“You can’t control what you can’t measure” goes the old chestnut. But that’s a little bit negative, in my opinion. Instead, think of the benefits of sprinkling sensors around everywhere: you gain insight where you simply didn’t have it beforehand.

We were thinking about this in the context of the recent video on pressure advance in 3D printers. Essentially, the unmelted filament acts as a springy piston, and that springiness means that the pressure built up in the melted plastic lags the feedrate of new filament. We usually calibrate this out with a guesstimate constant, but it can be different for every different filament. Measuring that pressure directly with a strain gauge in the hot end makes more sense.

But then there are knock-on benefits of having a sensor in the hot end. You can use the strain gauge as Prusa does to run the nozzle gently into the bed and set the z-axis height. Or you can use over-pressure as a sign that the nozzle is clogged. It’s quite possible that you can use it to signal other things that can go wrong as well, but you can’t tell until you put the sensor on in the first place.

Of course, you don’t want to put a pressure sensor where you want to know the temperature, or vice-versa. But as a general rule, the more you can measure, the more you can discover about the way your system is running. How many strain gauges are too many?