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#2895974 - 01/09/19 11:26 AM Re: Board longevity/durability [Re: GromsDad]
crotchgrab Offline
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Originally Posted By: GromsDad
Originally Posted By: indodreams
Originally Posted By: GromsDad
Originally Posted By: Mr J
Originally Posted By: GromsDad
...
Years ago I used to build and repair fishing rods on the side. In a way surfboards are a lot like fishing rods. Your high tech fishing rods are incredibly strong but when they fail they fail catastrophically much like the way a high tech surfboard snaps. High tech fishing rods usually fail at a spot where there was the tiniest of dings or abrasions on the blank, a minute flaw in the blank's construction or at a hinge point created where a guide is in contact with the blank or the user did something stupid. It only takes the slightest weak spot and the hoop strength of the rod is gone and it fails under load. Hoop strength in a fishing rod is very similar to the I-Beam effect of a surfboard created by layering fiberglass and resin over foam. The next time you break or buckle a surfboard take a real close look and you might find why it broke at that particular spot. A ding. A sand through. An inconsistency in the laps in the lam job. A kink in the outline or foil and so forth.


Cool GromsDad, so what sort of fibre/composite were the high end fishing rods? Carbon or glass or both? epoxy or polyester?

What do you make of the buckling tests varial did at the bottom of the following page?


http://www.varialsurf.com/infused-glass.html

Polyester comes out slightly stronger for the most popular HPSB build (4 + 4 + 4) and for team light (4 + 4). Those tests are vac bagged on varial, but gives us a clue as to hand lam on PU i.e don't expect epoxy to be noticeably stronger if at all for buckling resistance. Doesn't surprise me because we know epoxy is more flexible so would fold up more easily under compression. Also I remember being very disappointed with the strength of a single layer of 4oz vac bagged epoxy on EPS, but as soon as more layers were built up of epoxy it got strong.



The fishing rods I refer to are carbon and epoxy.

No doubt Varial vacuum infused is going to be an extremely strong board. I have not worked with their foam. I have one friend who's build a personal board with it and he loves it.

EPS need more glass because the core lacks compression strength on its own. My understanding is that Varial foam has a ton of compression strength compared to EPS and a bit more than PU.


Really?

My understanding is EPS foam retains its original shape from compression a lot better than PU foam.

For instance press in each foam before glassing and EPS will bounce back to original shape or close while PU foam will retain more of a finger mark.

Epoxy resin is generally softer and almost more rubber like than PE resin.

Hence why EPS/Epoxy is a good combo and less likely to retain the ding shape or crack when dinged because both are more likely to bounce back to original shape..

I would have expected??? if any extra resin was needed or composite construction used it was because the combo of EPS and Epoxy is lighter than PU/PE plus because of the more rubbery nature of Epoxy you are more likely to be able to create a composite construction that is strong but still allows the board to flex.

While id imagine a composite construction in PU/PE would create much more weight and be stiffer and less flex (risk of crack or delams) so not a good combo.

That was just what I've been told and understand and figured.



Ding resistance and buckle resistance are two different things. Yes EPS rebounds better than other foams but it is also inherently softer and easier to compress. On a typical compression ding scenario this would be a good thing as the foam and glass would rebound. Not so much in a board buckling scenario. I mentioned hoop strength and the I-Beam effect earlier. These come into play here. An I-Beam uses the center web to maintain the space between the top and bottom of the beam. This creates a very strong structure. A softer or more flexible foam like EPS will allow the foam between the top and bottom layers of glass to compress under a buckling load, the hoop strength of the rails breaks down and the board buckles or breaks. The foam core of the surfboard acts as the web in an I-Beam and helps maintain the hoop strength of the circular form of the rails and the I-Beam effect of the top and bottom skins.


Even the high density EPSs out there? The 2.1 or 2.3lb compressed marko? What does 45 degree bias weave S glass do in this situation, like what Stretch does?

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#2895997 - 01/09/19 11:59 AM Re: Board longevity/durability [Re: retodd]
Sharkbiscuit Online   content
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Originally Posted By: retodd

High volume hybrids are also rad but unfortunately the thickness and foam qualities will make them bumpy in choppy waves


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#2896285 - 01/10/19 03:24 AM Re: Board longevity/durability [Re: jkb]
Mr J Offline
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Originally Posted By: jkb
I'm surprised that Varial didn't publish strength test comparisons of similar density PU, EPS, and Varial blanks side by side. That would be the logical test to determine which foam is stronger. Perhaps they did and didn't like the results shrug

The glass schedule data is interesting though. Didn't expect PE to be as strong as it is.


I think what Varial is doing is excellent, I would like to see PU blank manufacturers lift their game and publish similar buckle test for their different stringer options. Its all very well offering blanks with different stringers for step ups, but we need to know how much better the different stringers are. At the moment we have no data on whether say a single wood veneer is stronger or weaker than a stringer of similar weight, but made from 3 plies.

However, I get your point jkb, if Varial are saying that their foam is better than PU, then show us the money!

Varial push their foam as stringer-less, so comparison would need to be stringer-less Varial against stringered PU with overall weight being the same. Would need to do a non infused comparison and infused, because I don't see builders rushing to do infused due to the complexity and cost. They do say 30% stronger on their foam page, but where did they get this data from and what exactly was the lam technique/glass schedule/stringer/PU density comparison.

Regarding polyester strength, GromsDad explains it quite well - there is more than one different type of strength. Buckling is like pushing two ends of a piece of cardboard together and watching it crease. Then there is tensile strength which would be grabbing both ends of the cardboard and stretching it until it snaps - sometimes a board does snap completely with buckle on one side and clean tension snap on other. Then there is impact strength - e.g certified bicycle helmet testing drops the helmet from a specified height onto a metal "anvil".

For impact I would expect epoxy to come out much stronger - we know from experience of banging our epoxy boards onto things such as rocks accidentally, that epoxy would do better for impact strength. For tensile strength I am not knowledgable enough to know which will do better.

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#2896303 - 01/10/19 07:33 AM Re: Board longevity/durability [Re: crotchgrab]
GromsDad Online   content
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Originally Posted By: crotchgrab


Even the high density EPSs out there? The 2.1 or 2.3lb compressed marko? What does 45 degree bias weave S glass do in this situation, like what Stretch does?


Higher density EPS is still not as strong in and of itself as P/U foam. EPS relies very heavily on the cloth and resin skins for its strength and that's precisely why you see all sorts of expensive and high tech fabrics and layups being used.
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#2897390 - 01/12/19 10:41 PM Re: Board longevity/durability [Re: freeride76]
Mr J Offline
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Originally Posted By: freeride76
I think pu/pe manufacturers were forced to up their game and improve durability due to asian surfboards, first Surftech, then FW who used improved durability as a selling point.


Ironically, pu/pe's got stronger, FW's got weaker and Surftechs went extinct.


Yes, there might be some improvement via competition from EPS/epxoy.

I have a couple of other possible suggestions. This wouldn't have affected Aus consumers, but in the US Clark foam used to have something of a monopoly on PU foam blank production. When they closed unexpectedly there was a mad scramble to start up some new blank production to fill the gap (as well as increased use of EPS). With several start ups and the end of the monopoly the US blank manufacturers lifted their game. Aus always had several competing blank companies and had a reputation for producing blanks with a harder outer crust than Clark.

My other thought is that with the arrival of the shaping machine the emphasis went from getting a hull rocker to match the shapers design to getting a deck rocker that matched the deck computer cut, thus machine shapes were more likely to preserve that hard outer crust. I don't have enough knowledge fo machine operating to know whether this could be happening or not. If GWS could come to the courtesy phone that would be great.

Myself I haven't noticed any big leap in PU/PE longevity. My last handshape from Aus lasted really well (about 18 to 20 years ago), others before that a bit variable in how they held up. A handshape from the US in early 2000's didn't do so well.

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#2897861 - 01/14/19 11:42 AM Re: Board longevity/durability [Re: Mr J]
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All right. I post less and less around here simply because everything turns into an argument. Not just this forum, all of them. But I got a personal request to spew on this thread and it's rainy, windy and cold. So here goes nuttin.

Originally Posted By: "personal message"
Hi GWS, I have a couple of question if you have a moment to answer on the thread:

https://forum.surfer.com/forum/ubbthreads.php?ubb=showflat&Number=2897390#Post2897390


basically they are:

1. has foam strength increased since the demise of the Clark monopoly.

2. has maintaining that outer crust strength on the deck improved since the arrival of the shaping machine due to the emphasis of the machine on matching deck rocker. As opposed to the emphasis on hull rocker by hand shapers.


Cheers,




I don't know everything and I definitely don't have the time to start evaluating foam densities in scientific fashion. So instead I will just relay to you what my shapers tell me and additionally give you my own personal observations.

All PU foam gets softer as you descend in depth of cut. Even if you think it is undetectable to your hands, supposedly with the proper equipment you can detect the softening. (this from the head of one of our current blank manufactures over a beer) Clark foam got really soft as you went deeper. Modern formulations do better. A personal observation, I can feel differences in supposedly identical densities of identical blanks produced by any one manufacture. You cut enough of them, and batch to batch there is variation. Sometimes its hard/soft, sometimes the foam feels more powdery, (this is a scientific term) sometimes its crispy. (more science). Sometimes I can see the difference in the foam before I even touch it. But, net net, we are all better off since Grubby threw a tantrum and took the ball home. Good riddance.

2. I started to write something here going over hand shaping technique and the importance of blank rocker. Suffice it to say nobody wants to cut rocker into some slab. A smart shaper is going to pick a blank that provides him, as closely as possible, his bottom rocker.

Cutting boards, the most commonly used machines cut the deck of the board FIRST. Smart shapers listen to their cutter re blank/rocker recommendations. When I am picking a blank I am looking for the closest match possible to the deck rocker. I want that cut as shallow as possible. Firstly because it leaves me as much foam as possible on the bottom cut. This means I don't have a problem with rail rocker crust on a single concave, or just in general, missing material when I cut the bottom. The fastest, most efficient thing for me is a good match on the deck rocker with some room on the bottom. There are variations in rocker batch to batch. A little extra margin on the bottom gives me some room to deal with these variations, or uneven glue-ups, etc etc.

Now there is another aspect to this methodology. Sometimes shapers come to me with a blank they already own or a blank they chose and, it's a poor fit on their deck rocker. Lets say for instance that their design has more nose rocker than the blank they brought me. I will point this out to them. They will frequently ask me if I can cut it anyway. In that case, you need to remember I am cutting the deck first. So what do I have to do? The tail-block drop in cut on the deck will still be as shallow as possible. However, in order to get the deck-side nose block in the foam, I am going to have to hold the tail block high in the blank and tilt the entire design downward in the blank. This means that as the cut progresses from the tail it sinks deeper and deeper with the angled design until the blade ascends and hopefully just barely cuts in the deck-side of the nose block. This is a pain in the ass. I have to baby sit the cut and I may have to stop/restart the cut which means more time on a piece-work deal. If there is MORE nose rocker in the blank than I am anticipating, it can be worse. Crust on the bottom say 12-24 back. Not good. Hopefully that makes sense to you all. This would be easy to show you visually if I had you in front of the computer. It's a bit harder trying to give you a verbal representation of what I am talking about.

Overall, you are now getting a foam that maintains its strength to greater depths than what Clark provided. And if things are done right, you are removing less material with the machine from the deck than most/all hand shapers would routinely remove with a planer. I literally have thousands of blank files on hard drive. All of those are hands on blank maps/file construction. I don't even want to think about how much time that all represents.

Hope that helps and I hope I explained that clearly enough.


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#2897916 - 01/14/19 12:46 PM Re: Board longevity/durability [Re: GWS]
rowjimmytour Offline
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Stretch CFT holds up great I have a f4 that is most likely early '00 and still looks great and has plenty of pop. More recent got a CB custom with S glass and epoxy
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#2898407 - 01/15/19 02:42 AM Re: Board longevity/durability [Re: GWS]
Mr J Offline
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Originally Posted By: GWS
...
Hope that helps and I hope I explained that clearly enough.



Yes you did. Your detailed response is much appreciated and after perusing it I have an idea of what you mean about the situation where your normal process of choosing an appropriate blank with appropriate deck rocker is undermined by a shaper forcing a blank on you.


Essentially you have confirmed what I was suggesting. I have had hand shaping lessons and also watched another hand shaper and know that although shapers do have their individual techniques, there is more emphasis on matching blanks hull rocker. It is more difficult for a shaper to adjust hull rocker on a blank than deck rocker without introducing inaccuracies into that all important planing surface and this is more likely to result in some sacrifice of deck crust strength. The "close tolerance" blanks sold by some manufacturers can only go so far in matching both deck and hull profiles of a refined design.

Whereas everything you are saying about the machine process is to match the deck rocker, or make the most of it in a situation where a specific blank has been forced on you, by say favouring matching the tail deck area which is where most delams from foot pressure occur.

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#2899062 - 01/16/19 06:59 AM Re: Board longevity/durability [Re: manbearpig]
GromsDad Online   content
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GWS, Do you guys machine EPS? If so do beads tear out or is the cutter so fast and sharp the there is no tear out? Is your machine the type that uses a router type cutter or the type that uses a circular cutter blade?
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#2899116 - 01/16/19 11:03 AM Re: Board longevity/durability [Re: GromsDad]
GWS Offline
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It's not a problem. I'm using a circular blade. I've thought about converting to "router type" but so far, haven't done it. It is kind of a problem when people bring me an EPS longboard blank with a thick stringer. I have to slow the blade down for that thick piece of wood. This creates friction, which creates heat which creates melted EPS on the surface next to the stringer. Not a big deal I suppose. Again I have to baby sit the cut, listening to the tone of the machine and attempting to find the perfect speed to minimize the problem. Then with the slab wire-cut EPS blanks, because there is no contour on the deck I have to stack in more cuts and again, slow my speeds because I am removing more material with each pass. I've started up-charging for that because again, more time on the machine needs to equal mo money fo me.

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#2899275 - 01/16/19 02:29 PM Re: Board longevity/durability [Re: manbearpig]
GromsDad Online   content
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Never thought about the possibility of blowing out the stringer with the blade style cutter. I would think though that the heat would still be an issue with a router style cutter too????
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This is a bad day for the news media. Lets not kid ourselves, Toobin said on CNN. The larger message that a lot of people are going to take from this story is that the news media are a bunch of leftist liars who are dying to get the president, and theyre willing to lie to do it.

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#2899407 - 01/16/19 05:30 PM Re: Board longevity/durability [Re: manbearpig]
shakajawea Offline
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epoxy has kept its "new" feel longest for me, more than pu.. my favorites that i use heavily usually last about a year if they don't snap.. once they start feeling a little heavier and less lively i just craigslist them and move on

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#2899539 - 01/16/19 08:43 PM Re: Board longevity/durability [Re: GromsDad]
GWS Offline
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Originally Posted By: GromsDad
Never thought about the possibility of blowing out the stringer with the blade style cutter. I would think though that the heat would still be an issue with a router style cutter too????


The problem is a hard crusty melt that has to be removed via the finish shaping. You probably would still have the problem with a router style cutter, but the advantage would be you can put in more detail. Channel bottoms etc. With the round blade I can put in concaves obviously, but I am limited by the radius of the blade when it comes to channels etc.

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#2899620 - 01/17/19 12:53 AM Re: Board longevity/durability [Re: manbearpig]
Retropete Offline
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Hey GWS,
I recently bought a board which started out as a long forgotten triple stringer blank that was found when the factory near my house was shutting down. Covered in a thick black crust apparently and only when the shaper took the crust off was it revealed as a triple stringer. He reckons it was a bitch to shape as the blank was so hard. It was shaped into a modern take on a round pin 70's single outline with a 2+1.
Glassed with volan (though don't know the cloth weight).
Since it was so hard to shape I'm assuming it should well be stronger...thoughts?
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#2899738 - 01/17/19 11:56 AM Re: Board longevity/durability [Re: Retropete]
GWS Offline
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That's cool. Yeah, I would think it would be stronger. Blanks aren't all that expensive compared to glass jobs, but I've salvaged a few cast-offs simply because I could and for some reason I wanted to. Sounds like your board will probably be weighty, but I'm sure you know that. My partner has this ancient poly wind surfer blank that is up in the racks. Probably circa 70's - 80's. The thing is a beast. Still hanging around. I have Ice9 blanks, both sugar based and Walker formula, Excel blanks, all kinds of weird stuff that has been abandoned in our racks. Sometimes I get an idea for a board I want and after I design the file I wander through the racks and see if anything unclaimed/left behind for a salvage operation. I have a 7'8" gun that was cut out a shaper's rejected gun cut and glassed with no logos. Board is a soldier!

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