bigsteve - 12-8-2008 at 06:05 PM
Has any one tried this? my first board was laminated with 4 layer of 1/8" birch, each layer was composed of 3 ply's.. I attempted to make a 141
session, and it seems to have way too much flex. So now I am thinking of trying a door, with 3-4 layers of the same wood, only this time putting 1
layer of bi-axial glass and then a wrap to seal it so I dont need to put a bunch of paint on it.
Do any of you guys have experience with this? I've got a buddy who makes surfboards so I'm not worried about the glass work, but I am undecided on how
many layers to use and how much added strength the glass gives..
I really should have taken a class on composites when I had the chance :/
nwsurfwakeskate - 13-8-2008 at 08:35 AM
yeah I missed out on the composites class as well, haha did the basic plastics class where I got to play with some composites but they never went into
any detail about strength in composites.
if it was me I would do an outside top and bottom glass and leave the core as wood only. its my understanding that you need separation between your
glass layers to give stiffness. be careful about weight though. I've heard people before talk about building epoxy/wood boards and them not floating
or being almost neutrally bouyant. if that ends up being the case just install some really big foam foot pads which should add some floatation
USA_Eli_A - 13-8-2008 at 01:06 PM
do you lay your own ply, or just buy prebuilt ply, lots of configs for ply wood, sometimes the grains cross at 90's or 45's, If you off set the
grain, instead of cutting out with your rails parallel to the sides of the plywood, try turning your pattern 45 degrees on the sheet, so that the
board won't flex as easily,,,try 3/16 "tech ply"
maybe I don't know what I'm talking about :P
bigsteve - 13-8-2008 at 06:20 PM
no that sounds pretty right. I've been using 1/8" baltic birch, each sheet is 3 ply, and its not the typical core wood they put in plywood but
actually decent grade. its 90 offset. Since there's three layers I usually lay up each of my laminates 90 offset so I get decent strength in both
directions, but the ext board I will keep the majority of grain running length wise.. my initial attempt had way too much flex.
NW you made a really good point. I hadn't thought about the increased density of it.
I think I'm going to hold off on this plyboard until winter and just get a 1/2 sheet of marine ply for a quick and easy door.
save the hard stuff for when the days are short and cold..
bigkahuna - 14-8-2008 at 05:20 PM
Plywood + glass = way too heavy. If you want a plyboard, just finish it with paint or varnish, don't glass it. It's a waste of money IMHO. If you
want to control the flex, couple things you can do: 1. alternate the direction of the plies when you laminate it. Most plywoods flex more along one
grain than the other. Cut a top layer smaller than the bottom so the tips flex, but alternate the lam so the middle doesn't. The other thing you can
do is mold in bottom concave, that will also stiffen it.
If you want a glass board, use a foam core. I used 1/2" divinycel foam, 2x 8oz glass top and bottom and WEST epoxy for my boards, and they are light
and bullet proof. Just like with ply, shape the foam to control the flex.
PHREERIDER - 15-8-2008 at 05:41 AM
BK, how did you "mold in" concave on ply? layer the edge then sand it or is this like laying glass down with shape?
the sanding shape seems straight forward.
any rocker?
the winds are down and boredom is approaching
bigkahuna - 15-8-2008 at 05:47 AM
Vacuum bagging, it's the only way to work with laminates. I picked up a used vacuum pump from an auto a/c repair shop for $30 and they threw in a
hose and gauge. I normally buy bagging supplies at a fiberglass supplier, but you can also re-purpose materials purchased at Home Depot and save some
$$.
PHREERIDER - 15-8-2008 at 09:31 AM
build the form thing, gottcha.
thanks