I wonder sometimes if manufacturers of foolproof items keep a fool or two on their payroll to test things. ~ Alan Coren
Designing Foolproof
An unobtainable goal worth chasing
First published July 31st, 2023
By any measure, "foolproof" is a complete abstract untethered by reality. It means designing something that withstands human error, incompetence, or misuse, but given all the remarkable ways humans screw up, nothing can be entirely such. That doesn’t stop designers of all shades from trying, with varying degrees of success. As a result, we occasionally come across a made thing that functions so perfectly it's as if the divine swooped down from the heavens and delivered it. But this, of course, is a very rare occurrence.
Making things well is one thing, but making them foolproof is quite another.
As I write, I sit in my shop looking around for something I would say is close to foolproof. And I am coming up empty. I have some well-made screwdrivers, for example, but in the wrong hands, these could bend, or the tips could break. And my Sterrett tap wrenches work as beautifully as they look. But these could also bend or dent if a tap is inserted wrong. And the computer I am typing on, a Lenovo ThinkPad, is one of the better laptops on the market. Yet, it is so frustratingly glitchy, owing partially to Lenovo’s hardware and more to its Windows operating system.
Any one of these “well-made” things can be severely damaged or destroyed if we don't pay attention or, worse yet, do not know what we are doing. And that's the problem of designing foolproof: anyone and everyone can be a fool. And we are often far more accomplished at it than we care to admit, making the designer’s task of foolproofing all but impossible.
When I make things for myself, I know their idiosyncracies and know how to care for them. The drill press stand I made is a great example. I used 1/4" plywood for the drawers instead of thicker stock often used for such things. And while I am convinced the drawers are sturdy, I do mind how forcefully I open and close them - just in case. That said, I do the same with almost everything I own because I take care of my stuff. But not everyone is so careful (obsessive?), and I wonder if I had made that stand for someone else, would it still be intact?
I've thought a lot about "foolproof" since designing and building the mini camper. It was such a rewarding build that I am entertaining the idea of making them for others. But there are several nuances about my completely custom build that might cause issues for anyone but me. My camper is a good design, but it is far from foolproof.
On the electronics side, I made one aspect of the camper close to foolproof: the switching between DC and AC power. In short, I wired the trailer to run on either DC battery (plus eventually solar) or AC "shore" power. These two sources need to power the same components within the system, and so switching between the two involves completely isolating one while engaging the other. I achieved this by installing two heavy-duty changeover switches and running the two power sources, plus inverters and converters, through these to ensure that the streams never cross.
As far as I can tell, there is no way to screw it up. I can plug in an AC power supply with everything still on battery, and nothing happens. And if the incoming supply surges, there's a 15 amp fuse to protect the system. Likewise, on the DC side of things. Even more robust is the changeover switching: the two switches have three poles each, 1, 0, and 2. I have the DC system on "1" and the AC on "2." "0" is completely disengaged from either. Even if one switch is on 1 (DC) and the other on 2 (AC), nothing terrible will happen (the system will not work, that's all). Still - I'm sure there is a way for things to go sidewise, but I can't think of what it is. Hopefully, I'll never find out.
Another example where my trailer is less-than-foolproof is the water tank fill port. The tank is under the trailer frame, and given the dimensions and design, I could not conveniently position the gravity fill on the outside of the body. So instead, I created a nifty little trap door in the inside floor for the fill. It was a great solution to a challenging problem. But not a foolproof one.
It would be easy to spill water while filling, and if enough spilled, it would infiltrate the subfloor where all the wiring is. Granted, I made solid connections and know to be extra careful when filling the tank. But would someone else be so cautious or as knowledgeable of the risks?
If I eventually build a mini camper for someone else, I'll need to evaluate these and many other systems in my design before passing the final build on to a new owner. There is a degree of user responsibility inherent with anything we have and use. Things need not be entirely foolproof to be still good. Where safety is a concern, we need to be extra diligent, of course. Such is the case with the power system. But other features might be fine the way they are, and anyone using them must be aware and careful to use them correctly.
Perhaps make things good, although not foolproof, and put a warning label on it? (This is the common way of addressing such shortcomings!)
But still, we all make mistakes; we are each the fool at some point. So making things that keep us from being an even bigger fool is a goal worth chasing. If only to save us from ourselves.
Until next time.
JRC