Can you link to a sensor that would work ?
LJ18A3-8-Z/BY 3-wire 8mm Approach Sensor Inductive Proximity PNP Switch NO DC 6-36V 300mA Amico http://www.amazon.com/dp/B007Q8137I/ref=cm_sw_r_udp_awd_SPZ-ub01K19T1 that’s the one I use, was even able to power it at 5v and it works, though YMMV
i confirm. It does work ( or i couldn’t print with this one 
. I think you need a 8mm range sensor.
@Smartfriendz_3d_prin did you happen to catch my comment this morning on http://youmagine.com about board thickness?
ho. sorry. no. I will go to check that .
checked Jerry, The thickness was in integer, so no decimals . I will update soon.
Good to know, maybe a comment in parameters so others know. 
I will change to float. there’s no reason why we couldn’t do decimals in fact
that explains my parts are not fitting well on 1/2 inch board (12.7mm) 
- thanks
Ho yes : inches ! I will setup all parameters in float in fact, so we can build with rods in imperial ? why limit the options ? We could even make one with nema17.4