Physics- Gears/Sprockets: builder scripts? Ideas?

So anyway, from my tests in the Sandbox Island sim, meshed gears using Hinge joints do indeed work, and I can indeed build a gear train that transfers real motion using physics only.

The problem is designing the gears. For a gear to work smoothly, they can't be squared off and they can't be closely spaced. There needs to be enough room for a meshing tooth to swing into the slot and not brush against a neighboring tooth. This is handled by making the teeth triangular and spacing them far enough apart to give a little "slop" if the gear motion is reversed.

It's a huge challenge to design and layout gear teeth by hand, but this seems a perfect job for a prim-builder script to design and position the teeth, and properly set the triangular sides of the teeth. Do any such builder scripts currently exist?


So anyway, each gear is physics-enabled, and like a vehicle has 31-prim limits. This has a number of possible tooth layouts:
- 1 tooth per small triangular prim: 31 max teeth
- 2 teeth per rectagular prim: 62 max teeth (a rod extends across the center axis to each side and the ends form the teeth)
- 3 teeth per triangular prim: 93 max teeth (a large triangle spans the center and the 3 corners form the teeth)
- 4 teeth per square prim: 124 max teeth (a cube spans across the center and the 4 corners form the teeth)


Not Tested Yet Due To Tooth Design Complexity:

It looks like a gearshaft should be possible with two or more gears fixed on one shaft. Fortunately there's no need for a physical hub or shaft to interconnect the teeth.. just linking the individual teeth is good enough. So prims can be conserved and used only for the teeth.

For appearance I should be able to put a phantom hub/shaft under the open-air floating teeth to make the assembly look more realistic, and yet put no extra physics load on the sim.


From what I've read about Energy it looks like low-mass gears would be a good idea. And really, there's no physical-failure/breakage mode for gears, so a gear that's a tiny sliver thick (0.05m) is going to be as effective as a huge 5-meter wide gear anyway.

I suspect that razor-thin gears just above the minimum-physics limit will also be easier on the sim since the contact surface between teeth is narrower and so there's less collisions to calculate.

Art Laxness had some success with cogs made using a circular disk and rods coming out of the rim of the disk parallel to the axis of disk. Good for cogs that mesh at right angles. I heard a rumour that someone at some point had a working clock.