Presentation from my 2.007 (Design and Manufacturing I) class, 2.00Go-Kart. My partner and I built a go-kart that finished 2nd out of 10 in the timed trials.

1. How We Built Derpkart
in a Week and a Half
Team 3: Colt Richter & Adrianna Rodriguez

2. Conception
● Our original concept was to make a four wheeled cart, driven by the two
rear wheels
● Each wheel would have its own motor, but a single throttle would control
the both of them
● Steering would be a standard Ackermann style linkage
● Utilize the free sketchy Harbor Freight wheels from Charles for the front
wheels
● Disc brakes

3. Criterion
● Go fast
● Be comfortable for both drivers
○ size
○ seat
○ length to throttle/brakes
● Tight turns
● Bulkier and more stable (but also low COM)
● Adri basically wanted a baby racecar

4. Conception
● Four wheels would make the kart more
stable and substantial
● Motors would be in the back next to
wheel assemblies

5. We chose...
● For our motors we chose the
Turnigy Aerodrive SK3- 6364
(190kv)
● Three batteries in series
● To get ample power out of them, we paired it with the 36V KBS36101X
Kelly Controller, which could handle the peak amperage we would require

6. A hitting-the-fan moment
Learning Point: A single motor controller cannot control two separate brushless
motors
This can only occur if the motors are are electrically identical and mechanically
connected
The chosen design only had one controller for two brushless motors. This could
have been solved by using a single axle for the two drive wheels and
connecting the wheel sprockets together, but the frame design did not allow for
that and 8020 extrusions had already been cut.
This we found out around MS8 - time.

7. Solution
Three-wheel vehicle with single rear-wheel drive, upped gear ratio
Allowed us to keep most aspects of our design

8. Some (Other) Problems & Solutions
● Problem: tractor seat was never ordered. Solution: found an old desk chair
on Reuse, cut the bottom into a new but somewhat ineffective chair
● More than one waterjet incident: brake rotor was the wrong size, needed
four of one part and we only got one. Solution: new design for brake rotor,
manufactured three more parts using the bandsaw and CNC mill
● We couldn’t get the right sized axle in time, so we had to order a larger one
and lathe it down
● We basically machined everything else

9. MACHINING!!!

10. Operation
Lots of torsion from the poorly supported rear end of the frame
To fix this we could use ¼” supports in different areas of the rear
Colt didn’t fit and couldn’t throttle the kart with his foot, nor could he throttle more
than 60% or the batteries would be sad and “sleep”
This was mostly due to the frame design, which couldn’t really be modified
because the 8020 had already been cut, but an initial longer design would leave
more space for the driver.
Brake pads wore down exceptionally quickly
We were having trouble adjusting the pad, so Charles took the caliper
apart and put it back together again and then it started being adjustable
Other than that, no major problems

11. Operation
Going back to the battery problem, whenever a passenger >110 lbs tried to
floor it, everything just shut off and one of the batteries would “sleep”. This is
probably because of the current draw from the controller to the motor. The
controller’s limits: 45 A continuous, 110 A for a 10-second boost

12. Why Materials Are Important

13. Performance
● Median time trial results, this was with Colt driving (and after the bush
caught on fire)
● Watt - meter not working for our laps so efficiency is unknown.
● The steering started falling out at one point, this is because a bearing was
put in upside-down. But we decided we didn’t want to take the whole
steering column apart.
● Rear and front left wheels were super wiggly - should have used more
precise spacers

14. Questions?
Reflections?