*QUESTION:* Which material combinations would you like to see and why? Want to get your 3D prints to the next level already today? Check out our Heat Set Inserts and Tools at cnckitchen.store (Free shipping worldwide starting at €100).
maybe PLA with a core of water soluble support like polydissolve, maybe to do some really light weight prints, insted of solid lines you will get tubes of PLA
This process can indeed open a path to multimaterial filament such as continuous carbon/glass fiber core embedded (inside an easy to respool material at first, for test purposes), the non strech fiber mechanical properties might be a hassle to deal with though... PA6/12, PC, TPU or Nylon for high end continuous fiber embedded filament, but might be even trickier to process. Anyway, good luck if you try this. Great video as always !
"Yo Dawg, I heard you like layer adhesion problems. So I put layers in your filament so you can have layer adhesion problems while you're having layer adhesion problems."
@@stevrgrs candy makers dont make candy with two different plastics and different melting points. Stuffed candy is generally coated or injected, as for hard candy it's rarely if ever done with a mix of, let's say butter based caramel and hard candy, as the butter caramel would leak out of the strip before it hardens, ruining the pattern. Irony or not it's apple to oranges. he's right about temp differentials being a problem with multimaterial printing.
Roughly every year or so, someone makes a completely game-changing 3D printing video showcasing an inventive new way of doing things which could open up so many new possibilities. This is one of those.
And at least a third of those seem to be done by CNC Kitchen. How many of the things Stephan has showcased over the years have become standard practice?
Yep I was wondering which 3D printer manufacturer is also watching this and thinking to add a filament-diameter scanner into the printhead to be able to automatically compensate for under/over extrusion during printing. Maybe this is even more important for flexible filaments to get a really consistent printing results?
Its interesting, but its already being done... Continuous Carbon Fiber filaments for high strength parts for example. "fiber" filaments rarely have increased strength, because the fibers have to be chopped up so small that they don't do much. So Continuous Carbon Fiber filament and the like were invented to change this. The game changer is being able to make multifilament at home, even as a proof of concept.
I work maintenance in a cable factory. The first 5 minutes of the video were pretty much most accessories of an extruder re-invented lol. You should really look up Kabmak extruders to get some inspirations because there are things like vacuum attachments and straightening rollers that could be added even to your machines. You could also add a mechanical brake to the pay-off spool to add pre-tensioning and it would make the plastic more consistent as it would feed through straight. The rollers serve the same purpose, but for wobbly lines. Another important addition would be a hot air blower to pre-heat the filament so you couldn't have to run a volcano type nozzle or anything special. You would need a lot less forces on that filament if it went into the nozzle already at say 50C. As for what you could be adding to it? Oh boy! Make 3 separate filament pay-offs with U-shaped "shells" on 2 of them and one filler. You could just add nylon strings or fishing line to the center spool and print multiple times as much filament at once. Hell, add a caterpillar-type tensioner brake to it and you're gonna have time to change filament on the go without interruption if you find a way to weld them in between.
I agree with all of these suggestions! Preheating the filament is a great idea, even with something simple as a halogen light bulb. And the roller suggestion is also great!
Preheat the filament too was first thing I thought when he was struggling to pull it through too. Can't believe he didn't think of that when he was basically already doing that to stretch down in size to insert it.
Off topic, but I think you might be the right person to ask this, if you don't mind helping out a random internet stranger :D I'm working on creating coaxial nylon-nichrome wires where I want to embed a nichrome wire in the core of a nylon monofilament line. The ultimate goal is to achieve this with 0.1mm D nylon and 0.01mm D nichrome wire, but I'll first try to do it with larger D nylon. What Stephan built here is roughly what I am also planning on doing, and in addition also feeding the nichrome wire through the core of the nozzle. Do you think this would be workable and do you have any tips? Thanks in advance!
This TPU core experiment is just GENIUS! That's why I love your channel, you do science with your experiments, not just funny things for likes and subs
Why a solid core instead of the TPU and PLA emulsified together? People already use silk PLA for flexibility in certain applications since it already has TPU in it.
@@zackj997 The solid core unmixed turns it into a composite. When you have two materials with different properties together, their strengths can add together in ways that wouldn't if they were thoroughly mixed. In this case, the flexibility of the TPU functions like dampening rebar, preventing fracture propagation while preserving the stiffness that PLA offers.
It sounds genius if you know very little polymer science. PU and PLA are not chemically similar so they form what we call non-compatible blends. These blends are basically those that cause boundary layer separation because the two materials are not chemically bonding with each other, this forms a weak material that is worse in most aspects than the homopolymers themself. This is why when making polymers blends with dissimilar materials we use compatibilizers to act as a glue and bind both the materials together.
That's insane, really, creathing a visible logo INSIDE of a filament spool, with hardware that's DIY and accessible to a hobbyist? Man, you just keep on delivering bangers, your ingenuity is amazing
Hard candy is made in a similar fashion. All the design is created in a large (8-9" diameter) chunk then stretched into the final bite-size form. The pattern is retained through the stretching process same as with yours.
His old video about the PC core ABS he mentioned actually talks about the same thing. I believe the original researchers made large blanks with the desired pattern that they then had a machine to extrude into a filament. Exactly what you’re thinking! But requires specialized equipment. Assuming I’m remembering correctly! 😅
This is why I love this channel, most of the other channels I used to watch are either all doing Voron builds or reviewing the same printer that's been done a hundred times already. This channel is unique!
4:13 This phenomenon is actually a result of two combined effects: necking and strain hardening. When tension is applied to the nylon filament, it begins to undergo plastic deformation at its weaker points, leading to a reduction in diameter. At the same time, the nylon string strengthens in these areas of reduced thickness, which concentrates the strain on the thicker segments of the string. The combination of these effects causes the string to shrink to a new, constant diameter before ultimately breaking. Articles for more information: en.wikipedia.org/wiki/Necking_(engineering) en.wikipedia.org/wiki/Work_hardening
It's kind of right but not quite, the effect is due to the majority of the chains in the polimer getting aligned and because all the chains are in the same orientation they become stronger
@@hugofernandez8522 Yes, you are correct, in the case of polymers this effect is the result of chain alignment and not crystal shifts like in metals, but still, this effect is called strain hardening (or work hardening) in both cases
As others have mentioned, this is not work hardening, it's chain alignment. No, they are not the same thing. Work hardening is a crystallographic behavior (polymers do have crystal structure) while chain alignment is just generally the idea that you can do things to the material that cause the long molecules to be oriented in roughly the same direction. Chain alignment doesn't require work-hardening because polymers are viscous and have huge molecules. Things like melt-spinning can also cause higher chain alignment. Chain alignment also doesn't have to interact with the crystal structure of the plastic, and happens even in amorphous materials. It's just about the average direction the polymer chains are oriented.
You could think of the TPU as muscle and the PLA as bone and have them switch places. The tpu absorbing more impact on the outside and the PLA receiving less shock because of being shielded by the flexible TPU the same way that flesh protects bones most of the time. Awesome experiment!
The WInFiDEL sensor lets you measure filament diameter. Now you can implement a PID loop to automatically figure out the proper temperature at a given speed. If you want faster production, turn up the speed and the PID should correct for the change.
So many new ideas continue to pop up in 3D printing. Non-planar printing, arc overhangs, and now you are showing off multi-material filaments. Ten years from now, 3D printing is going to be absolutely off the charts.
This is one of the coolest advancements in consumer 3D printing tech I've seen in a long time. What a great innovation. Even as a mechanical engineer I'm a little surprised how well you got this to work with such a simple setup, especially getting such disparate polymers into a single filament!
Every time you publish a Video it takes two days and your content is featured by all the 3D printing/ Maker Websites, this is amazing. Thanks for your R&D work and making it open to use for everyone Danke 🎉
I would love to see more videos on metamaterials! If the stiffness of the tpu-pla is close to normal pla it would truly be the king of all printing materials for parts that don't need high temperature resistance.
The nylon string reducing in diameter when tensile force is applied is called "necking". I got this definition from google, "In engineering and materials science, necking is a mode of tensile deformation where relatively large amounts of strain localize disproportionately in a small region of the material. The resulting prominent decrease in local cross-sectional area provides the basis for the name neck."
I work at a company called Hills inc. where we do cross section logo fibers and other wild multi extrusion projects. Cross section logo fibers like that are used a decent amount in industry by basically making a dot matrix on the core of each fiber and routing the colored polymer to it's place in the matrix.
4:25 I remember something like this, a quick google search tells me it's called "necking". Don't remember that term but on the tensile strength curve it's the part where force stops increasing with deformation due to the section becoming smaller.
This effect is called necking. It comes from the alignment of polymer chains. The modulus of elasticity of the material also greatly increases when necking occurs as the aligned chains creates higher crystallinity. This can also occur in multiple steps of necking down the diameter until the stress required to force the diameter down via aligning the chains further is greater than the yield stress of the filament at that point. PS: as a polymer engineering student, i love your videos.
A PLA core with a water soluble PVA mantle could create interesting structures or grids when you print it and put it in water. Kind of like how aerogel is made, but bigger.
Unfortunately with the constant cross-section shown in the video I don't think this would give useable results. The core never bonds to itself, so if you dissolved the outer layer the entire print would just fall apart. It might work if you could vary the cross-section so the core sticks out in places, but that would be much harder to get working.
If you printed it with stripes of PVA that are diagonal edge to edge but left solid PLA layers between, the PVA might be able to dissolve out while leaving behind a structure that wouldn’t come apart.
Extrusion process engineer here. The phenomenon where you can stretch hot plastic is known as "drawdown." That's also the name of the process you are using. The simple explanation is that this phenomenon occurs due to internal tensions pulling material from the "corners" of the part to fill in the middle, where the material is splitting under tension. It helps to visualize it as a continuous landslide from the hilltops into a valley that keeps growing longer. You can also get something known as "die swell" as plastic expands due to the pressure drop at the die openings. Die swell isn't really something we have to consider with 3d printers, but it should be considered if you are extruding filament with an Archimedes type extruder. As for your filament layer bonding problems, you may be able to solve that by preheating the filament before drawing it down. Also try over-extruding your print by 3-5%, this should help layer bondability. Also, tension is everything. Pre-tensioning will help both the bondability, and help keep the filament from rotating during drawdown. The more aligned and balanced the tension is on either side of the nozzle, the more consistent the final filament turns out. Good luck, and keep up the amazing videos! "Like everything else in life, 3d printing is just a primitive, degenerate form of extruding." -Bender
I would drill that nozzle up to at least 1,8-1,9mm and pull the filament at above the breakpoint of the diameter/pulling force curve to achieve correct diameter and fuse the layers together properly. Also a loadcell controlled motor driver circuit would help keeping the pulling force constant.
stephan, this is phenomenal, I've been thinking about a way to get around the markforged patents for a while. I consistently enjoy watching your videos, i really like how thorough you are.
@louisvaught2495 That's a great point, the production method can be improved. But the concept is still amazing. Hobbyist accessible metamaterials. That's still got me excited.
@@ouansungyidan You can work a bit to remove the molecular alignment, but in general the process being used to *make* the structure is what limits the final properties. This particular process being so accessible and macro-scale means you don't have much molecular control over what's coming out. The part of the video where Stefan discusses having to keep the filament from getting too soft is a great indication that the process is really dependent on the molecular order of the polymer, rather than the process having any control over it.
Such a cool concept! I wonder if you could print the pulled TPU-core filament into a second 4mm blank, and then repeat the pulling process to get even smaller TPU fibers
4:27 The phenomenon is based on the crystallization of thermoplastics. To summarize: when a thermoplastic is pulled apart, the polymer chains in it lie next to each other, making the thermoplastic stronger, as more intermolecular attractive forces can be formed. As a result the crystalline part of the thermoplastic isn‘t pulled apart, but the weaker non-stretched gets stretched. Have a look here: de.wikipedia.org/wiki/Kristallisation_(Polymer)
Wow. So glad I saw this comment and went to check out your channel. As cool as the idea in this CNC kitchen video is (and no slight to Stefan, this really is a great idea), I think your pellet extruder has way more potential to revolutionize 3d printing. Amazing work.
I've recently seen your video about that and I think you deserve a lot more attention. What would you think about about combining your idea of direct printing from pellets with Stephan's filament-extruder and Thomas' thickness-sensor to regulate the speed of the extruder to match the amount of filament that the printer needs to build a printer which makes its own filament on the fly? That would solve the problems with the much heavier printhead and reduced printing-quality.
I think this idea might work, there are also ideas like implementing a real-time pressure sensor or AI camera to measure the flow and to automatically adjust it in real time. The only thing that needs to be done is the research & development which is costly and since I have spent most of my savings on R&D for the extruder itself... For this reason I keep all these things in mind but for now focus on releasing the extruder so everyone can benefit from it... 🙂
You have really outdone yourself with this video. The research you have done in this video is easily enough to write another master thesis. Outstanding!
I have an idea. Make the filament have a clear core with transparent coloured shell, print a cool vase model on vase mode and find a way to send light thru the extruded filament. Maybe one of those 60mm LED pucks from eBay under the vase would do it. On the other hand, a black core with transparent shell could be very interesting as well.
There's so many interesting possibilities mixing different materials within one extrusion. This is definitely one of those ah-ha moments for the technology. CF Nylon with TPU or ASA with TPU could make interesting case studies. Delving further in mixing multiple materials to harness more properties is another product of these types of explorations. GJ Stefan always keeping us on our toes!
A couple of weeks ago I printed a TPU/PETG filament. It worked great for the printable balls! Improved bounce compared to TPU and much more durable than PETG.
You are a perfect example of what happens when you live and breathe a technology day in day out. Brand new ideas well beyond the reach of most people just keep popping up.
For the layer adhesion issues why not pull it twice once to get the diameter and then again at a higher speed and hotter temp just to make sure it fused together.
This is pretty cool! It's basically the same process confectioners use to make candies with logos and stuff in them, although they start with blanks like 10" in diameter and stretch them down by hand. Still very cool that this technique applies to plastics, too
You should try putting the Winfidel sensor in the feedback loop of an automatic controller for detecting filament thickness. It could actually be accurate compared with the pulling-a-paper-clip-and-hoping method.
the phenomenon is yielding and chain alignment. when it stretches to the point that polymer chains are fully aligned, it reaches a higher modulus and strength and stops being the weak point so the thicker sections continue to stretch
Its always a good idea to look at prior art. The resizing you do is basically the same as getting metal wire to size using a pull plate. Going in steps, e.g. 3mm -> 2.5mm -> 2.0mm -> 1.7mm, would make the proces much easier and probably quicker.
Your videos are always amazingly thought-provoking. You come up with truly innovative concepts for investigation that no one (or very few) have talked about. I love it.
It’s actually 3 phenomena Necking: Localized thinning and formation of a narrow region that can propagate. Cold Drawing: Stretching that aligns polymer chains and reduces diameter in a wave-like manner. Viscoelastic Behavior: Combined elastic and viscous response leading to slow deformation.
This is absolutely amazing, I'm so impressed with what you came up with, so creative and well engineered at the same time. You ended on what you would try differently after exploring the reforming method and I can't wait for the next step.
I recommended you do this a while back, not sure if you saw my comment or not, but Im glad some testing is being done, I dont have the equipment to do it myself.
regarding the diameter issue, you are correct in that is because you are pulling the soft filament. This "could" be mitigated by cooling it directly at the nozzle output but I would recommend changing to a push method just like the hot ends of ffd printers. Edit; I didnt realize you had a different machine in the hot end setup, good idea.
I would love to try some of the TPU filled PLA to see how well it works in some unusual applications. It almost sounds like the ideal material for high impact prints.
4:27 Mostly used to describe metals metals, this is called necking. The material becomes thinner as it is stretched longer, eventually leading to a total failure when the necked area breaks. The break happens at the thinnest section because the surface area becomes too small to support the tensile forces
This is just crazy and unbelievable cool! I think Filament recycling will become more affordable quite soon as a side-effect of more and more such videos popping up. But in any case, as an Austrian: saugeile Technik!
The technique of stretching is very cool. It is also used in micro-optics. Where you take a piece of glass, heat and stretch it, and amazingly it keeps its cross sectional shape exactly, without any deformation or rounding.
I love the update with an older experiment I think it would be cool to pull long strands of each material and line them up to form a pattern as a practical mass production setting. Also I think the thinning effect you talked about in the beginning is called strain elongation
Yoooooo this is amazing. So many possibilities! Can even make longer rolls by fusing multiple coils together by melting hem together. Then the resizer does it's magic to smooth out the joint
I work in an industry where we make plastic film. The way we get a different thickness with the same pressure from out extruders is to pull it at different speeds. If you could find a rudimentry way to force the large pieces in, you should be able to pull the final stock at higher speeds an making this more viable for larger projects.
Please do a dedicated video about the strength and toughness of some filament combinations. I am definitely interested in the mechanical properties and think that it could lead to some promising future filaments
This is just like a stick of rock, and how a lot of polymer clay art works. Very cool. Especially from a cottage industry researcher! The tpu/pla matrix blew my mind.
I've found that abs and tpu bond very well, if you're wanting to continue experimenting with that. Something like the Phaetus 78D TPU inside some ABS or ASA might make for incredibly strong parts
So basically you first used the technique of hard candy making to create a big cross section and then pull it thin and then you inverted fiber composites by embedding soft fibers (the TPU) in a stiffer matrix (the PLA). Absolutely wild! My ideas: could you create a feedback loop in your filament puller so it self-adjusts the tension and temperature for the perfect diameter? You could still print hex filament and put a bracket in front of the nozzle so the filament stays oriented the same way all the time. Might it be possible to "anneal" or remove stress after pulling using a gentle heating tunnel before and/or after the filament puller hotend? The heat still goes from the outside in, so not only do the two materials have different properties, they also are at different temperatures. That might reduce the filament-internal delamination (never thought I would write this scentence) Keep up the awesome work! I love how you quoted all these other channels, showing that we are not competitors, but a community
The phenomenon is called (unofficially) spaghetti straightening. Where the crosslinked/entangled polymer chains are pulled straight (aligned). This is from tensile pulling and makes the polymer longer and tougher!
Put copper wire in it to make 3d printed coils for motors use the plastic bottles that makes a tube to thred the wire through while extruding on your filament making machine
Had to check out this video after talking to you at RMRRF. This is super cool, now I'm going down the rabbit hole of what it would take for us to produce something like this at scale here at Polar Filament
For your machine that makes the filament, I think a nice solution would be to have a clip attached to a string, and a motor on the back end that can pull the material consistently. And then just have it set to stop pulling at a desired length, so it can save on wasted material
4:05 The pulling force plays indeed a major role, in real filament factories they also have a measurement device at the end of the line which adjusts the pull speed to get the filament to the correct diameter.
This is fantastic, there is so much scope for new printing materials. Also interested in additives in the process that are genuinely useful (unlike milled carbon fibre!). Microballoons for a start
Stefan (i'm sorry if i spelled it wrong.) you are a wonder worker. i've loved your content, it's always interesting, helpful or great applied research and development if you ask me. You're a printing scientist.
This is very much how candy making works. They make the pattern really (like r e a l l y) big, and then strech it so that it gets substantially thinner, and the patterns remain. Candy makers can put entire figures within their pieces, and often make things like Marios, Disney characters and such.
Ill have to look up when I get home, but theres an open source repo for an optical filament width sensor with 3 mirrors in a half hexagon configuration because you really need at least 3 different cross sections to get an accurate filament volume because roundness matters (if you want irresponsible accuracy)
4:20 the term for the thinning of the wire is called necking. Its an extremely common phenomenon when any material undergoes plastic deformation (permanent warping) through tensile stress.
This, as per usual, is amazing. Not a filament combination example but idea: Instead of going for a consistent shape throughout the filament, go for a pattern such that the printed result has meeting grids of certain filaments. For instance, I find it difficult to imagine such a shape, but imagine if the TPU and PLA both had contact with other lines of similar material the whole way through the part? Then you would have more than just layer strength from the TPU.
This is such a creative idea, well done! I think PETG + TPU would be a much better combo than PLA + TPU, better bonding. Also, I would advise printing at a higher nozzle temp and with a higher extrusion multiplier, in order to minimize gaps and improve layer bonding. Since you're just printing the filament coil as a solid object, the higher nozzle temps shouldn't adversely affect anything since you won't have any bridging. And since you're resizing the 4mm filament coil down to 1.75mm, any slight print variances from a perfect 4mm filament won't really matter, so over-cranking the extrusion multiplier should be a win-win.
PLA with TPU core is something I would really like to play with. The strength test didn’t really surprise me, because that’s a genius design and it should probably be producible with the right tools (as semi proven here). People would definitely pay double for a full roll like that
Nice Video! You always have this diameter reduction during spinning. It is a complex matter since there are a lot of factors involved: starting diameter, temperature, cooling, evolution of the viscosity with temperature, temperature gradient within the filament, etc. I would recommend copying the 3Devo. Add a cooling fan, increase the nozzle diameter, increase the temperature and add an extruder on the other side to minimize the tensile stresses leading to failure.
*QUESTION:* Which material combinations would you like to see and why?
Want to get your 3D prints to the next level already today? Check out our Heat Set Inserts and Tools at cnckitchen.store (Free shipping worldwide starting at €100).
Mix carbon fiber PETG with ninja flex TPU
ABS + chocolate 😋
Fiber glass composite pla 😋😋😋
maybe PLA with a core of water soluble support like polydissolve, maybe to do some really light weight prints, insted of solid lines you will get tubes of PLA
This process can indeed open a path to multimaterial filament such as continuous carbon/glass fiber core embedded (inside an easy to respool material at first, for test purposes), the non strech fiber mechanical properties might be a hassle to deal with though...
PA6/12, PC, TPU or Nylon for high end continuous fiber embedded filament, but might be even trickier to process.
Anyway, good luck if you try this. Great video as always !
"Yo Dawg, I heard you like layer adhesion problems. So I put layers in your filament so you can have layer adhesion problems while you're having layer adhesion problems."
You are having adhesion problems with pla?
@@ericwheelhouse4371 14:28
@@ericwheelhouse4371 never under estimate a bad printer (my 2018 wanhao duplicator i3)
So basically you’re doing what candy makers have done for over 100 years :P 😂
@@stevrgrs candy makers dont make candy with two different plastics and different melting points.
Stuffed candy is generally coated or injected, as for hard candy it's rarely if ever done with a mix of, let's say butter based caramel and hard candy, as the butter caramel would leak out of the strip before it hardens, ruining the pattern.
Irony or not it's apple to oranges. he's right about temp differentials being a problem with multimaterial printing.
Roughly every year or so, someone makes a completely game-changing 3D printing video showcasing an inventive new way of doing things which could open up so many new possibilities. This is one of those.
And at least a third of those seem to be done by CNC Kitchen. How many of the things Stephan has showcased over the years have become standard practice?
Yep I was wondering which 3D printer manufacturer is also watching this and thinking to add a filament-diameter scanner into the printhead to be able to automatically compensate for under/over extrusion during printing.
Maybe this is even more important for flexible filaments to get a really consistent printing results?
Its interesting, but its already being done...
Continuous Carbon Fiber filaments for high strength parts for example.
"fiber" filaments rarely have increased strength, because the fibers have to be chopped up so small that they don't do much. So Continuous Carbon Fiber filament and the like were invented to change this.
The game changer is being able to make multifilament at home, even as a proof of concept.
Wow, this is insane. Mans maxed out his engineering level and just grinding sidequests now.
He’s completed the CNC part of his username and will soon begin the Kitchen stage.
Edit: tbh he’s already cooking
He is manufacturing a new reality for earth in his kitchen !!!
Lol
😂😂
If you think our man has reached his final form you underestimate him.
I work maintenance in a cable factory. The first 5 minutes of the video were pretty much most accessories of an extruder re-invented lol. You should really look up Kabmak extruders to get some inspirations because there are things like vacuum attachments and straightening rollers that could be added even to your machines. You could also add a mechanical brake to the pay-off spool to add pre-tensioning and it would make the plastic more consistent as it would feed through straight. The rollers serve the same purpose, but for wobbly lines. Another important addition would be a hot air blower to pre-heat the filament so you couldn't have to run a volcano type nozzle or anything special. You would need a lot less forces on that filament if it went into the nozzle already at say 50C. As for what you could be adding to it? Oh boy! Make 3 separate filament pay-offs with U-shaped "shells" on 2 of them and one filler. You could just add nylon strings or fishing line to the center spool and print multiple times as much filament at once. Hell, add a caterpillar-type tensioner brake to it and you're gonna have time to change filament on the go without interruption if you find a way to weld them in between.
Thank you so much. This is exactly what I wish every comment on UA-cam was like
I agree with all of these suggestions! Preheating the filament is a great idea, even with something simple as a halogen light bulb. And the roller suggestion is also great!
Preheat the filament too was first thing I thought when he was struggling to pull it through too. Can't believe he didn't think of that when he was basically already doing that to stretch down in size to insert it.
Just putting a hot air blower or halogen lamp at the entry is not very energy efficient, for a process that takes hours this is something to consider
Off topic, but I think you might be the right person to ask this, if you don't mind helping out a random internet stranger :D
I'm working on creating coaxial nylon-nichrome wires where I want to embed a nichrome wire in the core of a nylon monofilament line. The ultimate goal is to achieve this with 0.1mm D nylon and 0.01mm D nichrome wire, but I'll first try to do it with larger D nylon. What Stephan built here is roughly what I am also planning on doing, and in addition also feeding the nichrome wire through the core of the nozzle. Do you think this would be workable and do you have any tips? Thanks in advance!
This TPU core experiment is just GENIUS! That's why I love your channel, you do science with your experiments, not just funny things for likes and subs
Absolutely genius!
Why a solid core instead of the TPU and PLA emulsified together? People already use silk PLA for flexibility in certain applications since it already has TPU in it.
@@zackj997 The solid core unmixed turns it into a composite. When you have two materials with different properties together, their strengths can add together in ways that wouldn't if they were thoroughly mixed. In this case, the flexibility of the TPU functions like dampening rebar, preventing fracture propagation while preserving the stiffness that PLA offers.
@@zackj997 Really? Most of my silk prints seem more brittle, not less. I'm a sucker for off-brand budget filament deals so that might be a factor.
It sounds genius if you know very little polymer science. PU and PLA are not chemically similar so they form what we call non-compatible blends. These blends are basically those that cause boundary layer separation because the two materials are not chemically bonding with each other, this forms a weak material that is worse in most aspects than the homopolymers themself. This is why when making polymers blends with dissimilar materials we use compatibilizers to act as a glue and bind both the materials together.
That's insane, really, creathing a visible logo INSIDE of a filament spool, with hardware that's DIY and accessible to a hobbyist? Man, you just keep on delivering bangers, your ingenuity is amazing
Hard candy is made in a similar fashion. All the design is created in a large (8-9" diameter) chunk then stretched into the final bite-size form. The pattern is retained through the stretching process same as with yours.
Same with “millefiori” glass art.
This was the first thing that came to mind. Watching how candy is made, is extremely similar and follow the same principles.
His old video about the PC core ABS he mentioned actually talks about the same thing. I believe the original researchers made large blanks with the desired pattern that they then had a machine to extrude into a filament.
Exactly what you’re thinking! But requires specialized equipment.
Assuming I’m remembering correctly! 😅
Beat me to it! I was about to say this is how they do designs in saltwater taffy too
Funnily enough, this is mentioned in the subtitles at 13:58, but he doesn't say it out loud
This is why I love this channel, most of the other channels I used to watch are either all doing Voron builds or reviewing the same printer that's been done a hundred times already.
This channel is unique!
4:13 This phenomenon is actually a result of two combined effects: necking and strain hardening. When tension is applied to the nylon filament, it begins to undergo plastic deformation at its weaker points, leading to a reduction in diameter. At the same time, the nylon string strengthens in these areas of reduced thickness, which concentrates the strain on the thicker segments of the string. The combination of these effects causes the string to shrink to a new, constant diameter before ultimately breaking.
Articles for more information:
en.wikipedia.org/wiki/Necking_(engineering)
en.wikipedia.org/wiki/Work_hardening
aka continuous necking
It's kind of right but not quite, the effect is due to the majority of the chains in the polimer getting aligned and because all the chains are in the same orientation they become stronger
In amorfous materials like polymers you don't have strain hardening like in metallic materials
@@hugofernandez8522 Yes, you are correct, in the case of polymers this effect is the result of chain alignment and not crystal shifts like in metals, but still, this effect is called strain hardening (or work hardening) in both cases
As others have mentioned, this is not work hardening, it's chain alignment.
No, they are not the same thing.
Work hardening is a crystallographic behavior (polymers do have crystal structure) while chain alignment is just generally the idea that you can do things to the material that cause the long molecules to be oriented in roughly the same direction.
Chain alignment doesn't require work-hardening because polymers are viscous and have huge molecules. Things like melt-spinning can also cause higher chain alignment.
Chain alignment also doesn't have to interact with the crystal structure of the plastic, and happens even in amorphous materials. It's just about the average direction the polymer chains are oriented.
Embedding your logo in the filament is such a flex and extra way of tagging your prints as genuine.
I love that, watermarked 3D prints
Except that everyone can do it.
You could think of the TPU as muscle and the PLA as bone and have them switch places. The tpu absorbing more impact on the outside and the PLA receiving less shock because of being shielded by the flexible TPU the same way that flesh protects bones most of the time. Awesome experiment!
The outside of the filament would also be bending more than the core, so having the outside made of tpu must be beneficial too
The WInFiDEL sensor lets you measure filament diameter. Now you can implement a PID loop to automatically figure out the proper temperature at a given speed. If you want faster production, turn up the speed and the PID should correct for the change.
So many new ideas continue to pop up in 3D printing. Non-planar printing, arc overhangs, and now you are showing off multi-material filaments. Ten years from now, 3D printing is going to be absolutely off the charts.
Once again he has changed the 3D printing world
This is one of the coolest advancements in consumer 3D printing tech I've seen in a long time. What a great innovation. Even as a mechanical engineer I'm a little surprised how well you got this to work with such a simple setup, especially getting such disparate polymers into a single filament!
Every time you publish a Video it takes two days and your content is featured by all the 3D printing/ Maker Websites, this is amazing. Thanks for your R&D work and making it open to use for everyone Danke 🎉
I would love to see more videos on metamaterials! If the stiffness of the tpu-pla is close to normal pla it would truly be the king of all printing materials for parts that don't need high temperature resistance.
The nylon string reducing in diameter when tensile force is applied is called "necking". I got this definition from google, "In engineering and materials science, necking is a mode of tensile deformation where relatively large amounts of strain localize disproportionately in a small region of the material. The resulting prominent decrease in local cross-sectional area provides the basis for the name neck."
Can this be modeled in a bottom-up simulation?
Oh god i was so young back then... excellent technique! love the 4mm to 1.75 downsizing!
Always pushing the limits of 3d printing, great job. The watermark filament honestly blew my mind.
That TPU/PLA is so cool! what a great experiment
I work at a company called Hills inc. where we do cross section logo fibers and other wild multi extrusion projects. Cross section logo fibers like that are used a decent amount in industry by basically making a dot matrix on the core of each fiber and routing the colored polymer to it's place in the matrix.
How about filaments with an embedded cf or Kevlar strand. Is that done?
4:25 I remember something like this, a quick google search tells me it's called "necking". Don't remember that term but on the tensile strength curve it's the part where force stops increasing with deformation due to the section becoming smaller.
Thanks
You are a pioneer in expanding the possibilities for 3D printer users.
This effect is called necking. It comes from the alignment of polymer chains. The modulus of elasticity of the material also greatly increases when necking occurs as the aligned chains creates higher crystallinity. This can also occur in multiple steps of necking down the diameter until the stress required to force the diameter down via aligning the chains further is greater than the yield stress of the filament at that point.
PS: as a polymer engineering student, i love your videos.
Dude you are the GOAT of 3d printing experiments. Is there anyone else out there doing stuff as cool?
Man, this is genius! The most interesting use case I've seen for the Prusa XL and this really inspires!
A PLA core with a water soluble PVA mantle could create interesting structures or grids when you print it and put it in water. Kind of like how aerogel is made, but bigger.
3d printed sponge lol
Aero light plastic for rc plane wings or something
Unfortunately with the constant cross-section shown in the video I don't think this would give useable results. The core never bonds to itself, so if you dissolved the outer layer the entire print would just fall apart. It might work if you could vary the cross-section so the core sticks out in places, but that would be much harder to get working.
If you printed it with stripes of PVA that are diagonal edge to edge but left solid PLA layers between, the PVA might be able to dissolve out while leaving behind a structure that wouldn’t come apart.
Extrusion process engineer here. The phenomenon where you can stretch hot plastic is known as "drawdown." That's also the name of the process you are using. The simple explanation is that this phenomenon occurs due to internal tensions pulling material from the "corners" of the part to fill in the middle, where the material is splitting under tension. It helps to visualize it as a continuous landslide from the hilltops into a valley that keeps growing longer. You can also get something known as "die swell" as plastic expands due to the pressure drop at the die openings. Die swell isn't really something we have to consider with 3d printers, but it should be considered if you are extruding filament with an Archimedes type extruder.
As for your filament layer bonding problems, you may be able to solve that by preheating the filament before drawing it down. Also try over-extruding your print by 3-5%, this should help layer bondability. Also, tension is everything. Pre-tensioning will help both the bondability, and help keep the filament from rotating during drawdown. The more aligned and balanced the tension is on either side of the nozzle, the more consistent the final filament turns out.
Good luck, and keep up the amazing videos!
"Like everything else in life, 3d printing is just a primitive, degenerate form of extruding." -Bender
I would drill that nozzle up to at least 1,8-1,9mm and pull the filament at above the breakpoint of the diameter/pulling force curve to achieve correct diameter and fuse the layers together properly. Also a loadcell controlled motor driver circuit would help keeping the pulling force constant.
stephan, this is phenomenal, I've been thinking about a way to get around the markforged patents for a while. I consistently enjoy watching your videos, i really like how thorough you are.
A CNC-Kitchen Video 🎉 my Evening is saved.. Why my evening? Because each one of them teaches me enough to continue reading for hours… thank you!
What a crazy idea PLA + TPU core, amazing job man! This is surely a neat improvement for prints that will face a lot of physical stress
Omg he made his own metamaterial at home. Kind of freaking out right now. That's a research gold mine.
It's not particularly useful due to the high shear during production. That imparts unfavorable structure on the material.
@louisvaught2495 That's a great point, the production method can be improved. But the concept is still amazing. Hobbyist accessible metamaterials. That's still got me excited.
@@ouansungyidan You can work a bit to remove the molecular alignment, but in general the process being used to *make* the structure is what limits the final properties. This particular process being so accessible and macro-scale means you don't have much molecular control over what's coming out.
The part of the video where Stefan discusses having to keep the filament from getting too soft is a great indication that the process is really dependent on the molecular order of the polymer, rather than the process having any control over it.
Such a cool concept! I wonder if you could print the pulled TPU-core filament into a second 4mm blank, and then repeat the pulling process to get even smaller TPU fibers
Babe wake up! CNC Kitchen just uploaded
4:27 The phenomenon is based on the crystallization of thermoplastics. To summarize: when a thermoplastic is pulled apart, the polymer chains in it lie next to each other, making the thermoplastic stronger, as more intermolecular attractive forces can be formed. As a result
the crystalline part of the thermoplastic isn‘t pulled apart, but the weaker non-stretched gets stretched. Have a look here: de.wikipedia.org/wiki/Kristallisation_(Polymer)
What a coincidence that we both made a video about mixing TPU with PLA at the same time hahaha 😅
But I was a bit faster 🙃
Upvote for more awareness. Your idea to mount a corkscrew extruder on a 3D printer could be a real game changer!
Not to brag or anything
Wow. So glad I saw this comment and went to check out your channel. As cool as the idea in this CNC kitchen video is (and no slight to Stefan, this really is a great idea), I think your pellet extruder has way more potential to revolutionize 3d printing. Amazing work.
I've recently seen your video about that and I think you deserve a lot more attention.
What would you think about about combining your idea of direct printing from pellets with Stephan's filament-extruder and Thomas' thickness-sensor to regulate the speed of the extruder to match the amount of filament that the printer needs to build a printer which makes its own filament on the fly? That would solve the problems with the much heavier printhead and reduced printing-quality.
I think this idea might work, there are also ideas like implementing a real-time pressure sensor or AI camera to measure the flow and to automatically adjust it in real time. The only thing that needs to be done is the research & development which is costly and since I have spent most of my savings on R&D for the extruder itself...
For this reason I keep all these things in mind but for now focus on releasing the extruder so everyone can benefit from it... 🙂
You have really outdone yourself with this video. The research you have done in this video is easily enough to write another master thesis. Outstanding!
I think 3d printer experts should learn more from candy makers...the more i learn the more i am convinced...
The amount of time that you put into these videos is truly astounding. Thank you so much for all of the dedication you have to 3D Printing!
I have an idea. Make the filament have a clear core with transparent coloured shell, print a cool vase model on vase mode and find a way to send light thru the extruded filament. Maybe one of those 60mm LED pucks from eBay under the vase would do it.
On the other hand, a black core with transparent shell could be very interesting as well.
Use the multicoulered matirial to print a fillament for recising and you will get an amazing fillament
Hexagons are the best-agons! CGP Grey Reference!!!
There's so many interesting possibilities mixing different materials within one extrusion. This is definitely one of those ah-ha moments for the technology. CF Nylon with TPU or ASA with TPU could make interesting case studies. Delving further in mixing multiple materials to harness more properties is another product of these types of explorations. GJ Stefan always keeping us on our toes!
A couple of weeks ago I printed a TPU/PETG filament. It worked great for the printable balls! Improved bounce compared to TPU and much more durable than PETG.
And again Stephan changed the 3D printing world again! What a legend!
You are a perfect example of what happens when you live and breathe a technology day in day out. Brand new ideas well beyond the reach of most people just keep popping up.
Imagine finding a way to embed continious carbon fiber in a filament this way!
This exists already in the high end commercial printer world.
Yeah, thats the way! And opensource it
For the layer adhesion issues why not pull it twice once to get the diameter and then again at a higher speed and hotter temp just to make sure it fused together.
Now that is neat.
This is pretty cool! It's basically the same process confectioners use to make candies with logos and stuff in them, although they start with blanks like 10" in diameter and stretch them down by hand. Still very cool that this technique applies to plastics, too
I love the amount of innovation and experimentation in videos like this.
Keep innovating Stefan, you're one of the main drivers helping to push open source additive manufacturing towards the future
Thanks!
This is probably the most impactful 3d printing video of the year and and it's just chilling in our feeds.
You should try putting the Winfidel sensor in the feedback loop of an automatic controller for detecting filament thickness. It could actually be accurate compared with the pulling-a-paper-clip-and-hoping method.
the phenomenon is yielding and chain alignment. when it stretches to the point that polymer chains are fully aligned, it reaches a higher modulus and strength and stops being the weak point so the thicker sections continue to stretch
Its always a good idea to look at prior art. The resizing you do is basically the same as getting metal wire to size using a pull plate. Going in steps, e.g. 3mm -> 2.5mm -> 2.0mm -> 1.7mm, would make the proces much easier and probably quicker.
Your videos are always amazingly thought-provoking. You come up with truly innovative concepts for investigation that no one (or very few) have talked about. I love it.
It’s actually 3 phenomena
Necking: Localized thinning and formation of a narrow region that can propagate.
Cold Drawing: Stretching that aligns polymer chains and reduces diameter in a wave-like manner.
Viscoelastic Behavior: Combined elastic and viscous response leading to slow deformation.
This is absolutely amazing, I'm so impressed with what you came up with, so creative and well engineered at the same time.
You ended on what you would try differently after exploring the reforming method and I can't wait for the next step.
I recommended you do this a while back, not sure if you saw my comment or not, but Im glad some testing is being done, I dont have the equipment to do it myself.
That was super interesting! I think you're onto something here with the TUP/PLA. Hope you pursue this further and provide some updates. Thanks.
You should use the tpu core pla to try and print one of those 3d printed basketballs. Everyone complains pla is too stiff, and tpu is too soft.
regarding the diameter issue, you are correct in that is because you are pulling the soft filament. This "could" be mitigated by cooling it directly at the nozzle output but I would recommend changing to a push method just like the hot ends of ffd printers.
Edit; I didnt realize you had a different machine in the hot end setup, good idea.
I would love to try some of the TPU filled PLA to see how well it works in some unusual applications. It almost sounds like the ideal material for high impact prints.
wow your english pronunciation is really well. you'r the first one english speaker I'v get to understand on high speed playback
That twisted 2 color where the colors shift is pretty awesome, that effect with another color could be really cool
4:27
Mostly used to describe metals metals, this is called necking. The material becomes thinner as it is stretched longer, eventually leading to a total failure when the necked area breaks. The break happens at the thinnest section because the surface area becomes too small to support the tensile forces
This is just crazy and unbelievable cool! I think Filament recycling will become more affordable quite soon as a side-effect of more and more such videos popping up. But in any case, as an Austrian: saugeile Technik!
The technique of stretching is very cool. It is also used in micro-optics. Where you take a piece of glass, heat and stretch it, and amazingly it keeps its cross sectional shape exactly, without any deformation or rounding.
I love the update with an older experiment I think it would be cool to pull long strands of each material and line them up to form a pattern as a practical mass production setting.
Also I think the thinning effect you talked about in the beginning is called strain elongation
Yoooooo this is amazing. So many possibilities!
Can even make longer rolls by fusing multiple coils together by melting hem together. Then the resizer does it's magic to smooth out the joint
I work in an industry where we make plastic film. The way we get a different thickness with the same pressure from out extruders is to pull it at different speeds. If you could find a rudimentry way to force the large pieces in, you should be able to pull the final stock at higher speeds an making this more viable for larger projects.
Please do a dedicated video about the strength and toughness of some filament combinations. I am definitely interested in the mechanical properties and think that it could lead to some promising future filaments
You have the patience of a saint my friend. Top experimenting, Keep it up Sir.
This is just like a stick of rock, and how a lot of polymer clay art works. Very cool. Especially from a cottage industry researcher!
The tpu/pla matrix blew my mind.
I've found that abs and tpu bond very well, if you're wanting to continue experimenting with that. Something like the Phaetus 78D TPU inside some ABS or ASA might make for incredibly strong parts
This is quite possibly the coolest video you have ever made, and that's saying a lot! Wow!
Can you mix a hard center soft outside to use for prosthetic hands?
So basically you first used the technique of hard candy making to create a big cross section and then pull it thin and then you inverted fiber composites by embedding soft fibers (the TPU) in a stiffer matrix (the PLA). Absolutely wild!
My ideas: could you create a feedback loop in your filament puller so it self-adjusts the tension and temperature for the perfect diameter?
You could still print hex filament and put a bracket in front of the nozzle so the filament stays oriented the same way all the time.
Might it be possible to "anneal" or remove stress after pulling using a gentle heating tunnel before and/or after the filament puller hotend? The heat still goes from the outside in, so not only do the two materials have different properties, they also are at different temperatures. That might reduce the filament-internal delamination (never thought I would write this scentence)
Keep up the awesome work! I love how you quoted all these other channels, showing that we are not competitors, but a community
The phenomenon is called (unofficially) spaghetti straightening. Where the crosslinked/entangled polymer chains are pulled straight (aligned). This is from tensile pulling and makes the polymer longer and tougher!
Put copper wire in it to make 3d printed coils for motors use the plastic bottles that makes a tube to thred the wire through while extruding on your filament making machine
This is so cool. So glad you did this, as I do not have the equipment, expertise, or time to do something like this. Amazing.
Had to check out this video after talking to you at RMRRF. This is super cool, now I'm going down the rabbit hole of what it would take for us to produce something like this at scale here at Polar Filament
For your machine that makes the filament, I think a nice solution would be to have a clip attached to a string, and a motor on the back end that can pull the material consistently. And then just have it set to stop pulling at a desired length, so it can save on wasted material
4:05 The pulling force plays indeed a major role, in real filament factories they also have a measurement device at the end of the line which adjusts the pull speed to get the filament to the correct diameter.
This is fantastic, there is so much scope for new printing materials. Also interested in additives in the process that are genuinely useful (unlike milled carbon fibre!). Microballoons for a start
I really like your videos and the R&D-oriented mindset. Great engineering !
Stefan (i'm sorry if i spelled it wrong.) you are a wonder worker. i've loved your content, it's always interesting, helpful or great applied research and development if you ask me. You're a printing scientist.
Abs outside, pva or any other soluble material inside could be a crazy tubing situation worth to research!
This is very much how candy making works. They make the pattern really (like r e a l l y) big, and then strech it so that it gets substantially thinner, and the patterns remain. Candy makers can put entire figures within their pieces, and often make things like Marios, Disney characters and such.
Ill have to look up when I get home, but theres an open source repo for an optical filament width sensor with 3 mirrors in a half hexagon configuration because you really need at least 3 different cross sections to get an accurate filament volume because roundness matters (if you want irresponsible accuracy)
make a carbon fiver core around nylon and rig a servo with a razor to cut it off each time you lift the print head.
4:20 the term for the thinning of the wire is called necking. Its an extremely common phenomenon when any material undergoes plastic deformation (permanent warping) through tensile stress.
This, as per usual, is amazing. Not a filament combination example but idea: Instead of going for a consistent shape throughout the filament, go for a pattern such that the printed result has meeting grids of certain filaments. For instance, I find it difficult to imagine such a shape, but imagine if the TPU and PLA both had contact with other lines of similar material the whole way through the part? Then you would have more than just layer strength from the TPU.
This is such a creative idea, well done! I think PETG + TPU would be a much better combo than PLA + TPU, better bonding. Also, I would advise printing at a higher nozzle temp and with a higher extrusion multiplier, in order to minimize gaps and improve layer bonding. Since you're just printing the filament coil as a solid object, the higher nozzle temps shouldn't adversely affect anything since you won't have any bridging. And since you're resizing the 4mm filament coil down to 1.75mm, any slight print variances from a perfect 4mm filament won't really matter, so over-cranking the extrusion multiplier should be a win-win.
PLA with TPU core is something I would really like to play with. The strength test didn’t really surprise me, because that’s a genius design and it should probably be producible with the right tools (as semi proven here).
People would definitely pay double for a full roll like that
Nice Video! You always have this diameter reduction during spinning. It is a complex matter since there are a lot of factors involved: starting diameter, temperature, cooling, evolution of the viscosity with temperature, temperature gradient within the filament, etc.
I would recommend copying the 3Devo.
Add a cooling fan, increase the nozzle diameter, increase the temperature and add an extruder on the other side to minimize the tensile stresses leading to failure.