17-20th January (days 3-6)
Around this point I realised that we really rather urgently needed some wheels that would fit on the drill shafts. I had originally planned on using the 5” Colson wheels, but I couldn’t find anywhere that could actually deliver them in time. Turns out there are a lot more 4" wheels out there, but we had already built a robot that was about 80 mm high, so that would be cutting it fine with the Robodojo area including a permanent 20mm pit.

Other options were therefore required. I chose scooter wheels in the end because, 1. They’re designed to take impacts, and 2. They’re widely available. The problem is of course, scooter wheels normally just sit on a dead shaft with bearings.
To fit the wheels onto the ⅜” UNF drill shaft I chose these little things. Very handy. That sentence took about 15 seconds to write, but it took me about 4 hours of searching to find them.
Over this weekend we managed to get the following done:

  • Mounting system to hold the motors in place (Becky and Simon sorted this). I’ll show it in some more detail when I put up the post-event teardown.
  • Wheels and hubs all fitted together and mounted to the motors. This was actually pretty straightforward; just knocked out the bearings from the wheels, then removed the flange in the middle with a 22mm spade drill. The hubs were then just an interference fit (which is one of my favourite engineering euphemisms; whoever made "we wodged it into the hole with a vice" sound so professional deserves a medal)
  • Connectors soldered to the motor and ESC as required. I used Anderson PP30s for the most part because I like the modularity (also because I’m familiar with them from work and I needed something comforting in this sea of unfamiliar things), and some XT60s.

Of course, that meant that we could actually plug the drive system in for a quick test:


What you see there is pretty much all we had finished at this point. Admittedly it doesn't look very different to the previous weekend. I did try to cut out a weapon mount but drilled ALL the holes in the wrong place which made me VERY SAD.