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Ender 3 Filament Run-Out Sensor

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Reducing Print Failure Anxiety

One of the most useful printer features is a filament run out sensor. A filament run out sensor is some kind of switch that detects the presence of filament, and lets the printer know when it has run out. In most cases this will pause the machine where it is at, and wait for the user to push a button to start again. With it I can start any print without the fear of how much filament left I have on my spool, or repeatedly checking my printer waiting to catch the exact moment when the filament runs out. My two Ender 3 printers were running 24/7 churning out face shield headbands for COVID-19, so I was going through plenty of filament, especially after upgrading the printer to use the V6 with a 0.8mm nozzle.

There are several available solutions to add a Filament Run-out sensor to my Ender 3, but after some internet research I chose to use Pin 29, as that has no impact to other existing components, and does not require me to purchase any specialized parts.

This post will show a step by step of how I added the filament run out sensor to my Ender 3. It is important to note that I made this upgrade at the same time I flashed new firmware, as I had the case open already and was editing Marlin anyway. 

Table of Contents

Tools Required

I used a simple Makerbot End Stop style limit switch for this, with a 3d printed case, and some small lengths of bowden tube. There are many kinds of limit switches out there, but this is what I had on hand, and it works well enough for this purpose.

I also use the dupont wire crimp tool along with one single female dupont plug end. Learning how to use this crimping tool has proven invaluable for customizing wire harnesses and electronics.

Lastly I required a soldering iron, as all of the easily accessible controller pins on the Ender 3 are accounted for.  Soldering wires onto a PCB requires a steady hand and great care, as it is easy to overheat sensitive electronic components.

The printed case I used was this one:

https://www.thingiverse.com/thing:2443425

This printed case is compatible with these limit switches, as an example:

https://www.amazon.com/CHENBO-Endstop-Mechanical-Switches-Printer/dp/B01CS82B8K/ref=sr_1_1?crid=358WM1VMVYFPM&dchild=1&keywords=makerbot+limit+switch&qid=1587578500&sprefix=makerbot+limit%2Caps%2C429&sr=8-1

Here is what I used in a list:

  • 22 gauge green wire, about 4 inches long
  • 1 male dupont connector
  • 1 Female dupont connector
  • 4 single dupont connector housings
  • Dupont connector crimping tool
  • 1 Makerbot style end stop limit switch
  • 2 pieces of 1.75mm bowden tube 3 in long
  • soldering iron

Unused Pin 29

Connecting The Limit Switch

Updating Marlin

A Simple And Cheap Solution

This solution was relatively quick for me to implement, while I already had the printer case open to burn a bootloader and flash Marlin. With a few extra steps and a quick solder, now I have the peace of mind of a filament runout sensor. There are many types of switches and designs to use, but pin 29 was the key feature of this design to minimize impact to other printer functions, and not spending money on custom solutions.

Author

  • Clifford Villerot

    Cliff is an Engineer and Maker in the Metro Detroit area

    http://www.CreatingWithCliff.com creatingwithcliff@gmail.com Villerot Clifford
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