If you’re a regular reader of the Hackster blog — and you definitely should be — than you have almost certainly seen us feature a number of Nixie tube clocks. Nixie tubes are completely outdated, at least by any practical standard. But they still look very cool, which is why makers like to use them to build decorative clocks. Nixie tubes can also be used to display other kinds of information, like what Dr. Scott M. Baker did with his Nixie tube 3D printer filament meter.
Filament meters are a convenient way of seeing how much filament your 3D printer has used during a print job. Print quality is dependent on how precisely the 3D printer can extrude filament, which means all 3D printers are capable of keeping track of exactly how much filament has been used. Your 3D printer’s firmware likely already has a built-in feature for displaying that information. But doing so requires going through the menu to find, which can end up being inconvenient.
Baker’s filament meter sits on top of his 3D printer, an Original Prusa i3, and displays how many meters of filament have been used and the completion percentage of the print job on seven IN-12 and one IN-15 (for the percent symbol) Nixie tubes. Those are connected to a custom PCB, which includes a header to mate with a Raspberry Pi Zero W. The Raspberry Pi pulls the filament data from OctoPrint, which is running on a second Raspberry Pi that’s connected to the 3D printer. Because Nixie tubes require a high voltage, the meter is completely isolated from the 3D printer in order to protect it.