Machine Making Episode 4 | Catapult and Tower

Episode 4 has been released and the main goal was to create gears of different sizes and calculate the teeth, rotation ratios and allow the gear set up to drive the catapult. Also I wanted to play around with rigid bodies and cloth simulations.

​​Episode 4 started out a little rocky. Originally this was going to be a backhoe with a wreaking ball. Here is a WIP image. 

Original Idea For Exploring Gears

​While working on the backhoe I never really found the composition I wanted to achieve, so I switched directions and built a small three-gear catapult system.

The catapult was way more fun to work on as well. 

Firing the Rock at the Blue Castle

Smash!

​There is an addon for Blender called Extra Objects. There are a ton of great features that are included in this addon. One of the options is called mechanical, this brings up a little gear creator window.  

Extra Objects Menu Items In Blender

​Although I found some limits with this set up. While I can change the size of the gear, the teeth and the radius, I was unable to calculate the number of teeth needed for a new gear with a different radius. 

​Looking around I found a great site called Gear Generator. This was extremely helpful for creating mathematically correct gears. 

​Once I learned a couple of the equations I plugged the numbers in Blender and build this three gear system. 

The key to gears of different size is for the pitch to match up across the gears. This can be achieved by dividing the teeth into the diameter. Once you have this number you can then multiply the pitch by a different diameter to calculate how many teeth are needed. 

​There are other ways to get this number, and I am glossing over some other equations, but I found this to be the quickest way to generate gears (for a functional rig in animation, there are better methods for 3D printing/manufacturing)
 
Check out my working file if you want more insight into my process.

Big thanks to Gleb Alexadrox and his great tutorial 9 Ways To Destroy Things.
 
Next up from Level Pixel Level will be a series of tutorials going over how to rig pistons and gears within Blender.
 
Please leave a comment if you have any question!