I usually do 1 layer 4 oz under, and 1 layer over.
think the bond would be just as good between skin and foam if I just used resin under and did double 8 oz over?
anybody have any experience?
I believe it best to sandwich the timber with an over and under. You didn’t say if bamboo or balsa layup. Most of my experience is with bamboo and I find that it will split if the full lam is not stiff enough or you have some cloth under to keep the bamboo bonded. My 2 cents.
my 2 cts
I have done a few boards with wood veneer skins
I used 2 lb eps core and shaped the boards, 2 were longboards and one was a fun gun and one was a smaller reto gun which has a pu blank.
#1 9"6" fun gun, standard stringer. carbon fiber bottomand rails, cherry burl veneer deck vacuum bagged directly to the foam, 4oz glass on deck, epoxy resin with poly gloss. this board is awesome, real zippy, down side is carbon bottom heats up when on the beach.
#2 10 ft LB, no stringer, poplar veneer skins top and bottom vacuum bagged directly to the foam, left rails foam, single 6oz top and bottom, epoxy resin and epoxy gloss. this board was a bit on the thick side about 3.5". it actually worked good, but a little corky.
#3 8'6" retro gun, no stringer, poplar veneer skins top and bottom vacuum bagged directly to the foam, left rails foam, single 6oz top and bottom, epoxy resin and poly gloss, wall hanger, never surfed.
#4 10' LB with stringer, english sycamore veneer deck vacuum bagged directly to the foam, 6oz bottom color job and 6oz over the veneer, epoxy resin and poly gloss. glider deluxe
these may not be considered compsand to some but
all of these boards have never broke down or delamed.
heres what they look like
I guess as Greg suggests it may depend on the strength of the veneers
I haven’t put glass under the veneer on the bottom of many of my boards with no ill effects. I always put something under the veneer on the deck, although I have gone to 2oz with veneer patches.
Have done many boards without glass under on Balsa skinned boards using 1/8" Balsa. Have also made boards with thinner veneers like 1/16 balsa and the exotic woods you can get that are 1/40th" with no glass under, but they are best with glass under.
We do 2 oz glass under 1/16" Balsa, and generally double 4 oz over the tops on all boards. 4oz under and 4 oz over works pretty good with Balsa. Not as strong with the thin veneers. We made a bunch of skins from the thin veneers and 4 oz glass, then put them away for future use. Tried to keep the glass very dry. We haven’t finished any of those boards, and it’s been a couple of years.
Are you guys sealing the blank and the veneer before bagging? Just the veneer? Just the blank? Not sealing at all? Any tips on wetting out?
I recall a few guys gluing skins to blank with Gorilla Glue.
well said guys. thanks.
hey John
I dond know what the other guys are doing but Idont pre seal the board. the veneer I use is .018 to.024 thin with paper backing.
epoxy it straight to the blank in a vac bag then glass it.
they seem pretty dent resistant
[quote="$1"]
I usually do 1 layer 4 oz under, and 1 layer over.
think the bond would be just as good between skin and foam if I just used resin under and did double 8 oz over?
anybody have any experience?
[/quote]
OK...
I challenge every poster so far to place their Wood Skinned Surfboard in direct sunlight for at least 90 min on a day over 80 degrees F.
I've been involved in building about seven surfboards with wood veneer skins. The only one that delamed was the one that had no cloth between the skin and the foam blank. When I posted my problem on Swaylock's most "experts" told me that a big part of my delam problem was no cloth between the wood and the foam. And the fact that I left the board in the sun too long.......go for it!
One layer of cloth under is much faster than a total delam repair.................
Stingray
Sandwich skin effect, increase of stiffeness, is based on thickening of skin by separation of fiber with a light core . If wood is your sandwich core, you need fiber on both side. But veener is really thin so there is not a big skin effect.
An other function of fiber between wood and foam is to keep as much glue (resin) as need for good bond.
If you don’t use fiber you need to tixotrope resin with cabosil to keep an efficient (thick) glue join. It’s a rule for all glue system too.
Sorry for my frenglish
hey ray
I put vents in all my eps core boards and have no problems.
once I didnt put one in the 10' poplar one that i just posted ,, it did pop when I was in Hawaii, but it didnt have a vent at the time.
There's a few things to consider here......eg. the core density..... lighter eps takes more resin= change the viscosity to suite the foam you gonna use ( q-cell ....fibres etc )..........treating the core surface or using glass under , basically do the same thing. Most epoxies are twice as hard in a week , so forget about "flip-times" , unless your workin in a busy factory........there's certainly no need to rush theses things !
I would like to add that ,, I think if your not doing the extra glass under the skin it maybe wise to have a stringer in the blank.
as I see it the thicker the skins the less flexy the board will be ,, seems to me t he stringer will keep the livlyness of the board when useing thin skins
I talking longboards, short boards may not need it.
I've thought about it - no inner glass - wondering how to get extreme flex...to be able to literally change the rocker with foot positioning. I guess like a high performance softboard...
But I figured it would eliminate dent resistance entirely - However, as Kayu says, depending on the foam density. With my 1lb cores, no-inner-glass would virtually remove the whole point of sandwich construction.
I work with 3mm d'cell and pawlonia planks rather than veneer. I imagine veneer has minimum sandwich effect - almost no distance between inner and outer for the beam effect to be significant. Is that what the WMD fellas have found? Is dent resistance in veneers due to 1/16in of wood fibre or the fact that EPS bounces back a little?
Nine-lights did one which Consafos posted about - the open-sandwwich - no bottom skin at all - that'd be interesting.
JD
Josh, I have a PU foam with 1/8" balsa veneer, no glass under. I’ve had my head bounced hard on that board and no pressure dent’s. I was trying to paddle through a wave a friend was on. We thought we were OK, but at the last minute the wave hit him and he landed on my head as I was trying to push under. I was surprised that there was no dent in the board, but my cheek bone had a nice lump for the rest of the day. The board has no signs of the impact, no soft spot under the wood. I think the thicker woods have something to do with the dent resistance.
All of the compsands we do now have a layer of glass under the wood to create a true composite skin, but I don’t do many of them these days.
[quote="$1"]
But I figured it would eliminate dent resistance entirely - However, as Kayu says, depending on the foam density. With my 1lb cores, no-inner-glass would virtually remove the whole point of sandwich construction.
JD
[/quote] ..Josh , I would view your boards as having 2 beams......one as the comlplete board , and the deck skin being a working flexible beam in itself. Regarding deck-only skins , Ive done a few like that and found it needed some added strength to control the flex and still have good dent resistance , which can be done in various ways....
Yes
CMP taught us that way shark bait must have forgot with his head injury.
Epoxy painted directly from a dixie cup on the balsa skinned then flipped and taped to a PU (yes PU) shape and bagged. That’s how Charlie taught us, KIS all the way. Heavy but strong.
Bert, Sabs and Paul were then one’s who showed us the glass under but they were also secretly pre-treating their skins to keep them light. Remember paul’s top hat? And bert’s springer? Remember Bert ripping off his skin?
The most impact resistant deck is going to have glass cloth under the veneer. That way the veneer is in compression and the glass cloth is in tension. If flexability is desired then the glass cloth needs to have the weeve running diagonal across the board. If you want to learn more about this subject West systems have done impact tests, stretching,and compression test and the results can be found some where on their web sight or the Epoxy Works web sight or in one of their publications on vacume veneering.
in all wood PRE FAB the skin not just stick some resin on and flip on to core
most woods have there own characteristic nature and it works best when you know your wood?
cheers huie