Saturday, March 16, 2013

2.00gokart - the beginning / middle

2.007 is MIT's Design and Manufacturing I class. Nearly every Mech E major here takes it their sophomore spring. It's a project based class that traditionally revolves around the design and creation of a small robot that competes in an event at the end of the semester against all the other remote controlled robo minions.

I will not be building a robot nor competing at the end of the year to complete Operation themed tasks. I will be building a go kart and racing it against seven other teams of vehicle builders. Carolyn Wozniak and I make up Team 23, forged from the hope of branching out and falling flat on our faces.

How do two people go about designing a go kart? To be honest I have no idea. We both liked the idea of a three wheeled vehicle "tadpole" style so we started there. It snows in Boston and we put that to use. Here's a photo from our first design session.

There have been many drawing and iterations on this design but it remains pretty similar.

Here's what we've got to date in SolidWorks:

Our three wheeled beauty, yet to be named.

Some stats:

  • 36" x 48"
  • Brushed DC motorestimated to put out just over 1000 watts at maximum power
  • Three 12v LiFePO4 A123 batteries making up a 36v system capable of  40A peak
  • Kelly Controls KDS36100
  • Sweet chrome hand truck wheels with upgraded bearings
  • Handsome wood detailing

CAD, however, is not the same as real life. Here's what has actually been built:

Not as impressive, but it has potential.

Those connectors are eventually going to be waterjet from 1/4" aluminum, these are lasercut 1/4" plywood to test the fit.

We have some things we need to hash out, and soon. Our steering needs work. We're trying to decide between a "traditional" rotating steering column and a parallel linkage. The biggie at this point though is what we have named "the block". The block is what will support the rider and provide vertical stiffness in our frame. It has some interesting geometry.
Once upon a time we were going to waterjet the large gray panels from 1/8" aluminum, but as it turns out, that's expensive. Instead we are now considering using thicker plywood which will hopefully give the stiffness we need and not cramp the internal components too badly. For the top covering we are going to use a neat laser cutting trick involving some thinner plywood.

With some sanding and lacquer we should end up with a spiffy, structural component.

Spring break will be our major fabrication week. Lots of stuff needs to get done, rolling chassis inspections happen at the end of break.

We need a name for this contraption and suggestions are very welcome. Our instructor has already come up with two informal nicknames: "skeleton kart" and the somewhat more inappropriate "doggy style kart".

Until next time.