Auto bed leveling using piezo discs

Auto Bed Leveling using piezo electric discs for very high sensitivity.

Update v 0.2!

Now using a single piezo disc glued (temporarily at least) to the x-carriage (see image). With the piezo element glued between the two bearings gliding on the x-axis shafts, and tiny amount of twisting (like the hotend touching the bed) will ever so slightly bend the plastic in the x-carriage. Since the piezo is glued on top, this will bend as well creating a relatively large signal. Thus even a minuscule force acting upon the hot-end can be detected using some electronics. This solves the problem of the previous setup with differing sensitivity of the three piezo discs (due to the discs them self and/or the mechanical setup) in v 0.1. Auto leveling is now even better, giving a perfect first layer every time (as long as the nozzle has been wiped clean of plastic, that is).

New video:
https://www.youtube.com/watch?v=LWRq2t9Pr-E
https://www.youtube.com/watch?v=0oBzWWZYKgE

Still to do: El