OK all you motorheads and gearbox designers, how do YOU measure torque? Not calculate a graph, I mean directly measure torque at the output shaft of the motor or gearbox. As in, I want something that works like a tachometer for RPM but for torque. I know that there are such things a torque sensors but what I find seem to be big heavy industrial stuff and/or VERY expensive. I would like to be able to take a motor of the size ranges we use in FIRST (FP, CIM, Globe, Drill, etc.) and apply a known voltage and current limit to it and clamp something on the output shaft and measure the torque. It could be a direct reading sort of like a torque wrench (i.e. ft-fbs, nM, etc.) or just some sort of analog output like a voltage range that is proportional to the torque that I read and convert. Do R/C hobby folks use anything like this? Even something that would output a 0-5V sensor type thing that could be read with the Robot Controller might be cool. Maybe even some sort of bar clamped to the output shaft with a linear strain gauge setup or something. It would, of course, need to be cheap! What am I looking for? I don't even know where to start. How about some search terms, maybe some direct links, or even just tell me that I am crazy and no such critter exists? Help! Educate me!
For example stuff like this:
http://www.transducertechniques.com/...nt-Sensors.cfm is way too expensive for me!