The Lego Problem


As with a lot of children of the 1970s, I had my share of Legos. They were a great toy to inspire me to invent, create, and use my imagination. The colorful blocks I prefered were the the ‘Expert’ sets that had gears, wheels, and other moving parts to make working things like cranes and cars, not those little people in the Lego movie with pirate ships. I made stuff – stuff that worked.

From there, I went on to learn how to make real stuff that worked, you know, engineering. In school, the budding engineer first learns a lot about the science of things and how things work, in theory. They may also get exposed to the real world, depending on the school. But it’s not until they get into the real world of practical design of things do they understand that almost nothing is ideal. Real world experience is really the second half of engineering education.

In real world engineering, there are three categories of problems; things we don’t have enough information on, things that are not ideal but we have to do anyway, and things that we just can’t control.

Not having enough information about things we are working with is not necessarily a lazy engineer. At some level, we have to buy materials, components, subsystems, that we integrate into a product. The supply chain that sells us these things are filled with salespeople that can’t answer all your questions, marketing embellishments and selective omissions about products, and in many cases, just flat out wrong information. So the design engineer’s job becomes a process of not believing anything, and proving that the design works. This doesn’t always produce a useable design out of the gate.

The Design Engineer is also faced with a second challenge – not over designing the product. If money were no object, then everything would be bulletproof. “You require a 100 watt power supply? Well I’m going to design you a 500 watt power supply, just so it never fails”, says no one, ever. So in reality, that 100 watt power supply is just going to barely meet its requirements, and will have a measurable failure rate.

There are also the dark arts of things that we cannot control. Nobody wants to hear about these things. This would include such voodoo as the supply chain didn’t make the materials to spec, and we have no way to detect that, or components that just simply didn’t work as advertised which resulted in a complete redesign, or one of my favorites, the supplier that tells you this part is going to be around for a long time, then discontinues it three months into production.

(continued on next page…)

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