Пікірлер

• 
  @MdRaqibulHasanPrince2 сағат бұрын

  May I know where did you get this worktable? I need a similar one. TIA

• 
  @Anton-zb9dc2 күн бұрын

  Hey, but what about pressing hard with the thumb on rohacell foam, will there be a visible dent left or not. What about pressing with fingernail?

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  @AhilMohan13 күн бұрын

  Have you tried the grid as an internal layer?

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  @ExploreComposites10 күн бұрын

  I haven't. My concern is that it would be very hard to get the top layer of fabric to go up and over each rib gracefully without a lot of bridging. A short-fiber chopped reinforcement might work well though.

• 
  @AhilMohan9 күн бұрын

  @@ExploreComposites Ah true. The bridging, at the expense of a little extra weight might add significant torsional rigidity (much like bead rolling on a flat automotive panel). Hopefully vacuum bagging will minimise the effect. Might be worth experimenting with

• 
  @rolkling119 күн бұрын

  XPS foam has a coating on it due to the manufacturing process. That coating should be removed via sanding or hot wire so the epoxy will form a good bond.

• 
  @AHMuzik21 күн бұрын

  Can you help me? Do you know the name of the material at 0:40 in this video? Thank you very much! kzread.info/dash/bejne/payJtdOPXcTJfqQ.htmlsi=r1apnNRr3bbs2PlC

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  @wagnerjose2345Ай бұрын

  What is the viscosity of this polyester resin?

• 
  @raptordad6653Ай бұрын

  Do you ever conduct mechanical testing of the samples you make?

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  @ExploreCompositesАй бұрын

  Not really, but I'd like to. The problem is that doing mechanical testing right takes a lot of work and some equipment I don't have. I do a little core shearing in a newer sample - #43b - but it's nothing special!

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  @eevox680Ай бұрын

  Can you machine this piece?

• 
  @ExploreCompositesАй бұрын

  It would machine nicely with the right cutters. I have machined many similar pieces...

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  @hannesaltenfelder4302Ай бұрын

  Please make a video on how to calculate carbon fiber layers when you have a 3dimensional oart with different thicknesses like an orthotic in-sole (flat at the front, individual at the middle and rather thick at the end).

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  @ExploreCompositesАй бұрын

  What about the layers do you want to calculate? Analyzing a tapered or contoured part can be a bit of work - is it the composite properties you're after?

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  @hannesaltenfelder4302Ай бұрын

  @@ExploreComposites no, in my case it is just the fitting/shape of the part. I would like to precut the layers and with an easy shape like a cube, this would be rather easy (lots of squares). But how many? And when I have like an organic landscape shape, do I need to have a CAD model and slice it in layers? Or could a plaster model, grinded down work as well as an template? And finally my most important question: is there an upper limit for compressing fibers? Could I (theoretically) press 100 layers under a 300 tons press or at which point would the fibers break. Because I saw a video, where they tried to break a (cured) carbon fiber cube under an hydraulic press with many, many layers and they could not break the cube.

• 
  @TraqrАй бұрын

  ... So any comments on bulk CTE after nearly a year? I'd imagine most of the strength & rigidity comes from the woven outer plies, and 18% fiber volume means 82% resin in the core - could have a substantial CTE impact unless that's the uncompressed figure?

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  @ExploreCompositesАй бұрын

  You're right, there's a lot of resin and the carbon mat does act a lot like a core. Even at 18% FVF, the carbon probably keeps the CTE low but it is hard to know how much the uniform face plies are doing the work. I'd shoot for about 1/3-1/2 the thickness in structural face plies and use the recycled mat as a core to increase thickness and stiffness of the tool shell. It can be a challenge to wet through though, so testing is important and slow filling helps. Resin is still cheaper than carbon but not by as much!

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  @zardiwАй бұрын

  You didn't roll the core to get air out........part of your problem..........Z

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  @ExploreCompositesАй бұрын

  I think you're right - though I would have had to start from one edge and work across. Without any holes through, the air would only be able to escape if worked all the way across the surface to an edge.

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  @N0body247Ай бұрын

  XPS foam is a polystyrene foam. Epoxy as we all know is exothermic meaning that it generates heat. Foam and heat do not mix . That being said. There is a way that you could’ve done it if you would’ve used a penetrating epoxy with a slow hardening on the foam And put it in your vacuum sealer and basically allowed that to cure with just the epoxy, sanded it, and then add your other substrate with your fiberglass, obviously sanding to create a mechanical bond, you would’ve not had delamination. It would’ve been a solid structure way more solid than you did.

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  @ExploreCompositesАй бұрын

  This is interesting - the way it failed looked very much like failure of the foam, but if your penetrating epoxy could get a better (deeper) grip, maybe it would be tougher. Usually penetrating epoxies have very low viscosity and that helps make them penetrate - do you think this would help here? Thanks!

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  @TariqKhan-77Күн бұрын

  @@ExploreComposites FINNFOAM has been used to make at least 2 boats, believe deeper penetration of epoxy helped but really vacuum infusing it is the way to go, only that would cause it to deform under pressure.

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  @CCROSS5882Ай бұрын

  I don't like it! LOL great work Chris

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  @ExploreCompositesАй бұрын

  Me neither Jerry, me neither! Thanks!

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  @cochorrorshow1005Ай бұрын

  If I've just did a layer of laminating polyester fiberglass, when can I add another layer of laminating polyester fiberglass without having to sand? Between 0 minutes and 24 hours, will I be fine?

• 
  @ExploreCompositesАй бұрын

  A good rule of thumb is "after it has hardened and cooled off and as long as it's still tacky on the surface - best not to go more than a day or two". Depends a ton on the temperature, resin type, humidity and probably lots of other stuff.

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  @user-qv6zo7dm2o2 ай бұрын

  I need job please i have 10 years experience on this field. Fiberglass

• 
  @CarlosChavez-gs1ld2 ай бұрын

  The close up shots at various times of the video were really good- very informative- thanks.

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  @kaboom-zf2bl2 ай бұрын

  i wonder if 4.5 to 5 o of resin would have worked better on each side ...

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  @kingofherdaz78602 ай бұрын

  Why do you not use full vacuum?

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  @ExploreCompositesАй бұрын

  I think I was trying not to push too hard on the top skin - to avoid pushing the fiber down into each honeycomb cell. Not sure it would have happened anyway - Kevlar isn't sure stretchy! For bagged wet layup half vacuum is often plenty.

• 
  @vevenaneathna2 ай бұрын

  uhmwpe next? thanks for uploading. feel like there is somthing special about combining aramid and polyeth

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  @ExploreComposites2 ай бұрын

  I'd love to learn more about uhmw polyethylene fiber - do you mean like Spectra or Dyneema? Do you know where I could find more information about aramid/uhmwpe hybrid fabrics?

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  @vevenaneathna2 ай бұрын

  @@ExploreComposites google this S0734743X15001773

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  @vevenaneathna2 ай бұрын

  okay when you said "we are relying on the resin to form little fillets in the honey comb", that made no sense to me, like it would make tiny little cut away's, but then i thought of the auto cad symbol for fillet and instantly knew what you were talking about with that right angle bond lol. wait is fillet vs fill-ey a different word or just different pronunceations? lol

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  @ExploreComposites2 ай бұрын

  I guess it can be spelled with one or two L's depending on where you're from. I'd say "fill-ay" for a piece of a fish and "fill-it" for an inside radius thing.

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  @vevenaneathna2 ай бұрын

  ​@@ExploreComposites :p found a super cheap source of g10 0.5mm, 40 cents a slice as lifepo4 battery insulation sheets. more videos on that please if you get the time =] thanks for your time

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  @jamincorrodi80842 ай бұрын

  Do you think this would make a quality backing plate/solid core replacement in a PE hand layup vs G10? Say a solid glass core section under a windlass or stanchion.

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  @ExploreComposites2 ай бұрын

  Sure, especially if you need a really big or odd-shaped piece when G10 gets less cost effective and practical. Also look into Coosa / Penske / Airex PXc high density core. Also aluminum backing plates and just dropping core out of the laminate in that area - though you'll probably want to thicken up the 'glass too. Infusion maximizes fiber content, but a hand-laid plate would be ok too and maybe cheaper - certainly easier.

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  @vincentwidjaya92332 ай бұрын

  Apa yang terjadi jika tidak menggunakan kain flow ?

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  @jasonbaker98622 ай бұрын

  I feel like this would be great for filleting instead of cotton flock.

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  @ExploreComposites2 ай бұрын

  The fibers are really long and might be too hairy and clumpy to cut a decent fillet of a normal size. You can buy shorter chopped/milled carbon - 1mm or so - that might make decent fillets if mixed with silica or some other filler.

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  @bitsurfer01012 ай бұрын

  Can you buy just the PMI foam offcuts?

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  @ExploreComposites2 ай бұрын

  It is a hassle to buy a small amount of Rohacell - and $$$! These were from a job I worked on long ago where we used quite a bit of it.

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  @charlesfrench9083 ай бұрын

  Thank you

• 
  @xAdapt3 ай бұрын

  how would you add a non compressible mounting point somewhere on the panel? is a hole drilled in the foam core and filled with graphite powder mixed with resin or some sort of metal insert better? do i need a specific kind of graphite powder? i'm building a front splitter for a car that needs to withstand substantial downforce

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  @ExploreComposites3 ай бұрын

  Drilling and backfilling with filled resin works. It needs to be a sizable fill completely touching each skin. Core can be dug back with an L-shaped tool in a drill. You can also mold it in with G10 of carbon plate if location is predictable. G10 tubes work well for through fasteners as compression bushings too - sized right they can be tapped too. Assuming carbon because you say graphite filler (silica filler is good too) but aluminum inserts or tapping plates are common with glass laminates but no good long term with carbon.

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  @wouterhendriksen40993 ай бұрын

  @ExploreComposites how do you estimate core bonding resin uptake of the foam? cant seem to figure it out

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  @ExploreComposites3 ай бұрын

  You really have to test to be sure, but estimating the volume of perforations and flow grooves is pretty easy if you measure with a caliper and do lots of multiplication. Plain foam surfaces take up resin inversely proportional to density of the foam because high density core has smaller cells. Nothing like a few square meters of test panel to get it figured pretty well including surface flow and feed lines.

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  @markwashington24123 ай бұрын

  What’s the reason for glassing the mold?

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  @ExploreComposites3 ай бұрын

  Mostly so the mold will be air tight and the vacuum bag will work. It also helps support the fairing and primer.

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  @OffGridOverLander3 ай бұрын

  I’m curious how it would perform with the same core thickness in LW-PLA. Obviously I would use the foam core for strictly flat panel layups, but LW-PLA might work great for curved surfaces in aviation. Maybe this idea could be done in episode 49/50?? This idea could work great for having replaceable panels, kinda like fenders, hoods, or doors, on aircraft to make repairs easier.

• 
  @ExploreComposites3 ай бұрын

  Thanks for the suggestion! I have been wanting to try LW-PLA for a while but hadn't considered it for a core. Next time I order filament I'll try to get some. Could probably be printed as a skinned honeycomb and just get laminated over with a light layer of fiber on each side...

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  @OffGridOverLander3 ай бұрын

  @@ExploreComposites For an outside skin on aircraft or cars I don’t think the comb would be necessary. For stringers and ribs I would use 3D formed reinforcement, like half a circle to hopefully match up with some carbon tube. I haven’t drawn it on F360 yet but that’s how I’m imagining it in my head. I’m thinking carbon tube for transferring loads between 3d printed panels and along the fuselage.

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  @szekerespista37584 ай бұрын

  Two sheets of 0,5mm carbon fiber on each side, instead of Kevlar, would be more stronger?

• 
  @ExploreComposites4 ай бұрын

  Stiffer maybe, and stronger in some ways - but not as resistant to hammers! Carbon might also have long term galvanic issues with the aluminum core. But yes, carbon would be a more practical and common choice here.

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  @szekerespista37584 ай бұрын

  @@ExploreComposites OK, thank you for your response!

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  @putramelanthing78014 ай бұрын

  how much the fiberglass weight ?

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  @ExploreComposites4 ай бұрын

  This is 6oz / 200gsm e-glass.

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  @MaartenOosterbaan4 ай бұрын

  guessing u meant 40 grams, not 40 kilograms...? no way that bit of nomex was 40kg...btw, any reason why you would do both sides of carbon in 1 go?

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  @ExploreComposites4 ай бұрын

  I meant that that piece of Nomex is of a density that is 40kg per cubic meter - but yes, the little piece is light! And the reason to do both sides it to see how it comes out... which in this case isn't ideal.

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  @MaartenOosterbaan4 ай бұрын

  that makes way more sense indeed...I actually meant to ask was why do both sides separately and not 1 on lay-up? @@ExploreComposites

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  @ExploreComposites4 ай бұрын

  @@MaartenOosterbaan I was trying to get two "finished" sides - but I only got two pin-hole filled but flat sides. With honeycomb cores and thin skins, the bag side laminate gets pushed into the holes in the honeycomb leaving a dimpled (and rough from peel ply) surface. Also resin in the "top" skin can drain out into the honeycomb cells leaving the laminate dry.

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  @MaartenOosterbaan4 ай бұрын

  ah, ok...well better to be safe than sorry...no cheap materials...@@ExploreComposites

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  @julianlauterfeld62734 ай бұрын

  My porosity problems seam to occur because of the bleeding of the resin into all the areas that are under vacuum. Do you have any tips regarding that?

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  @ExploreComposites4 ай бұрын

  I am not sure I understand the exact issue - does too much resin bleed out, or is it migrating under the bag to places you don't want it (where?) leaving dry areas? A couple of ideas: 1. Perforated release film (hole patterns can sized vary by product) is necessary for limiting bleed. Laps should only be 10-15mm (1/2"). 2. Use less vacuum - half or even less can be plenty to consolidate. 3. Allow resin to start to gel (slightly) before pulling vacuum. Some wet-layup resins specify a time to first compaction or some other thing - so the resin isn't sitting uncured and very liquid for a long time under vacuum. 4. Sometimes you are best off dividing a lamination into multiple curing steps - especially if there is core or things are complicated.

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  @julianlauterfeld62734 ай бұрын

  @@ExploreComposites thank you very much for the detailed response. I will try your Tipps in the next laminations. Thanks again

• 
  @ubacow71094 ай бұрын

  Do you have a video on the different properties of diff honeycomb core materials like aluminum, nomex, polyprop, etc...

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  @ExploreComposites4 ай бұрын

  No videos, but some general core data here: explorecomposites.com/articles/design-for-composites/basics-cored-structures/

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  @ubacow71094 ай бұрын

  Thanks! @@ExploreComposites

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  @wellscampbell98584 ай бұрын

  I built a couple of surfboards with XPS, wet layup e-glass and epoxy. I used a couple of techniques to encourage good skin bonding, like a row of 10-12 exacto blades to score grooves, and initially it was ok but they all delammed eventually. My understanding is that XPS has around 10 percent polyethylene added. This keeps it from sticking as it's extruded. It also keeps anything from actually chemically bonding to the foam, so physical bonding helps. Over time it seems to lose it's grip, perhaps because cycling slowly breaks all the weak surface bonds that initially stuck to the PE. Another issue is that it's closed-cell enough to trap air pockets that will expand with heat and grow with cycles. Too bad, that foam's physicals are really good. Thanks and the library is awesome!

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  @ExploreComposites3 ай бұрын

  Thank you for the information about XPS - I didn't know about the PE added or consider the trapped air expansion risk. I came off as pretty down on it in this video, but only because I was trying to get more from it than it can offer. If you're building super light stuff with little risk of impact - it can be great!

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  @noe6164 ай бұрын

  This is a complicated and long process that is only applicable to aerospace work. The waste is considerable and certainly can't be considered a green process.

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  @ExploreComposites4 ай бұрын

  Oh for sure! So much composites work is very wasteful especially as things move up the performance/weight curve. It is a fundamental problem that needs lots of attention and effort!

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  @TurbineResearch5 ай бұрын

  Do you use spiral wound tubing on the outlet as well as the inlet ?

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  @ExploreComposites5 ай бұрын

  Yes, my arm kind of hides it but it the spiral is fit over the tube for the last foot or so. It is probably overkill here but is a good inexpensive solution when you have room for a decent sized resin/vacuum break to keep resin from just rushing into the vacuum outlet side.

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  @SomeGuyInSandy5 ай бұрын

  Shot in the dark here, but here's my question - The vacuum regulator you show @10:43 ... Is that a hydraulic flow valve? It looks a lot like one.

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  @ExploreComposites5 ай бұрын

  You are right - it is a hydraulic flow control and says "Parker Par Trol PN600B -40BT" and "MAX 2000 PSI" which is more than vacuum is ever going to give it. I don't recall where I got it from, but it was part of something I bought used because I never purchased it by itself or even considered what it might be besides a vacuum regulator. Thank you for making me learn!

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  @SomeGuyInSandy5 ай бұрын

  @@ExploreComposites Most excellent reply! Thanks! edit: I found one similar on eBay - Thanks for confirming that. That's one more piece of the puzzle!

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  @hannesaltenfelder43025 ай бұрын

  kzread.info/dash/bejne/X5Zmks9vetG_ac4.htmlsi=jJDHl4CBRDTKtJUv What kind of material would you recommend for these boots?

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  @MontanaBallistics5 ай бұрын

  “See air through” lol. Light. A couple of tips, firstly you didn’t use nearly enough epoxy. Second, after you’ve gotten it uniform, don’t try to mash it down. Just put the first piece of plastic on top, then roll it out. Pick up the plastic and make sure you don’t see any air lol. If you do see through, put a few shreds on, place plastic back down and roll again. Repeat until uniform. THEN, vacuum seal.

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  @ExploreComposites5 ай бұрын

  Air - didn't notice that - come to think of it, I see air everywhere! Your idea about squishing between plastic and checking for uniform coverage and adding more as needed is great! I've never made anything this way before and was really just playing around to see. All my "chopped carbon" stuff has been prepreg or infused/injected so you saw me being pretty clueless here. Your advice is always welcome - thank you!

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  @mustafamahimid52825 ай бұрын

  Sehr gut

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  @FredBlair-bk4cf5 ай бұрын

  Not very strong really a speed record holding aircraft from California was built using this very same foam in the wings so get your bloody facts straight 😢

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  @ExploreComposites5 ай бұрын

  Always happy to be wrong - do you have any more info? Was it a core or a semi-structural bit of leave-in-place tooling?

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  @kennyhill80655 ай бұрын

  i have a Dresser vacuum pump DC2 high volume oil pump. I am having trouble finding the info on the required oil type? What should i be looking for in a oil. My unit looks low and want to flush and replace. Thanks

• 
  @ExploreComposites5 ай бұрын

  I’m no expert here - use what the manufacturer suggests if you can find it. Not much out there on a Dresser DC2 though! Most (rotary vane) vacuum pump oil is ISO68 viscosity mineral oil and unless you’re using a special pump generic vacuum pump oil should work ok. You won’t likely ruin the pump with the wrong oil but it may not last as long or work as well.

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  @KoalityofLife6 ай бұрын

  Thank you. This is just the video I have been looking for. Took about a month to find this video but it answered my question about making a boat out of purple foam. :)

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  @markthomasson50776 ай бұрын

  I used XPS as a foam core in a few windsurfing boards. They were exceptionally light and lasted very well. I did use on of the denser grades. I would not hesitate in using this again. It certainly is worth considering for other uses, say a small dinghy / yacht tender. I would not use it for the main structure on a yacht, but for non critical parts, perhaps. Particularly if you were after good insulation, for the least cost

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  @ExploreComposites5 ай бұрын

  I haven't found an easy source for higher density XPS, but I bet it would work pretty well even at 2-3 pound density. Compression strength and peel-resistance is probably closely correlated with density. Hoping to try some out soon!

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  @davidcoupalbergeron26 ай бұрын

  I wonder if the dust is dangerous like silicium and amiante

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  @ExploreComposites5 ай бұрын

  It isn’t good! Cutting dry fiber in direct sunlight is always an eye-opener - lots of little glass or carbon “sparkles” floating around. Dust mask or respirator is a good choice. Not asbestos (amiante) level dangerous though.

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  @ulperformance40876 ай бұрын

  Wouldn't it have been better to achieve a far stiffer panel to have first vacuum bagged one layer of cloth with the tows, wait for cure, sand and remove the tow dust, lay down the second layer of cloth independently, wet it out and then lay the toed panel over it and then vacuum bag it a second time? You lost flatness of the second glass cloth layer by putting it over the toes.

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  @ExploreComposites6 ай бұрын

  I'm not sure I agree that it would be stiffer, but it would be more work! And I'm with you that nothing here is optimized for stiffness and the glass is flat on one side and wavy on the other. Thickness will drive stiffness - so stacking tows up or putting the glass in the middle would help - a little. Here I wanted to see how infusing in one shot would work and what it would look like. Imagine the carbon tows more load-oriented in any actual structure made this way.

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  @wombatau7 ай бұрын

  Which did you prefer generally overall using, epoxy or vinyl ester? Do you find that the vinyl ester is as strong and lightweight as a middle-of-the-road epoxy equivalent? Also why did you run 300mbar? Thanks and great videos

• 
  @ExploreComposites6 ай бұрын

  I like epoxy because I've got much more experience with it - but VE is sometimes easier to deal with. Hard to tell the difference between epoxy and VE infused parts unless you consider color or smell - epoxy is probably tougher in general but high quality VE is excellent - and gelcoat is easy. Shrink can be a hassle though and skin coats are heavy. Here I kept the vacuum up to minimize the risk of resin components (styrene, MEKP, moisture other volatile stuff) boiling off and making bubbles. This is a pretty common thing with PE and VE - you don't need all the pressure differential (you still need a leak-free system) with low viscosity resin and as vacuum approaches complete (0 mbar, 29.9 inHg, etc) all kinds of vapor pressure/gas bad behavior stuff happens at even room temperature. Common to pull full vacuum for a bit on larger parts and back it off during the infusion itself and clamp off at a lower vacuum level.

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  @SONO4B11T7 ай бұрын

  Are multiple cooks possible ? Like consolidating the skins first and then adding the film with honeycomb... Especially in the context of complex shapes.

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  @ExploreComposites7 ай бұрын

  Yes, that would be the typical way to make anything complicated or requiring better outer-skin compaction. One challenge can be keeping very light skins in the mold while you fit core /cook and outer skin. Often parts are kept vacuumed into the tooling with a perimeter seal feature after the first skin is cooked to prevent pre-release.

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  @SONO4B11T7 ай бұрын

  @@ExploreComposites Random question, what kind of core do you think they use in MotoGP to make carbon fibre swing arms ? I want to try to make own, off the shelf aluminium ones are expensive. Thanks for the response.

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  @ExploreComposites7 ай бұрын

  @@SONO4B11T I have no idea, but for high end competition parts like that I would guess any core is probably Rohacell or similar, but that parts like that may be mostly solid except in the open web areas where there is flat-ish panel. Core can be a liability of parts like that with lots of varying stresses and torsional loads. I am sure that carbon is going to be more expensive than aluminum when tooling and engineering is considered. And the connection details where metal hardware interfaces with composite are a concern...

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  @jeremiahkemnitz22187 ай бұрын

  Thank you