Auto-level trigger for induction bed sensor

thingiverse

This is an updated version of my "Poor Man's BLTouch" auto-trigger. It works for any printer that leaves enough of the induction sensor barrel exposed to attach this trigger part. USE AT YOUR OWN RISK. This auto-trigger relieves users from having to attach pieces of metal to a non-metallic bed, exposing the full bed surface for printing after performing automatic leveling calibration. After measurements are done, just remove the trigger and put it away until the next bed leveling calibration is needed. IMPORTANT: If you are using the fully automated auto-leveling behavior in your printer firmware, YOU MUST attach this trigger to the carriage before starting the bed level measurements! Failure to do so may result in a nozzle crash, and related mechanical/electrical damage. The part works for me when printed in TPU. The part will become slightly warped if used for extended duration over a heated bed, but should still have plenty of flex in it and press the trigger down firmly when used. Take it off the printer and put it safely away when not in use to help retain its shape. Build Instructions: Print this part out in TPU (aka Ninjaflex) or something similarly rubbery. I found that semiflex PLA was not flexible enough, didn't return to shape, and couldn't withstand a high temperature heated bed without becoming permanently warped. YMMV. REMEMBER TO REATTACH THE TRIGGER BEFORE AUTO-LEVELING AGAIN, OR YOU'LL HAVE (FOR STARTERS) A NOZZLE CRASH! For those using Repetier firmware 0.91 or higher, and new to automated bed leveling with an induction sensor, I've attached a text file walking you through the process of using this trigger after you've followed Repetier's documentation. Consult the Repetier community if you have issues, before even attempting to use this trigger part. http://www.repetier.com/documentation/repetier-firmware/z-probing/ Outline drawn in Qcad as DXF, then extruded in OpenSCAD with holes for the barrel. Save the DXF file in the same folder with the SCAD file. Print Settings Printer: Cobblebot 1A Rafts: Doesn't Matter Supports: Yes Resolution: 0.4mm Infill: 25% Notes: Alchement clear TPU, 220°C nozzle, 70°C bed, 0.4mm height, 20mm/sec all non-travel speeds, Cura slicer with 4-outline brim and lines support "everywhere". The LJ12A3-4-Z sensor barrel diameter I have is 11.7mm. Scale the object up/down to fit yours if different, or you can adjust the OpenSCAD file directly if you know how. Post-Printing Use wire cutters or scissors to trim out the supports and any excess blobs/stringing. Then use the cutters to make a single snip through one side of each circular layer, so they become a tightly closed "C" rather than a circle. This allows easier mounting onto the sensor barrel. If the fit is too tight and causes the trigger to deform too much to stay flat on the bed, trim the circular holes some more, or print the part larger. Affix a section of box knife, razor blade or other piece of perfectly flat, thin rigid metal to the bottom of the part, at the location beneath where the induction sensor is triggered. I used dremel-cut pieces of ribbon-thin ice scraper blades, and 3M "Hi-Strength 90" spray adhesive.