Thursday, August 4, 2011

tinyKart: Round 4

I've been preoccupied with Robocon, the International Design Contest which this year is hosted at MIT. But somewhere in the past week we found some time to complete the rolling chassis on tinyKart. The tires came in, so this was the moment of truth for the custom aluminum frame. And as you can see in the video above, it actually rolls (past the unfortunately copper-deficient LOLrioKart). The chassis itself weighs only about 40lbs, so we were quite happy to see it handle the full weight of a driver and not simple bend in half.

The tires are 8"x2" pneumatics with tubes from ElectricScooterParts. They're certainly not for racing, but they are remarkably light, which is the point in this case. They are high-pressure (70-80psi) so they roll very well, though the ride may be a little rough outside. We will probably run them closer to 60psi since we have four points of contact with the ground and they're normally used on scooters with two.

Other than that, the only addition here is a Vise-Grip steering wheel. That will soon be replaced with a custom job. One interesting thing about tinyKart will be the hand-based throttle and brake (no pedals). More on that to come when we install them, but I think it will be incredibly fun to drive. 

A few more pictures of the substantially completed chassis:

Slackermann steering geometry at work.

More 80/20 for the steering column support.

Thin as a razor blade...

Convenient storage position.
Next up: Electrons. Thousands of them. Actually thousands of billions of billions of them...per second.


  1. two things:
    1) I don't think I'd run the tyres lower because they're carrying less weight, one of the best ways to destroy a tyre is to underinflate and then drive at speed.
    2) these tyres are designed for a scooter so they're expected to take a pounding, but they're not designed with any sidewall stiffness in mind. Are you clamping the tyres to the wheel in any way (like in RC cars), or are you just hoping the tyres will not fall off the wheels when you go round a corner fast?

  2. Both good points, thanks. I don't think 65psi would be underinflated, since only a maximum pressure of 80psi is given. The 70-80psi mentioned in the post is not the rating from the tire manufacturer. But for the time being, we are running 70psi.

    There is no mechanism for clamping the tire to the wheel. The cornering forces may be slightly higher than they would be on a scooter, and you can't lean into the turn, so I'm not sure what to expect. As with all our experimental vehicles, we'll start slow and observe.

  3. "hand-based throttle" <-- Great way to put more electronics! :D

  4. I think the trigger throttle might be my favorite feature.