This is a question for the wood experts and or engineers (wood ogre, richard mc, doc…)…
What would the technical term be for a wood’s brittleness and/or stinginess/toughness. The madrone I used was kind of brittle as was the imbuya. The hickory I’ve used is tough and stringy, kind of like oak. It seems ideal and I’m wondering what the technical term is and what the scale would be. The obvious reason is to know which woods would be suitable for board building and which would not. I’m think in terms of t-flex skins.
Maybe someone even has a table handy and some parameters…
Uhmmmm- good question. Doug Irwin prolly has a better handle on it than I, as he builds bows and such.
However....you got me curious and I looked:
To start with, there's a few general 'properties' you'll see in tables and handbooks and building codes and such. http://www.fpl.fs.fed.us/documnts/fplgtr/fplgtr113/ch04.pdf isn't a really bad reference, with tables for quite a few species and lots of definitions and so forth. At 46 pages, it'd be worth firing up the laser printer for a printout.. The US Forest Products Lab has quite a lot more, I mean, they're pretty much the go-to guys for technical wood information. http://www.fpl.fs.fed.us/
Oddly enough, NASA has some info too, if you look into some of the older documentation they have on wood in aircraft. That'd be more useful, I think, than the boatbuilding references you might find.
If you’re only using a thin veneer (1/42" or 10mil) on a timberflex type board it may not be that much of an issue. If you’re going to mil your wood it would be something to worry about.
Some of the veneers we got from Veneer Supplies had similar problems with the stringy grain structure, or with cracking when we tried to laminate them directly to the board. Bernie and I taped up a bunch of sheets about 18" wide and laminated a single layer of 4oz glass on one side. We tried to keep the lam really dry since we’ll be using these later. We just have to cut out the shape with a set of tin snips whenever we want to use them.
Other than something like Bamboo, I don’t think there is any strength in wood that thin, it’s all aesthetics. You can adjust the strength of the skin by using different weights of glass or even different materials like carbon or kevlar. I think the things like oil content might be more problematic.
“Other than something like Bamboo, I don’t think there is any strength in wood that thin, it’s all aesthetics.”
I feel like there is a big difference between the hickory and the madrone I used. The madrone snapped easier and I could crumble up a piece in my hand. The imbuya was even crumblier (if that’s a word). The hickory is way stronger and stringier. They used to use it for baseball bats and golf clubs. I felt bamboo veneer and it feels similar to hickory. That’s kind of why I wanted some reference tool to compare woods without having to purchase. I asked several veneer suppliers for samples but got no response. I know you and Oneula have used lots of various wood species, so you would have experiential data. I think Oneula even used madrone. But really , you don’t think there’s much difference?
Doc, thanks for that. It’s going to take some time to digest that. I’m sure the info is in there. Looks like I have to work for it…then again I am a school teacher. I shouldn’t complain about a little home work!
Hickory....is interesting stuff. They make hammer handles out of it and the like, a fairly tough wood.
Now, in something similar, I like ash. It steam-bends very nicely, it's a pretty wood, snaps back well when it bends when it's used as working oars. Not terribly light ( like some of the nicer spruces ) but rugged stuff, as shown by how it's the wood of choice for shovel handles and such. http://www.thewoodbox.com/data/wood/ashinfo.htm has more.
And.... sorry about lumbering you ( pun intended) with that vast wad of information just after the holiday break, but from a quick scan through it I'd have to say pretty much everything you'd want is there. You might find it useful to have strips of various woods handy when you read it, might kinda do show and tell for ya in a way, give you something you can immediately relate to and compare with with all the numbers.
I don’t think the 1/42" veneers have enough thickness to add much strength. If you get into multiple layers, maybe. Once you get to about 1/16" and you have some glass under and over there’s a big difference.
I think you may find that some woods would be better for strength, but I just don’t think with the thin veneers it matters. Even with 1/16" balsa I’ll use 2 layers, and lay out the top layer diagonally or something for the looks.
The most important factor is probably the grain pattern. If you have highly figured wood with a lot of grain direction changes, then it will be harder to work with than a piece with uniform grain. You don't want grain runout either. Quarter sawn wood is the best. Bamboo is good because the grain is cut parallel to the surface.
If you want to touch and feel a huge variety of veneer products, then make your way down to San Diego, and check out Hesser Handcrafted (www.hesserhandcrafted.com, 619-231-9191). They have a big warehouse filled with stacks of raw veneer pieces. They also have veneer cutting/gluing machines, so you can have them lay up the pieces exactly how you want them to be. It is a much better experience than ordering off of the internet. They will be able to answer all of your questions.
Do I have it wrong? I only use wood for art. For surfing I like the new tech materails. I never thing of using a wood veneer on a board you surf on. There are so many cloths that are so efficient. Plus the Bamboo looks like flooring from a hardware store.
Huie the difference is that you make it beautiful with full lengths. The ones I see generally look like planks. I’m sure yours are light and ride good as well. Plus you know how to shape. Big difference in the way you make them. I think Speedneedle does them like you do as well.
Maybe I will rethink the veneer concept. Use it for beauty and keep the high tech on the deck and blank core.
Doing is on a well foiled well rockered board with the proper rail profile could be interesting.
I have some incredible looking veneer that is curly and glimmers in the light that would look like the dash board of a Bently. Make the board 5.25 pound with a veneered bottom and a Hybrd deck with a balance core? WOW!!!
Huie the difference is that you make it beautiful with full lengths. The ones I see generally look like planks. I’m sure yours are light and ride good as well. Plus you know how to shape. Big difference in the way you make them. I think Speedneedle does them like you do as well?
Maybe I will rethink the veneer concept. Use it for beauty and keep the high tech on the deck and blank core.
Doing it on a well foiled well rockered board with the proper rail profile could be interesting.
I have some incredible looking veneer that is curly and glimmers in the light that would look like the dash board of a Bently. Make the board 5.25 pounds with a veneered bottom and a Hybrd deck with a balance core? WOW!!!
Hey Surfding, did you see the “WMD compsand” thread? If not you should check it out. WMD Compsand | Swaylock’s Surfboard Design Forum I always thought of veneers as purely aesthetic until that thread. Greg Leohr kind of blew away that misconception. When you say “planks” you’re probably thinking of balsa compsands. They have been maligned as “pergo” boards. Instead, most of the veneer boards are full length. It makes no sense to do it otherwise. My whole point in starting this thread is that I’m sure some woods are better than others for this kind of build (I think Greg calls it “timber flex” now). Bamboo is probably ideal- cheap and strong. LIke you, I don’t like the aesthetics that much. The hickory I found is also cheap and strong but looks great. I’ve been looking at others but want to know the physical properties. Now I have to do some post graduate study of the document that DOC posted.
I would caution you about curly veneers. I used one and the vac pressure was not enough to press out the waviness. I had to cheater coat and sand it several times before getting a really smooth surface. I think Shwuz had similar issues. That said, I was in a guitar store the other day and saw a maple fiddleback guitar stained black that just looked killer. I was thinking how drop dead a board would look done that way.
I would caution you about curly veneers. I used one and the vac pressure was not enough to press out the waviness. I had to cheater coat and sand it several times before getting a really smooth surface. I think Shwuz had similar issues. That said, I was in a guitar store the other day and saw a maple fiddleback guitar stained black that just looked killer. I was thinking how drop dead a board would look done that way.
I think one of the good things about bamboo is that it is extremely strong. It’s water proof, has been used to store water for years, and it grows very fast. It may look ugly, but if you used 2 or 3 really thin veneers of bamboo in a skin, then board would be ding proof. The woven mat is also ding proof, but it’s hard to get a smooth surface without adding weight. I don’t have any scientific data, but I’ve left the textured surface on several of my bamboo mat skinned boards to see if it will add speed. It’s an easy way to have a very complicated pattern on the bottom instead of a smooth surface.
We used Wiliwili on several boards and it is very light, strong, and has a nice grain pattern. It’s really beautiful when it’s glassed, but it is very hard to find now, and like balsa, it will suck up the water. We made a couple of boards with Tiger Wood and that was beautiful too.
As far as looks, the 2’x8’ and 4’x8’ 10 mil sheets from veneer supplies make great one piece skins. We did a couple of boards with Cherry, Maple and bamboo, but with the soft eps cores we used, you need to have 4oz glass under it and 4 oz over for strength. I think there’s got to be some kind of data that shows how thin you can go before the wood loses it’s value as a core in a composite skin. Boat builders must have equations for the thickness of the core material and the fiberglass outer layers for specific strength and flex. Some materials absorb resin more than others, and that would also affect the composite strength.