I need some assistance choosing a force/pressure sensing device for a project I’m going to be working on. I recently came across this project on Instructables, on using a force sensor to help level the print bed of a 3D printer (see https://www.instructables.com/id/FS-Tou … ling-Tool/) and I’m going to build something kinda similar. I was going to use a force sensor, but read, “…These sensors are simple to set up and great for sensing pressure, but they aren’t incredibly accurate. Use them to sense if it’s being squeezed, but you may not want to use it as a scale”
The 0.5" force sensor (SEN-09375) and 0.16" force sensor (SEN-09673) both have that disclaimer. From the disclaimer, it sounds like force sensors are more-or-less a glorified push button - you can tell they are being pressed, but the amount/resistance isn’t dependable. Or is it? I won’t be using it for measuring an exact/calibrated force, but I do need the relative readings to be the same. If I use it to measure the force the print head presses on it, move up, then move to another corner and measure, will it be relative (and repeatable) to each other?
The 1" FlexiForce Pressure Sensor (SEN-11207) doesn’t have this disclaimer. Does that mean the SEN-11207 is more accurate, and can be used like a scale? (instead of a glorified on/off (pressure/no pressure) button)
What about a load sensor (50kg - SEN-10245) - I read that it requires a SparkFun Load Sensor Combinator (BOB-13878 ROHS)… are 4 of the load sensors required, or can I use the Load Sensor Combinator breakout board with just a single load sensor?
I suppose another option would be to use a load cell disk, but the cheapest one you sell is $60, and that’s more than what I’d like to spend on this project.
Any of the three force/pressure sensors will probably work well for this project. The reason we have those notes on the FSR pages is to clarify these are not great for quantitative results but rather, qualitative. You will be able to see a change in pressure up to its maximum weight range but it will not work well as a scale for actual weight readings. With the right setup, the data should be quite repeatable and reliable for any of these three sensors but you’ll want to do some testing to make sure. Using a solid object of known weight on the sensing area can help to kind of calibrate your readings. The [Force Sensitive Resistor Integration Guide from the manufacturer and our [Hookup Guide will have more information on setting up your circuit and testing it.
As for a load cell/load sensors, those will be much better suited to set up an actual scale if you want to measure in pounds/grams but, as you mentioned, they do require some extra peripherals to set up and, ideally, work best in a [Wheatstone Bridge configuration. You could use just one but all of our documentation for wiring them up is based on that load cell with four strain gauges circuit.