Tag Archives: Filament Feeding Monitor

Tunell Monitor stops filament feeding problems

This upgrade can save prints that would otherwise be lost to a filament jam, tangle or empty spool.

We’ve all been there — you’re just about to finish 3D printing an object and the machine runs out of filament; your filament gets stuck because the spool was loaded incorrectly; or your hot-end gets jammed due to accumulation in the nozzles. When these problems occur, the job is usually lost due to air-prints.


Looking to put an end to such scenarios, the ToyBuilder Labs crew and Aaron Tunell have developed what they call the Tunell 3D Printer Filament Monitor. This device will spot a filament feeding problem right as it happens and pause the machine so that you can fix it immediately, instead of having to throw a partial print away. For long-running prints, this indispensable add-on will pay for itself in no time.


The Tunell Monitor uses a mechanical 24 PPR (positions-per-revolution) encoder to detect filament travel as you print. If the filament stops moving for longer than the (adjustable) timeout period, a fault signal is sent to your printer.

Beyond that, the device features a connection point for an external pause button and an alarm/relay/signaling LED, as well as FlashForge Creator, Wanhao Duplicator, and MakerBot Replicator with a four-pin latching cable. Powered by an ATmega168 MCU, the Tunell Monitor is Arduino programmable via an ISP hardware programmer, like the AVRISP mkII. It is compatible with a number of MakerBot printers running the Sailfish firmware upgrade, in addition to Marlin-based units with an available end-stop and expansion I/O pin, and other printer controllers that support external pause signaling.


Tired of wasted print jobs? Check out the Tunell Monitor on ToyBuilder Lab’s official site here.