Thursday, August 13, 2015

My first marble machine

Marble machines are one of the best ways I know of for experimenting with mechanisms such as levers, pulleys, inclined planes, gears, or cams. The one in the following video is the first one I've built:

But let's start from the beginning. During last year's Maker faire I got surprised by the skills of Denha sensei at building his own complex marble machines.

After the Maker Faire, I spent hours admiring his creations and how he checks every detail in a methodical way. I came to the conclusion that a marble machine is usually made of some of the following components:

For my first marble machine I tried to make it simple. For that reason, I only used two common artifacts: a wheel elevator and an inclined plane. For finding the centre of the wheel, I used simple geometry. However, I had to drill a big hole for the bearing to fit in. That affected the accuracy of the centre. For that reason, I had to use a small spring that would automatically adjust the distance between the wheel and the motor's shaft (probably it would have been easier if I had used brass wire for the wheel's axis instead of a bearing). The inclined plane was made using a chisel. This is the list of materials I used:
  • Geared motor: MOT114A1B 6V 60RPM 12GA (Sengoku 1280yen)
  • Gear for the shaft of the motor (Sengoku) and a rubber cover (Ishikawa-neji)
  • Balls 7mm diameter (Tokyu hands)
  • A small spring (from a pen)
  • Brass wire 1mm diameter (Radio depaato in Akiba)
  • Wood (a home center and Daiso)
  • On/Off push switch (from an junk board)
  • 2*AA batteries with a case (Daiso and Akizuki denshi)
  • Aluminium plate (Yokyu hands)
  • Bearing (from an broken stepper motor)
This is a list of tools I used:
  • A precision hand drill
  • A precision wood saw
  • Dremel 4000 with various bits
  • Tweezers
  • Cable cutter
  • Long/round nose pliers
  • Tape
  • A universal vise
  • Chisels
  • Sand paper
Conclusions: I failed many times, but I also learned a lot during the process of building my own marble machine. Indeed it was harder than what I had expected. I will try to build upon these lessons learned, and make a better marble machine next time. You can check my notes for more details.

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