Ask Hackaday: Can The Lix 3D Printing Pen Actually Work?

Introducing Lix, the world’s smallest 3D printing pen that allows you to draw plastic structures in 3D. It’s only been on Kickstarter for a few days now, and already it has garnered close to a million dollars in pledges. An astonishing achievement, especially considering we can prove – with math and physics – that it doesn’t work as advertised. However, we’re wondering if it could work at all, so we’re asking the Hackaday community.

The device is powered through a USB 3 port. In the video, the Lix team is using a MacBook Pro. This has a USB port capable of delivering 900 mA at 5 Volts, or 4.5 Watts. Another 3D printing pen, the 3Doodler, uses a 2A, 12V power adapter, equal to 24 Watts. Considering the 3Doodler works, and they both do the same basic thing, there’s something extremely odd going on here.

Just as a comparison, here’s a wirewound resistor commonly found in the heating element or ‘hot end’ of a 3D printer. It’s a 6.8  Ohm resistor powered at 12 Volts. That’s 21 Watts. Here’s a heater cartridge, also found in quite a few hot ends. It sucks down 40 Watts. Once again, the Lix Kickstarter clearly shows the pen extruding filament using only 4.5 Watts of power. Something is really, really fishy here.

Intuition doesn’t hold a candle to math, so let’s figure out exactly why it won’t work.

The computer used in the Lix promo video. If that isn't an Apple device, I will buy a hat and film myself eating it.
The computer and USB port used in the Lix promo video. If that isn’t an Apple device that can only supply 900mA at 5 V,  I will buy a hat and film myself eating it.

We’re thinking the easiest way to figure out if 4.5 Watts is enough for a 3D printing pen is from a purely thermodynamic analysis: a specific amount of filament goes in, is heated up to its melting point, and is squeezed out of the nozzle. The equation to calculate how much energy is required for a specific temperature change in a system is Q = cmΔT, where Q is the amount of energy in Joules, c is the specific heat of ABS (1.3 J/g°K, source), m is the mass in grams, and ΔT is the change in temperature. All we need to do now is figure out how fast this pen is extruding, and the mass of that extruded filament.

In this video, starting at 10 seconds in, you see the Lix extruding about 13 centimeters of filament through the 0.6mm nozzle included with the Lix in five seconds. A little bit of math happens (volume of a cylinder with a height of 13cm and a diameter of 0.06 cm), and we can figure out the Lix is extruding 0.038 grams of filament per second (ABS density of 1.04 g/cc, source). This calculation was done by counting pixels and frames, which can be inaccurate, but not by much.

An estimated 0.038 grams of filament extruded per second, a change in temperature of 210°C (20°C room temperature, 230°C extrusion temperature), and a specific heat of ABS of 1.3 J/g°C (source) means 10 Joules are required to extrude one second’s worth of filament from the Lix pen. Since 1 Watt = 1 Joule  for 1 second, about 10 Watts are sucked down whenever the Lix is extruding filament. Once again, the Lix can only draw 4.5 Watts from a USB 3 port. The math simply doesn’t work, and no USB 3 powered device can extrude ABS filament that fast. The math is also generous, as it doesn’t consider the phase change of the filament which would require even more energy. I didn’t include this because I can’t find a reference for the heat of fusion for ABS. The math also doesn’t consider losses to the heater block, the air, and a host of other inefficiencies in any real-world device.

But ABS requires a fairly high temperature to extrude. Even though the Lix team claims the pen works with ABS, let’s say they’re using PLA plastic, extruded at 180°C. Doing the math for a ΔT of 160°C means 7.9 Watts are sucked down from a USB 3 port that can only provide 4.5 Watts. Something is terribly wrong here. That’s why we’re turning to you and asking the rest of the Hackaday community.

The only way we can figure the Lix actually works is if the extrusion rate is really, really slow. Halving the extrusion rate of PLA to 1.3mm/s gets us into the ballpark of what the Lix power supply can do; that only requires about 4 Watts, leaving enough left over to run the motor and electronics inside the pen. This is exceptionally slow for any plastic extruder – RepRaps can extrude plastic about 50 to 100 times faster. There’s a good bit of evidence the video of the Lix has been sped up dramatically, given the disclaimer, “some of video scenes have accelerated speed” appeared on the Kickstarter sometime between the first and second day of the campaign.

While we know the video is an outright misrepresentation of what any USB 3 powered device can do, We can’t figure out if the Lix is a viable product. We’re turning to you. Can you figure out if the Lix pen actually works? All we know is the Lix pen has a 4.5 Watt power supply from a USB 3 port. It’s possible for a USB 3 powered 3D printing pen to work, albeit slowly, but the engineering is difficult and we don’t know if the Lix team has the chops.

* For the hardware heads out there, yes, I know there is a USB 3 spec  – the USB Power Delivery Specification – out there that will supply up to 100 Watts through a USB port. Apple does not support this spec in any of their products, and the Lix Kickstarter video uses a MacBook Pro for power. The maximum amount of current the Lix can draw from a MacBook is 900mA, and the Lix has a power budget of 4.5 Watts. There really is no arguing that fact.
As an aside, this post has inspired us to consider a column on Kickstarters that seem to defy the laws of physics. We’re thinking about calling it Kickherder, as the vast majority of Kickstarter backers for these types of projects are mindless sheep. If you have a better name, leave it in the comments.

281 thoughts on “Ask Hackaday: Can The Lix 3D Printing Pen Actually Work?

        1. Other than in the video. The question is with a normal 120 V could you do this.. yes easily and faster than video. Would you not purchase it if you had to plug it in instead?
          Or does the 100 watt USB have some monster batter life where we wouldn’t just be using the laptop as essentiallyy an extension cord.

    1. That was my thought. I have an electronic cigarette about that size that plugs into USB and can generate plenty of heat. It just has an internal battery that charges up between uses. I doubt it even needs to reach normal extrusion temperatures, just get the plastic a little soft and tacky.

    2. It looked like there may be a setting where the pin is just pushing raw (unheated) material out. So, some speedy video suggestion might just be a gimmick way to draw a straight line in the air… set the base with heat and then spool out unheated material…

    3. Probably not a supercap, nor a battery, but there is going to be thermal energy stored in the metal of the hot-end itself. It wouldn’t support a 100% duty cycle, but I doubt someone is going to be continuously extruding filament at its maximum rate.

    4. theres a picture of the internals on the kickstarter page, or atleast there is a pen shaped PCB, next to one of the pens in question, assuming it is what we think, there is no way it could hold either burly caps, or a battery in the body.

        1. Time constraints probably meant reversing the film of a USB removal was desirable over trying to insert the plug, then turning it over and trying it again, then turning it over again…

  1. I don’t understand the practical use of this device..if it is real.. also hi, i’ve been reading this site for years now but never posted because the conversation is usually more technical than I comprehend.. doesn’t make me love this site less though. :)

      1. I’ve been going to for over a year now and thanks to Google and Wikipedia I know a lot about electronics. Most of the new posts are on a subject at least a bit known to me. Seriously guys, google everything and you’ll learn anything.

      1. You really can’t get a good weld with this type of too — you need to heat up the parent plastic too. Harbor Freight has a cheap “plastic welding iron” that works *ok* for quick fixes.

        1. Actually if I was going to use it for impromptu fixes, it would be right on my actual 3d printer, when I see a line get skipped, or fail to connect. Nothing worse than having to decide midway through a 500g printjob if you scrap it all, or accept whatever happens when you notice that a corner is being clipped because of a connection failure.

          As for general uses… I have seen some INSANE artwork done by people with just a pencil. Give those kinds of creative folks a 3D pen… I cannot wait to see what they come up with. Nothing I could possibly do with it other than “spot welds” when I pause my print job after a hiccup.

    1. It’s not necessarily important that the gizmo has a practical use. The 3Doodler (which does work – I have one) is just a fun toy. I’ve yet to find a real use for it – except ‘doodling’. However, that’s not important here. So long as the device is correctly described – and there is reason to believe that their backers will actually get these devices delivered to them within a reasonable amount of time – then people who like the idea should certainly back it.

      What’s worrying is that if (as it appears) the laws of physics mean that it can’t possibly work – then this is either a scam or an honest Kickstarter that will never deliver. Either way, people shouldn’t back it. Handing over half a million pounds for something that can’t work is a very bad idea.

      At the very least, the development team should clearly explain how they are getting the energy to melt plastic at a useful rate. If they have a convincing explanation – then fine…give them money, they must be clever people. But if they ignore this discussion and simply fail to address the problem then I’d like to remind Kickstarter backers that they can reverse their pledge any time before the project completes…but not one minute afterwards!

    1. Apparently because making eye-catching claims about defying the laws of physics attracts more attention that attention to details. This is only one of at least three flawed assumptions:

      1) the extruded material 10 seconds into the video is about the width of a thumb. How did you estimate 13 cm? I agree the length is much closer to 13 mm.

      2) you assume 100% of the extruded material is heated, why? Look at the kickstarter video where they make the 3-legged pyramid. It sure looks like they heat the material only at the base, then just push out cold plastic.

      3) you assume that, after plugging in the device, it can be used continuously. Why? Could the device simply contain a battery and operate with a 20% duty cycle and thereby obey the laws of physics?

      Clearly, its easy to make wild claims, rile people up and attract attention to your website, but is this ethical? I hope you get sued for slander.

      1. Did you miss the part where the article is a call for discussion on the topic, and not a straight up statement?

        Your questions are the sort that the author here is expecting people to ask and discuss and hopefully someone with enough technical know-how can explain exactly what’s going on here. This site has for quite some time been about helping people understand what is possible with electronics, and it’s pretty clear that the author here is seeking understanding and not simply trying to hurt the business of these kickstarters.

        Also, the unit of cm was obviously a flaw in typing and not used in the math used, so your #1 is irrelevant.

        After having watched the videos a couple times, I believe the reason the assumption that 100% of the material is heated is due to the way it so clearly stretches when the pen is moved too quickly for the extrusion.

        As far as the battery power goes, it looks to me like some sort of battery/capacitor at work. I believe the produce probably works as pictured, but I don’t have much faith in the durability of the components if they are relying on such a system.

        1. It would be insane to use a battery / capacitor to make up for an inadequate power supply. Even for the dubious benefit of using USB. Most people wouldn’t want melted plastic near their laptop anyway, and if they did there’s usually a mains socket present.

          Unless they’re just that cheap, that they’re not even including a power supply, and having to make up with it with extra components. The cost of a battery or large cap would challenge the price of a cheap PSU anyway. That’s beside the issue of making the whole thing three-quarters useless!

          Either they’ve invented something impossible, something really stupid, or they haven’t invented anything at all, and it’s either a scam, or a too-early funding campaign by people who don’t yet understand the fundamentals of melting plastic.

          Could well be. There’s all sorts of people in business, at high-up levels, who are completely clueless about anything outside of talking the talk and schmoozing money out of people. If you had to put a percentage figure on the efficiency, dollar for dollar, of the modern world’s economy, what would you give?

        2. The cm-vs-mm error was NOT just a typo – there really is an error of 10x. My calculations show a total power required being about 1.6 watts, INCLUDING doubling the heat of fusion in order to allow for the phase change between solid and plastic.

          That said, I do think this device would be useless for most purposes, just because of the very fine (< 1mm) extrusion it makes. Fine for making tiny figurines, insanely inadequate for anything larger.

          Finally, NO, the article was not written as a "help me understand" – that was just one sentence added at the end. The whole article was about "these guys are full of it – this can't work and I can prove it". It is irresponsible and possibly actionable to make accusations like this without checking your math first.

        3. Keyboard_Failure,

          So apparently you think it’s so obvious that the unit of centimeter was a typo that the author couldn’t have possibly made the same error in their calculations?

          Well, Mr. Failure, you’re wrong and so is the author.

          Next time, do your homework before dismissing an accurate assessment as “irrelevant”.

          1. +1, Won’t someone, what I would LIKE to see is a response from the author, Brian Benchoff, either confirming or disputing the error. While Kickstarter frauds are a big danger to the whole alternate-funding movement, then so are people who make erroneous claims such as Mr. Benchoff’s. Come on, BB, man up: either defend your calculations or admit the error. Enough of the idiocy of people just saying what they WANT to believe. This is getting old.

  2. Claiming flatly, “IT CAN’T WORK!”, is almost always wrong, with or without all the fun time maths. Eventually, someone finds a way to make it work. There would be a variety of compromises that could make this device work as claimed. Firstly, the filament could have lower softening temperature than others. Secondly, a standard heater might not be employed. For example, a two and a half watt burning laser could be used internally. It wouldn’t need to burn anything. It would only need to warm a one millimeter cylinder enough to soften inbound filament. Thirdly, options one and two could be combined. Never be the first one shouting, “IT CAN’T WORK!”

      1. In their comment section they have claimed it works from a single USB port at 5W. They are even saying it could potentially work from a USB2 port.

        A laser is an interesting point, but I still don’t see how you get energy for nothing. Even with 180C melt point ABS you still need 8W of power to physically melt the plastic, the delivery method of that power is moot is it not?

        1. Absolutely not moot. 8W of power is a meaningless term without knowing how that power is applied. A detail that is easily forgotten, which encompasses every meaningful detail beyond the power rating.

          1. It is moot, because we’re dealing with purely theoretical math, at 100% efficiency with no power loss, as stated in the article. According to the author, even at 100% energy transfer, it still doesn’t add up. No type of energy transfer, not even a laser, is going to break 100% efficiency.

          2. To melt a certain amount/volume of plastic, you must raise from ambient to the melting point by supplying energy. That is dictated by the heat capacity which is a chemical property of the plastic. The energy has to be the same regardless of *heating methods*. So a lower wattage means a lower amount of melted plastic i.e flow rate.

          3. Krb686 meant to say “No type of energy transfer, especially not a laser”. Converting electricity directly to heat is very efficient. An incandescent lightbulb, which is designed to try and reduce heat emission, is about 98% efficient at converting electricity into heat. An electric heater is effectively 100% efficient. Converting electricity to light with a diode laser is about 60% efficient. Assuming converting light to heat is 80% efficient (and I have no idea if thats true), the total efficiency of this system is 50%. As krb686 says in the rest of his post, it doesnt matter what high-tech methods you apply to get the heat into the plastic, if you dont have enough power there is no way you can heat it up, as it is not physically possible.

    1. A laser isn’t going to change the fact it takes a set amount of energy to melt the plastic, regardless of how that energy is delivered to the plastic.

      And what they’re saying here isn’t that it can’t work at all. It’s that it doesn’t look like it can work in the way that they’ve represented it in their video (with a single Mac USB port, and the apparent speeds that they’re going, etc.).

      1. Does it have to be fully melted, or does it just need to be bendably soft with a sticky surface? I would think fully melted would slow it down since you have to wait for it to set back up.

      1. They could be using a heat pump in combination with a resistor… heat pumps have apparent efficiencies greater than 100%. (i.e. X watts go in, X/2+Y watts of heat appear on hot side, X/2-Y watts of heat appear on cold side)

        They can only fight entropy so much before thermal diffusion counterbalances their effect, so it’s certainly not sufficient by itself… but they could be using a peltier junction preheater or similar.

          1. Doesn’t matter. Any positive efficiency is better than pure resistive heating. Even 11% efficiency means delivering 1.1W of heat instead of 1W.

    2. According to the description it uses ABS or PLA. The method of heating is irrelevant. You still need to heat a volume of material to the melting point, and this takes a certain amount of energy. Not even the world’s biggest genius can change the laws of physics.

        1. I would imagine the “special filament” would be already at the diameter of the nozzle, thus allowing you to push through unheated lengths at will.

          Making it hollow would have no effect, if you are actually melting to liquid state, at which point it would slip into a tiny nozzle and no longer have any void. Remember, the math in the original post was done based on what comes out, regardless of what may have come in.

        2. Their website mentions ABS and says it “begins to melt at 356 °F and works at 446 °F” which matches the author’s 230°C extrusion temperature.

  3. some usb ports support higher current capacity to fast charge devices like tablets. I know my motherboard supports it.

    I mean if that’s all your crying wolf over – do some research. Granted I didn’t watch or look at their kickstarter

    1. I had considered adding that, but I highly doubt they’re spoofing an official Apple device. There are only two contacts on the power plug in the video. I don’t know how you’d do that.

      Even if they were, it’s a difference of 900mA vs 1100mA.

      1. Im justifying it as maybe the people who made the video arent the people who designed the device, maybe it actuallly uses a ipad 2amp charger but the “artists” who made the video thought, hey its usb; lets shoot a video of it being plugged in, and because it would look smoother with a reversed clip of unplugging it we’ll do that instead.

    2. Huh, that article is incorrect. My 2011 MacBook Air can charge an iPad with at 2100 mA:

      Additionally I have a 2013 Mac Mini at work that will charge two iPads at 2.1 amps. Connecting a third iPad presents a somewhat ironic/incorrect message stating the iPad cannot charge and should be connected to “a USB port on this Mac” — despite it already being connected.

      1. Specialized circuits and cables are required to permit this… the spec states that USB 2.0 may draw a maximum of 500ma. If they state that the pen works with a ‘standard usb port’ then this is what they have to work with.

        1. The standard also requires that the device requests the full power before it can draw 500mA. In practice that isn’t required and most USB ports can source considerably more than the standard specifies.

          Many USB gadgets wouldn’t work if USB implementations strictly followed the standards, it may be the case here too.

          1. True that many gadgets can supply more… but they are engineered to supply more power to devices that can properly identify themselves. Apples products are a prime example. Plug an iPad into a new Macbook Pro and it charges at 1000ma – plug the iPad into an older USB port and it may not charge at all. Lix would have to duplicate that circuitry to ‘spoof’ the source to provide the added power… and even if they did not all ports are going to be able to operate at higher current.

            So… the rule of thumb is that you must serve the lowest common denominator to prove the technology.

    1. Ah, but crowd funding is the new way to launder money. I put together something, such as a movie plot, a doodad, or perpetual motion machine, and suddenly I get millions of dollars from various “supporters”. I surpass my goal, change my identity and scheme and start another successful “venture”. And my largest “contributors” never complain about vaporware….

    1. I’m wondering if somebody made a simple mistake. Like they’re using a powered USB hub for testing and it just happens to deliver a couple of amps, that would easily do it and there are plenty of 2 amp usb compatible chargers out there.

  4. Gentlemen, if you say things like “…means 7.9 Watts per second are sucked down…” you’ve lost credibility already.

    That said, Lix says (in the FAQ) a single rod of plastic 1.75mm dia x 30 cm long lasts “for about 5 minutes.” That’s 0.75 grams in 300 seconds, or 0.0025 g/s, 15 times slower than your 0.038 g/s estimate. Mighty slow, but that rate would only need around 0.5W for heating the plastic. I’m sure other thermal losses and the motor eat some power too, but it sounds well within the capability of USB3, even USB2.

    1. Add that they are assuming that it is heating the full 13cm length of the pen, and not just 1cm at the tip, which would reduce the energy usage by 1/13th (linear math is easy) which puts it right back in the realm of possible even at the higher g/s rate assumed.

      1. That’s incorrect. As others have stated, Brian’s calculations were off of the total mass melted per second. It really doesn’t matter how you think about it, it’s just total amount of energy required to melt all the plastic versus amount of energy input per second gives the max amount of plastic melt-able per second.

    2. 15 Times faster? So the pen is totally plausible, you just have to go 1/15 the speed of the video, that sounds wonderful and totally not misleading. I guess the other possibility is that it is preheating the amount, the video only shows about 2 inches (guess) at one time with a nice video cut between each, so maybe it takes 20 min to pre-heat for each 2 inch line. Either way they are lying about how well it works.

  5. And you didn’t consider kickstopper? I mean.. its just so perfect.

    Anyway, having seen the 3Doodler in action, when running full tilt it often shuts down for a few minutes to get the heat back up. my suspicion is there is some preheating down the tube. But this can only do so much for you before the abs gets too soft and jams. But it is true that any such device is going to have to operate on some duty cycle to manage heat, current consumption, etc.
    It is very possible it just has a terrible duty cycle. Something like 2 seconds of extruding and 20 seconds of preheating.
    Also, I see very little if any room in there for a drive motor. How are they cramming abs through it?
    I suspect it is POSSIBLE it works, but not without a lot of video editing shenanigans. Just using it would have to be uncomfortable. Especially since it is toted as being an aluminum body. The vast majority of the 3Doodler plastic case hides a hole lot of air, just so you can hold onto it without burning yourself.
    Lix looks to me like holding onto the hot end of a soldering iron.
    And whats with the people on that video? Always looking 45 degrees off camera. Yo! Over here!

  6. …also, ABS is a general term that doesn’t account for additives that could be used to make a softer plastic. Yea, employing a proprietary or otherwise special consumable is kind of a jerk move for a business. It’s also common marketing.

    1. That was what I thought about 30 seconds into reading this article.

      They could add a solvent to the filament that lowers the melting point enough, then just evaporates as it’s extruded.

      1. That’s actually a very interesting point; it led me to google, and this:

        …so – what if this pen isn’t using heat at all? Or so little as to be negligible? Then again, they do talk about lengths of ABS for the device…

        Still – forget the pen for a moment.

        What is the possibility of making a “cold” ABS 3D printer? Mix your ABS with solvent, keep it in a sealed “tank” or storage area, then “pump” it (maybe using a peristaltic pump?) to the extruder – which may be heated, but nothing like today’s 3D printers – just enough to help evaporate the remaining solvent as it exits the nozzle…

        That – or combine the ABS and solvent right at the nozzle, heating it (slightly) to help with the dissolving of the ABS for extrusion, and perhaps evaporation…

        The potential – if it worked – would be interesting. At standard resolution sizes (0.3 – 0.4mm), it would be interesting just to have a “cold” end for the extruder; but it could go even further: If the ABS was made liquid enough, you could potentially lay down very thin layers; perhaps approaching something close to UV resin printers!

        The greatest issues I can see with such a printer (which also applies to UV cured resin) is the smell from the evaporation of the solvents; you would need to vent through a charcoal filter and/or to the outside (which your neighbors wouldn’t like – they might think you are running a meth lab!).

        There’s also the potential fire hazard of having such solvents (both while printing and storage). Even so, the possibilities that would result from such a solution almost beg for it to be explored…

  7. I don’t know. Of course not, how could I? But I wouldn’t support this. The lack of shadows in parts of the video where I would expect to see some make it seem to fishy for me. I think Hackaday is right be be wary on this one.

    1. common photography trick for no shadows is a light box to bring in light from all angles. Makes shadows much harder to see, and are basically thin paper with lights behind them.

      Not to say there isn’t video trickery, but it’s possible to take a photo with no shadow; or with shadows in places that aren’t expected.

    2. Maybe turn down your monitor brightness, I see faint shadows throughout the video or specify what time range in the video bothers you most.

      The diminished shadows are because of the goofy lighting. They tried to imitate professional videography but in my opinion failed.

      You can tell they are using softboxes too much from the blobby faint shadows under the hand operating it when drawing LIX halfway through the KS video. One of the most annoying parts in the video were the weird shadows on the inside corners of the eyes particularly of the guys that were too close to the camera and the softboxes on either side of it. Moving one further away would have helped diminish the creepy look this gave. That however was topped by them reading from an off-camera monitor in an unnatural manner. Either rig up a DIY teleprompter or memorize your lines.

  8. “A laser isn’t going to change the fact it takes a set amount of energy to melt the plastic…”, “Why does the delivery method matter?”; Yea, actually it is, because other methods would be more dissipative. Also, this is just one example of how this _could_ be made to work. It’s not the _only_ way this could be made to work. I’ve never admired people who work hard to tell me the means through which something will fail. If you see some kind of problem, use your big brain to find a solution.

    1. The math in the article already assumes a perfect heat delivery method. It even says so: “The math also doesn’t consider losses to the heater block, the air, and a host of other inefficiencies in any real-world device”

      1. I feel like taking these raw power equations and trying to apply them in this particular manner is a lot like the old adage of spherical chickens in space concerning physical simulations. There’s a point where it stops applying cleanly to real world devices, with very real differences between the expectation and the reality. This is what makes engineering hard.

        1. The only reason why it stops applying cleanly to real world devices is 1 of 2 possible reasons. 1, inaccuracies in measurement, aka the USB port ISN’T supplying the 4.5W stated but is actually supplying more, or the amount of energy necessary to melt the plastic was measured incorrectly or 2, inaccuracies in accounting for loss. Since the author isn’t even including loss, point 2 doesn’t apply here.

          If the USB port IS supplying 4.5 watts, and the specific heat of the plastic IS correctly 1.3 J/gK, and those 2 points are probably accurate, then the upper limit on what’s possible is already established, unless you’re refuting the background thermodynamic equations that have been proven time and time again.

        2. You’re right, the theoretical calculations don’t account for real life losses. However if the theoretical calculations don’t add up to enough power, adding real life losses won’t help.

    2. Trui explained perfectly why the laser doesn’t matter, at all. It has nothing to do with how dissipative it is, since perfect heat delivery was assumed. Remember he is going off of pure math without any heat loss.

          1. Why is everybody obsessed with lasers?

            Heat is heat, whether it’s from a laser, resistive wire or pouring boiling oil down the pen.

            The problem with lasers is while half (at best) of your power get converted into light you can shine on the filament, the other half is wasted as that waste heat is nowhere near the filament.

            You can’t get more efficient than the regular run-of-the-mill extruder.

            Where a laser would work is using fibre-optic to run the beam down the pen to the heat the extruder. You can get a lot of power down that fibre, the only electric power is to drive the motor.

            In other words it’s like the wand they use in hair or tattoo removal.

  9. They clearly state it is using a special filament, so it could be a special soft or low temperature blend. (They also state the hot end is running at 200 deg C, not 230, and that it’ll ship with a USB power supply, so, while it may be using a USB connector it might still be using higher current, or it might be smart and vary it’s speed depending on how much power is available). It is also most definitely not powered by that exact laptop in the video **because it’s turned off** (and Macs only power the USB ports during sleep when the charger is attached) so the logic in the article does not follow… it’s merely a misleading video, not impossible. Jumping to conclusions and justifying them with maths is the worst kind of “science”…

    1. Here’s a direct quote from the kickstarter:

      > The power of LIX is supplied via USB…
      > Lix has a hot-end nozzle that is power supplied from USB 3.0 port

      There’s also a picture of someone inserting a USB cable into a MacBook with the caption, “Plug in the power cable to USB port”

      I’ll acknowledge the fact that a MBP can’t supply power to USB when the lid is down. That’s video and making things look good. Not being able to make the Lix work with a MacBook Pro is bordering on deceit.

    2. I have a Retina MBP, and this is what it does if it’s not plugged in. If the USB device is plugged in while the computer is awake, and then the computer is put to sleep, then it continues providing power. If the USB device is plugged in while the computer is asleep, nothing happens.

      If the computer is plugged in, it will start providing power if a USB device is plugged in while it’s asleep.

      1. It’s not a USB device though, it only has two pins. It would get 100mA as it hasn’t done negotiation to get higher currents, let alone get power when the host is asleep.

          1. There’s all sorts of pound-shop rubbish that draws more than 100mA from a USB port without asking. I once bought a USB air freshener (it was a pound!). Inside were a couple of SMD resistors adding up to 500mA current draw, across the power lines. Nothing else in there. It worked.

            I admit I haven’t studied the spec, but aren’t USB ports allowed to give more than 100mA without negotiating? They’re not required to, but are they allowed to? Certainly not bothering putting current limitation in the chips would be easier / cheaper than putting it in, and it’d mean all the horrible non-spec USB rubbish out there will work without confusing the user.

            The air freshener BTW came with a phial of the wierdest-smelling chemicals I ever smelled, the idea was to put a drop on, and the device would heat it up. It got, er, 2.5W of warm, which is as warm as you’d think.

        1. I don’t know about mac’s, but like I said before, I used to be involved in the design of PC motherboards, and the USB ports were fused in pairs with 1 amp polyfuses. There is absolutely nothing to prevent you from drawing 1 amp indefinitely from one of the two ports on each fuse if the other is unused.

          And the power negotiation has NOTHING to say about the matter. That’s just part of the USB software stack, which has no control over that polyfuse. It’s just wishing and hoping that the device complies and doesn’t draw more than 100mA until it’s told that more is OK.

  10. I think the answer to this is probably fairly simple. Clearly, it looks like the pen is working, so I think the outright claim “this is impossible” is a little too early.

    In my opinion, the most likely case is that the pen is not meant to extrude plastic as fast as your calculations indicate. In the description of the project, they say you must wait 60 seconds for the heating element to reach the necessary temperature to begin extruding. That sounds reasonable, so this lends some credibility in my mind. So I think what would happen is that if you try to extrude the plastic too fast, it just won’t melt properly. Ever tried jamming the glue stick through a glue gun too fast?

    So ultimately I think the pen probably works just fine. There are plenty of photos and videos to lend this credibility. But it may not work terribly fast.

    1. *In other words, I think it’s probably an inaccurate assumption about the extrusion speed of the pen. The fault is probably when you assume that the pen should extrude 0.038 grams continuously. It may in fact just be in short bursts, until new cold plastic removes too much heat from the heating element.

  11. With a resistive heating element controlling where the heat goes is a bit difficult. A laser would allow better control. The feed rate is slower so the mass to be heated is smaller (melt zone). As with all proposals it is wise to ask what they are not showing/telling.

    1. Practically nobody uses lasers for heating, except in nuclear fusion. I don’t know where you’d even get a 2.5W laser that small, though doubtless somebody’s going to tell me.
      Still a lot more complex than just a resistor or two, or maybe nichrome wire, with some insulation and mechanical bits to keep the heat in as small a space as possible.

  12. I don’t know if this applies at all to this situation but I used to work for a company that designed motherboards for PC’s. The USB ports could put out much more power than they were supposed to. They were fused with polyswitch auto reset fuses, but instead of fusing each one at 500mA, they were fused in pairs with 1A polyfuses, connected directly to the PC power supply 5V rail. The 1A fuses rarely actually trip at 1A — you could probably suck down 1.5 A for quite a while, and maybe 2A for quite a few seconds before it would trip.

    Also, there was no software control over the allowed power output. That’s just part of the USB software driver stack to help prevent overloads — to warn you and hope the devices comply, but there was no way to actually force, say a 200mA limit, even if the USB software told the device that’s all it could draw.

    1. This is an incredibly important point, something I discovered with tablets. A customer had a machine that blew the 2A fuse (I had an identical working machine) that was right next to the USB port. Turned out he had recently gotten a tablet and it pulled all it could…

      1. Hm, I see this becoming a medium-sized problem, since USB ports have been adopted as the standard for chargers, and devices need more and more current to charge ever quicker. In your case, sounds like the tablet was relying on the USB port to limit the current, and the USB port was relying on the tablet.

  13. My eye tells me the small shakes in the artist’s hand seem to be accelerated. The video is sped up. Simple. Definitely dishonest, just like every paper towel/mop commercial where one quick wipe clears the whole mess.

    1. That’s definitely the issue here. Its obviously possible to use that little power to melt plastic in short bursts or incredibly slowly. Its just not possible for it to work as advertised in the video which is one of the fundamental problems I have with Kickstarter these days. Funding a prototype product is a dicey enough proposition as it is, we don’t need to have faked performance added to that mix.

    2. It certainly could be sped up, yes, but I don’t see any indication that his hand shaking is any different from anybody else’s hand shaking when doing some sort of task that requires fine hand control

  14. Whether this device works or not is beside the point. These manual 3D printing pens are just silly. The point of a 3D printer is to create a precise rendering of a computer designed object. It’s ‘printing’ because of the precision mechanical interface. Do we call a Sharpie a ‘2D printing pen’? If I’m modeling freehand there are plenty of better materials and methods than an awkward, over priced hot glue gun.

    1. It’s part of the evolution of 3D printing. The device if it performed even remotely like it does in the video, would be incredibly useful. Comparison to a hot glue gun is problematic, I feel it’s more akin to a plastic welding machine. You wouldn’t use a brick as an adhesive, nor a hot glue gun to spot weld plastic.

      1. @Kremlin:

        The 3Doodler *DOES* perform exactly as the Lix video shows their pen working. So if you’d find the Lix “incredibly useful”, then just go out and buy a 3Doodler for $99…they are a somewhat fatter, chunkier “pen” with a fan on one end – and you have to plug the power cord into the wall instead of your laptop. The 3Doodler is $10 more expensive than the Lix – but they absolutely do work “as advertised” and you’ll have it in your hands in 2 weeks rather than 6 months.

        Mine is mostly just a toy…I don’t think I’ve ever used it for anything “useful” beyond playing around trying to freehand draw a stellated-dodecahedron or showing it off to friends. But it’s a fun, novelty gadget – and I don’t regret spending $100 for it. Because I got it on their Kickstarter, I got a big pile of PLA plastic thrown in – and I’m not even halfway through using it.

        You can buy it at for $99 – which comes with enough plastic to get you to the point where you decide that it’s either a toy or a device that you can’t live without!

    1. Kick starter appears to be used as a place to hock far fetched idea, or to tart up some kind of scam…

      I’d call the column farstarter,

      say it aloud.
      either Far-starter – the place where far fetched ideas are brought to life.
      or farce-tarter, the place where old scams are given a fresh gloss and recycled again.

  15. Yup these dropKicks have made a clearly misleading vid. Clearly reading dialogue of prompt cards (thus the 45 degree look to the profile footage).

    They show a cable end being plugged into a pen and another being plugged into a USB3.0 computer. The middle of this cable could have a power booster (plugged into mains) to rectify the math/power issues.

    They only show short/small segments being built at once. so Maybe its heating all the time so it can deliver a spurt of plastic.

    The image they have portrayed is fairly close to ideal, lets hope they solve the issues we have raised with the $1M they have raised.

  16. You would think, for a project supposedly in London, England, they could have had someone proof read their Kickstarter page ;)

    I am sceptical of the performance of the pen, but two things also jump out at me from the campaign:

    (1) Very tight timelines for production. Having done this myself (crowd funding a product to market), I would double the two months they’ve given themselves then double it again ;)

    (2) No mention of any safety testing. To be sold in Europe, there are at least a couple of EN certifications this product would need.

    Maybe they’re cleverer than me ;)


    1. Maybe the production is already finished and they are just trying a novel way of sales? (Or the more obvious, they are going to run into real world problems when it comes to production :P)

      1. If it has an EM field… motors, heating elements, etc. or could short-out a device that sources its power… it would need to be tested to verify that it does not interfere with the normal operation of other devices in proximity or to which it is connected.

    1. Take a look at the video at 1:50. It clearly extrudes what is probably somewhere in the region of 10cm in less than 2 seconds or so. Its interesting that they then cut the video between each extrusion, it gives the impression its continuous but its most likely to hide the 30 second delay between each few cm of extrusion.

      None of this is to say however that the tool isn’t a great accomplishment and looks pretty and could probably be quite useful in certain situations, its just a horribly misleading video.

      1. I think that would be the “video at accelerated speeds” that they mentioned. Looking at other parts, like the very first extrusion, you can see that it’s going much slower.

        Also, it may be enough to just soften the edges for sticking and bending, since most of what they show extrudes the filament as… a filament. It’s not like depositing liquid or anything. I think it practically can work, though the video does make it look better that real life. But so do McDonald’s ads.

      2. But the article points to 10s in into that video for the “13cm in 5 sec”, and that is nowhere near 13cm (provided that it’s the same video still).

        The right way to do this would of course be to ask the people behind the thing for a clarification of the performance, the rate of extrusion and duty cycle. If they say “2cm/s at 0.6mm continuously”, you can call them out on that, or if they say it’s 0.5cm/s 50% duty you could possible call them out on that video. They write it’s “accelerated”, and that is in it self bad when doing a kickstarter, any speedups should of course be marked clearly in the video (the standard “Xx” in the corner). Calling people “mindless sheep” is not a very good way to start a decent conversation :).

    2. clearly not 13cm, but later in the video it does kick out a pretyt long line, i imagine the time taken to push out the column at 10seconds, was used to extrapolate the longer lengths. since we are assuming no duty cycle, and the length pushed out at 10seconds is definitely longer than the heating element, its not actually that unreasonable.

  17. Is it possible that they’re preheating the filament before they actually start using the pen. Put the filament in the pen, wait 5 minutes before actually clicking the extrude button. There by relying on a reservoir of 6-8 inches of liquid filament, rinse and repeat? This way you could buffer the time/heat calculation, so the extrusion process is smooth.

      1. I had some samples of aerogel-infused insulation material and it is a nightmare to shape in any way (think fiber glass mats plus huge amounts of fine dust). My bet is on vacuum insulation and a small reservoir with a lower aspect ratio).

  18. Maybe they put a real tiny cold fusion reactor inside and generate a few additional watts for heating the thing up. Did you know, you can even let it generate more power and put it back into the macbook through the USB Port? You just have to reverse the polarity…

  19. I noticed the fastest extrusion in the video was for straight lines – impressively straight lines (The “LIX” and the tetrahedron). Perhaps the filament is softened enough to fit thru the extruder – ie. it’s coming out thinner, but not wholly melted. I simply don’t know enough about 3D printing to know if this is feasible, but it would also explain why the lines are so straight – the interior of the filament is still basically unmelted – and in effect, the end of the line is fully melted to fix it to the surface – then the rest of the line, slightly softened on the outside but not fully melted, is *pulled* thru the pen.

    Or – maybe not. Speculation aside, if the pen is legit, the unaltered source video could be made available to prove it easily enough.

  20. What is with the weird shots of the co-founders all staring off somewhere to the side when reading their scripts? It is like they’re talking to somebody else and you’re just staring at them from the side.

      1. It seems to be the new way of talking “directly” to the camera. See the latest silly hipster GOP ads for an example. I think it’s supposed to make you feel like you’re there, standing next to someone else the person is talking to……which is total BS, because in a normal situation, the speaker would bounce back and forth between the two of you.

        Unless the speaker thinks you’re a dork and is hoping you’ll go away. In which case, the technique insults you.

    1. How has nobody noticed that all of the shots where faces are shown are rendered? Has everyone in the world played so many video games that they can’t tell renderings from reality anymore? Go watch it again.

      1. You may not have seen many kickstarters. They all have shitty camera angles and a cold, dead look in their eyes.
        It looks weird, sure, but it’s a push saying it’s CGI.
        Even with ray casting you’d need some pretty bloody good mocap.
        Really the only reason I can think of for doing this is to hide the ID’s is if this where a money laundering operation.

  21. 1) The video is really misleading in regards to the actual ‘extruder speed’, way slower in real-life.
    2) From their website: “Plug in the power cable to any traditional USB outlet.” I’ll be interested in reading end-user reviews when/if Lix ships.
    3) The fact that you have to use “straight filament rod” and can not use filament from spools would be a no-sell for myself. Of course you could cut segments from your spooled filament, heat them (oven/heat gun/etc.. and straighten them yourself, but what a pain.

    Myself, I’m really interested the <12mm "micro planetary gear motor" and "such as another gear box for the filament supply system" (their words) that they are fitting into a 12mm dia. tube along with a 'two button' speed controller… Need to find the paperwork for the "patented mechanism" but they to not say if it is USPTO based, EU, … no patent number is published.

    I do know of a few 12mm planetary gear motors that have plastic gears, housings, etc… that are designed for locks, but continuous use of these types of drives are a show-stopper. OF course those are 12mm and Lix need an even smaller one as 12mm is the outside dia. of their pin…

    But if the USB power draw is 'not' a problem, their form factor is the only original item as there are lots of 3d pens on the market now: the Doodler, Yaya, 3DAirPen, Myriwell, …, …, … and some can use spooled filament as they use bigger, higher current motors that can over come the fiction caused by the filament arc.

    1. This is the entire key. If there is a patent somewhere, then there is no secret. Given their ‘fast and loose’ relationship with evidence-supported facts in other areas, I might suspect that they have filed one form of patent application (possibly even a provisional patent, which either of us could do in the time it took to read the article) and stretched “application kinda-sorta filed” to “patent pending” to “patented”.

      A simple EPO/USPTO reference would eliminate all of the speculation about lasers, pseudo-ABS, etc.

    1. I agree with IanHanschen’s “Making posts like these doesn’t seem like the best road for hackaday to go down. You guys can do better than this.” It diminishes the brand by revealing the bias of the writer as well as his critical thinking skills. Focus on repurposing electronics not on whether a video is lying. we all knew that.

      1. Determining whether things are real or not – analyzing reality – is a fundamental part of hacking culture, and the mindset of a good hacker.

        The bias of the writer is towards reality. That is a desirable bias to have. It also reveals the writer’s critical thinking skills. I don’t know why you see this as a bad thing – having critical thinking skills is a good thing.

        They already do focus on repurposing electronics. It makes up a majority of the content on this website. They don’t focus on things like this. An occasional post is not a focus.

    1. Actually, many. The oddly named Squiggle motor is a commercially available piezoelectric motor described thus:

      – Fast: variable speed to 10 mm/sec (linear) or 12,000 rpm (rotary)
      – Strong: models with up to 5 Newton force (linear) or more than 3 mN-m (rotary)
      – Tiny: as small as 1.8 x 1.8 x 6 mm

  22. Not very likely, but a heat pump would break your ‘100% efficiency’ barrier. Since heat pumps are only moving heat, not creating it, they can often operate with ‘coefficient of performance’ of 2.0-2.5 or higher, meaning for every watt in, you get 2.0-2.5 watts of heat out.

    Again, not likely in such a small form factor, more to serve as acknowledgement ‘100% efficient’ is not a ‘barrier’.

  23. Please build Kickherder.

    As an engineer, I’m thoroughly fed up of the boosterish mentality that says “all you need is an idea”. If you want to change the world, what you need is an idea, a solid understanding of the laws of physics, the skill to realise that idea, and then the energy to iron out all the bugs and glitches.

    The idea is the easy part.

  24. The calculation is wrong.

    The volume of a 13mm cylinder with a diameter of 0.6mm
    is ~3.67mm^3 (3,67497E-009m^3)

    With 1040 kg/m^3, the weight is 0,0038 g

    In the video, it takes about 5s to extrude this, which makes
    0.00076 g/s.

    1. Yes – of course there are other pens on the market. The 3Doodler was undoubtedly the first, it was Kickstarted, I own one, it works exactly as advertized. Then there were multiple knock-offs, this isn’t surprising, the technology isn’t difficult and 3Doodler didn’t patent it – so that’s inevitable.

      HOWEVER: Without exception, those knockoffs are fat pens (about an inch in diameter) and they get power from a wall socket.

      If the Lix is “real” – then it’s clearly a “next-gen” version of the 3Doodler – it’s thinner, lighter, doesn’t need a fan and runs off of very little power. That would be amazing…which is why they have (so far) earned half a million pounds in advance sales on Kickstarter.

      The *ONLY* issue here is whether it can possibly work. So: (a) is it a scam? (b) will it simply exhibit a uselessly slow flow rate? (c) is there something so amazingly clever going on that nobody here can figure it out? My bet is (b)…they admit that “some” of their video is speeded up – but that might be just the bit where they write “LIX” in the air – or it might be all of the action shots of the pen working. Without Lix coming clean about their flow rate, we don’t know.

      IMHO, people should back out their pledges until/unless Lix come back with some clear statement of what this thing ACTUALLY does. But Kickstarter being what it is, a lot of those backers are going to say “Kickstarter is all about helping clever innovators – and you guys don’t understand that – maybe these guys have found a way to make it work and so they deserve our backing to perfect it”…so even with the most obvious scams, Kickstarter tends to deliver about 80% of the funding even when the scam is exposed.

      Take this one, for example:

      …I was instrumental in proving conclusively that this not only cannot work – but must be a scam. However, 200 backers put $13,000 into it and didn’t back out their pledges even after a bunch of people came along to back me up. Fortunately, we managed to hold down the pledge level to the point where the project failed…but that’s not going to happen this time.

  25. I want to focus on the one thing that is seemingly ignored. The macbook itself. there were 4.9 million macs (total including Macbooks) sold in 4th quarter 2013. (tech crunch) As of september 2012, 310 million active computers in the continental US. Of that 5% are apple. So whether or not the Lix is a viable product has nothing to do with the mac book sitting because we all know they did copious editing on the video.
    The better question is if I shove the cord into a USB wall outlet (yes those exist google it) will it work. Yes I believe it will because the specs says it will. The fact you keep wanting to go back to your supposition that its a Mac Book is immaterial because its not marketed to mac book/apple market. The info says an USB port. There are a whole lot more Windows systems out there that have USB 3 ports than Mac.
    The questions we need to ask to determine viability are:
    How fast does it extrude ABS/PLA?
    Is this consistent with other 3d printers?
    How hot is the barrel of the pen while in operation?
    Are there special additives to the plastic?
    does the cable have a power brick that we didn’t see?
    What is the duty cycle?
    How much clean up and maintenance is required?.
    What is the cold start heating time?
    What is the cooling time for the tip? (at 300+ degrees it would have to be treated like a soldering iron)
    What is the bore diameter and how fragile is the extruded plastic? (if I can draw in the air I want to know how big I can before gravity affects my creations)
    These are the questions I expect to be asked. Not a screed about how MacBooks cant power the device because you assume that white laptop is one because of the port orientation.
    I can build a windows laptop inside a macbook shell with the same port configuration, sand off the damn apple and put an f***ing pear and do the video. Thats how pointless the argument is. Yes, I agree the Lix video is suspicious. Basing that suspicious on a port profile is ignorant considering this is a blog about re-purposing Electronics in different unique ways. I honestly expect better..
    So in my opinion it is viable. Its a plastic extrusion soldering iron. Will it hit its target audience? Who knows.
    Finally shame on everyone who posted commenting about the macbook rather than the actual merits of the pen. All of us here should know USB specs. We all knew there was video slight of hand. Ergo, the pen wasn’t being powered by a macbook period. How, because we don’t see the apple logo or the pen extruding while the full cord is attached to a power source do we?
    Curious how this plays out, yet my confidence in Hackaday has diminished because of this.

    1. I agree, the focus went way off track. Here are some answers to your questions. I have three 3d printers, so I’m pretty well versed on some of it.

      This will be far slower than even a slow 3d printer. Even slow ones can run 80mm per second, with fast ones can breach 200mm per second and a few break 300. However, the printer is entirely pre-configured, while an artists has to plan each stroke pretty much as they come, maybe a few ahead, so even if the pen could reach those numbers, the person controlling it wouldn’t.

      The barrel of the pen should remain cool, only the heated tip should be hot (note the heat shield).

      They are likely using a low temp formula, PLA temps can range by nearly 40degrees C depending on the mix. It still has to be pretty hot, 160-170c minimum. Leave your filament exposed to air/moisture, and it could require 200c or more. Filament color also effects temperature, sometimes by as much as 15c. The more solid the color, the higher the temp needed.

      Maintenance should be little, provided nothing goes wrong… If something does go wrong though, it could be an easy fix, or you may require a blow torch or a new pen. Same as a 3d printer. But things do go wrong.

      skip a few

      The extruded plastic is such a small diameter, that it will be fairly brittle. Think crumpling paper. That t-shirt the woman walks around in, she’s walking careful for a reason. You can’t wash it, even if it survives the dryer heat (ABS only), it would be crushed by the other clothes before it ever got there.

      Cool time should be similar to a soldering iron. Heat time is difficult to say.

  26. Real or fake, I want to know what all the backers plan on doing with such a gadget (assuming it actually works).

    I’m reasonably clever, but after thinking about it since the post first appeared, I can’t think of a single thing that I would want to make that this would be the “best” tool for the job.

    Seems like a expensive toy to (slowly) make plastic blobs.

    1. That’s pretty much what the 3Doodler is. I bought one so that I could try to make a 3D printer out of Lego Technics….a project that I have yet to get around to. The 3Doodler has a connector to let you drive the motor from an external device – and they molded in connections that work with Lego Technics – which they did because people like me asked them to during the Kickstarter!

      It’s mildly entertaining to try to draw things in 3D with the 3Doodler – but most of the actual art you see was done by drawing in 2D onto a paper template then using the pen to weld together those 2D parts into a 3D structure. The Eiffel tower model that the 3Doodler team show so often is done that way.

      I’m not sure that being powered from USB and being smaller is really going to be much of a practical “win” over the well-established, known-to-work 3Doodler anyway.

      The “why” of why people would want to own such a thing is decidedly dubious. But people do clearly want them – and if someone wants to sell it to them then Kickstarter is PRECISELY the right way for that to happen. It connects the weird products to the unusual customers in a perfect way.

      However, not all of those customers are technically savvy and it’s horrifyingly easy to scam them out of a lot of cash with a crappy product. If that’s what’s happening here (and I think it’s not entirely clear that this is so) – then it’s good that we make sure that everyone involved is aware of the problem.

  27. Fairly sure all 3d printer temps are the nozel temp, the plastic won’t fully meet this. In fact you clearly don’t want to fully melt it when working like this.

  28. “The math is also generous, as it doesn’t consider the phase change of the filament which would require even more energy. I didn’t include this because I can’t find a reference for the heat of fusion for ABS.”

    ABS is an amorphous polymer, and thus has no heat of fusion.

  29. It will work, the question is how fast, which means it’s slow.

    However, forget that it works, they are following the razor blade business model.
    The cost of filament is insane, thirty, 12in rods for $10?

    Cheap 1.75mm filament is around $1 per 30 meters
    Expensive stuff is about $1 per 7 meters.
    This stuff is just over $1 per meter.
    It’s six times more expensive than even Makerbot filament.

    3d printers are already money pits for most people, this is a black hole.

  30. It seems everyone is focusing on the power required to melt filament… is there a remote possibility that the filament is a special blend that melts at much lower temperatures? There is no mention of this, so…

    Designing this to depend on 900ma would be a disaster… since the spec for USB 2.0 is 500ma; which is a ‘standard’ USB port. Designs that draw more than 500ma would likely trip all kinds of circuit protection. It would be reasonable to ask them to disclose what kind of power that thing would draw since it may damage whatever it’s plugged into. Will the final product be FCC / CE certified?

    Now… consider the additional power requirements needed to drive the mechanism(s) that feed plastic through the pen. Extruders with the right kind of torque to keep the filament going will consume 500ma easy. This would be in addition to the power needed to melt filament. Uh…

    As I look at the size of the pen, I can’t see (mechanically) how this can be accomplished given the wall thickness of the pen body, area displaced by the filament, and air-gaps need to keep circuits at reasonable temperatures. Yeah… this doesn’t add-up.

    Speaking of heat, the thermal conductivity of aluminum is pretty good – which raises more questions about insulation and protecting the person holding the pen from getting burned. Seriously people, 180°C to 220°C is required to melt PLA.

    If you still believe this is possible – take a look at any impartial review / teardown of a 3Doodler. It extrudes painfully slow and has documented thermal management issues. I would guess that the Lix videos are at least 4x normal speed.

    Interesting to note that none of the videos show extrusion / drawing where the pen, cord, and filament are all in full-view. I get the benefit of close-ups, but in this case it only makes me more suspicious.

    1. With a properly designed thermal break, the heat in the pen body should be minimal.
      I have seen 3d printers where you could touch 1/2in from the nozzle and not get burned (warm, certainly, but not scalding).

      Also, I have seen PLA filament melt at 170c or a bit less, depends on formulation.
      You don’t see filament because they are 12in long filament sticks, not a spool, and they are far from cheap, about 6 times what Makerbot filament costs.

      I agree though, this will be painfully slow to work with.

  31. I already avoid 3D printers when they are printing they smell terrible. Two words Fume Hood but I digress. Even if this thing worked there is no way I would want to sit there and 3D doodle while breathing in all that funk :P

  32. If you read the whole kickstarter page, you’ll notice that the FAQ says “One bag of refills will contain 30 straight rods of colored plastic filaments and they will not cost more than 10 dollars for a bag. The exact price is not yet defined because we are still working on it.
    Length ~30cm (11.8in)
    Randomly selected colors.

    1 Straight rod of plastic filament will last you for about 5 minutes.”
    therefore, over 300 seconds, it will extrude “~30cm”, or about 1mm/sec, just BELOW the calculated threshold they mentioned above. While I’m not saying it’s necessarialy a useful or good product, I will say that the math just BARELY allows it to work. It’s probably much less useful at just a tiny fraction of a normal 3d printer output, but it is entirely possible.

    1. Also, using one of the pictures included in the kickstarter, you can see the motor that, as can be reasonably assumed, extrudes the filament. It seems to be one of these, or a similar motor with a different gear ratio:
      These can run as low as ~50mA, under light load. They mention a standard AND custom planetary gearing, so it’s not unreasonable to assumet that one of these motors could easily drive the extruder at the extremely low speed, and power needed, with the torque to extrude easily. As I mentioned above, the extruder extrudes at only 1mm/sec, meaning that it has a healthy ~1.5 watts of power left, or 300mA to run the motor, LEDs, controller, and to compensate for lost heat. That’s more than enough. I’d say this is entirely possible if done correctly, but difficult, finicky, and not altogether too useful.

      1. The motor you linked to is 0.94″ x 0.39″ x 0.47″…so the pen would have to be 0.47″ wide to accomodate it (actually more to leave room for the casing and a path to get the filament to move past it) – but the Lix pen is about half of that. So you need a motor that’s at least half that size. The only reasonable motors you can get at that size are the ones they use to make cellphones vibrate. Those use about 200mA at 3 volts.

        The conclusion you come to – that the maximum extrusion rate is 1mm/sec is essentially proof that this product has to be completely useless. 1mm/sec is simply not enough to do 3D doodling…it needs to be at least ten times faster.

        So, they’ve added a note to their video that says that parts of it are speeded up…but it doesn’t say which parts – or how much speedup they did. My guess is that all of the drawing sequences are speeded up – and probably by a factor of at least 10 to 20.

    2. 1mm per second of filament equates to 1.75mm per second of actual drawing speed…

      Before anyone considers this thing, try drawing even a straight line at that speed. Now imagine doing that for an extended period. I can’t imagine how long or how much of a pain in the @$$ making some of their demos took.

  33. The main argument about using an USB port is kinda of hilarious to me. WTF would they even bother with using a USB port? It is a terrible source of power really, and if you have to plug in the laptop or computer anyway…

    I wouldn’t buy the product just for that reason even if it did work. My house has plenty of convenient two pin plugs in the walls… Making sacrifices just to be able to plug it into a USB port means a grossly inflated price.

    It is not a ‘feature’ I would find appealing. Sounds more like a purposeful tease to those who are not as gullible.

      1. So it can run some driver software or tuning app over the 2 wire connector? And even if it can, just makes it that much less useful. Then you’d HAVE to have a computer to use it. Wow.

        1. Like I said, just a guess.
          Remember, what’s shown, may or may not be the final product. On printers, among other things, you have to tune for different filament temp requirements, type, and density, I don’t really see a whole lot of adjustment on this thing, so a software answer would be the most likely. Personally, there are a lot of questions regarding the tech aspect of this thing.

          However, the connector as you note is 2 wires, and they never mention the OS requirements.

          1. 3D printers need that adjustment because they are producing a higher quality of layering where you want the layers to amalgamate together but not slump into ooze – also the temperature and flow rate need to be balanced for a consistent result….and you need to be able to work with a bunch of different plastics.

            This pen – just like the 3Doodler (which I own – and which works well) don’t need that adjustment. The 3Doodler has a two position switch for two different plastics – but it’s up to the operator to adjust the speed that they draw to compensate for the fixed flow rate that the pen provides. If the Lix only copes with one kind of plastic – then I wouldn’t expect it to need any controls at all except for the two buttons it has to drive the extrusion motor forwards and backwards.

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