Hi, this is my design for a Z-Axis opto sensor mount for the Orca 0.3. It is much more secure than the cable tie method, and follows on from my X-Axis Opto Mount. (http://www.thingiverse.com/thing:14155).The parts position can be adjusted easily, just slacken off the nut and bolt, move it to where you want it, and tighten back up.v2 - uses method similar to orca 0.40. One bolt adjusts, the other bolt and the 8mm bar guides. The spacers are used to tighten the bolts with nuts to stop them moving. I am using extruder springs and they seem to work well. The bolts are M4x40 cap heads.The picture is different to the current stl, i've modified it since fitting the one in the picture.Print one of the z-opto mount.stl, drill out the holes to fit, push the sensor into the part, use an M3x20 nut and bolt to secure the opto sensor, and an M4x25 nut and bolt to secure the part to the smooth z-axis rod.The opto-flag shouldn't need adjusting.v2 - Will require cutting two new holes in the aluminium plate. The way I did this was to remove the bar clamp, place the part over the 8mm rod, and use it as a template to drill the holes. Only thing to be careful of is that the part is roughly in the right orientation before drilling.