Balsa and EPS without interior glass

General Discussion
1

I am curious whether anyone has constructed an eps/balsa ‘skinned’ board with only exterior glass and how that panned out durability-wise.

In the spirit of POS surfboard building, I think I’m going to try this out and will post my results here on this thread. In particular, I plan on embarking on the following:

  1. construct rocker table inexpensively

  2. apply taped balsa sheets to sheltersheath ‘blank’ on rocker table using PU glue and sandbags (hehe–I love this crap!)

  3. glue on balsa rails (C method)… If you understand this reference then you need to click the little x immediately because you spend too much time here.

  4. shape rails and deck

  5. glue balsa sheets to deck in same way as bottom.

I’m planning on using 1/16 inch thick ‘skins.’ and rails to 5/8 inches thick.

Exterior glass… six top/ six bottom with another 6 oz deck patch.

  1. Surf and break it.

  2. glass heavier next time.

I have a HD blank board where I did the deck only this way and the deck is crazy strong. I can punch it as hard as I please without consequence. Of course, it has 3 layers of 6 over it.

However, it occurs to me that I surf really weak beach break, and I feel no real pressing need to punch or jump on any of my surfboards.

Thoughts, comments, threats, insults, and pseudo-scientific engineering nonsense are all welcome.

2

Check out www.surfgear.cc

He’s always been doing it without any underglass (for quite a long time!), with great results. But he does vacuum bag it, and that will definitely make a big difference.

3

Cool. Thanks shwuz. I remember reading that he does exterior glass. For some reason I was under the misconcetion that he used poly cores or denser EPS. His site seems to indicate otherwise. That’s encouraging.

I know you to be experienced in this arena… what are your thoughts on my proposal?

4

Sounds like it should do just fine. How many sheets of the sheet foam are you using to get your thickness? Depending on how many glue lines you have, you might wind up with a little snap-back of your rocker, but probably not much. The biggest thing I would be concerned about would be getting even clamping pressure so you don’t wind up with any voids anywhere between sheets. The one time I used sheet foam that way I wound up with huge delams from not having it clamped well enough. That’s why I used vacuum pressure now, but the foaming glue (which I didn’t use) should help quite a bit with that particular aspect.

Really, if you can refine the process you’re describing to where you can get consistently good results, it would certainly be worth the time, as it could eliminate much of the inital cash outlay involved in getting started in making compsands. Good for new shapers and “dabblers” like myself. I see consistency and quality control being the biggest hurdles there, I’m still very leery about using the foaming glue for anything requiring a close-tolerace fit, especially over big flat planes. I just don’t trust myself to get a perfectly even film of glue so the foam-up is the same everywhere. Plus, the foaming glue will penetrate your foam core, making achieving predictable flex patterns a crapshoot.

All that being the case, however, I think it is worth trying out. Just remember to post photos when you’re done!

5

you can skip the expense of a rocker table if you have already have a rocker you like and a roll of plastic stretch wrap and some tape. (see attached)

You don’t even have to pre-cut the shape first just line up the board down the middle.

once dry, the external skin will hold the rocker

we do this all the time but use vacuum bags now.

you can make some real cheap and strong boards this way but I’d use a vent to reduce any incident of delams unless you don’t plan on keeping them like us cause we just give away the ones that delam or we don’t want to keep to neighborhood groms who can’t afford a board on their own…

CMP used to not glass the inside because he just didn’t know it made a difference at the time and he wanted to keep the costs down. He basically just used epoxy to glue on his skins and he never used EPS until recently all his boards were just a standard shaped Clark blank with his wood skins on it so the boards were heavy but pretty close to indestructable. I recently bought one of his boards he made about 3 years ago and I swear it weighs about twice as much as the Lowes boards we’re making… But with all the info coming out of sways since late 2004 contruction techniques have changed quite a bit we owe alot of that to Bert and Greg.

What you’re doing is pretty much the SOP (standard operating procedure) with out a bag… it’ll work just fine

Ultra light boards should be the call for a weak beach break if that’s where you surf… Try and go as light as possible then work your way up. Maybe try it with 4oz first…

Bottom line

to make it fun

you can’t go wrong to keep it simple…



6

I’m digging your approach. This is more or less how I’ve rockered my other HD style boards. This seems like a no brainer for applying the bottom skin, but what about the deck?

Will the bottom skin and the perimeter rails be stiff enought to ‘lock’ the rocker while the deck is being pressed on? This was my rationale for a rocker table–supporting the rocker I want as the deck is applied. Does this make sense or am I overthinking it? Also, do you think it will be problematic if my rocker capture subject is a fair bit narrower than my proposed planshape?

7

When you refer to HD foam are you referring to soft #1 eps?

If yes, then it’ll self destruct really fast…meeting your target project goal #6 quite quickly.

:wink:

8
Quote:

This seems like a no brainer for applying the bottom skin, but what about the deck?

Will the bottom skin and the perimeter rails be stiff enought to ‘lock’ the rocker while the deck is being pressed on?

The applied bottom skin and glue on rails will lock in rocker for the deck application

we bag our deck skins onto our boards at 15psi with no support and don’t get any flattening of the rocker

the question is do you have enough weights to push in all the contours presented to you by the deck the compound curves have a tendancy to create gaps in certain areas on the flats like top middle towards the nose and near the tail but the thickness of wood you’re using in balsa should deform like jello.

Quote:

This was my rationale for a rocker table–supporting the rocker I want as the deck is applied. Does this make sense or am I overthinking it?

You can build a table if you are skeptical you don’t have to if you just think of your board as the table

Quote:

Also, do you think it will be problematic if my rocker capture subject is a fair bit narrower than my proposed planshape?

If your wrapping with plastic wrap just be careful of side wrap/warp

stick a piece of 2’ wide ply or mdf in between the “rocker table bending form” and the blank if you want to build out an extended flat surface for the blank to rest against.

9

im with dave on this one

it will proly fall apart

thats after it fills up with water

:wink:

really get a pump and a bag!

you will get away with it if you glass it really heavy on the outside

but if your looking for performance and durability

get a good setup

and do it proper like

i use cheap insulation foam but it comes in 50 mm thick sheets

so no glue ups

whats the problem with using glass under anyway!

10

No real problem with glass under the balsa. I just wanted to try something cheapo style just to see. Since eps is so cheap, the glass and resin becomes the most expensive part.

I figured, hey, I don’t need to jump upside down on my boards and this will be for grovel surf so what the heck. I want to test the limits of cheap and light.

I happen to have a bunch of birch veneer from my grand dad’s cabinet shop that I could use for skins in lieu of balsa to really cheap this thing out. It looks about 1/16 thick. Any thoughts on this as a skin. It seems like it would be less willing to accept some of the curves.

Thank you for that insight Oneula. I will do it your way. I’ve been thinking for some time on how to avoid the rocker table. It’s great to hear you’ve had success without it.

craftee: Yes, I’m refering to the 1lb stuff. I don’t doubt your prediction, and silly’s second. I was wondering, though, whether it was based upon experience with this approach or educated speculation?

11

a bit of both along with some recent non-surfing experiments Ive been doing as of late. the birch would work but may give you probs at the nose…relief cuts work as does thinning and minimal dome at nose…

…if you really want to go POS cheapo style, buy some thin HD door skin and slap that on your eps w/o underglass…you might even be able to pass on the over glass with some post wood sealing with thinned epoxy…now THAT’S cheap bro…

…put all you HD purchases on credit, then when the CC co’s hound you for payment, file for bankrupcy…NOW were REALLY getting somewhere…you’d make cheap surfers everywhere (and believe me, thats an EXTREMELY large crew) green with jealousy.

got plenty more handy cheap tips if you need’m…no extra charge…man Im on a roll!

12

Bustin’ my balls… hehe

Don’t think I hadn’t thought of all those options.

How about this… blue XPS with thin cypress skins and rails–PU glued on and no resin or glass at all. Cypress is supposedly a 100 year wood–my dad uses it to build duck boxes in swamps (don’t ask). This plus waterproof glue plus waterproof foam could be cool. I don’t know anything about the grain and bending characteristics of cypress though.

Before you continue on your roll crafte, remember that E Fl is within my sphere of ass-whoop ;).

hunter

13

May I remind you councel, you are an officer of the court.

Any further threats of violence and I will move for sanctions…after which I will open up my own tallboy-can of whoop-ass.

Touche!

:slight_smile:

14

if you want cheap and low risk

use 2 pound foam as it will help negate dodgy construction issues.

if you get delams in 1 pound stuff the boards start to fall apart pretty quick if you dont fix them

im speaking from 11 compsands experience (not many)

but ive tried alot of the suggestions being posted lately

and i think that a few of you guys are chasing your tails so to speak

at the end of the day to get a great result

applying the fundamentals of berts original post

with little variation

will get you “all” the way there

and a tough board that will last you years and be infinatley rebuildable

and light weight.

a cheap bag and pump would cost no more then a 200$ and im stilll using the same bag i made for my first board

some dudes have paid no more than 30 dollars for there setups

re. rail material

i think the cypress would be perfect!

and the birch ,cypress,or spruce skins

you got the right ideas

just use a vacuum

you will save money in the end

( it think if you use heavy material for the skins like birch or ply etc you could get away with not under glassing

if you use a vacuum bag and decent glue like pu glue or epoxy, but it wont be a true sandwhich )

if its not a true sandwhich and wont be as strong. but then again cypress is really strong anyway so prolly doesnt need to be a sandwhich

15

I tried it, The Boys. I laid out my balsa sheet on my workbench and pre-laminated it with glass & epoxy which would go on the outside. When it was cured, I thinkly spread foaming pu glue on my blank and very lightly misted the open wood side of the balsa skin. Pop it in the bag and wait. I was really looking forward to the 3-4 hour bag operation rather than the 8-10 of epoxy. What I actually got was wholescale pump/bag/board failure. I don’t know if the materials & process had anything to do with it, but when I had to peel off the ruined skin it looked like this:

On the plus side, I guess you could say foaming pu glue sticks balsa to EPS pretty dang well. But filling & fairing my (beautifully) shaped blank (and adding a couple needless pounds in the process) was not a good day.

I went back to epoxy & glass underneath afterwards, and have had no further troubles. :slight_smile:

Eventually, the board ended up like this:

16

In the spirit of POS surfboard building, I think I’m going to try this out and will post my results here on this thread. In particular, I plan on embarking on the following:

hee, hee! i can’t wait! the last POS thread from “the boys” (POS sup) had me

laughing hysterically!

17

If you use a thin veneer, you’ll need to either have a layer of glass under it, or a heavy duty glass job over it. We’ve done several veneer boards with glass under the veneer. They don’t have the same shell strength as balsa. These are the only boards that have shown wear. If I use the veneer again, it will be over 1/16" balsa and only for the visual affect.

When CMP taught us how to make these boards, we used 1/8" balsa. Then he told us that we could go with 1/16" and a layer of glass under it. We’ve been doing that for a while because it wrapped around the rail better. But now with the solid balsa rails, we could actually use up to 1/4" balsa and no glass under.

My favorite combination is a layer of 4 oz glass and 1/8 balsa vacuumed over the light 1lb EPS. Then a layer of 4 oz glass top and bottom to finish it (2 layers of glass on top would make it really strong). I put a generous fill coat when glassing. I just sand down that coat and spray a thin layer of clear coat (spray cans from the local hardware store) to finish our boards. A gloss coat would look better because you can’t get a nice finish from those spray cans.

The last board I made is a 6-11 x 20 1/2 x 2 1/2 made from .75 lb EPS with 1/16 balsa, 4oz glass under/over. It has 1/2" thick solid balsa rails (no stringer) and weights 7.5 lbs. If we used glass on fins it would be lighter.

I’m currently making a 7’ board with a 1/8" sheet of mahagony ply for the bottom skin, and it’s going to end up being quite a bit heavier than the balsa.

I figure that in calculating the cost of our boards using the HD or Lowes sheet foam, at least 50% is for the epoxy resin. It would be more like 35% to 40% for the resin if you go with a name brand box fin.

18

Mixing certain variables, I think I’ve come to the same conclusions as Shark Co & Oneula. My preferred (longboard) build now is 4 oz under & over, 1/16" balsa, and 2# foam. I suspect that 1/8" balsa over 1# foam yields very similar strength & durability and slightly lower weight. For traditional noseriders the slightly higher weight is desirable…

19

The only reason I don’t use 2lb foam is because I have to pay a lot more for blanks. I can get the lowes or HD foam for 1/10 the cost of a 2lb blank. I’m working on trying to get a block from the local manufacturer, but they’re pretty slow in responding.

I made a 10’ board with 2lb and no balsa, but it’s just not as strong as a balsa compsand. I think the balsa compsand boards are the strongest, even with extremely light core foam.

20

Thanks Benny and Sharkco! This was exactly the input I was looking for. Hmmm, I’m a little undecided right now. … Must think… difficult… screaming baby=no sleep.

On a similar vein, I saw my first firewire in person yesterday. I was surfing a small swell at a local beachy and I saw a guy walking down the beach with an ugly ass board with a huge arrow on the deck. I caught a wave in and gooned out by chasing him and making him let me hold it. 'I just want to hold your board squidlips!" Nah, the guy was really cool. He let me froth on it for a while. He said he’d picked it up in SD. It was the fish design like onuela’s board. It was heavier than I expected and the balsa rails seemed thicker than anticipated. The guy was stoked on it and said it was allowing him to do things his other board didn’t, but I think he was comparing it to shortboard. I was contemplating requesting a test drive and letting him hold my new Pavel superbank as collateral but figured that would be pushing it. Oh well. My 5/8 toby really didn’t seem that much heavier than the firewire. Sheez, I could loose that amount of weight on my ‘primary’ surf craft by skipping lunch and taking a dump.