for a Gear Set for 3D printing
cnewb1 year ago
There are a number of programs available on the internet to design simple gears.
However, to do one capturing the detail of a LEGO part would quite time consuming.

Try searching for sellers of LEGO parts.
check here for interesting approach
http://fffff.at/free-universal-construction-kit/
Tomdf (author)  cnewb1 year ago
Thanks cnewb, I did eventually find a way to do this. I ended up generating the gears with inkscape, and then used solidworks to import the files and extrude them.
Kiteman1 year ago
Have you tried Thingiverse?
Tomdf (author)  Kiteman1 year ago
There are quite a few gears there lol. I had seen a few of those before, but the problem I run into is that they are .stl files and 123D sees them only as meshes, they cannot be edited. I would really like to have the ability to change the size of the center holes and to be able to add more holes for cams and stuff.
cnewb Tomdf1 year ago
try the free SCAD program to design parts from the ground up to get to the stl file stage.

www.openscad.org
Tomdf (author) 1 year ago
Thanks Steve, the generator is awesome for creating the patterns and I have used it before to make laser cut designs, but I haven't figured out how to import it into 123D yet. I think I may have just hit a wall with 123D and am wanting more than it can do.

I really am surprised that there isn't a simple standard for gears and that they aren't used more often in 3D prints.
Get a copy of the gear generator from woodgears.ca Superb tool for making gears of arbitrary properties.

http://woodgears.ca/gear_cutting/template.html
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