Adding a Power Switch to Your 3D Printer

I love my printer. It's been such an invaluable learning tool over the course of it's lifetime, and having it while in school has been awesome. One thing that has bugged me, however, is the lack of an easy way to turn it off and on. I was frustrated that the lack of an easy way to turn my printer off and on, because with the Prusa i3 you had to physically plug the printer in everytime you wanted to use it. I wanted to be able to settle into my place easier and this helped out a lot!

For a while, I had it plugged into a surge protector and used that as a switch, but I wanted to be able to plug other devices into the surge protector and control the printer independently.

I found a nice 3 prong rocker switch the other day and decided to do something about my problem!

Please note that you will be working with 120V in this instructable and extreme caution should always be taken when doing any of these steps. Never touch any exposed wire, don't plug anything in until you are done, and wear safety glasses while soldering. Be safe and enjoy!

Here's what I used!

• Rocker Switch - mine actually had 6 prongs but i really only needed 3 to control my printer. The others went untouched.
• Case - this can be easily 3D printed, but I had a nice sturdy cardboard box that I was able to modify to fit perfectly over the 2020
• Power Cable - make sure of two things:
  • this needs to be rated for wall voltage (120V)
  • make certain that this is long enough to reach your outlet!
• Extra wiring
  • this must be rate for wall voltage (120V)
  • be sure that the length you have can reach from your power supply to the location of the switch
• Soldering Iron
• Solder
• Vise (or some way of holding your work for soldering)
• Wire Strippers/knife
• Kaptan tape (this can be replaced with crimped terminals)

I started this off by cutting a hole in the case I was using for the switch. I measured the dimensions of my rocker switch and carefully used an X-acto knife to cut through my case. I also cut holes to fit the 8020 frame that my printer uses. I did a quick test fit and then when I was satisfactory I went to go wire the switch.

Before we actually start wiring our switches, it's important to know how rocker switches work. You'll see that there are three prongs on your switch (mine has six, but half of them are unnecessary).

In this diagram, you'll notice that the A1 switch will always be connecting to either A or A2. Because we want to give power to our printer, this means that the A1 pin will be wired to AC power. This is usually the black wire, but is sometimes brown.

When our printer isn't powered, we want it to be connected to neutral. My switch didn't have any labeling on it, so if yours does it's important to note which prong relates to power to avoid confusion. The prong directly below the "off" position will be wired to neutral. The neutral wire can be a few different colors, usually white (aka not the ground wire, not the AC power wire)

This leaves one more prong, which will also be wired to power in order to provide power to the printer. Double check that this prong is directly underneath the "on" position on your switch.

The middle prong (AC power) and the "off" prong will will be wired directly to your power supply, while the "on" prong will be wired to the wall outlet AC power wire. Make sure that the lengths of (voltage rated) wire you're using will reach from the power supply to the location you want your switch!

Alright, now that we know which prongs are being wired where, go ahead and get started! This process can be a whole lot easier if you have terminal crimps. I however don't. So I stripped and twisted the wire (you REALLY don't want any wires popping out and having the chance to touch other terminals), and wrapped it through the terminal. Then I took out my soldering iron and safety glasses, and soldered the wire in place. Make sure you have a good connection between the terminal and the wire (the wire should not be able to move around).

Once your wire is nicely soldered, wrap around the terminal in kaptan tape so that there is no exposed wire (anywhere).

Repeat on the other two terminals!

Now (if you don't have a pre-wired wall plug you can skip this step) you're going to wire the wall side of your power cable. Grab a NEMA 5-15 wall plug, and open it up (as seen in the photo). You'll notice that the terminals where the wires go are actually color coded for your convenience.

Strip and twist your power cable wires so that there is no exposed wire when connected to these terminals. Also be sure that the power cable jacket isn't cut too short (so that it doesn't come out of the plug enclosure). This helps to give some strain relief to these wires.

In the green terminal add your ground wire (green).

In the silver terminal add your neutral wire (white).

in the black terminal add your AC line wire (black).

If your terminals are not color coded, use the photo above for reference.

Insert the switch into your container, and wire it to your power supply as such:

• The AC power line from your center prong should be wired directly to the power supply (there should be no other wires in this port.
• The neutral line from your "off" prong should be wired directly to your power supply. There should be another wire in this port coming from the wall power cable.
• The ground wire from your wall power cable should be connected to your power supply (and should be the only wire in this port).

And that's all!

Double check all of your connections and then enjoy the freedom of of a nice rocker switch to power your printer!

Enjoy!