Just a quick and dirty hack on MakerBlock's chattering teeth gears. I did switch to the MCAD version of the involute_gear library since I had it installed already.

There is now a module called gear_box() which takes an positive integer as input (I called it 'stages') and replicates a pair of those same gears between the gear holding the spring, and the gear holding the cam.

I also changed the gear ratios slightly to get an even 2 rather than 1.57 and change.

By my math, each gear-to-gear contact adds another factor of 2 to the total gear ratio of the gear train. You get one for free between the spring and the cam gears, and you get another two per stage... so unless I'm shaming my math teachers here are some values you can get:

stages=1 total ratio=2x2x2=8 stages=2 total ratio=2x2x2x2x2=32 stages=3 total ratio=pow(2,1+2x3)=128

And so on, each successive value of stages gets you an additional factor of 4.

The generalized formula, using the parameter names from the script is: total ratio = pow(n1/n2,1+2*stages)

Go to the bottom of the script and change the parameter value passed to gear_box() to whatever you like. Hit F5.

If you change n1 & n2 to adjust the unitary gear ratio, you will need to regenerate all three types of gears. Just uncomment each one separately and hit F6 before exporting the new STLs.

Now someone needs to design the stack into the original spring drive!

If it is not possible to run a shaft where the spring-gear is, it may be necessary to rotate the spring gear out of the way, but then the mechanism will be less compact.

GitHub repository: https://github.com/syvwlch/Thingiverse-Projects/tree/master/chatter%20gearbox