Fail Of The Week: How NOT To Smooth A 3D Print

Many of the Fail Of The Week stories we feature here are pretty minor in the grand scheme of things. At worse, gears are ground, bits are broken, or the Magic Blue Smoke is released. This attempt to smooth a 3D print released far more than a puff of blue smoke, and was nearly a disaster of insurance adjuster or medical examiner proportions.

Luckily, [Maxloader] and his wife escaped serious injury, and their house came out mostly unscathed. The misadventure started with a 3D printed Mario statue. [Maxloader] had read acetone vapor can smooth a 3D print, and that warming the acetone speeds the process. Fortunately, his wife saw the looming danger and wisely suggested keeping a fire blanket handy, because [Max] decided to speed the process even more by putting a lid on the pot. It’s not clear exactly what happened in the pot – did the trapped acetone vapors burp the lid off and find a path to the cooktop burner? Whatever it was, the results were pretty spectacular and were captured on a security camera. The action starts at 1:13 in the video below. The fire blanket came in handy, buying [Max] a few seconds to open the window and send the whole flaming mess outside. Crisis averted, except for nearly setting the yard on fire.

What are we to learn from [Maxloader]’s nearly epic fail? First, acetone and open flame do not mix. If you want to heat acetone, do it outside and use an electric heat source. Second, a fire extinguisher is standard household equipment. Every house needs at least one, and doubly so when there’s a 3D printer present. And third, it’s best to know your filaments – the dearly departed Mario print was in PLA, which is best smoothed with tetrahydrofuran, not acetone.

Anything else? Feel free to flame away in the comments.


2013-09-05-Hackaday-Fail-tips-tileFail of the Week is a Hackaday column which celebrates failure as a learning tool. Help keep the fun rolling by writing about your own failures and sending us a link to the story — or sending in links to fail write ups you find in your Internet travels.

78 thoughts on “Fail Of The Week: How NOT To Smooth A 3D Print

  1. So he heated acetone, over a gas flame? I don’t think there’s anything anyone needs to learn from that.

    The lid at least probably prevented the vapour from spreading any further before it ignited.

  2. Using the place where you prepare food for anything else is foolish, aside from the great balls of fire, because you risk giving yourself a toxic dose of whatever nasties you are working with or created in the process.

  3. Back in the early 80’s, I got reamed by a lab supervisor for acetone fumes in a room with open flame. Prior to opening the stock bottle, the room gas valve had to be cut out and the vent on, as the task couldn’t be done in fume hood. IIRC, I had the vent on, but hadn’t tripped the gas cutout. No incident, but the lesson stuck. Keep in mind we still mouth-pipetted, used carbon tetrachloride, benzene, and methylene chloride without recovery systems, and mercury thermometers in those days. Acetone conflagration is big time bad.

    General rule (there are exceptions): DO NOT HEAT ACETONE. It has a high enough vapour pressure to begin with, and the molecular weight is high compared to air, so it tends to sink. A lid on the pot does no good. the vapour will get out. Even with an electric heat source, if the source is not explosion proof, bad mojo. Ditto for putting it in the refrigerator. You will get enough vapour to make an explosive mixture, which may be ignited by the thermostat switch in the fridge, if not explosion proof.

    1. The proper vapour smoothing method *does* heat acetone, but it’s not anything like this.

      First, you only use a teaspoon’s worth of acetone. You do it in a large enough vessel that the vapours stay in it (it’s heavier than air, even when warm), and you do it using the heated bed from your printer, which is temperature controlled and never gets near the ignition point of acetone vapour. Then it’s quite safe.

  4. A guy jumps out of a plane for his first solo skydive. He yanks the cord and nothing happens. He calmly rolls over to pull his reserve chute, just as he was taught, and it too failed to open. As he’s plummeting to the Earth, he see’s a guy flying up towards him. ‘Hey, do you know anything about parachutes?’ he asks, hopefully.’No’ replied the other, ‘do you know anything about meth labs?’

        1. It’s a pretty good system – I’m using it with an RPi Model B and an old webcam and it works pretty well. Email push to my mobile to notify me of movement, uploads to Google Drive for offsite storage (plus local storage), auto-reset if the network goes down. I still struggle a little with false positives caused by sunlight, but that’s mostly due to the camera positioning, the cheap camera and not enough fine tuning of the configuration.

      1. I have 3 cameras in my house. How else are you going to get a picture of any action in your house.
        We are home most of the time but they come on at night.
        I would not have it any way, But saying that my family had a hard time seeing it my way but do now.

  5. I don’t know, some of that print looks pretty smooth… Maybe he should’ve started with fire in the first place. ┐(ˇーˇ)┌ And is no one else going to mention that from the looks of the remaining print, that was Luigi, not Mario? Just Saying.

    This is a real head-scratcher and makes me wonder about my whole “Every consumer should have a 3D printer” stance. This guy was clearly out of his depth. He had no idea how to handle acetone safely, and to top it all off, didn’t even know you can’t smooth PLA with acetone… :S

      1. What type of extinguishers? CO2? Lightwater? Foam? Powder?
        First you would have to educate people about different fire hazards and that you have to have the right equipment to deal with that type of fire. Burning wood, electric fire, burning liquids (oil, gasoline) should be treated accordingly. Maybe they should start with a presentation of what happens when you try to extinguish a frying pan full of burning oil with water, just to show them the huge ball of fire you get out of that reaction…

        1. Cheap ABC powder extinguisher.
          Works great on small projects, lol.

          A box of baking soda for battery fires too.

          Maybe a DVD presentation of proper extinguisher use could be provided for free. It is a great idea pretty much anywhere IMO.

    1. Yeah baby, you can say that again! I can’t tell you how many ways I am fortunate that my wife won’t let a lot of the stuff I do in the house. Some time ago I was contemplating using acetone in an ultrasonic cleaner. I never did, it just didn’t seem like a good road to go down. (Jumping topics at random here). Even if I had, it would have been a small amount outdoors in a place where bursting into flame could be tolerated and sort of expected. Why you ask – cleaning water soluble materials.

        1. And before anyone picks me up, it was in controlled condiitons outside well away from anything it could set fire to, I used a larger quantity of acetone rather than a small one in the bottom (small amounts heat up from the cavitation and catch fire sonically I believe) and it was a unheated unit and we didn’t leave it churning away unattended for hours.

  6. Well, I for one appreciate that he would take the trouble of uploading a video of his own mistakes for our entertainment and to help others prevent the same. There’s no point stating he should have known better, we’ve all done things of which people say in hindsight that it was not very smart.
    And don’t worry about the yard, Dutch gardens are so small there’s not enough material to sustain a fire.

  7. Ohhh, this video brings back lot of memories. I had a similar situation 20 years ago while pouring acetone from a large bottle into smaller, more handy one over the kitchen sink. Yeap, that was stupid of me.

  8. So… Acetone Vapor has a flash temperature of -20°C or so, if mixed with oxgen at the right concentration. Heating Acetone must create an acetone “bubble” with exactly these conditions somewhere at the “boundaries”. Not to mention that all the convection from the stove will pretty certainly lead to well mixing of acetone vapor and air. Also, can you imagine the smell? I’m surprised he’s standing in front of the stove; can’t imagine that much solvent vapor’s good for the good ol’ grey matter. And will make you plenty drowsy, usually, if inhaled.

    1. You seem to be confusing the flash point with auto-ignition temperature. The flash point only denotes when the vapor becomes flammable but an ignition source is still required, the auto ignition temperature is when the vapor will spontaneously ignite in normal atmosphere.

      https://en.wikipedia.org/wiki/Flash_point
      https://en.wikipedia.org/wiki/Auto-ignition_temperature
      https://en.wikipedia.org/wiki/Fire_point

      Also the auto ignition temperature of acetone is 465 °C (869 °F).

  9. From the reddit thread: “Then i turned on the stove at its lowest setting as it was just a small layer of fluid to heat up” and “vapor is moving over Mario into the exhaust hood”. He was lucky it just caught fire and didn’t explode, either the naked flame or the motor in the hood could have set it off. Could so easily have been “Darwin Award” rather than “FOTW”.

  10. Heating flamable liquid with open fire… what an idiot.
    Even if the pot didn’t catch fire he sure would have been in trouble with his wife. Because the vapors would also have smoothed (or to be correct damaged) the parts in close vicinity of the pot. He simply was producing too much vapor and that would have condensated on his kitchen cabinets, the filter of the fume extractor above the furnace, etc.

    Fortunately this ended no so bad. Not OK, but it could have been much worse.

      1. We all do stupid things from time to time. My “favorite” one: soldering copper tubing containing (but not contained enough) R134a with an open flame… That’s a really stupid one.

  11. Acetone, naked flame, indoors. Dude, please, don’t do things like this, and if your stupid enough to anyway, don’t tell people, because some bright spark might see it and decide to license acetone, or make owning a 3d printer controlled “for our own safety”…
    I like the way his wife gets nervous and pushes the cat out for its own safety, because well, it seems like she’s a bit more clued up on the risks than he was. I was hoping not to see said cat come back in on fire after it had been napalm’d where it was watching the kitchen window out of curiosity and thankfully that turned out the be the case. I like cats.

  12. Quite impressive and i was really worried about the cat.
    Yes it’s stupid to heat acetone with an open flame but honestly, didn’t we all at least once did something that could have gone REALLY wrong?
    I agree that it’s very important to have an fire extinguisher, but before buying one please inform yourself about fire classifications, not every extinguisher is suitable for every fire. Powder is really effective but makes a HUGE mess and for grease fire you need special equipment. NEVER NEVER NEVER throw water or water based stuff on a grease fire, you would get an explosion!

    >People are obviously more worried about security than privacy.
    Seems like… I would never put a camera inside my home except if i’m away for a long time. I suppose these things are connected to the cloud (so “everybody” can watch)?

    1. I was fireman in the chemical industry in a previous life.
      We learned a story of risks… A girl was heating her depilatory wax in the stove. Suddenly, while watching the mixture, a bubble of warm wax exploded on the poor wife face… Imagine the results :-( ==> hospital with 3th degrees burns on her face and neck. Because wax sticks…

    2. Powder?
      You stop a small fire in the kitchen which could be stopped by a blanket.
      Half a year later the fridge breaks down, then the television starts acting up, next month it’s the PC.

      Powder is only for in your car (it won’t freeze) and only to save lives.
      They powder one car (which was already lost anyways) and as a side effect they get powder in the two cars down wind.

      In house you’re best of with foam and a blanket.
      Foam can’t stop gas fires but to be honest, you shouldn’t try to extinguish them anyways as you will risk explosion due to the gas building up.

  13. This would have easily been avoided if they would have done to three most basic precautions when working with dangerous materials.

    Firstly if you can explode, is flammable, or makes a toxic vapor take it outside in heat it on the grill, wood fire, camping stove etc.

    Secondly always have a fire extinguisher on hand. Co2 is preferred as it doesn’t make a mess.

    Thirdly turn you fucking brain on and use caution.

    This being said you can’t fix stupid.

  14. I had a useful hack for boiling acetone to smooth out some ABS prints I made. I lived in a small apartment with only a gas stove (one with pilot lights, too–yikes), so I boiled a pot of water. I then took this into another room, opened up all the windows there, and placed the acetone pot in this pot of hot water double-boiler style. It was more than enough to boil the acetone, and the acetone was nowhere near a spark or open flame.

  15. Maybe I got a sadistic mind but I enjoyed watching the GF running around in panic. :p

    One tip, you now got a used safety blanket.
    Buy a new one and use the old one to practice how to actually use it.
    Put a pot in the yard with some firelighters (aanmaakblokjes) in it, light it and then try to stop it with the blanket.

    Don’t just throw it on, the blanket protects you from the heat. Drag it over the pot and fold/wrap it around the pot so it ‘seals’.
    This way it will starve the fire and it won’t ignite back again as it did on your candid movie :)
    Let the wife try it to in case you ignite yourself the next time.

    With the fire going in the exhaust hood it’s advised to contact firefighters just in case.
    In most cases there’s a lot of junk stuck to the exhaust pipe walls which could ignite.

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