Radio Control K'nex Car

I made this quite some time ago but it still gets a few hits from Google and there is a big K’nex “scene” on instructables so I’ll include the content from the old page. K’nex is a brilliant construction toy and I have kept all of mine (and bought more at car boot sales!) but I only use it occasionally for prototyping and visualising things. It’s hard to make something permanent from K’nex, pieces are usually borrowed for other projects and then it falls apart!

This car was dismantled a long time ago and I can’t remember any of the finer details of making it. Everything I know about it is pretty much on this page. However, if you do have a question or comment about it then feel free to contact me.

Introduction

Inspiration for building a car from K’nex came when I wanted to make an R/C Car easily and cheaply. My dad has an old Tamiya Cheetah which I used for parts like the servos, and Remote Control Equipment. If you are planning on doing a project similar to this you will probably need good quality proportional control Radio Control System and a basic knowledge of R/C vehicles.

The different elements

Steering

Steering

I used  Ackerman Steering. K’nex doesn’t have any specific parts for steering so I had to build my own framework. This is not as sturdy as I would have liked however and I spent much of the time building reinforcing the axels so they wouldnot bend under the weight of the car when the servo turned it. This leads to a slightly ugly front end but as I was not out for realism this doesn’t bother me. The K’nex rod is attached to the horn of the servo by thread wrapped round tightly. It would be better for some kind of glue but I didn’t want it to be permanent.

Motor

Motor

I had an old motor from an off road K’nex toy that I got as a present a couple of years ago. Sadly the model is no longer being produced and the other K’nex motor not as powerful. I suggest using a couple of small motors together as you would not be able to get much power from one. Turning a motor into a remote control motor is relatively simple, you’ll need a speed controller. The speed controller I used is an old mechanical one which works but some power is lost in it and it takes up more than an electronic one.

Remote Control Equipment

Radio Control K'nex Car

I used an old remote control system that belongs to my dad. The most important thing is that it has proportional control because you often need to fine tune the steering as the vehicle moves. The videos show that car with 4xAA Ni-MH Rechargeable 2300mah batteries. Unfortunately they are rated at 1.2v instead of the standard 1.5v of Alkaline batteries. This .3 of a volt difference in Alkaline and Ni-MH batteries make the car run much slower when using rechargeables. However, as the car was never built for speed so I’m happy using them.

Parts Needed

  • Remote Control
    • Handset
    • Receiver
    • Speed Controller
    • Servo (For Steering)
  • K’nex
    • Basic Parts
    • Joining pieces for the steering
    • Gears or Rubber Bands (Unless your using direct drive)
    • Motor

Final Thoughts

If you are already making R/C cars then you’ll probably be designing better cars than a K’nex one could ever be. But if you don’t have the parts or want a change, to make a car from K’nex is perfectly possible. Don’t expect huge speeds and strength though.