Easier Fiber-Reinforced Resin Printing! Stronger and Conductive Resin Prints?

oh wow would you look at the mess we made so a couple of months ago i did the resin plus continuous fiber reinforcement video which was a lot of fun but it was super messy and the results were a bit all over the place that is you know enough reason for me to do it again this time with non-continuous fibrin additives so i'm going to try three different materials chopped glass fiber cotton and graphite so the thing about resin is they can be a bit messy to work with but they have the huge advantage that you can stir and mix stuff into them if you so desire which is a bit tricky with continuous filament i mean you need a filament extruder and everything that comes along with that which we looked at last video but yeah with resins you can just you know take the resin storage stuff into it and you've got yourself a composite material so today we're going to find out if these three additives actually make the resin better or if they just look cool spoiler alert the graphite powder looks absolutely fantastic and thank you to eligo for sponsoring this video you know doing these sorts of experiments always comes with the risk of breaking things so it's great to have a bit of backup there i'm using the elegu mars ii pro and the mercury curing and washing station which is a fantastic combination and if i had used elugu's water washable resin cleanup after the experiments would have been a lot easier too when you can just use water instead of isopropanol to get things clean check them out at the link below so we're gonna try three different additives today the first one is maybe the most obvious one which is chopped glass fiber so this is three millimeter long chopped strands and the idea is this is going to get distributed randomly throughout the material so that it kind of randomly and evenly invoices um your your base material your resin in this case the next one cotton maybe is not so obvious or so intuitive ah so this is this is raw cotton flakes and this is also commonly used for making you know pastes or reinforcing concretes or resins or you know whatever you want to throw into it and the good thing is this is fairly non-aggressive you can see a bit of dust but it's just it's just cotton it's not like it's aggressive glass fiber the idea with cotton is that it's fairly fine fibers and it's a good mix between like longer continuous fibers and shorter strands that can fill in the gaps in between so this should be able to squeeze into each layer height of our resin prints the last one is graphite and this is a bit of an oddball graphite is a fairly common film material for resins and you know other materials like that but it is not specifically made to improve strength now i'm hoping maybe it's going to change the impact resistance and improve that but one of the cooler things that this claims to do is to make your resin conductive so it says you know adding one percent by weight is gonna make it electrically conductive we're gonna test that so i started out my experiments with the cotton as a filler because i felt like that was the like the friendliest the least aggressive uh filler i could put into the resin i always went about this in the exact same way i started with a 150 grams of the elegu standard clear photopolymer resin not the more impact resistant abs like one but just the standard sla resin that they have then i measured in a certain percentage of my fill material and stirred it all well with this magnetic stirrer until it was well evenly mixed up so my first attempt was five percent of cotton by weight and let me tell you seven and a half grams of cotton doesn't sound like much but it is a huge amount by volume and it did actually create quite a messy end product as far as you know how the resin ended up looking the magnetic stirrer was barely able to make it through anymore and it did look kinda gross so honestly at that point i didn't think this was going to be printable so i stepped down to 0.25 percent cotton one tenth of concentration and that actually makes in really easily so at that point you could barely see that there was any sort of additive in there and the only indicator that this was not just plain resin was that the tiny air bubbles that got introduced from the magnetic stirrer um actually lingered a lot longer than what you would expect if it was just plain resin this is basically kind of underwater canopies that the fiber is forming that's trapping the bubbles in there so to fix that i got myself a vacuum chamber and a vacuum pump obviously i did have to go for the clear youtuber edition uh typically these are like steel pots with a transparent lid but what's the fun if you can't actually see what you're doing watching the degassing process of the resin is quite fascinating because it does rise up quite a lot i didn't quite get all the bubbles out all the time but the ones that remained were always at the very top layers so in the printer the bed would just squish them aside and it was printing bubble free resin so speaking of printing i printed all these parts on the elegu mars 2 pros that i have one of these is the damage and shipping version but it still prints fine and because the mars 2 pro has a monochromatic lcd screen the prints will finish a bit faster than on a standard sla printer and i have two so in case one of them breaks i can still continue printing with the other one and not kind of have to revalidate all my results prints were done with the default print settings which means a three and a half second layer exposure time and 50 micron layers after that the prints were washed in the elegu mercury plus in a mix of ethanol and ipa typically you'd use ipa but ethanol works just as well and it's a bit more commonly available i washed these parts attached to the bed for eight minutes and then did four minutes of curing on one side flipped them over and did another four minutes of curing after that this is well on the higher side of the curing time i just wanted to make sure that you know whatever additives i add into these materials they're going to get cured all the way through to the core and it didn't want to change settings for different additives and after that the parts were done and ready for testing um there was still a bit of fluff left on the cotton parts but that is very easily rubbed off and actually it kind of makes the parts feel soft which i do actually like but in the case of cotton if you needed to get rid of these you could probably just burn them off with a with a torch or something after that i continued on with the cotton experiments and just you know you reused the resin and added more and more cotton to it until i felt there was a point where it might not be printable anymore that point for me felt like it was around one and a half percent by weight and at that point you can definitely tell that there is stuff added to the resin and it's not really flowing that well anymore you know it wasn't turning into this nasty cougar slush at this point yet in all cases the cotton reinforcement seemed very evenly distributed throughout the parts still next moving on to the graphite powder and would you look at that look just just look at how this i mean it's probably hard to convey on camera on a 2d image but it's got this 3d holographic effect to it which looks amazing in person i mean just this effect by itself already makes graphite worth a try this looks fantastic [Music] [Music] for the graphite i went with a 0.5 one and five percent of concentration by weight and all those still looked like resin just you know darker one thing to note about adding graphite to resin is that by the time you degas at those bubbles that form also look amazing like i don't know what it is about graphite but it's just it is so beautiful the bubbles that you see when de-gassing graphite filled resin are just so colorful they're shimmering in all sorts of different shades uh if one of you knows how that happens and what the cost for that is let me know in the comments below i'd really be interested in learning what causes that so graphite with point five percent by weight and one percent to an extent printed pretty much perfectly um five percent did give me some issues and the larger ben test test piece didn't come out properly one thing to note though is the lower concentrations of graphite actually produce a darker shade of anthracite or gray black kind of tone whereas the five percent concentration one is almost silvery glossy to an extent these do not really rub off in a black graphite kind of weights it's really well encased but from an optical side of things these do look very different to get the five percent concentration graphite mix to work i tried using a profile that i made that has higher lifts longer cured times and slower movements but that also didn't give me an improvement over the standard profile and the pen test like i said i don't have for the five percent one because it didn't print so one thing to note with the one percent graphite prints as well is that they seem to have these sort of burn marks on them uh this is the bottom layer so i'm thinking because some of the graphite may have settled down this just had way too much graphene in that first layer and ended up peeling off but that's something that i only saw in the 1 graphite print so for practical use i would probably say that the half percent of graphite is already on the high side of things now for the chopped fiber if you take a look at the fibers in this macro shot you can see that they're fairly large bundles of what looks like individual fiber strands i was hoping that these bundles would separate into like individual fibers that didn't really happen so i still ended up with a very coarse mix of the larger fiber bits and the resin itself also because these chopped fiber bits are so large they do settle out incredibly quickly it just takes a couple minutes until they're all at the bottom of your resin now there was a bit of a problem with this as well and that is that i did not get a single successful print with these chopped fibers i just thought okay maybe these fibers just stack on top of each other and press the bed too far away from your lcd and the fep film so that it doesn't properly cure and i was like well this is maybe just not working until i tried to reprint a set of unreinforced just plain resin test parts which also didn't print thing is this printer right here this one has a bit of a smashed lcd screen turns out you know these stir bars that i use for the magnetic stirrer um one of them dropped into the vat i home the printer onto it and i was like why isn't this homing well i guess i just need to re-level the bit yeah i was driving the bet against this disturb or right into the lcd and obviously the lcd had no choice so this one is kind of broken now so i mean that is absolutely not the printer's fault i feel a bit bad for breaking the lcd like that but you know in my defense uh you know if your resin vat looks like this it's pretty easy to like miss one of these little stir bars in there so after that i switched to the second mars2 pro i redid the tests with two and a half percent cotton added in that printed almost well i redid the test with the two and a half percent um chopped fibers added in at that point i had run out of the regular clear resin so i had to use some leftovers but this is the same type of resin so it should be fairly comparable but yeah at that point i had all my prints done and i was ready to move on to testing but before we move on to testing let's actually give that claim a look of you know whether graphite makes these resins conductive so let me try this right here let me grab a piece of this is five percent if you know if one of these is conductive then it should be the five percent graphite one this is on resistance metering and let's just go ahead and poke it in about three millimeters apart and there's nothing i mean if i touch my fingers to it that's more conductive than the material itself so i think oh yeah i'm making a quite a quite a good dent there and that's the same that i saw in any of the testing that i did before this the graphite does not seem to make this sla resin conductive in any way that you would call conductive i did see a you know roughly in the mega ohm range uh resistance when i poke those probes into the liquid resin but that is a level of conductivity that maybe is helpful for getting rid of some static charge but it is definitely not conductive in a way where you could actually use this to carry any sort of current or data so for these tests i printed two different types of test specimen the first one that you saw is the izod impact test this is a 1x1 centimeter bar with a defined notch in there and it gets inserted into this holder then the hammer swings and breaks that and by looking at how far that hammer swings back up after it has broken the probe we can see how much energy was absorbed so if i swing this without anything in there you can see it makes it just past the zero millijoule absorbed mark and if we absorb any sort of energy in there that is not going to swing up as high the other type of probe that i have is this bend test that i've been using for years now basically this gets loaded sideways i hook a scale into this and i measure at which force this breaks and this tests um tensile strength compressive strength and shear strength all in one test and kind of gives me a combined number for that and i find that this is fairly representative of what real world loads your part is gonna see so yeah let's get testing some days [Music] hey and if you're liking these sorts of videos and experiments make sure to get subscribed just one click thanks and here's the results now for the parts with the highest amount of fibers or additives added in it was already pretty clear that these wouldn't have a massive improvement in strength if at all because they were already kind of falling apart right out of the printer with this much fiber added in the layers didn't really bond all that well in the printer anymore so those were pretty obvious but still none of these tests actually showed a significant improvement over just regular old plane resin now what did surprise me though was how quickly the strength dropped in the impact tests any amount of fiber added into these parts significantly decreased the impact resistance of the material i don't know maybe there is something going on where there are micro cracks forming around the fibers and that kind of pre-break the part i don't know i don't have an electron microscope to actually verify it in any way now specifically with the chopped fibers the strength dropped a lot and i think this is kind of similar to what we're seeing with the continuous fibers in the last video on this topic in this case i think there's also just not enough of the chopped fiber in the material to give an even improvement in strength and if i would add more it would not be very printable anymore so what we're seeing is that there's just blotches of very strong and rigid bits in the material where there's the fiber added in and then right next to it there's bits where there is no fiber in it at all and that just creates a huge stress concentration right there but that has me thinking one of the potential materials that could still be tested is milled carbon fiber which is a really fine carbon fiber powder almost would this actually be able to make the strength of these materials any better at all or would we have to add in so much of that milled carbon fiber to a point where the resins or the resin slush that we're trying to print with is not going to be usable in the printer anymore is there like a minimum amount of fiber that we have to add to actually get an improvement and not just to create those those stress concentrations i don't know i'm not a material scientist and i don't have the background knowledge about composites to actually make an informed judgment on whether that's actually going to help or not but if you know more about this than i do please let me know in the comments below the graphite actually ended up being the most predictable material in the way that the more i added the weaker the parts got i would think that these are cured all the way through you know the resin feels the same in the center as it does on the outside but you know graphite probably just isn't your first choice when it comes to actually making these parts stronger but it is actually the material that i think i'm going to be using the future again just because it looks so nice maybe you know with a 0.1 percent of graphite added to your prints you could get that 3d effect back you know with five percent that's a bit too much it's just a metallic gray but you know if you just add a really low amount of graphite this could be very nice metallic kind of 3d depth effect to your parts and of course when you just add so little of the filler it just prints like a standard resin one thing that could be cool with this graphite is that it might be slightly self-lubricating i've not tried that but you know as it wears down it should expose a few of the graphite particles that do lubricate whatever is rubbing against it so if you're looking for something like that that might be an option but still i don't seem to be able to improve the strength of these resins no matter what i add to this so far every experiment has made the parts weaker and not stronger i guess that's a testament to how strong just your plain oh this is actually the cotton filled one but whatever it's a testament to how strong the plain resins already are because it's just a single continuous part with no layer separations or anything like that but i still want to know if a fiber reinforcing resin is doable at all in an sla process so if you've experimented with this or you know if you have any suggestions for materials i could add again let me know in the comments below i read all of them but still even if it doesn't make the parts any stronger you know we're still finding materials to add that make the parts prettier and that is worth something as well if you enjoyed the video and want to see more like it make sure to get subscribed and if you super like this channel you can support me on patreon thank you for watching keep on making and i will see you in the next one bye ah

Channel: Thomas Sanladerer

Views: 98,994

Keywords: 3D printing, Tom's, 3D printer, RepRap

Id: BQWV12kIy6E

Length: 18min 17sec (1097 seconds)

Published: Fri Mar 05 2021