FIRE SAFETY FOR ANET 3D PRINTERS

Over the last few days, there has been a lot of concern regarding fires that occur with 3d printers. I want to take a moment to address these concerns and disperse the smokescreen of fear and uncertainty that some people may be caught in.

The main causes of fires with these printers can be attributed to two categories:

1. Heatbed power connector failure

2. Thermal Runaway due to the heater cartridge and/or thermistor falling out of the heatblock.

Both of these situations are very easy to prevent and the safety of your printer can be drastically improved by following these simple steps.

1. HEATBED POWER CONNECTOR FAILURE

The connectors that are included on the Original ANET V1.0 board are not rated to handle the current required to operate the heated bed, and as a result may heat up and ignite under certain conditions. These are the steps you can take in order to prevent this:

1. Make sure the wires are inserted correctly into the connectors and that the insulation is not being clamped onto in any way. DO NOT tin the wires before inserting them into the connectors.
2. Install a heated bed MOSFET power expansion module. These are available for around 7 dollars on Aliexpress. Installation guide available here: https://3dprint.wiki/reprap/electronics/heatbed_mosfet 
3. Replace the green power connectors with the blue screw terminals which are capable of handling over 20 Amps of current. (Search online for “AKZ120”)  Guide available here: https://3dprint.wiki/reprap/anet/a8/replace_connectors 
   OR
   Remove the connectors entirely and solder the wires directly to the board.
4. Remove the molex connector from the heatbed and solder the wires directly to the appropriate pads on the heatbed.

2. THERMAL RUNAWAY DUE TO DROPPED CARTRIDGE

If the heater cartridge is not fastened into the heater block properly, it can fall out. When the heater cartridge falls out of the block, the thermistor will begin to cool down and then the board will tell the heater cartridge to heat up even more to compensate for the falling temperature. Since the thermistor is no longer in contact with the heater cartridge, it will continue to heat up or “run away” until it catches fire. This is very easy to prevent by following these steps:

1. Tighten the setscrew on the bottom of the heater block periodically, and check that the heater cartridge is secure before every print.
2. Secure the heater and thermistor wires to the X-carriage using one of the white cable clamps included with the printer.
3. Wrap the heatblock with kapton tape to prevent the cartridge and thermistor from falling out. (This also helps keep your heatblock clean)
4. Skynet Version 2.0 (Marlin) includes a thermal runaway prevention feature that will shut off the heater if the temperature drops and fails to recover within a specified amount of time.

OTHER 3D PRINTER SAFETY PRECAUTIONS:

1. It is strongly recommended that a 3d printer is not left unattended. Use at your own risk. You can keep an eye on longer prints using a webcam and octoprint within your home. I would not recommend leaving your house empty while you have a print going.
2. Always operate a 3d printer in a well-ventilated area.
3. Have a proper CLASS C fire extinguisher on hand (CO2 or Dry Chemical).
4. Ensure that you have a working smoke detector in the same room as your 3d printer.
5. Store flammable materials and liquids a safe distance away from the printer.
6. The use of a fireproof enclosure can help prevent a fire from spreading.