(Beta) Piezo UnderBed Mounts by Precision Piezo

thingiverse

These are Delta printer bed mounts designed to house 20mm Piezo discs. These are beta designs. My intention was simply to experiment with underbed sensors as I have not tried using piezos before, apart from FSRs a while back. And they work well when coupled with the Precision Piezo/Moriquendi piezo PCB, which is very sensitive. Probably best suited for smaller beds. Feel free to adapt them or use this guide to create your own. The idea is that the piezo disc is supported around its edges, and the weight of the bed presses the upper part lug into the centre of the piezo. Instructions for the bed mounts: Print these in ABS as accurately as possible, leaving some tolerances built in. Each mount consists of three parts. The base is the lower part shown in the diagram, with a 5.5mm recess and a 3.5mm hole for an M3 screw to attach it to your printer. You may need to adjust this hole to fit your printer. Make sure the screw head sits in the recess. Insert a 20mm piezo disc, then pass its leads out through the small hole. The middle part shown in the diagram is where things get interesting. The upper part lug of the bed mount passes through this part. Achieving accurate tolerances here can be tricky without adjusting, so use a fine warding file to file the hole until it fits snugly with the upper part lug. This middle part has a cutout for the solder pad on a Murata 20mm piezo disc. You may need to adjust this to ensure it doesn't sit on the solder of the piezo disc. Place it over the piezo disc, making sure not to press onto the disc but instead supporting it around its circumference. Secure it with superglue to the lower part. Insert the top part and repeat for the other two units. The piezo leads need to be connected to a piezo amplifier available at http://www.precisionpiezo.co.uk/shop, then tuned as shown in the second photo above. These should work for 27mm piezos, just scale them up so that a 27mm piezo fits instead. If the piezo probes badly when hot but works well when cold, you may need to add some cork insulation to the mounts to keep heat from the bed away from the piezos. Future releases might include clamps on the top parts.