Anet A8 problems – Are They Real?

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Anet A8 3d printer – A fire hazard out of the box?Anet A8 problems : Anet A8 3d printer

There has been a lot of talk on the internet about the Anet A8 problems.

I disagree that it is in itself dangerous.

The Anet A8 printer has sold in its thousands and is continuing to sell.

There will always be problems selling a product in this quantity and due to the fact you put it together there is another factor at play.

I have one of these machines and at the moment it is working fine.

The areas that are of concern are :

  1. The power supply is not up to the job.

  2. The mosfets on the main board for the bed and nozzle are not up to the job.

  3. The connector for the heated bed is not up to the job.

  4. The frame is not up to the job.

With all of these known problems it is a wonder that it sell in the quantities it does!

Lets take them one at a time

Anet A8 problems #1 : The power supplyAnet A8 problems: power supply unit

The supplied power supply is a 12v 20a supply or a 240W power supply.

This has been talked about as being inadequate for the job – not having enough current.

With the heated bed heating and the nozzle heating and the motors moving the total current requirement is about 18A peak.

Yes it is close to it’s limit but it is still within its capability and noting that the bed and nozzle will not be on all the time it is well adequate for the job.

What I would suggest is to add a fan to cool this unit, prolonging its life.

There have been the ones which blow up, unfortunately the manufacturer of the printer has no control over the quality of the power supply manufacturer. So with the quantity supplied you will probably find that it is in the order of less than 1% failures.

When you have built your printer and operate it, you will find that the fan on the extruder comes on immediately,

When the heated bed turns off you will notice a different pitch in the fan noise and speed, this is quite normal and the dip due to the heated bed is only 0.2V, nothing to worry about.

If your power supply does give up the ghost, then it would be worth replacing it with a higher current one like this (link to 30A psu).

With the standard power supply you can run lighting to the extruder to see what is going on, but it must be low power led lighting – if you start using car led lighting then this may overload the power supply.

Anet A8 problems #2: The mosfets on the main boardAnet A8 problems : mosfets

To control the heating of the bed and the nozzle a ‘switch’ is turned on by the controller.

This switch has to be able to handle the current required for the heating of the bed or nozzle.

The ideal switch will have no resistance, therefore not heat up at all, but in real life all semiconductor switches (mosfets) have a small amount of resistance.

This resistance will cause a small voltage drop and a small amount of power will be dissipated in this mosfet.

The power will cause a temperature rise in the device and it is fitted with a heatsink to get rid of the heat quicker.

A lot of people cannot believe that the small device on the board can handle the current of the heated bed, but due to the fact that it is very low resistance when switched on and only drops a little voltage it only consumes a little power.

The data sheet for the device says it will be an on resistance of about 0.003 ohms when fully switched on and can pass 113A max – well above the 11A required by the heated bed.

So from this there is nothing wrong with the onboard mosfets.

As for bigger is better, I totally disagree, the larger the heatsink the more the expected power dissipation – the more losses.

People have reported better heat up times when fitting external mosfets, this may be due to the improved path for the voltage to get to the mosfet and back to the power supply – the wires! These tend to be a lot thicker than the tracks on the circuit board and will have less losses. The wires from the mosfet to the heated bed are normally upgraded as well at this time, again less losses.

All of these gains ( less losses) will add up to improved times for heating.

If you have a problem with the bed not heating then fitting an external mosfet may bring your printer back to life, fitting one of these is dealt with in my post here.

Anet A8 problems #3 : The connector for the heated bed.Anet A8 problems : bed connector

The heated bed on the Anet A8 is fitted with a 6 pin connector.

This is a 3.96mm pitch connector rated at 10A, so it is being used at its maximum rating, not always a good thing.

The connector has the positive, negative and the two wires for the thermistor, with two pins unconnected.

The connectors datasheet says it has a contact resistance of 0.02R, trying to reduce the power losses in the connector.

This power loss will heat the connector up slightly.

As the connector is in direct contact with the heated bed then whatever temperature the bed is at the connector will be at, so if the bed is run at 60C then the connector will be at 60C, if the bed is run at 105C then the connector will be at 105C.

As the connector maximum temperature is 85C then you can see that running the bed at 105C is taking it outside its limit.

With the heated bed moving while the print is going there will be movement on the connector, this may cause partial disconnects and arcing build, leading to increased resistance and increased heating.

It is not uncommon, in the forums to see connectors with brown marks on the sides where the connector has overheated and burnt the shell material.

Is this connector suitable for the job, yes it is just ( again, as with the power supply). My reasoning is that the bed will heat – so it is on continuously, then it will switch off until the bed temperature drops, when it will switch on again. So the current then becomes cyclic rather than continuous, allowing the connector to cool.

If you are printing ABS, however, the bed temperature is up at 110C, so you can see this is already outside the operating temperature of the connector and on top of that the bed will struggle to maintain this temperature, so the current will be on for longer.

With the increased temperature the connector will expand, loosening its grip on the pin slightly increasing the resistance , which in bad cases could lead to thermal runaway, where the increased resistance causes increased heating- this in turn causes more expansion, increasing the resistance … until failure of the part in either melting of the housing or loss of contact with the bed pin.

What is the answer?

Don’t exceed the temperature of the connector and stop the wires moving the connector while printing.

Insulate your bed to prevent heat losses from underneath – I will be investigating different types of insulation in the near future.

If you are going to be printing abs or other filaments which require a bed temperature of 60C or greater then it maybe worth replacing your connector on the bed with soldered joints, this can be a bit of a pain due to the thermal mass of the bed ( heatsink effect) but it can be done with preheating the bed with a hot air gun or even a spare hotend, another post will show how to do this successfully.

Securing the wires to the bed so the connector does not move while printing may prove interesting, there are supplied ‘p’ clips for securing the wire, also cable ties. Both of these are nylon and will withstand 85C, so again not suitable for ABS work.

You could secure it to the lower plate by a nylon cable clip, as this plate does not get hot, it will need to go on the top of the plate as this goes very close to the rear frame.

Anet A8 problems #4 : The frame is not up to the job.Anet A8 problems : frame

The Anet A8 has a frame made of acrylic, not known for being the most robust of materials but a little more stable than the early wooden frames offered.

The construction of the A8 does leave a little to be desired, but with a few modification you can get a very good printer for a little money.

One of the major items is to put it on a stable base and secure it to it. This will stop the front frame and rods from flexing, so your Z height calibration will stay correct.

The other major weakness of the frame is when you tension the belts, as the Y axis belt is secured in the middle of the frame this part flexes when you tension the Y axis belt.

Starting a print and holding a ruler to the front frame you can see every time the bed goes towards the rear and stops the frame flexing, a very good idea is to get some right angle aluminium and secure this to the front and rear frames.

Out of the box the printer can be used, these modifications are to improve the performance.

Can you use the Anet A8 3D Printer ‘out of the box’

There are those who proclaim on the forums ‘ it’s a fire risk’, ‘a danger’ , ‘not up to the job’ , ‘ you need a fire extinguisher next to it’, are they right?

Anet A8 problems : pocket grapple
Pocket grapple : thingiverse 2148161

Well I personally would take care with anything I have built myself, especially if it involves electricity and heat.

I would run it for longer and longer, rather than downloading the biggest stl which will fit on my machine and run it for fourteen hours or more straight after building it. I still haven’t left the house with the printer running, even though I have tested the ‘weak’ points and they are all alright. Is it paranoia – I don’t think so, to me it is common sense.

There have been problems with some kits supplied and people have built them and they have failed. But it is a cost effective kit and things like this will happen. You need a mindset of – ok so this has broken, I can fix it with…

There are mods you can do to help yourself soon after you have built the printer and get a feel for setting it up, see my post here on 5 mods for your anet a8 printer.

It does have limitations but can perform as well as other printers costing 5 or 6 times as much.

A little understanding of what you have purchased and a lot of time learning about the printing process will not go amiss.

This is a very capable printer which you can modify if you want to, or you can operate it out of the box. If it goes wrong then fix it, the parts are available easily on the net and information on sites like this one and in the forums will help you get out of trouble.

So should you buy it – yes of course you should. It is a cheap printer with good performance, needing a little care, but they all will.

Are they dangerous, a fire hazard – well anything which involves heat up to 200C and electricity is a fire hazard, would you leave your cooker on for 14 hours? Be respectful and it will reward you with many thousands of fine prints, once you get it set up.

What Anet A8 problems have you come across – have you had any problems other than the ones listed above? Leave a comment in the box below so we can all learn about the new risk.

Thanks for reading and I hope I have put your mind at rest over the hyped risks with the Anet A8 problems.



  1. I absolutely agree with your article. I’ve had my a8 for over a year and have not encountered any major problems. Admittedly I’ve only printed PLA but still, if you make sure your electrical connections are secure, I can’t see any reason for problems. I’ve upgraded with frame braces, belt tensioners, an extruder blower and a few other odds and ends which do make a difference to print quality. That said, it’s a great introduction to 3D printing in it’s stock form and the fact you build it yourself adds to both the enjoyment and understanding of 3D printing.

    • Hi Carl- thank you for visiting and reading my post.
      I’ve had my Anet A8 for just over a year, like yourself, and while the bed is heating up i put my fingers either side of the Bed connector. A little over a week ago i nearly burnt my fingers on it. I have only been printing PLA and the bed temperature was set to 42C, but i had not secured my wiring – my mistake.
      What i have done is to replace the positive and negative crimp connection with two crimp connections and secured my wiring. I have used slightly different crimp pins – made by molex, as these have four points of contact and should last a bit longer.
      As you say it is a great little printer which gives you the chance to print from a printer you have built yourself.
      It lends itself to upgrades, when necessary, and can print straight after building- no mods.
      Although it does improve the quality if you do the mods detailed here.

  2. There are other issues.

    First, the factory firmware is dangerous. If the thermostat, especially on the extruder, detects that the temperature is too low, it turns on the heating element. But there is no sanity-checking; if the thermistor falls out of the hot end, the firmware will keep the heating element on until it catches fire – it doesn’t say, “Hey, wait a minute, the heater is on, why isn’t the hot end getting warmer?” and shut it off. Add to this all the home-printed “upgrades” of potentially flammable plastic all over the extruder, and you’ve got fuel for the fire.

    Marlin firmware is an essential upgrade for this safety reason.

    The connectors on the motherboard, especially the power in and the heated bed connectors, fail at the solder joints to the circuit board because the connectors, solder, and PC board foil traces are not sufficient for the load. The problem is compounded by do-it-yourself assembly where the solder joints may be stressed by handling or over-torquing.

    A good quality 12V 20A power supply is barely capable of running a stock machine with PLA filament. Add a glass or other bed surface and the heated bed will take longer to heat up. A cold bed and extruder takes more current than a warm bed and extruder. Turn on your glass-bedded A8 from cold, hit “Preheat ABS” and then “Home All” and watch how many amps the thing pulls. Since the supply is as cheaply-made as the rest of the printer, how lucky do you feel?

    The Anet A8 is inherently an unsafe machine in its default form, and should never be run unattended or around combustibles. The DIY Ikea Lack enclosures for them scare the hell out of me – you’re running your printer in a nice big chunk of fuel.

    Sure, yours hasn’t caught fire yet. And not every Ford Pinto blew up either. Not every Boeing 737 Max 800 crashed either.

    Don’t get me wrong. I have an Anet A8 myself, and I love the thing. But it is not even remotely capable of meeting any electrical or fire safety standards. And I keep that in mind when I use it. I don’t leave my stove on when I’m not home either.

    Please use this machine with caution.

    • Hi Lawrence, thanks for dropping by to add your views to the post.
      I agree with most of what you say, but you know you are buying a cheap 3d printer and all of these will have issues.
      Mine has been working for a few years now without too many issues.
      the bed connector is not rated for continuous full power use, but the bed is only at full power to heat it up and then intermittanlty keeping it at the high temperature.
      if you use it for abs and try to heat hte be up to 100 degrees then this is outside of the connector temperature- so with pla and any other filament thet only requires lower temperatures then it will last, the main reason for failure is lck of strain releif or loose connections – overheating the plastic.
      The software bug, yes it could do with fixing but if you maintain the machine then this problem is unlikely.
      As for running it unattended – would you go out and leave your toaster on – i wouldn’t.
      Anything home built for this price will need maintenance and most of the failures i have seen have been construction issues. Taking your car analogy – would you just drive your car or do you carry out maintenance to it. or aircraft for that matter. These printers have vibration levels well above what you experience within your car environment – and you expect the screws to stay put without regular checking.
      When you enter the world of 3d printing you know that you will need to replace parts, there are consumables and maintenance – all of the printer are not up to print and forget yet.
      I would use this machine like anything else of its type, never leave it unattended, check the construction for tightness of fasteners.
      does this restrict me – yes – i cannot stay up for over 24 hours watching it. so i limit myself to prints that i can stay with it.
      does it meet electrical standards – you just need to bring a radio close to it and hear the loss of stations to know that it is not ce compliant, and you have built this with mains, a recipe for tinkerers.
      I am just about to create a chamber for my printer out of Kingspan insulation material, this way i can filter the air coming away from the printer and reduce the effects of drafts on the print surface.
      we’ll see how it goes.
      But thanks again for your comments Lawrence, I will bear them in mind.

      • We seem to think a lot alike. I really love the Anet A8 because it is such a hands-on machine, it’s like the “crystal set” of 3D printers, and it really forces you to understand how they work in a way that a more refined machine does not.

        My concerns are cautionary and should be kept in mind by anyone buying a cheap 3D printer, especially those who aren’t as electrically experienced. I used to work for Litton Systems and I’ve got over 30 years collecting and restoring antique electronics; that experience isn’t there with a n00b who can blow me away with his CAD skills but calls a Philips screw a “star” and don’t know what i=dq/dt means. These are the users (kids, mostly) who put themselves and their homes most at risk with this and similar machines.

        I am considering using a discarded bar-size refrigerator as an enclosure for the printer. The steel box will help with fire and RFI protection, ABS fume extraction, as well as creating a nice heated build chamber. Migrating to a 24V heated bed will reduce the current to the bed and reduce the tendency to burn the connector.

        Collaborating on cheap-to-free safety ideas for this and other low-end FDM printers might not be a bad idea.

        Lawrence Wade
        Ottawa, Canada

        • Lawrence, I am an engineer like yourself – with an attitude of curiosity. 30 odd years designing avionics equipment ( search and rescue beacons and test equipment)
          I really like the 3d printer – now have three -including a delta ( this makes wonderful music when working, but a lot more difficult to setup.
          But… yes i agree that anyone throwing it together and expecting good results or not having difficulties printing is fooling themselves.
          Maybe i should create a basic skills course for electronics and 3d printing.
          The refridgerator sounds interesting – i would replace the door with an emc glass window to be able to see what is going on.
          you may also need to relocate the electronics outside the chamber to keep them cool and extend their lifetime. unlike valves modern electronics doesn’t like heat.
          But if you have any other ideas for cheap-to-free safety ideas feel free to add them here or coantact me and you can create an article about them.
          Good luck with the chamber

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