Fab Academy 2014

“If there is a 50-50 chance that something can go wrong, then 9 times out of ten it will.”

Paul Harvey

What could possibly go wrong?

A lot actually, but as Ken Robinson puts it: “If you’re not prepared to be wrong, you’ll never come up with something original.” The course is covering a lot of topics, and he who is not familiar with any of these will face many hurdles.

The scope of wrong-goings is fairly wide and covers a range areas, out of which are:

  • Poor Engineering
  • Machine failure (here in Barcelona machines have been put under massive stress)
  • Perilous handling or klutziness.


On the good side, poor engineering decisions is an area on which we can improve: that's why we're here. Lack of knowledge is what most often leads to the bad decision. Of course there are spec sheets and manuals rich with extremely valuable information, but as you progress you need to get your priorities straight and as it happens, you can't always apply the famous RTFM rule.

Bad choice of motor

In the free hand sketch I did on the first week of class, the result was compact (something you could imagine running around on your desktop), so I naturally intended to make the final object as compact as possible. In doing so I chose the smallest stepper motor that were proclaimed as high torquebut did not actually check the torque values.

That motor holds a torque of 180g-cm which is too little for my project, so I had to go back to the drawing board a design a bigger DooD. I need to measure and calculate with more precisions, but in ball-park figures if I assume DooD's center of gravity is 10cm away from the wheels axis, and a weight 300g I should not go for anything less than 3kg-cm (I suppose I could go for a weaker motor if I don't care about self-balancing).