Self-positioning induction trigger for WeldingRodBot

thingiverse

UPDATE: I uploaded a universal trigger that friction fits on the induction sensor barrel. It works with any printer that has at least the lower half of the induction sensor barrel exposed. http://www.thingiverse.com/thing:1523184 This part is designed to work only on WeldingRodBot (http://www.thingiverse.com/thing:981664), which has an induction sensor mounted in the center hole of the carriage. I made this as a Poor Man's BLTouch. The flexible part slides onto the bottom of the carriage, positioning a metal trigger beneath the induction sensor. This allows almost fully automated mesh bed leveling measurements. After the measurements, I slide the TPU part off the carriage and can use the entire bed without any foil, clips, or other metal triggers left in the way of the nozzle. This part saved me time and let me turn off the manual "trigger" behavior in Repetier Firmware - previously, I manually positioned the razor blade on the glass for each measurement, waving a tool under the sensor to trigger it. This took up a lot of time and was error-prone if I let the tool linger under the sensor while triggering it. IMPORTANT: If you're using the fully automated auto-leveling behavior in your printer firmware, you MUST remember to attach this trigger to the carriage before taking another bed level measurement! Failure to do so may result in a forcible nozzle crash and related mechanical/electrical damage. The part will become slightly warped with usage on a heated bed but should still have plenty of flex and press the trigger down firmly when used. I found that semiflex PLA wasn't flexible enough, didn't return to shape, and couldn't withstand a high-temperature heated bed without becoming permanently warped. Instructions: Print this part out in TPU. Use wire cutters or scissors to trim any excess strings and also trim the part's upper deck and rail slides to fit the lower profile of your WeldingRodBot carriage. Affix a 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 3M spray adhesive). Ensure your bed is perfectly clean with no residual crumbs or streaks of material. Perform your usual bed measurement ritual. Remove the trigger and print as usual. Files were designed in Qcad and OpenSCAD. Video of trigger in use: https://www.youtube.com/watch?v=hFfmfnSvlVQ Fun fact: You can see in my photo and video that my own printed out TPU part was incomplete and only half-printed due to the difficulty of printing in TPU. This was still enough for me to use, so I didn't bother to print the full object.