The graphite bubble color is "structural coloration". Unlike a prism, where white light splits due to changing speed between mediums, here the size of the particles is comparable to the wavelength of light and parallel rays will constructively or destructively interfere causing the light to split. It is like a diffraction grating you might have played around with or a grating wavelength selector in spectroscopy.
Is there an explanation of how there seems to be a kind of orientation going on? e.g. 6:45. When mixing different parts of the resin they seem to have a state or common orientation. Or is that just different settling of particles?
Integza, have you tried encasing ceramic resin in sand while kilning it to keep heat equal throughout the part and reduce warp? I have done that with other materials...
Great video. Since inconsistent curing from settlements can weaken a print, we recommend using a thicker, tough resin as the base for this type of experiment. This way, the materials do not settle too quickly, and you have a very strong resin to start to stay functional. Happy to get you some Blu or Tenacious to play.
@@csakip That's surprising, I wonder if his theory on the micro bubbles and cracks is what's causing it. Maybe in a pressure chamber or something the bubbles would be minimized.
@@Rocketkid2121 I think it would be basically too late after you have already printed the part. You would need it to be in the pressure pot before it becomes cured.
@@shelltoe_soul I agree, I know that wouldn't be super easy to pull off and maybe not worth the effort, but it just seems counterintuitive that the fiber would weaken the print, and that test would possible eliminate bubbles as the culprit. Possibly UV resin doesn't bind well to glass?
I would say with injection molding one can start at 15 to 20%weight. The major difference might be that rather short fibers are used and not large pieces like 3mm long. My understanding is that something like milled fibers (carbon or glass) might work similarly to the way it works in injection molding.
@@gutrali On materials I worked with we bought the pellets already made, you want abs-GF30 you buy abs-GF30 pellets so they are even already mixed during batching ^^ You can mix longer ( a few millimeters) fibers in the barrel but it requires special coatings and geometries as I recall so as to dont break the fibers
@@gutrali fibers like the ones he usess are bonded with styrene, sobthe resin needs to be able to dissolve styrene to be able to soak in to the fibers properly.
One thing to note: Short fibers are useless for strength or structure. However, I believe by adding the short fibers to your resin, it may have a larger impact on ABRASION resistance, than adding strength. Being in custom/restoration/collision for 30 years, when I have to fix an older Corvette door I use the long strand glass mat for structure then a shorter fiber/filler mix to cover any hard edges before applying a finish putty before primer and paint. USC Duraglass, and a product called Fiber-all are basically body fillers with short strand glass fibers pre mixed in. I use them sometimes where chipping might be a problem, like a corner or edge of a door for example, where the panel doesn't line up perfectly to the next panel. Hope this helps. Been subscribed since I bought my Wanhao i3 v1.2 back in 2015 (currently rocking an SKR 1.4 and 2209's), and since have upgraded the poop out of it thanks to more than a few of your videos and tutorials. I have a Mars 2 Pro also and found this video very interesting and educational. Cheers from the USA!
Hey man, great video! If you want to achieve a truly mechanical reinforment of your SLA resin you have to add functionalized fibers/particles. Functionalization of fibers/particles improves the chemical affinity between the fiber/particle and the polymer matrix. You can purchase functionalized fibers/particles ready to use or you can functionalize them yourself (using a silane coupling agent). Cheers
Hi Thomas, great job. Your videos are inspirational. Btw, I am a materials eng. Scientist. Is a long time that I don't get into the polimers side, but as you analyzed, add fiber or other materials can deteriorate the properties because a lack o bound between the matrix and the aggregate. It not necessary forms micro cracking around but can help the cracking propagate faster on the aggregate material surface because it's is not properly bounded. Most composites have a mix of polimers or other compounds that helps bound the matrix to the aggregate, same principle of soap and water to remove fat. Let me know if you need more information about it.
I've printed cycloidal gears with graphite additives, also adding a small amount of flex filament to 10%. Makes for a very strong part that is partially self lubricating and tough. The flex adds more strain relief albeit at the sacrifice of rigidity- but that slight flex is great to make up for the slop and inaccuracy of the print.
I like the music montage of the stress testing. I never cared to watch each and every test. One test filmed to show the procedure, yes, but then cut to the results. Your presentation was very enjoyable to watch. I wish more people would film this way.
Tom I've been watching you for years. I very much appreciate that you're on the same track I am, for me a particular print that I am trying to make stronger for someone. Before I saw your video for the last time you added fiberglass I was at the beginning of my adventure and that time the only glass fiber reinforced prints I saw was someone making a shell and then filling with epoxy mixed with glass fibers. I am very appreciative to see that the first test with glass blankets was not that good in strength. Saved me from the mess. I had just boughten chopped glass fibers and received them when I came across your video and was like "damn it someone beat me to it". but I appreciate you going through all the messy stuff and displaying your results saves me a lot of headaches and I just want to say thank you. Also, I never thought of cotton. Brilliant! Also the graphite I want to try now. thank you for the wealth of knowledge you have shared over many years.
These results make sense...the strength of resin comes from the cross-linked polymer chains. Any foreign fibers you're adding just means there are fewer of those chains, and those fibers are stronger when locked together than chopped up and mixed with a foreign substance. The graphite did look cool though.
I very much appreciate tech creators who also show failures, not just success after success. That's the engineering/scientific process. Good engineers/scientists have a high tolerance for failure, building on it rather than giving up. It is often the failures in pursuit of a goal that create spin-offs enabling entirely new directions and new goals. Such as adding carbon for color and perhaps lubrication, rather than for strength.
@@RinksRides yeah. Didn't think about that properly. Still can't be good for the display, vat or noise level. Is the fan in the mars Pro 2 as loud as the fan in the mars?
Great Video Thomas...you ask about the reason why the filled parts are loosing strength...most fillers in a resin binder system need an additive that allows the resin to bond to the surface of the filler. Otherwise, as you have shown...the properties will suffer. One of the more common families of bonding or coupling agents is silanes from Dow Chemical...depending on the resin, the particular coupling agent is chosen for a particular filler...I formulated 2 part spray-able polyurethanes and polyureas that after leaving the spray gun would be dry to the touch in just seconds. Your other problem is likely you need a Much Higher shearing action of the reinforcing materials far beyond what a magnetic stirrer can provide...they are fine for liquid to liquid mixing, but Do Not really totally wet out the surfaces of the filler to liquid interface. Thus, first you need to find the proper coupling agent for the fiber and polymer, second use a High Speed Disperser, and finally vacuum out all of the air bubbles. Keep up the Great Work!!!
It's only a theory, butI believe the fibers will impede the ability of the resin to fully cure by occluding the light paths to all areas of the resin. The masked resin is left to cure partially with refracted light from the subsequent layers. I'm not a composite expert, but I've been around materials a lot, and have some related experience.
The problem is that in a composite material, the purpose of the resin matrix is to transfer load from one fiber to the next. If you don't add enough fiber, you're just introducing impurities and therefore reducing strength. And you can't add enough fiber and still have a successful print with the way that lcd/sla printers operate.
I really enjoyed watching the video. I can imagine how messy those tests must have been. As this video was recorded two years ago, it would be great to see how the new generation of resins would perform. Without mixing anything additives into them, but mixing resins with each other.
Hours and hours spent to make this. Awesome Science-ing. Mind you it has given me clues for resin printing. I was so keen to cut over to Resin printing for the absolute beauty of the outputs, snag is the parts are not tough enough for me.
The best method of reenforcement I've found is likely not what your looking for. But when I need strength, I print with a hole though the part and use an epoxy resin to secure a metal rod inside.
Don't these fibers / additives primarily bond properly only in one layer individually? If so, they may add strength in that one particular layer if the fiber is ideally oriented, but as any fiber not laying perfectly flat and being fully contained inside that layer, would now be stiffened and protrude from that layer, it will push against the bottom film when coming down to do the next layer, and would drastically _weaken_ the layer bonding to the next. So parts will fail due to a rapid cascade of individual layer breaks and delaminations. We have to keep in mind about mechanics when trying to reinforce prints, that SLA is still individual layer by layer creation. That will require a significantly different approach to (filler) reinforcement, than casting and injection molding.
Very cool experiments, thanks for showing your results! My one contribution as someone with a materials science/mechanical engineering background is to remember that there are still more mechanical properties than strength. A lot of times composites represent a tradeoff between stiffness and strength, where you increase the stiffness over the base resin/matrix, but make it more brittle. This would reduce the energy absorbed during impact. With the short fiber systems, though, you tend not to see much increase in strength, particularly at low volume fractions, because you don't have enough load "continuity" for lack of a better word. In long/continuous fiber systems, for example, even when the matrix fails, the fibers can still bear load. Here, there's enough space between fibers that failures can just propagate through. I'd also agree with other comments that improper bonding/wetting between fiber and resin could contribute. Could be interesting to look at in future tests. Doesn't require an electron microscope, just a decent power optical. You can even experiment with the $20 or so digital microscopes to see what kind of images you can get.
I once made epoxy resin reinforce with carbon nano tubes, in several concentrations, it did not improve the tensile strength but they where more conductive.
So, I just watched Tech Ingredients' video on making graphene, and he showed an impressive increase in the bending resistance strength by putting a tiny amount of graphene in some epoxy resin. Of course, one of my first thoughts is if this could be used in UV resin. Would love to see you do a video on this!
Great Video Thomas! I never tried a resin printer, but I have some experience with glass and carbon fibers. I think some other fillers could also be interesting. There are for example glas micro balloons with 0,12 g/cm^2 and a particle size of just 65nm to make very light weight components. To reinforce the resin a good try could be to mix milled glas fibre (0,2 mm) and finer cotton flocks (0,35 mm fibre length). Some fumed silica like Aerosil could also help to thicken the resin, that the chopped fibers don't saddle down to the bottom. It looks a bit like, that the chopped fibers in your prints are not completely wetten, normally they should get very transparent in the resin.
The graphite results with regard to visual appearance and potential for self-lubrication are definitely interesting. Worth keeping in mind. Loved the music/stress test montage. You are definitely stepping up your video productions.
Nice methodical approach. I found your videos because I wondered about adding fiber materials to the resin mix to improve strength. I would repeat some of the experiments using "tough resin", which has ground rubber mixed in to reduce the brittleness. Use a squeeze bottle to blow a little milled carbon in the first 5 and last 5 layers. Blowing will confine the carbon to the outside layers while keeping the inner layers almost pure resin. It will create a stronger skin on the outside.
Light is reflected from the outer surface and the inner surface of the bubbles, As the thickness is very thin,there is a difference in the refraction angle and it forms a miniature prism effect. Love the experiment.
Yes, this is what limits how opaque 3D printing resins can be, and why a solid black (for example) isn't really possible from what I've seen. You need to get enough light through (say) 50 microns to cure the layer.
@@michaelnoble2432 yes and no, light absorption is also wavelength dependent. However since most use 405nm it's kinda hard to have something that's really dark. There are blacks that are close though and depending on special use cases a very dark resin for a special printer could be made.
If you want to improve the mechanical properties of your resin parts, you can do two things. 1.) Print at an elevated temperature of 25°C-35°c 2.) Cure under water (prevents oxygen to inhibit the curing process) + cure under hot water (heat equals vibration, vibration helps in the bonding process between the molecules during curing). Both of those measures should help significantly (About +50% more strength) Adding anything to the mix weakens your parts since those molecules can not bind properly anymore and have to bridge a gap because of the "impurities" you have now introduced. Fiber reinforcement works well with epoxy resins because those don´t need UV light to cure, properly mixed they will always bond to anything.
I'm close to buying a resin printer and is still learning about them before my purchase. My main hobby is RC cars/trucks, where we use dry wall to reinforce the body shells, and of course most knows that the higher quality cars always have a composite plastic used. Maybe this would be your source of information? I have for some time tested parts for a manufacturer and the character of the parts significantly changed depending on direction/amount of fibers used. But the key secret is that the fibers are overlapping so the force can't slip through, but still in a small amount that the parts still have flexibility. Great videos as always Thanks you
I work for a National Laboratory and 3 years ago we tried Graphite and/or Iron filings in the resin of a Laser SLA printer to try and see what concentration (if at all) it would take to get conductive/magnetic properties out of a 3d printed part and determined really quickly that at higher concentrations the slurry becomes to tick to work with the printer and at the maximum saturation point that does allow the prints to work the resin acts like an insulator at a microscopic level and simply will not allow a continuous current to run through it.
Not a materials engineer either, here; but, you can think of what you're doing as creating inclusions in the resin. Inclusions in metal causes the metal to fracture over time in certain conditions. If the particles you are mixing in are larger than the particulate size of the material making up the resin, you may or may not get a good bond. Remember, in fiberglass for example you are working with a woven cloth base that already has strength in and of itself. By incorporating simple fibers, you don't have the strength you tend to get from weave. And if you aren't careful with the resin application, it won't soak through the weave - leaving voids and leading to delamination. Love seeing you do these tests tho. This is the core of the hacker experience - test, experiment, learn. And good to see Siraya Tech chiming in. Though it does make me wonder if approaching this with a fine weave material at each layer or every so many layers would make a difference. Food for thought. Something like silk...
the colors on graphite bubbles are caused by an effect called *thin film interference* , where basically light passing through the upper and lower part of the bubbles interfere with one another enhancing the reflected light.
Freaking love my elegoo. Been mdf printing for years but avoided sla because I'm very allergic to IPA. But saw the water washable resin and jumped in. Been printing non stop for a couple weeks now.
The reason for the "holographic" effect you saw in the graphite resin is that the flakes of graphite are orienting themselves with the flow of the liquid, so that their reflective surfaces are tangent to its flow - creating what is known as a "rheoscopic" or current-showing effect. In the bubbles, I'm pretty sure what's happening is the super-fine particles of graphite are causing an effect called thin-film interference, where the reflected light from the top and bottom surface of the material are different wavelengths and start to interfere with one another, causing those wild colors to emerge. The same effect is visible in soap bubbles to a milder degree
Yep, confirm what many people say here. Milled fibers or glass spheres are usually used as reinforcement. Large chunks of GF in small quantities are just useless. Hoping to see the update to this experiment. Also, GF should be mixed by volume, not weight. Try 30 to 50%
I was hoping you'd mention the lubricating effects of resin, glad you said something at the end. It makes me think of oil impregnated bushings. In addition to that, I'm very curious about thermal conductivity of those graphite parts. We messed around with some plastics at work filled with something and I want to say it was graphite. Although they lost flexibility, they had a very "cool to the touch" feel and that's exactly what we were going for. Trying to get thermal transfer improvements through the part.
Tom, I reckon that the graphite is so opaque that it's not letting the UV through the outer shell of the part to properly cure the inner. That could explain why adding more makes the part weaker.
You should try cotton and fiberglas at the same time. The cotton makes the resin thicker, so the fiberglas can stay chaotic in the resin and doesnt sink to the bottom and stay flat. But maybe the printsurface squeeze everythink down and flatten it. Thats why a bigger resin container could be needed. So the fiberglas mixture can easier flow to the side and back after the printsurface goes down and up.
That was a brilliant test montage! 👍 These experiment videos are so good, they explore concepts I never would have otherwise come across, thank you Tom! 💙💜
Nice video, suprising results! Maybe cleanroom wipes as material? Either chopped up or in layers. Those are a bit like paper towels, but specifically designed to not shed particles and are extremely strong in one direction. So if you criss-cross the layers it might result in a really strong part.
Not sure if it's been mentioned. I use resin as a filler/primer by mixing it with sodium bicarbonate, about 40/60 and it helps the resin thicker and stays suspend quite well. It could help hold the heavier filler/additives.
The glass fibers are clumped together because they're coated in something called a sizing agent. Sizing agents are essentially coatings that cover the fibers. Because glass fibers are chemically inert they will not bond with any kind of resin or epoxy matrix. These sizing agents have two fold benefits, they allow for this chemical bridge (aka a coupling agent, for glass fibers it's typically a silane) to bond to matrices and add a protective layer to the outside of the fibers for easier handling. They also bond the fibers together, that's why its so hard to pull the individual fibers apart, they're essentially glued together. That being said you can just sonicate the fibers to loosen and separate them.
I think a lot of the problem with this is that, while the particles (cotton and chopped fibre especially) are adding strength to each layer, they are only adding strength within that layer. Because of the way SLA builds the object, you're not getting any cross-links between layers, so it is exactly as strong as a normal object in unenhanced resin.
When you start your print hook up a pwm as it prints out so that when it prints out with the graphine/graphite, there will be a line for the electricity to follow
After degassing, if you VERY briefly blow hot air over the top of the liquid from either a heat gun or torch, you will get rid of the bubbles on the top.
Ferrous and Nonferrous metal powders are available in various micron sizes. Also, some mica powders glow in the dark and have color shift. It would be really cool to see the properties of copper powder, aluminum powder, silica, ceramic and color shift mica powder.
I'd be really interested in seeing additional testing with both the milled carbon fibre powder you mentioned, as well as a more fine glass particle powder. These are the two materials I've been thinking about testing myself recently, and I feel like have the best chance of improving the material properties in some way. I have personally been interested in these two materials to help improve rigidity more so than ultimate strength, in order to create lightweight, thin, yet rigid and still acceptably durable materials. Something I've seen on the topic of the glass powder specifically is Formlab's Rigid series of resins(Both their Rigid 10K and 4000), which are claimed to be glass reinforced resin. Specifically for their Rigid 10K, they claim "Simulates stiffness of glass and fiber-filled thermoplastics" and describe it as "This highly glass-filled resin is the stiffest material in our engineering portfolio.". This to me seems to suggest that it's likely just a simple glass powder mix, which also leads me to believe other suitable materials(specifically milled carbon fibre) mixed using a similar method should produce good results. This along with a strong base resin such as some of the engineering resins from Siraya Tech like Blu, I think could potentially produce some nice results. Great videos by the way, love them, keep it up :) I'm excited to see what other tests and videos you create in the future.
The form 2/3 has a fibre filled resin. I think u need small chopped strands. Large enough to connect or bind resin to increase strength but small enough to mix evenly to stop stress concentration
Please try sonicating the additives into the resin (or a compatible solution that can be added to the resin)! Sonicators are essentially ultrasonic mixers that produce a colloidal dispersion. In the case of graphite, it may also cleave into graphene, liberate bucky balls or nanotubes, etc. For chopped fiber, the bunches may separate, though milled fiber would probably be better. No idea what cotton would do. Let’s test it!
Hi Tom. Gr8 video. The reason the graphite bubbles are shinny is probably due to thin-film interference. Also if you want try out graphene (1-3%) should do the trick. I suggest you make it yourself, just buy a ultrasonic cleaner, get some graphite electrodes from zinc-carbon batteries and a bit of ammonium sulphate (common fertilizer).
I never did any experiments with resin prints but I have used imbedded needles or piano wire in FDM prints. I guess you could print channels into the parts and and pull long strands of fibres covered in epoxy through these holes. Or even take it further and print a thin walled mould in resin and then fill it with resin and fibres afterwards. The final part would benefit from the shape of the printed part and the more controlled placement of fibres.
I used paint with graphite added to make prints conductive for electroplating. After painting you need to brush it with iron wool to make it conductive, to expose the graphite Maybe you should try that on your prints
Another great video, thanks... a sugestinon is to use microbaloons, (for ligther pieces), a ligther piececould be a great caracteristic depending where is use the part
I think a great idea to test is trying to print on higher temperatures. Heat the vat and print and see how it affects the part. Bc polymer chains would usually be longer under higher temperature, and the material might be slightly better in terms of strenght, heat resistance etc.
I like the visual effect of the graphite. I wonder what it would look like if you were to use some of the pigments that they use in poured resin tables, coasters etc.
The colored bubbles look like interference between the light being reflected by the outer and inner surfaces of the bubble's wall, which boost a certain frequency depending on the wall's thickness. I think the reason why these are visible is that the graphite is accumulating at the interface between resin and air, which makes for a partially reflective surface
Have you tried heat soaking any parts? Form Labs has a process to do that. It supposedly allows the bonds to increase from migration and post curing of semi cured resin.
Did you consider trying a mix of the glass and cotton or carbon and cotton. You can make the cotton conductive first then add it. I would suggest pausing the print with normal resin and adding only a little bit in midway(with a brush I think)
Realistically, if you want even distribution while avoiding the particle settling out, it may require a mechanical contrivance to add a measured amount of fibers to the part/vat after each exposure
Interesting. You may be on to something here- It's clear to see by far the most homogeneous of these is the graphite mix, so that's out for strength, but what about 3d printing a mold in 2 parts, pour some well mixed chopped fibre and cotton in (don't use the stir bar it's super ineffective, lollypop sticks are the norm for mixing resins, pigments etc into molds and use a very thin application of mold release like vaseline), then using UV to cure it. Demold and test one more time? The mold needs to be really thin and have an exposed open top to allow the UV to penetrative the test part, all it needs to do is hold its shape.
The most popular additive for improving tensile strength is probably Siraya Tech Tenacious resin. Everyone seems to have their own preferred ratio. I'd love to see this kind of rigor put to testing different ratios. Maybe you can get Siraya Tech to sponsor a video.
I really wanna try to make a continuous fiber laying tool for my doot changer but i'm tired and lazy and doubtful i could get it working, specially with my tools and skill! BUT THIS IS WHy i love this channel so much :D awesome video!
Interesting idea for Thomas: Make replaceable Gibs for a dovetail mill out of graphite infused resin. As the resin is worn away the nodules of graphite can act as dry lube for the mill ways
So about the electrical conducitvity, you can estimate the overall conductivity of a composite by using the rule of mixtures. In essence, it states that the composite will have (if properly mixed and other idealization) an electrical resistivity equal to [volume percent of graphite]*[resistivity of graphite]+[volume percent of resin]*[resistivity of resin]. So a five percent (volume?) of graphite means (resistivity of graphite and resin in ohm per meter based on Google searches of similar materials in Ohm*m): 0.05*[resistivity of graphite]+0.95*[resistivity of resin]= 0.05*10^-5+0.95*10^15 ~= 10^15 = rho So due to the high resistivity of the resin the resistance should still be high (note Resistance = rho*length/area)
On the colourful bubbles, I think another explanation is that bubbles are just always colourful (from interference on the thin layers) and the dark graphite behind it just provides good contrast.
Just another comment in all the ideas thrown out here. Your chop glass fiber has what is called sizing applied to it to keep the fibers in their shape. Manufacturers use different sizing for different resins.. As an example most chop glass matt is sized for polyester resin and will not work with epoxy resin because it won't properly dissolve the sizing. It may pay to contact the filler manufacturer and try to identify a product with sizing compatible with your resins. Other interesting fillers to try.. West Systems 404 High density filler and Cabosil aka Fumed Silica. I've use both in composite work. Fumed Silica is primarily a thickener so I wouldn't expect it to add much in strength.
For conductivity specifically, what about copper powder? It could be really interesting if you're actually able to print what'd effectively be a skeleton of a copper-resin trace to inset into something else
Tom: Cotton can’t possibly have (that) much higher tensile strength than the base resin, but mixed well and ‘wets out’ and functionally prints. Maybe just try milled Kevlar or similar. Resin compatible Wetting agent around fiber I hear is also critical. Also, pretty sure you must use high shear (speed) mixers to blend any fiber additive; try a blender. I think the scale of your fibers need be closer to the cubic exposure volume of the machine (layer height being limiter) . So: probably Nanometer rather than millimeter. Also you need similarly to keep the fibers in suspension at all times.
The main goal for my prints is to have impact resistance. So in a way I'm thinking making the resin softer rather than "stronger" Perhaps some kind of soft material like rubber or the silicon powder from makeup would create a finished print that would flex slightly instead of snapping when hitting the floor.
Maybe experiment with creating an emulsion between the resin and something such as mineral oil so that you can better suspend the particles in the mixture. I would also suggest trying materials with particle sizes (diameters) similar to the layer height. Specifically, I think microballoons would be a good thing to test.
An idea that comes to mind would be either wood dust, or very fine shavings to get fibers along the grain. The wood theoretically should allow the light to pass through for full curing, and the wood fibers should add strength. Some tests with hardwoods, such as Oak, Teak, or Maple, and softwoods, like Pine, Spruce, or Bass, would be neat to see. Maybe the particles would allow the resin to be stained or such for purely visible effects as well. I would assume it would work similar to the cotton, but the fibers would be stronger by weight, but would still suspend in the resin due to the buoyancy.
I don't know about these chopped fibers specifically, but for CSM (chopped strand matting) at least there is a binder keeping it together. This binder must be dissolved for the resin to bind to the fibers. So for instance CSM made for polyester resin will not work well with epoxy resin, because the epoxy does not dissolve the binder, but CSM made for epoxy resin works just fine. So maybe you want to try different solvents on the glass fibers, to see if you can get rid of the binder before you mix it to the resin, and try again.
The graphite bubble color is "structural coloration". Unlike a prism, where white light splits due to changing speed between mediums, here the size of the particles is comparable to the wavelength of light and parallel rays will constructively or destructively interfere causing the light to split. It is like a diffraction grating you might have played around with or a grating wavelength selector in spectroscopy.
1. Excellent and accurate explanation.
2. Your last name is perfect, especially with the high VanderWaal forces at play in graphite.
@@42436freak all my chemistry professors got a kick out of it too
This physicist is glad someone posted a better explanation than because bubbles
I think Steve Mould did a video on this recently...
Is there an explanation of how there seems to be a kind of orientation going on? e.g. 6:45. When mixing different parts of the resin they seem to have a state or common orientation. Or is that just different settling of particles?
I love this kind of experimenting! Also you need to try ceramic resin
Integza, have you tried encasing ceramic resin in sand while kilning it to keep heat equal throughout the part and reduce warp? I have done that with other materials...
THAT TURBO JET WAS SO COOL~!!
cant wait to see the v2, soon people are gonna make homemade jet aircraft lol
Try to hammer some tomatoes with your shock device.
hmmm, i wonder why you want him to test ceramic resin in particular, lol.
@@josephgauthier5018 to make a more powerful engine of course!
Great video. Since inconsistent curing from settlements can weaken a print, we recommend using a thicker, tough resin as the base for this type of experiment. This way, the materials do not settle too quickly, and you have a very strong resin to start to stay functional. Happy to get you some Blu or Tenacious to play.
would you also support him mixing different resins with tenacious to get the ultimate engineering blend?
Thanks for the tips - I'll let you guys know know when I'm back at doing resin experiments!
@@MadeWithLayers So far I go with 30-50% Tenacious in Elegoo ABS-like for impact resistant NERF parts, but that's trial and error.
@@globalrevolution we will be happy to. Blu 70% + Tenacious 30% seemed to create a good balance between impact resistance and hardness
@@sirayatech2 30-40% Tenacious seem to be a good spot
Really liked the cinematics during the break test clips.
Give milled fiberglass a try instead of chopped fiber, it looks similar to the cotton you used, its a common filler with composites.
FLOX... pretty easy to mix in too.
Tried it, it makes it weaker too.
@@csakip That's surprising, I wonder if his theory on the micro bubbles and cracks is what's causing it. Maybe in a pressure chamber or something the bubbles would be minimized.
@@Rocketkid2121 I think it would be basically too late after you have already printed the part. You would need it to be in the pressure pot before it becomes cured.
@@shelltoe_soul I agree, I know that wouldn't be super easy to pull off and maybe not worth the effort, but it just seems counterintuitive that the fiber would weaken the print, and that test would possible eliminate bubbles as the culprit. Possibly UV resin doesn't bind well to glass?
In most injection molded parts with glass fiber there is at least 30% fill. Most structural composite layups are at least 50% fiber
I would say with injection molding one can start at 15 to 20%weight. The major difference might be that rather short fibers are used and not large pieces like 3mm long. My understanding is that something like milled fibers (carbon or glass) might work similarly to the way it works in injection molding.
Seems pretty obvious the fibers need some treatment first -- as they are melted and mixed together before the injection mold. Right?
@@gutrali On materials I worked with we bought the pellets already made, you want abs-GF30 you buy abs-GF30 pellets so they are even already mixed during batching ^^ You can mix longer ( a few millimeters) fibers in the barrel but it requires special coatings and geometries as I recall so as to dont break the fibers
@@gutrali fibers like the ones he usess are bonded with styrene, sobthe resin needs to be able to dissolve styrene to be able to soak in to the fibers properly.
One thing to note: Short fibers are useless for strength or structure. However, I believe by adding the short fibers to your resin, it may have a larger impact on ABRASION resistance, than adding strength. Being in custom/restoration/collision for 30 years, when I have to fix an older Corvette door I use the long strand glass mat for structure then a shorter fiber/filler mix to cover any hard edges before applying a finish putty before primer and paint. USC Duraglass, and a product called Fiber-all are basically body fillers with short strand glass fibers pre mixed in. I use them sometimes where chipping might be a problem, like a corner or edge of a door for example, where the panel doesn't line up perfectly to the next panel. Hope this helps. Been subscribed since I bought my Wanhao i3 v1.2 back in 2015 (currently rocking an SKR 1.4 and 2209's), and since have upgraded the poop out of it thanks to more than a few of your videos and tutorials. I have a Mars 2 Pro also and found this video very interesting and educational. Cheers from the USA!
Hey man, great video!
If you want to achieve a truly mechanical reinforment of your SLA resin you have to add functionalized fibers/particles. Functionalization of fibers/particles improves the chemical affinity between the fiber/particle and the polymer matrix. You can purchase functionalized fibers/particles ready to use or you can functionalize them yourself (using a silane coupling agent). Cheers
Hi Thomas, great job. Your videos are inspirational. Btw, I am a materials eng. Scientist. Is a long time that I don't get into the polimers side, but as you analyzed, add fiber or other materials can deteriorate the properties because a lack o bound between the matrix and the aggregate. It not necessary forms micro cracking around but can help the cracking propagate faster on the aggregate material surface because it's is not properly bounded. Most composites have a mix of polimers or other compounds that helps bound the matrix to the aggregate, same principle of soap and water to remove fat. Let me know if you need more information about it.
I've printed cycloidal gears with graphite additives, also adding a small amount of flex filament to 10%. Makes for a very strong part that is partially self lubricating and tough. The flex adds more strain relief albeit at the sacrifice of rigidity- but that slight flex is great to make up for the slop and inaccuracy of the print.
I would be interesting to see the LCD replacement process.
I would as well considering I picked up this exact setup today (machine and wash station)
I am excited to see a follow up for the other fiber-reinforced prints
I like the music montage of the stress testing. I never cared to watch each and every test. One test filmed to show the procedure, yes, but then cut to the results. Your presentation was very enjoyable to watch. I wish more people would film this way.
Tom I've been watching you for years. I very much appreciate that you're on the same track I am, for me a particular print that I am trying to make stronger for someone.
Before I saw your video for the last time you added fiberglass I was at the beginning of my adventure and that time the only glass fiber reinforced prints I saw was someone making a shell and then filling with epoxy mixed with glass fibers.
I am very appreciative to see that the first test with glass blankets was not that good in strength. Saved me from the mess.
I had just boughten chopped glass fibers and received them when I came across your video and was like "damn it someone beat me to it".
but I appreciate you going through all the messy stuff and displaying your results saves me a lot of headaches and I just want to say thank you. Also, I never thought of cotton. Brilliant! Also the graphite I want to try now.
thank you for the wealth of knowledge you have shared over many years.
Thanks! Glad you're getting something out of the videos!
When you use fiber glass you better remove the bonding agent with acetone.
Me: Maybe try glitter?
Katelyn: Hey, Evan - hold my beer...
Right
Haaaaaaaaaaaaaaaaam!
"Ham! Ham!"
These results make sense...the strength of resin comes from the cross-linked polymer chains. Any foreign fibers you're adding just means there are fewer of those chains, and those fibers are stronger when locked together than chopped up and mixed with a foreign substance. The graphite did look cool though.
I very much appreciate tech creators who also show failures, not just success after success. That's the engineering/scientific process. Good engineers/scientists have a high tolerance for failure, building on it rather than giving up. It is often the failures in pursuit of a goal that create spin-offs enabling entirely new directions and new goals. Such as adding carbon for color and perhaps lubrication, rather than for strength.
Man, the editing during the testing was A++!
Some one has been watching project farm.
I was waiting for the "We're gonna test that" t shirt to pop out of nowhere.
@Greg Tubby that guy is incredible
At 8:30.. maybe lock your vat down?
Just what I thought 😂. Layershift incoming.
I saw that too. And have done that too.
@@scruffy3121 no layer shifting, it's not the build plate moving around.
@@RinksRides yeah. Didn't think about that properly. Still can't be good for the display, vat or noise level. Is the fan in the mars Pro 2 as loud as the fan in the mars?
Exactly :-)
I absolutely love graphite powder, I combine with epoxy resins all the time when casting
Great Video Thomas...you ask about the reason why the filled parts are loosing strength...most fillers in a resin binder system need an additive that allows the resin to bond to the surface of the filler. Otherwise, as you have shown...the properties will suffer. One of the more common families of bonding or coupling agents is silanes from Dow Chemical...depending on the resin, the particular coupling agent is chosen for a particular filler...I formulated 2 part spray-able polyurethanes and polyureas that after leaving the spray gun would be dry to the touch in just seconds. Your other problem is likely you need a Much Higher shearing action of the reinforcing materials far beyond what a magnetic stirrer can provide...they are fine for liquid to liquid mixing, but Do Not really totally wet out the surfaces of the filler to liquid interface. Thus, first you need to find the proper coupling agent for the fiber and polymer, second use a High Speed Disperser, and finally vacuum out all of the air bubbles. Keep up the Great Work!!!
It's only a theory, butI believe the fibers will impede the ability of the resin to fully cure by occluding the light paths to all areas of the resin. The masked resin is left to cure partially with refracted light from the subsequent layers. I'm not a composite expert, but I've been around materials a lot, and have some related experience.
The problem is that in a composite material, the purpose of the resin matrix is to transfer load from one fiber to the next. If you don't add enough fiber, you're just introducing impurities and therefore reducing strength. And you can't add enough fiber and still have a successful print with the way that lcd/sla printers operate.
I really enjoyed watching the video. I can imagine how messy those tests must have been. As this video was recorded two years ago, it would be great to see how the new generation of resins would perform. Without mixing anything additives into them, but mixing resins with each other.
Hours and hours spent to make this. Awesome Science-ing. Mind you it has given me clues for resin printing. I was so keen to cut over to Resin printing for the absolute beauty of the outputs, snag is the parts are not tough enough for me.
The best method of reenforcement I've found is likely not what your looking for. But when I need strength, I print with a hole though the part and use an epoxy resin to secure a metal rod inside.
Say more… you make a hole in the model and then fill it with resin? Is that the idea ?
@@kaltland765 More like use the epoxy as a glue for metal rods
Don't these fibers / additives primarily bond properly only in one layer individually? If so, they may add strength in that one particular layer if the fiber is ideally oriented, but as any fiber not laying perfectly flat and being fully contained inside that layer, would now be stiffened and protrude from that layer, it will push against the bottom film when coming down to do the next layer, and would drastically _weaken_ the layer bonding to the next. So parts will fail due to a rapid cascade of individual layer breaks and delaminations.
We have to keep in mind about mechanics when trying to reinforce prints, that SLA is still individual layer by layer creation. That will require a significantly different approach to (filler) reinforcement, than casting and injection molding.
Ive been adding stuff to my resin for months.. but you got to remember the way the layers work to get some nice effects for knife handles and models.
Very cool experiments, thanks for showing your results! My one contribution as someone with a materials science/mechanical engineering background is to remember that there are still more mechanical properties than strength. A lot of times composites represent a tradeoff between stiffness and strength, where you increase the stiffness over the base resin/matrix, but make it more brittle. This would reduce the energy absorbed during impact. With the short fiber systems, though, you tend not to see much increase in strength, particularly at low volume fractions, because you don't have enough load "continuity" for lack of a better word. In long/continuous fiber systems, for example, even when the matrix fails, the fibers can still bear load. Here, there's enough space between fibers that failures can just propagate through. I'd also agree with other comments that improper bonding/wetting between fiber and resin could contribute. Could be interesting to look at in future tests. Doesn't require an electron microscope, just a decent power optical. You can even experiment with the $20 or so digital microscopes to see what kind of images you can get.
I once made epoxy resin reinforce with carbon nano tubes, in several concentrations, it did not improve the tensile strength but they where more conductive.
So, I just watched Tech Ingredients' video on making graphene, and he showed an impressive increase in the bending resistance strength by putting a tiny amount of graphene in some epoxy resin. Of course, one of my first thoughts is if this could be used in UV resin. Would love to see you do a video on this!
Great Video Thomas!
I never tried a resin printer, but I have some experience with glass and carbon fibers.
I think some other fillers could also be interesting. There are for example glas micro balloons with 0,12 g/cm^2 and a particle size of just 65nm to make very light weight components. To reinforce the resin a good try could be to mix milled glas fibre (0,2 mm) and finer cotton flocks (0,35 mm fibre length). Some fumed silica like Aerosil could also help to thicken the resin, that the chopped fibers don't saddle down to the bottom. It looks a bit like, that the chopped fibers in your prints are not completely wetten, normally they should get very transparent in the resin.
The graphite results with regard to visual appearance and potential for self-lubrication are definitely interesting. Worth keeping in mind. Loved the music/stress test montage. You are definitely stepping up your video productions.
self-lubrication would actually be a fairly big deal. 3D printed/integrated bushings and thrust bearings were my first impulse.
Nice methodical approach. I found your videos because I wondered about adding fiber materials to the resin mix to improve strength. I would repeat some of the experiments using "tough resin", which has ground rubber mixed in to reduce the brittleness. Use a squeeze bottle to blow a little milled carbon in the first 5 and last 5 layers. Blowing will confine the carbon to the outside layers while keeping the inner layers almost pure resin. It will create a stronger skin on the outside.
I appreciate you runing all your equipment and free time to hopefully help me avoid doing so as well
Light is reflected from the outer surface and the inner surface of the bubbles, As the thickness is very thin,there is a difference in the refraction angle and it forms a miniature prism effect. Love the experiment.
8:30 The vat is moving up and down with the moving platform?! (See corner on the right) Did you forget to tighten the two screws?
Dorsnt the fiber impede the curing light from shining through? Especially the carbon I would think would absorb the UV
Yes, this is what limits how opaque 3D printing resins can be, and why a solid black (for example) isn't really possible from what I've seen. You need to get enough light through (say) 50 microns to cure the layer.
@@michaelnoble2432 yes and no, light absorption is also wavelength dependent. However since most use 405nm it's kinda hard to have something that's really dark. There are blacks that are close though and depending on special use cases a very dark resin for a special printer could be made.
This is what I thought. For sure the fibers must screws with the light curing the resin right?
If you want to improve the mechanical properties of your resin parts, you can do two things.
1.) Print at an elevated temperature of 25°C-35°c
2.) Cure under water (prevents oxygen to inhibit the curing process) + cure under hot water (heat equals vibration, vibration helps in the bonding process between the molecules during curing).
Both of those measures should help significantly (About +50% more strength)
Adding anything to the mix weakens your parts since those molecules can not bind properly anymore and have to bridge a gap because of the "impurities" you have now introduced.
Fiber reinforcement works well with epoxy resins because those don´t need UV light to cure, properly mixed they will always bond to anything.
You can get kevlar that is similarly fine to that cotton. May be worth a try...
I'm close to buying a resin printer and is still learning about them before my purchase.
My main hobby is RC cars/trucks, where we use dry wall to reinforce the body shells, and of course most knows that the higher quality cars always have a composite plastic used.
Maybe this would be your source of information? I have for some time tested parts for a manufacturer and the character of the parts significantly changed depending on direction/amount of fibers used. But the key secret is that the fibers are overlapping so the force can't slip through, but still in a small amount that the parts still have flexibility.
Great videos as always
Thanks you
I work for a National Laboratory and 3 years ago we tried Graphite and/or Iron filings in the resin of a Laser SLA printer to try and see what concentration (if at all) it would take to get conductive/magnetic properties out of a 3d printed part and determined really quickly that at higher concentrations the slurry becomes to tick to work with the printer and at the maximum saturation point that does allow the prints to work the resin acts like an insulator at a microscopic level and simply will not allow a continuous current to run through it.
Not a materials engineer either, here; but, you can think of what you're doing as creating inclusions in the resin. Inclusions in metal causes the metal to fracture over time in certain conditions. If the particles you are mixing in are larger than the particulate size of the material making up the resin, you may or may not get a good bond. Remember, in fiberglass for example you are working with a woven cloth base that already has strength in and of itself. By incorporating simple fibers, you don't have the strength you tend to get from weave. And if you aren't careful with the resin application, it won't soak through the weave - leaving voids and leading to delamination. Love seeing you do these tests tho. This is the core of the hacker experience - test, experiment, learn. And good to see Siraya Tech chiming in. Though it does make me wonder if approaching this with a fine weave material at each layer or every so many layers would make a difference. Food for thought. Something like silk...
the colors on graphite bubbles are caused by an effect called *thin film interference* , where basically light passing through the upper and lower part of the bubbles interfere with one another enhancing the reflected light.
I liked this video - seems different than most recent videos to come out recently - was getting tired of everyones printer reviews, thanks mate :)
Really love the SLA experimenting!
Freaking love my elegoo. Been mdf printing for years but avoided sla because I'm very allergic to IPA. But saw the water washable resin and jumped in. Been printing non stop for a couple weeks now.
Good to see that 5% of Colton made it into a print. :P
The reason for the "holographic" effect you saw in the graphite resin is that the flakes of graphite are orienting themselves with the flow of the liquid, so that their reflective surfaces are tangent to its flow - creating what is known as a "rheoscopic" or current-showing effect. In the bubbles, I'm pretty sure what's happening is the super-fine particles of graphite are causing an effect called thin-film interference, where the reflected light from the top and bottom surface of the material are different wavelengths and start to interfere with one another, causing those wild colors to emerge. The same effect is visible in soap bubbles to a milder degree
Yep, confirm what many people say here. Milled fibers or glass spheres are usually used as reinforcement. Large chunks of GF in small quantities are just useless. Hoping to see the update to this experiment. Also, GF should be mixed by volume, not weight. Try 30 to 50%
I was hoping you'd mention the lubricating effects of resin, glad you said something at the end. It makes me think of oil impregnated bushings. In addition to that, I'm very curious about thermal conductivity of those graphite parts. We messed around with some plastics at work filled with something and I want to say it was graphite. Although they lost flexibility, they had a very "cool to the touch" feel and that's exactly what we were going for. Trying to get thermal transfer improvements through the part.
Tom, I reckon that the graphite is so opaque that it's not letting the UV through the outer shell of the part to properly cure the inner. That could explain why adding more makes the part weaker.
You should try cotton and fiberglas at the same time. The cotton makes the resin thicker, so the fiberglas can stay chaotic in the resin and doesnt sink to the bottom and stay flat.
But maybe the printsurface squeeze everythink down and flatten it. Thats why a bigger resin container could be needed. So the fiberglas mixture can easier flow to the side and back after the printsurface goes down and up.
Dude, LOVE the editing in the montage for the testing!
Add metal fileings. Place resin vat in a magnetic field to line up the filings.
The field might mess with the screen used to cure the resin though, correct me if im wrong.
I plan on making bushings and gears with graphite. Guides as well. Great video.
That was a brilliant test montage! 👍 These experiment videos are so good, they explore concepts I never would have otherwise come across, thank you Tom! 💙💜
Nice video, suprising results! Maybe cleanroom wipes as material? Either chopped up or in layers. Those are a bit like paper towels, but specifically designed to not shed particles and are extremely strong in one direction. So if you criss-cross the layers it might result in a really strong part.
Not sure if it's been mentioned. I use resin as a filler/primer by mixing it with sodium bicarbonate, about 40/60 and it helps the resin thicker and stays suspend quite well. It could help hold the heavier filler/additives.
Which resin do you use to fill your model?
The glass fibers are clumped together because they're coated in something called a sizing agent. Sizing agents are essentially coatings that cover the fibers. Because glass fibers are chemically inert they will not bond with any kind of resin or epoxy matrix. These sizing agents have two fold benefits, they allow for this chemical bridge (aka a coupling agent, for glass fibers it's typically a silane) to bond to matrices and add a protective layer to the outside of the fibers for easier handling. They also bond the fibers together, that's why its so hard to pull the individual fibers apart, they're essentially glued together. That being said you can just sonicate the fibers to loosen and separate them.
I think a lot of the problem with this is that, while the particles (cotton and chopped fibre especially) are adding strength to each layer, they are only adding strength within that layer. Because of the way SLA builds the object, you're not getting any cross-links between layers, so it is exactly as strong as a normal object in unenhanced resin.
When you start your print hook up a pwm as it prints out so that when it prints out with the graphine/graphite, there will be a line for the electricity to follow
After degassing, if you VERY briefly blow hot air over the top of the liquid from either a heat gun or torch, you will get rid of the bubbles on the top.
Ferrous and Nonferrous metal powders are available in various micron sizes. Also, some mica powders glow in the dark and have color shift. It would be really cool to see the properties of copper powder, aluminum powder, silica, ceramic and color shift mica powder.
I'd be really interested in seeing additional testing with both the milled carbon fibre powder you mentioned, as well as a more fine glass particle powder. These are the two materials I've been thinking about testing myself recently, and I feel like have the best chance of improving the material properties in some way. I have personally been interested in these two materials to help improve rigidity more so than ultimate strength, in order to create lightweight, thin, yet rigid and still acceptably durable materials.
Something I've seen on the topic of the glass powder specifically is Formlab's Rigid series of resins(Both their Rigid 10K and 4000), which are claimed to be glass reinforced resin. Specifically for their Rigid 10K, they claim "Simulates stiffness of glass and fiber-filled thermoplastics" and describe it as "This highly glass-filled resin is the stiffest material in our engineering portfolio.". This to me seems to suggest that it's likely just a simple glass powder mix, which also leads me to believe other suitable materials(specifically milled carbon fibre) mixed using a similar method should produce good results.
This along with a strong base resin such as some of the engineering resins from Siraya Tech like Blu, I think could potentially produce some nice results.
Great videos by the way, love them, keep it up :)
I'm excited to see what other tests and videos you create in the future.
You tried graphite powder, but what about graphene powder?
The form 2/3 has a fibre filled resin. I think u need small chopped strands. Large enough to connect or bind resin to increase strength but small enough to mix evenly to stop stress concentration
Please try sonicating the additives into the resin (or a compatible solution that can be added to the resin)! Sonicators are essentially ultrasonic mixers that produce a colloidal dispersion. In the case of graphite, it may also cleave into graphene, liberate bucky balls or nanotubes, etc. For chopped fiber, the bunches may separate, though milled fiber would probably be better. No idea what cotton would do. Let’s test it!
What might be good to try for artistic looks is mica powders. They are used in resin projects but haven't seen in SLA.
Hi Tom. Gr8 video. The reason the graphite bubbles are shinny is probably due to thin-film interference. Also if you want try out graphene (1-3%) should do the trick. I suggest you make it yourself, just buy a ultrasonic cleaner, get some graphite electrodes from zinc-carbon batteries and a bit of ammonium sulphate (common fertilizer).
I never did any experiments with resin prints but I have used imbedded needles or piano wire in FDM prints. I guess you could print channels into the parts and and pull long strands of fibres covered in epoxy through these holes. Or even take it further and print a thin walled mould in resin and then fill it with resin and fibres afterwards. The final part would benefit from the shape of the printed part and the more controlled placement of fibres.
Love it! Please do more resin review videos, we would love to know which resins to buy as there are many confusing products out there.
I used paint with graphite added to make prints conductive for electroplating.
After painting you need to brush it with iron wool to make it conductive, to expose the graphite
Maybe you should try that on your prints
Another great video, thanks... a sugestinon is to use microbaloons, (for ligther pieces), a ligther piececould be a great caracteristic depending where is use the part
Look up epoxy thickener. Not only is there much finer fiberglass options but there are also other options that would be cool to test.
You can get specific fibres for re-enforcing concrete floors they're chopped fibreglass but single strands, not clumps like you used.
I think a great idea to test is trying to print on higher temperatures. Heat the vat and print and see how it affects the part. Bc polymer chains would usually be longer under higher temperature, and the material might be slightly better in terms of strenght, heat resistance etc.
„We're gonna test that!“ Getting strong Project Farm vibes here! 😄
I like the visual effect of the graphite. I wonder what it would look like if you were to use some of the pigments that they use in poured resin tables, coasters etc.
The colored bubbles look like interference between the light being reflected by the outer and inner surfaces of the bubble's wall, which boost a certain frequency depending on the wall's thickness.
I think the reason why these are visible is that the graphite is accumulating at the interface between resin and air, which makes for a partially reflective surface
Have you tried heat soaking any parts? Form Labs has a process to do that. It supposedly allows the bonds to increase from migration and post curing of semi cured resin.
Did you consider trying a mix of the glass and cotton or carbon and cotton. You can make the cotton conductive first then add it. I would suggest pausing the print with normal resin and adding only a little bit in midway(with a brush I think)
For the look and possibly for conductivity: please try metal powder. They're available down to 5 microns (at least in aluminium).
Keep going!
Realistically, if you want even distribution while avoiding the particle settling out, it may require a mechanical contrivance to add a measured amount of fibers to the part/vat after each exposure
Interesting. You may be on to something here- It's clear to see by far the most homogeneous of these is the graphite mix, so that's out for strength, but what about 3d printing a mold in 2 parts, pour some well mixed chopped fibre and cotton in (don't use the stir bar it's super ineffective, lollypop sticks are the norm for mixing resins, pigments etc into molds and use a very thin application of mold release like vaseline), then using UV to cure it. Demold and test one more time? The mold needs to be really thin and have an exposed open top to allow the UV to penetrative the test part, all it needs to do is hold its shape.
PUT the glass fiber in a blender to separate them, if it doesn't work heat them to destroy the binder. (Thank you so much for testing this!)
The most popular additive for improving tensile strength is probably Siraya Tech Tenacious resin. Everyone seems to have their own preferred ratio. I'd love to see this kind of rigor put to testing different ratios. Maybe you can get Siraya Tech to sponsor a video.
I really wanna try to make a continuous fiber laying tool for my doot changer but i'm tired and lazy and doubtful i could get it working, specially with my tools and skill!
BUT THIS IS WHy i love this channel so much :D awesome video!
Interesting idea for Thomas:
Make replaceable Gibs for a dovetail mill out of graphite infused resin. As the resin is worn away the nodules of graphite can act as dry lube for the mill ways
So about the electrical conducitvity, you can estimate the overall conductivity of a composite by using the rule of mixtures. In essence, it states that the composite will have (if properly mixed and other idealization) an electrical resistivity equal to [volume percent of graphite]*[resistivity of graphite]+[volume percent of resin]*[resistivity of resin].
So a five percent (volume?) of graphite means (resistivity of graphite and resin in ohm per meter based on Google searches of similar materials in Ohm*m):
0.05*[resistivity of graphite]+0.95*[resistivity of resin]= 0.05*10^-5+0.95*10^15 ~= 10^15 = rho
So due to the high resistivity of the resin the resistance should still be high (note Resistance = rho*length/area)
On the colourful bubbles, I think another explanation is that bubbles are just always colourful (from interference on the thin layers) and the dark graphite behind it just provides good contrast.
Just another comment in all the ideas thrown out here. Your chop glass fiber has what is called sizing applied to it to keep the fibers in their shape. Manufacturers use different sizing for different resins.. As an example most chop glass matt is sized for polyester resin and will not work with epoxy resin because it won't properly dissolve the sizing. It may pay to contact the filler manufacturer and try to identify a product with sizing compatible with your resins. Other interesting fillers to try.. West Systems 404 High density filler and Cabosil aka Fumed Silica. I've use both in composite work. Fumed Silica is primarily a thickener so I wouldn't expect it to add much in strength.
For conductivity specifically, what about copper powder? It could be really interesting if you're actually able to print what'd effectively be a skeleton of a copper-resin trace to inset into something else
Tom: Cotton can’t possibly have (that) much higher tensile strength than the base resin, but mixed well and ‘wets out’ and functionally prints. Maybe just try milled Kevlar or similar. Resin compatible Wetting agent around fiber I hear is also critical. Also, pretty sure you must use high shear (speed) mixers to blend any fiber additive; try a blender. I think the scale of your fibers need be closer to the cubic exposure volume of the machine (layer height being limiter) . So: probably Nanometer rather than millimeter. Also you need similarly to keep the fibers in suspension at all times.
What about small glass spheres? Or what about glass fibers, but in a powder like form?
The main goal for my prints is to have impact resistance. So in a way I'm thinking making the resin softer rather than "stronger" Perhaps some kind of soft material like rubber or the silicon powder from makeup would create a finished print that would flex slightly instead of snapping when hitting the floor.
Maybe experiment with creating an emulsion between the resin and something such as mineral oil so that you can better suspend the particles in the mixture. I would also suggest trying materials with particle sizes (diameters) similar to the layer height. Specifically, I think microballoons would be a good thing to test.
An idea that comes to mind would be either wood dust, or very fine shavings to get fibers along the grain. The wood theoretically should allow the light to pass through for full curing, and the wood fibers should add strength. Some tests with hardwoods, such as Oak, Teak, or Maple, and softwoods, like Pine, Spruce, or Bass, would be neat to see. Maybe the particles would allow the resin to be stained or such for purely visible effects as well. I would assume it would work similar to the cotton, but the fibers would be stronger by weight, but would still suspend in the resin due to the buoyancy.
I don't know about these chopped fibers specifically, but for CSM (chopped strand matting) at least there is a binder keeping it together. This binder must be dissolved for the resin to bind to the fibers. So for instance CSM made for polyester resin will not work well with epoxy resin, because the epoxy does not dissolve the binder, but CSM made for epoxy resin works just fine. So maybe you want to try different solvents on the glass fibers, to see if you can get rid of the binder before you mix it to the resin, and try again.