Quote Originally Posted by gavztheouch View Post
I did think about the callipers, but im not sure they would be the easiest to implement as they do not have the A and B channels that I am used to with encoders?
It would be easy enough to make something to convert the signal into something compatible, but the callipers response time is far too low to use for motor control, so forget that idea.

Linear encoders are generally very expensive. One cheap way to make one that should be plenty good enough to experiment with is to use a rotary encoder, put a timing pulley on it and have it run on a flat (open ended belt). Wrap the belt round the pulley with two idlers, so when the linear slide is moved it causes the pulley to rotate...I doubt it would be good enough to use in 'real life', due to small errors in the belt pitch and stretching, but worth a try I reckon.