- In theory, there is no difference between theory and practice. In practice, there is. (quote by Walter J. Savitch or Jan L. A. van de Snepscheut)
- Know how much torque / force you need before you order parts. Or just plan for "lots".
- Plan for failure (e.g. a demo that stops functioning 30 minutes before you're set to demo). Or wheels breaking off on your way to the competition.
- Pay very close attention to power every time you change something.
- Put clutches on the motor side of gearboxes. This way they don't have to hold nearly as much torque.
- Tensioners go on the unloaded side of a belt.
- If a part in a drivetrain can slip, it will slip. This is why keys, flats, and splines exist.
- 3D printing is great for checking fit, less great for parts that are under load.
- The first design usually needs a lot of improvement.
- One bolt is never enough.
- Tighten down everything.
- Don't put a side load on a gearbox.
- Make sure things are plugged in before you try to demo them.
- If an electronic component exists, somebody has written an Arduino library for it.
- Hard e-stop switches exist for a reason.
- Roombas charge really slowly. Hence, spare Roombas are useful as charging mules. Thus, having a small Roomba fleet is useful and not just weird. (only a tad bit weird)
- Serial communication on Roomba is unreliable (sucks).
- Pillow blocks are heavy and expensive (unless you buy them from Surplus Center, in which case they're just heavy).
- Minor version changes can mean drastically different behaviors (looking at you, Roomba).
- If your motor isn't strong enough, you can always add more gearbox. 800:1 total reduction seems to work.