Machine Class / Mechanical Design

Welcome to machine class! Designing things that move around and do stuff in the physical world under computer control requires a breadth of knowledge that we seldom find in singular individuals: in practice, you should hope to find teams of folks collaborating across the disciplines of mechanical design, electrical design, and software design in order to build good machines. Any one of us is unlikely to master each of these topics, but we can each endeavour to understand enough of our colleagues’ practice to work collectively alongside them.

It is worth noting at the outset that this is (in many ways) a design class: we are not often interested in precise or exact answers to problems - instead, we want complete systems that work, given limited time and expertise.

For the hour and a half, I’ve tried to break this down into a few sections but I want to qualify at the outset that none of this is exhaustive and whenever the time does exist it’s awesome if you can take things down to first principles. Unfortunately, we rarely have time to do so in practice, so this will largely be an attempt on my part to boil a few years of intuition into something consumable. Maybe consider it advice.


Stiffness, backlash, alignment, angular error, flatness, and resolution vs. accuracy.


Layout, transform matrices, mounts and perfect constraint.


Belts, gears, screws, etc.


What’s available COTS (commercial / off-the-shelf), where to find them, and how to qualify them.


What to make it with, and how to make it.


Design patterns from the field.

Tailing Notes:


A perfect machine that follows all of these principles to the letter doesn’t exist, so the exercise is often about finding a medium between each that suits the task at hand. In the world, ‘generalist’ machines seldom do anything very well: the more specific our design criteria

On Sketching

Draw it before you CAD it.

About Spreadsheets

Write them, love them: you will find your errors here before you find them in the prototype or you will find the locale of where your modelling efforts are worth the time.

Spiral Development

Probably Neil’s top piece of advice.

External Resources

Slocum: FunDaMENTALS of Design
Hyperphysics Table of Tables: HyperPhysics

Reference Machines

Fabricable Machines