Digging through the archives trying to read everyone of Bert’s posts I found a snippet that shows how far off we are doing this “bag technique” Bert showed us in his thread… Both he and Greg must be either laughing or sitting there like proud parents watching all these little baghead crash dummies wallow in their new discovery. Kind of like watching your kids play around in the fluffy snow making angels while you are snowboarding down some black diamond crevass in Utah…
Any way here are the snippets which show how much further we need to go to get one of Bert’s ultra strong flex boards…
Quote:
yea i prefabricate my skins as well .in an autoclave style setup ,that way i can apply mach pressure without killing the boards ,i can get my resin to glass ratios from 6 to 1 for standard hand lay up , down to 1to 1 …as well as that ,the glass resin and wood become one coz of being pressurised together and heat pressed…
to give an example of how light i can get a board i can build a 9’ longboard just over 8 pound ,a standard shaped p/u blank weighs 10.5 pound …so basically i can get a finished board lighter than the foam inside a conventional board…
regards
BERT
4wood6 bottom,6wood6x6 deck plus reinforced rails and extra patches nose ,tail,foot areas,more glass less resin…go the vac ,flex without cracking…basically i have more glass in my decks than what you’d find in a whole standard board…
regards
BERT
Bert kind of makes my point. What he’s doing is not standard custom surfboard stuff. When I was working at Pro-Tech sailboards we did a similar lay-up to his. We would build the lamination core in the mold first. That gave us the opportunity to put a lot of heat and pressure on the exterior laminate. The interior EPS core would have never taken that kind of heat and pressure without melting. We would then slurry an oversized interior blank and close the mold in a hydraulic press. This gives an extremely strong/light finished product.
On the other hand, vacuum bagging an exterior laminate on a standard foam blank doesn’t save you much.
GREG
Kind of interesting…
Bert builds his sandwich skins seperately in an autoclave using RTM to control the ratio to 1:1. Then heat pressure adheres the pre-fab skins to the core. Probably doesn’t even use a bag anymore…
So the problems for us backyarders…
How do you finance and build your own autoclave to get the pressures and heat leavel required?
What do you build your mold out of to create these skins that will withstand all this heat and pressure, Steel?
How do you fasten your completed shells to your core with the needed heat and pressure required?
Can any of this be done without some for of manufacturing facility and what’s the $$.
Is this stuff just too dangerous to be doing in your residential garage shop?
The archives are a gold mine be neat to link it to some type of intelligent query engine like “ask Jeeves” where it could respond to these ongoing repetitive questions automatically like we can do with the automatic email support robots we use for customer or product support.
Anyway I guess its back to making angels in the snow for the most of us…
coz of being pressurised together and heat pressed…
i dont think you really need an autoclave to get berts results…and too much pressure will crush balsa…
interesting though…infusion…i saw an engineered wood floor sample yesterday that stated in the back “acrylic impregnated engineered wood”…a while back i posted something that went right over everyone’s heads…titled mad ozzy science…then there was the mystery pic…go with the flo bro
I’ve heard that Bert preforms the skins before but it didn’t hit me how incredible his technique is considering that that he makes CUSTOM boards!
if he uses molds and he makes custom boards does that mean he either has a mold that can conform to different types of boards, or he makes molds for each custom board, or what??
it really boggles the mind because I can’t imagine a mold that can adjust rocker, wide point, nose thicknes, tail thicnes, and whatever without compromising overall shape.
So if he makes a mold for each custom board, does he scrap it after each use?
Anyways, keep us guessing Bert…
what a great time to be in surfing isn’t it??? even if you don’t shape or glass boards. The technology available in stores today is pretty awesome as compared to ~20 years ago. I can go to my shop around the corner and pick from boards that are made from traditional lay up, epoxy, s-core, surftech, carbon fiber, and whatever.
We might be a few steps behind Bert, But the evidence seems to suggest that we are miles ahead of pu/pe and eps/pvc.
I haven’t tackled a Bert yet though I’m just about set up for it. There were a few issues that Bert aluded to that kept me wondering. I missed the mystery pic, but I had figured out that something was needed in there. I’m just about getting a handle on the flex, but I think thats going to be a case of suck it and see to fine tune.
What bothered me was that Bert stated that he gets the balsa to a state that its hard to get a hacksaw blade through it. I had considerd infusion as the likely method and explored using casein glue. But its the heat and pressure combined as Oneula notes is the key. I think this is hugely important not just for strength but for the flex and return.
There are a couple of treads deep in the archives, where Bert showed a picture of his balsa and then took it down after about 10 minutes. The following discussions talked about it being scored for resin flow. Then a later post showed some endgrain balsa pre-sealed for resin infusion. I have no idea how much this stuff costs, but there are other idustries doing the same type of stuff.
*** Waring *** This is all in my head with no application experience what so ever. *** Waring ***
I think if you copy what he did in the sandwich tutorial and change it a little you could get a lot closer.
What is the 3/4# EPS there for? To rap the skins and the rails easier. So you build a rocker table to handle increased temps and super pressure.
Then you set the skins on the rocker and run the flow media underneath, I think there is a post about gravity around there too. Someone will say its in a vacuum because of the term vacuum bag, but you will not get be to believe its a true vacuum like space, so gravity will still apply.
There is also thread telling how to make rail stringer sheets.
Now you have 2 sets of skins and rails set to the proper rocker. Place rails, top and bottom sheets, EPS and wrap with outer glass and flow media. A perfectly infused custom made surf board.
Will it work? I have no idea.
If it does you could have gost baggers preping skins for orders that haven’t even come in. Just tweek the rocker, length and width at the final wrap and infusion.
Well two other tidbits I saw that may help but I’m going to paraphrase them…
“Don’t glass your skin to the foam core”
“Support your rocker when you do”
This is hypothetical but I’m thinking that you build the skins just in flat sheets so you don’t need a fancy mold in the shape of a surfboard. (how I still don’t know)
Benny already showed up that even after glassed the wood glass sandwich is still flexible enough to bend. Which means it can be formed to/around a curved shape (the core)
Secondly Bert seals his EPS and builds a layer of solid wood around the perimeter of the foam with his Balsa rails.
So maybe these shells or sandwiches are actually flat sheets that are formed around the board as they are being adhered to the foam/balsa core at the rails with glass (kevlar/carbon). Also maybe there is another layer in between the foam and the skin Aircel? Honeycomb Airex? PVC?
To prevent the need for custom molds all you would need is an adjustable rocker table made of some thing that can withstand the temperature and pressure. Bag it and then apply some type of lid to clamp it down and apply the heat.
This is way out concept but…
one possibility to think of is a large heavily insulated wooded box with an adjustable rocker table for a bottom that you can lay the core with it’s shell layer on in a bag pulling the max vacuum allowed for the EPS them wrapping the entire setup in an altered electric blanket kicked up to a very high temp, wrapping and sealing all this up and then burying it all under 1-2 feet of sand for compression and insulation. I fyou hotwire you’d just need a big box with the offcut on the bottom for support then fill with sand…
That were I also started, reading all of Bert’s threads. He has said that he does not use a true autoclave (not that I know what he uses). When I asked Bert about why he did a certain technique he replied that he doesn’t do it that way anymore (in fact, it was a technique he had use about 10 years ago). He had given an answer that best help the person solve a problem even though he no longer worked that way. In regards to rocker tables he made some comment like - you would be surprised had how many rockers you can make from a single rocker table and wedges and shim (I’m going from memory here. You don’t need to do infusion to get a 1:1 ration. When I bag on my glass that is the same ratio that I get.
Here’s the area that I think is the most important to understand - pretreatment. I don’t believe that he seals his whole board. There are parts of his board where he want the resin to sink in further and others where he doesn’t. I look at the problems I’ve been having with the board outgassing during the hotcoat. This occurs even in places where I have two layers of 6 oz under the balsa. This tells me that it is the wood, not the eps that is letting out gas. I’m going to try and solve this problem by pretreating the balsa with epoxy to try and seal the balsa’s pores.
Meecrafty asked me why my shortboard came out so heavy. I ran the numbers and I was very surprised. All of my glass was at 1:1, my hotcoat/gloss was too heavy (maybe added a pound or two). For a long time I didn’t understand what went wrong until I realized that I was making my board too strong where it didn’t need to be. For instance, I used 4 oz between the foam and balsa all over the board. I should have used 2 oz on the bottom, 2 oz plus a deck patch (better yet, two small patches where both feet go) for the deck The main quote that echo in my mind that both Bert and Greg say is “make it strong where it needs to be strong”. Instead of covering the board with a blanket you need to use a patchwork quilt.
The next step needs to be for people to start cutting out structure and see where it fails and where it succeeds (at least this is where I’m going to go). The fact that none of us sandwich guys have been busting boards makes me think that we are going too strong (not that I want to be the first to loose a board). Bert make a post a couple months ago talking about one of his trial boards breaking. He acted like this happened all the time (as if its what happens when your pushing the limit and learning.
My interest is going to be longboards. I’ve been surfing my monster 11’3" semi tandem. The thing is huge, strong, and heavy. Meecrafty made a comment that short boards really benifited from being light, but he didn’t know if longboards would. Its my feeling that longboards might be the key market for lightness. My monster board works me. Turning it around to catch a wave takes so much energy. Sure I can paddle like the wind (I’m by far the fastest guy in the water) but its weight is limiting. I think it might be possible to get a lot of the action of a short board (at least 70%) with all of the fun and versitility of a longboard. For this too happen I’m going to need to get rid of my roll of 6 oz (I’m not sure that it belongs in vacuuming) and make the boards wide and thin.
look at the problems I’ve been having with the board outgassing during the hotcoat. This occurs even in places where I have two layers of 6 oz under the balsa. This tells me that it is the wood, not the eps that is letting out gas
THEN
For a long time I didn’t understand what went wrong until I realized that I was making my board too strong where it didn’t need to be. For instance, I used 4 oz between the foam and balsa all over the board.
For an autoclave I think Bert’s using those industrial strength bags you can get from Joewoodworker…
Quote:
After many months of headache inducing phone calls and negotiating, I’m proud to offer vacuum bags made from the 30 gauge Dura-Max vinyl. Each bag is welded on a state-of-the-art custom RF welding machine operating at 7000 watts and 50 lb/in of pressure
-Joewoodworker
He calls them his “permanent” bags but I think he needs them for the pressures and temperatures he’s subjecting his sandwiches to, the other bags would just melt away. The woodworking guys run their vacuums way higher than what we would do as we create and apply the skin to the foam the way we are doing it today…
He also mentioned something in another post that indicates he’s also doing something to his wood (pre-treating) to get them lighter and maybe de-gas them at the same time . (an alcohol bath?) He also measures out the weight of each piece and strategically placing the wood in specific places in his sandwich.
I still don’t know how he adhere’s his preform sandwich layers to the foam since they are already a glass-wood-glass composite. Greg indicated that they “slurried” their foam and them clamped the shells around it in a pressure mold. A “slurry” to me would some type of baste maybe a mayonaise concoction of resin, Qcell or chopped mill fiber for strength and adhesion to the interior glass side of the shell. For strength and stiffness especially on the bottom rear fin area I would almost bet Bert is layering a 1/8 or 1/4" panel of divinycel to stiffen things up and provide a base for the fin boxes…
As far as infusion I think it’s more to bind the three layers “as one” as Bert says…
Regarding cutting out the core…
CMP already did that boring out holes in the foam of an 8’ longboard and I believe he had skin failure where the holes were…
Light longboards are great but I think it more about light an flexible versus light and stiff than anything else…
Both he and Greg must be either laughing or sitting there like proud parents watching all these little baghead crash dummies wallow in their new discovery.
Thursday I had lunch with Bert. I thought I would let you know he expressed that he was impressed by how quickly many of you have taken the small amount of “old” technology and turned out outstanding boards. Also that Ken (airframe) has some cool stuff coming out of his place. (looking forward to Cerritos boards and BBQ)
While my only experience with sandwich has been boardworks/surftech and my thinking I was cutting edge well read ( thanks to Mr. Paler) I was shocked at how light the Sunova boards were. The trampoline display, done in person is very impressive.
I’ve always felt that instead of “Swaylocks Inspired” it should read “Inspiring Swaylocks” as it is you, us, them the masters, and the ghosts contributing to the collective growth. ( that and it is damn inspiring )
They were two different boards (tandem-short board). My point was that I was still getting outgassing in places that that 12 oz under (6 x 6). The short board was that it was stonger than it needed to be (thus heavier).
look up the thread I started called “Building an Oven” (I think thats that the rigth name…) anyway, I’ve thought of this awhile ago…piecing together the board…make a super strong shell(the inside isnt wat matters anymore…) Also don’t downplay the idea of a perimeter stringer its not only what ties everything together, it strengthens the rails, and it plays a big role in flex… BTW does anyone here know anything about Resin Film Infusion?
I have the oven thread bookmarked. I think its probably very important for creating consistent hot to cool temperature changes (leaving it outside just doesn’t cut it. I am 100% behind the concept of perimeter rails. I can’t imagine doing a board any other way. When you look at them they just look right.
When I posted before I didn’t read everything…now somethings are really making sense…It all plays into Shear movement; make the top and bottom lams super strong by using a glass-wood-glass sandwiche with resin infusion, heat, and increasing pressure then adhere them not to the foam but to rails. Or the lams are done just glass - wood and then adhered with the layer of glass that goes under the wood. I’m not sure if you could have a strong enough bond if just the rails are connected directly…that would mean alot of stress on the rails. I guess it could work because the top and bottom wood panels are directly top and bottom and not curved over the rails…I’m sure you could do a few oter things to make sure they would stay. CMP when we talked I know you were talking about the hole method as well as soemthing else…I’m curious as to what you’re methods were when boring out the holes; meaning what kind of glassing was involved? how big the holes were? was there a pattern with the holes? how far apart they were? I have to say i’ve been lurking around here for awhile and there really hasnt been a thread that has gotten me as excited or inspired as this one, now I remember why I keep coming back here…
if you autoclave the resin you use has to match the temps you are subjecting it to ie hi temp, different resin ,there is not a lot of point in raising a resin thats designed for 10-30 degrees c cure to 100 c
If you up the temp too much the eps becomes unstable
My boards now are 1.8 kgs with fins
I do not seal the eps
I never apply resin direct to the eps
I bag every thing excluding the outer glass in one hit
I vary the flex with the outer laminate thickness and the balsa skin thickness
I have a morph bottom by simple placement of transverse thin balsa in certin areas
They are still too strong I still have yet to break one or dent one trust me I give them a hard life
I do not use glass any heavier than 3 oz any where I do however use more than one layer in some places
I do seal the balsa in some areas
Follow the simple rules light and strong is really not very hard to achieve
The task of learning how to fine tune the flex is what takes time
Have I approched what Bert has, how knows
I do know however that what I can build today far exceeds what I imagined I would be able to achieve one year ago
I guess the bottom line that I am trying to put across is that you dont have to copy every thing that Bert has done, if you try logical things your end result will improve
There are many ways to skin that cat and many different roads all of which can lead to a better surfboard
BTW does anyone here know anything about Resin Film Infusion?
I do! I’ve seen it used before. It’s basically a film of resin that is stacked with the dry glass layer. Used in a heated vacuum, the resin flows into the glass. You get a perfect resin to glass ratio. And it’s fast. You don’t have to wait for the resin to flow from one end to the other like regular vacuum resin infusion. It takes just a few minutes to saturate the glass. The guy that was doing the demo said that it was the future. I’m going to check to see if they have any at Cerritos College tomorrow. If they do, or if we can get some in time, I’ll include it in the demos next week.
I vary the flex with the outer laminate thickness and the balsa skin thickness
not sure what you mean…what about overall board thickness?
Dan,
you applied your hotcoat while the room/board temp was rising…bert preheats his boards b4 applying resin…all stages. whenever i hc i make sure the room temp is falling and i’ll put the board somewhere where it gets hotter than the room(car or attic) before HC…i havent got any issues, even in an extremely hot workplace (my garage avgs 92 degrees)
Oneula,
youre assuming the prefab skins are very stiff…if they werent things would change
I agree with Sabs…there’s many ways to achieve similar results…i like what he’s doing…so far he’s the ultralight king…my 5.5 pounder was built with durability in mind cuz out here, boards will actually start to melt in your car…but, its nice to have a bunch 2.3oz waiting in the wings…
generally, the more wood you use the less resin/glass you need…i really dont see the point of heavy results using these techniques…one could get the same with clark and heavy s-glassing with epoxy and its a hell of a lot easier…if youre gonna go thru the effort of vac bag composite might as well shoot for the moon and go ultralight