COMMUNITY : FORUMS : 3D MODELING & 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