Install MOSFETs on your Anet A8 (Electrical safety)

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I presented in another article some improvement for the Anet A8. Their purpose and mainly to improve the quality of your prints by reducing vibration or improving cooling and others are more practical and aesthetic. Today we are going to focus on the security of your 3D printer, and more specifically on electrical security.

Why install a MOSFET

A lot of energy flows through the motherboard to power the extruder and the heating bed. Installing a MOSFET will unload the motherboard from this task. At the very least, it is advisable to install a MOSFET for the heating bed, it is the one that pulls the most on the power supply and which requires the most current (10/12 A) and therefore the most heat. In my case, I decided to install two. One for the nozzle, one for the bed. It’s just a matter of how it connects and what we need.

How do you plug it in?

Before installing it, you will need to bring some equipment. You already need MOSFETs. I bought mine on Gearbest. You will need at least 16A power cable. I used electrical sheath cable where I will not use the ground cable. A crimping pliers, terminals (I used fork type terminals, those in the shape of a U). A medium cruciform screwdriver and a small one. A plate that your MOSFET (s) will receive that you have to print. I personally opted for this model on Thingiverse.

1) Prepare your power cables
Strip your cables and crimp them on both sides.

2) Connect them to the power supply
Connect your cables to the power supply while respecting the terminals. The three left terminals are negative, the three right terminals are positive. You should have something like that in the end. Then run the cables underneath the printer (there is a notch where a cable must already pass through).

3 ) We disconnect
On the motherboard, unscrew the two power cables of the heating bed (left connector) and the nozzle (middle connector).

4) Unscrewing the connector and crimping
The two cables of the nozzle surrounded by a fabric girdle are connected to a connector. Unscrew both wires and replace the connector with two terminals.

5) White cables from the MOSFET
With the MOSFET, a white cable with a connector has been supplied. He’ll take the place of the cables we just unplugged. We will get the green connector that we just unscrewed and apply it to one of the white wires (the one for the nozzle). For the other (heating bed), it will have to be crimped.
6) Final connection
Now that everything’s prepared, all we have to do is plug it in. Install the two MOSFETS (with M3 screws) on the board (if you have chosen the same board as me, do not forget to insert an M3 screw into the hole in the middle of the board before connecting the MOSFET). Install the cables as follows:

Once everything is checked you can turn on your printer and test.

The final wiring diagram

To have a broader vision. And check your connections.

Does it heat up any faster?

I read on the internet that by installing MOSFETs, the heating speed of the heating bed and extruder had to be faster. Well, okay, why not. But I still wanted to test it myself.
Nothing very scientific in my experiments. I just took a timer and measured the time it took to make a PREHEAT PLA, to the temperature of 190°C to reach for the extruder and 60°C for the heated bed.

Without MOSFET:

  • Extruder: Temperature: 2.6°C => 1min40 => 190°C
  • Hot bed: Temperature: 3°C => 4min20 => 20°C

With MOSFET:

  • Extruder: Temperature: 5°C => 1min35 => 190°C
  • Hot bed: Temperature: 5°C => 4min15 => 20°C

So I don’t know you, but to save 5 seconds of heating time I don’t find it super significant 🙂 especially since the starting temperature was slightly higher during the test with the MOSFET.
So in my opinion it doesn’t heat up any faster… But it secures your electrical installation and that’s the main thing:)

Spare parts:

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