Is that FG that has fiber strands running 45 degrees instead of 0,90?
Yea … It’s a knit. The strands are flat and straight instead of woven. Nice stuff at 5.9 oz. A bit resin hungry but for veneer backing on longboards, funboards, semi’s and guns it’s some great s#it. In tests it blew everything else away. I’ve seen good results on straight layups too.
Thanks. Ive seen that stuff, biaxials. Looks like a challenge to work with.
How did weaved cloth turned & oriented in the same 45deg direction respond in those tests?
No comparison … I was kinda surprised that a knit would be so different. There was a bit more weight to the knit but wayyyy more strength. I’ve found some uni online which is webbed backing that might be extremely good backing for veneers. Comes in s glass and carbon. Lays really flat and could be done in two layers crossed and be lighter and more effective than the X. Maybe at 60 degrees instead of 45. Not sure.
The X is actually pretty easy for working … although I’ve never lapped it. For veneer backing though it was as easy as anything else … of course eveythings easy flat on a table.
Is it similar to this http://www.amt.no/files/documents/devold_amt_manufacturing_information.pdf ? It’s layers of non woven strands AFAIK, loosely stiched together. Makes alot of sense, especially when cosmetics is not a concern such as under a sandwich skin.
Yea, that’s the stuff
Just bringing this back to page one for poeple who have questions. Haavards info is first rate.
Just remebered this article from the boardlady which might explain why this type of cloth (and other types of flatter weave cloth) are potentially stronger than regular woven cloth.
While the flat stuff is great for strength to weight and other bennies, there are benefits to using weaves in surfboards. One benefit is ease of use. Thanks for the article, interesting.
Ease of use and cosmetics. Both real important for boards. I’ve mostly used X for T-flex backing which it is phenomenal for. Since my exterior glassing is relegated to 2 oz or 4 oz these days I don’t expect to use it in a cosmetic appliction.
It’s funny how it always seems to come back to cosmetics. I keep telling myself that on the next one I’ll build I won’t care about cosmetics, paint it white and go for tech and minimum weight instead. But then I’m pretty sold on the wood look so I’ll probably never do it.
I’m guessing that you to some extent get similar benefits from using cloth with twill or crowfoot weave. Not as easy to work with as plain open weave surfboard cloth, but easier that the x-cloth and with a good finish. The boardlady article may also explain a thing or two about why thinner laminates with same glass content(vacuum bagged, low resin content) are stronger, why 2 layers of 4 oz is stronger than one 8oz and why some people try to keep the cloth in tension when laminating and vacuum bagging.
about why thinner laminates with same glass content(vacuum bagged, low resin content) are stronger…
…for a given weight.
FG is strongest in tension. If the fiberglass is the strongest link in the chain, then equal amounts of the same glass fibers will result in the same strength in tension regardless of relatively small variances of resin content. A FG laminate with more stiffening resin will resist compression failures.
why some people try to keep the cloth in tension when laminating and vacuum bagging.
yes if you want a stiff board. To promote board flex, something has to move. A perfectly flat and straight glass fiber will not move much if at all in tension.
If the laminate is thick, this means that the threads in the warp direction go up and down in a similar fasion to a spring. It’s the resin that holds it in place against tension. When you flatten the laminate, the threads straighten out closer to the straight line in which all the tension load is on the fiber. Does more resin make the laminate stiffer,or is it the added thickness that does?
I don’t think that glass cloth laminate will flex much in tension
(stretch) regardless of the weave (or lack of weave), so there must be
something else that gives which make a board flex. Though with the minimal amount of flex we have in the boards, I guess the potential change in bottom length is minimal anyway and may be within the limits of the stretch in laminate.
Good post Havaard. But Im gonna have to nitpic a bit here, apologies in advance:
If the laminate is thick, this means that the threads in the warp direction go up and down in a similar fasion to a spring.
I don’t think that glass cloth laminate will flex much in tension (stretch) regardless of the weave
It would seem to me that these two statements are contradictory. I would have to respectfully disagree with the second one.
The weave that go up and down is held in place by the resin. Which means that if it stretch, the resin will have to follow and strech, or fail. I don’t think the laminate will stretch far before the resin fail. The resin is not exactly a rubber band either.
So epoxies (like RR) offered in different modulus and fabrics offered in different styles, weaved and non-weaved, open and tight, should not make any difference.
Why use harder to use and more expensive X-glass when weaved glass is easily available and cheaper?
Should we say no to X-glass?
But according to the link/presentation you provided earlier, those folks suggest there is a difference. Do you disagree with them?
I think the difference in epoxies may play a role when flexing a laminate and one side is in tension and the other is in compression. The elongation is minimal, if you roll up a laminate into a circle the inside will be PI times the thickness of the laminate shorter then the outside. Note that the average length of the laminate have not change in those circumstances. With that little elongation the different flex in resins may certainly play a role.
I’m certain that the x glass will give better properties in tension as a woven cloth will rely more on the strength of the resin and the resin/glass bond will fail earlier because of these stresses. Greg suggested using it under the deck for a near break proof board, if the deck is in compression I beleive the inside of the skin wil be in tension. Also because it’s non woven there is no weave to fill with resin which may potentially give higher fiber to resin ratio. I wouldn’t be surprised if this is one of the ingredients in a coil recipe. On the other hand, I think it’s very rare that a laminate fail in tension on a sandwich board (though I may be wrong) nor do they seem to break very often, and the problem with x-glass availability, added cost, high cloth weight and harder to use may certainly outweigh the advantages.
PS. Been thinking about tension vs. compression loads and concave vs. convex decks. If you put your heal against a convex deck, the laminate will be in compression. If you put your heal against a concave deck deck, the lamiante will be in tension. Does this mean you can get away with much thinner laminates on the deck if it’s concave without risking heal dents?
There is an example of 5oz epoxy x glassing at the bottom of this surfermag thread. Last post of the Hynson glassed by Keahana.
http://forum.surfermag.com/forum/showflat.php?Cat=0&Number=1535328&an=0&page=0#Post1535328
That look like a different beast as it seems to be woven. Certainly have it’s merit though.
Came across this on fibreglast.com:
"Styles Of Woven Fabrics
There are many styles of woven fabric to choose from. The most common
are the plain weave fabrics where the warp and fill threads cross
alternately. Plain woven fabrics are generally the lease pliable, but
are easy to cut and handle because they don’t unravel badly. However,
their strength is compromised due to the severe “prebuckling” already
present in the fabric. As stated under tows, **fibers only produce
their greatest strength when they are perfectly straight. The frequent
over/under crossing of the threads reduces the strength of plain weave
types, though they are still adequate for all but the highest
performance applications.**
Twill weaves and satin fabrics are highly pliable and stronger than the
plain weave styles. In a satin weave, 1 filling yarn floats over 3-7
other warp threads before
being stitched under another warp thread. Threads run straighter much
longer in this loosely woven type, maintaining the theoretical
strengths of the fiber. Obviously,
pliability is higher and these fabrics conform easily to complex
shapes. Once cut, however, they can unravel easier because each thread
is not held as tightly. Twill weaves offer a compromise between the
satin and plain weave types, as well as an often desirable herringbone
cosmetic finish."
The strands looked straight to me in those photos, but they are probably woven in a diag.