@MighTthanks for your interest.
The noncircular gears are one tooth cut from the spline cogwheel object and cloned on to a spline. You can't just use eg a rectangle with smoothing because the teeth go out of sync - so I have a few different methods.
The clip with 2 extreme ovals started as a circle object set to ellipse with about 2:1 aspect. I added some points with the knife tool and used the scale tool to distort. I added some teeth and made an instance of the gear. I rotated the 2 gears to check for sync and adjusted cog 1 until they fit.
Another method is to look online for blueprints and trace them in Cinema using ellipse, rectangle, N-side etc and the above knife method. Here's a set of drawings I have used - they all work well with each other.
I also have a math method (used for my set of gears above) using the formula spline object. Starting with a circle using the formulas
x = R * cos(angle)
y = R * sin(angle)
which gives a circle radius R. If you substitute for the radius a constant + small amplitude sine wave, you get traces like this -
Since the size of 1 sine is the same in each example, they fit together when rotating. Here's the formula for a 3 lobe gear - base radius 300, small sine amplitude 40. For a 5 lobe gear replace the 3 with a 5 etc.
With regular circular gears, you can use XPresso to get the correct speeds based on number of teeth, but that doesn't work for these noncircular gears, so I used dynamics. Each gear has a hinge and a motor with the motor target speed based on gear size.
2cogs.c4d