Can crusher
Hi Menticol,
I also like the idea of capacitive sensing.
Concerning the OP I'm afraid to say that his approach is not in the right sequence. As he wrote me in an email he wants the electronics done first and then turn towards the mechanical part.
May be somebody else can convince him of the fact, that electronics work is far more flexible than mechanical.
He wants a lot of "cool effects" which have to be taken care of by knowing his mechanical design. If I plan to make a can counter and he decides not to have it I must redesign the circuit because a valid count has some influence on the control circuit too, meaning to employ some more logic in the circuit.
May be I'll go for some "cool effects" too and have R2D2 (Starwars) scream while the can is being crunched.
Cleaning of the machine shouldn't be any problem reducing mechanical parts to a minimum, that is, using pneumatic cylinders instead of oily gears, open sprockets and possibly chains. If the chassis is made of stainless steel you could even take the device to a car wash station. (after having removed the electronic part)

An additional advantage of a pneumatic actuator: No compensation necessary for different size cans. Just the stroke long enough to cover all sizes.
An inadvertantly vertically dumped can might (just to avoid the double can

) be corrected for correct positioning easily by shaping the "load" channel accordingly (like a bowl), so the can will get out of balance and tilt either way.
Experiment: Drop a can 100% vertically on a hard surface tilted 2 degrees. Guess how it will come to rest. (Top heavier than the bottom anyway)
Regards
Hans