It's been over five years since I've designed a 'bot chasis. I'm finding that the CAD skills are still there, and am enjoying the process of laying out the design.

Since I now have the wheel, axle, sprocket, motor, batteries and other items in hand, the layout is being refined. I had several goals for the overall design:

  • I don't want the ride height to be overally high.
  • I want a good range of possible angles so that reasonable hills can be climbed.
  • The position of your feet should feel natural.

I have a Bongo Board at the office, and have gotten used to its layout. It seems to work well for the large number of people who have tried it over the years. It seemed like a natural source of measurements. Taking a close look at it, I found:

  • When level, the rider's feet are 6" off the floor.
  • With the rock centered, a 20 degree angle is possible off of either side.
  • The shallowest angle possible is about 13 degrees with the rock all the way to one side.
  • Your feet typically aren't farther than 21 inches apart while riding it.

After playing around in the CAD program, and trying several different options, I arrived at a layout that was fairly close to the Bongo Board:

  • Ride height is 6.4", only .400" higher than the Bongo Board
  • 20 degree angles are possible in either direction
  • Feet spacing is roughly the same, just a smidge higher, anywhere from 12 to 26 inches apart.

The down side of achieving these number is that everything will really be crammed in there. I'll have room for a third battery, but generally all compartments will be just slightly larger than the components they're holding. I ended up with a very familiar looking "Team Cosmos" style frame. It's just a bit larger than our typical 'bots.