Improved Filament Run Out Sensor

Activates a switch if your filament spool runs out during a print.

3D printer parts and enhancements

Creative Commons Attribution Share Alike

Commercial use is allowed, you must attribute the creator, you may remix this work and the remixed work should be made available under this license.

Learn more or download attribution tags


A very small, one piece, printed filament-out sensor designed to fit a miniature snap-action switch. Mount this device on either the inside or outside of your printer between the filament spool and the extruder. Pushing the filament through the hole opens the switch. When the filament runs out the switch closes. You can use that to pause or stop your printer by connecting to the right pins on your controller board and programming the firmware to recognize the switch closing as a fault.

Materials and methods

About 7g of PLA or ABS, a miniature snap-action switch without a lever, a screw to lock the switch into position, and a couple screws to mount it on your printer.

Solder wires to the common and NC contacts on the switch, insert a piece of filament through the body, then slide the switch into the slot with the nub in the filament hole. Listen for it to click, then tighten the screw to hold the switch in place. Pull the filament out and make sure the switch closes. Connect the wires to a switch input on your controller board and modify the config file to read the switch and pause the print when it closes.



Issues are used to track todos, bugs or requests. To get started, you could create an issue.


7667ed3f9e90ed7e584269da8cfa62b5?default=blank&size=40Kim Watson added this to the Printer Mods collection ago
B74009ad3a84796e1da4c11ec4b7b46c?default=blank&size=40JAMES CORPREW added this to the EX BUILD collection ago
A1dee076298ce2808c2208fb395f52c5?default=blank&size=40Curven added this to the Custom UMO upgrade collection ago
Ab070ed6bd35e37649fec781889e92f4?default=blank&size=40stachas added this to the filament collection ago
7f746f3fe4c3f7bdd0d014185e823348?default=blank&size=40Steven added this to the UMO+ upgrades collection ago
7866cc7ff35e36c50a7971124ae67a92?default=blank&size=40Brent Bendes added this to the printer collection ago
Mini gold hands croppedMark Rehorst published this design ago