Quote:
Originally Posted by DavidGitz
We are having problems with this method now ... I suspect that it is due to a mechanical alignment of the shaft that we inserted, as described above.
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Was the hole put in the end of the shaft using a lathe? Any other method will never be straight enough to work. If it is a joint on an arm in the classic sense, then it may be better suited for a potentiometer anyway. The optical encoders are better for continuous rotation applications like drive wheels.
Potentiometers are usually easy to get at places like Radio Shack. Plus, it has the added advantage of knowing the absolute position of the arm at all times instead of the relative position.
They are easy to mount too, make a little bracket for them and then our team sometimes uses what we call the "Cyber Blue method" where we stretch a very short bit of surgical tubing over each end to act as a flexible coupler.
Wire it up to an analog input and you are done!