It doesn’t happen that often, but this is the last time that [Lucas] comes back from hours of unattended 3D printing to find a large portion of plastic spaghetti mess and a partly disassembled Kossel. The crash sensor he designed will now safely halt the printer if it detects that something went wrong during the print.
Unattended 3D printing is even more thrilling if your delta printer’s effector platform attaches to the delta arms through magnetic joints. While magnetic joints have their benefits, a small irregularity in the printing process can cause them to detach. The unknowing printer will then continue to drag a half-attached effector around, until the whole thing, including the still running heater block, comes to rest somewhere. [Lucas’] crash sensor tackles this issue by adding three limit switches. Each switch sits in a 3D printed mount that attaches to one of the delta arm pairs, effectively detecting if the rods are still in place.
[Lucas] wired the switches in series with his filament sensor, so if any of the arm joints fail, the printer will assume that it ran out of filament, stop the print and cool down. If you want to give this clever design a go without the filament sensor, both the Marlin and the Repetier firmware provide a dedicated defect sensor routine for this purpose. Enjoy the video below, where [Lucas] explains his build: