I recently found a foam supplier around town, EPS foam boards to be exact. Right there I think it’s an alternative way of aqcuiring foam other than ordering a block, specially when I’m thinking of shaping one board at a time. The thing is, they only have foam boards up to 3" thick. Impossible to hotwire, I guess. So bending in the rocker is the only way to go.
Question: Is it advisable to bend a 3" thick foam board (like gluing em up to the shape of a pre rockered stringer)? Or, am I better off ordering 2pcs. 1.5" thick foam board, then glue em all up to get the thickness and the rocker shape?
Well I’m thinking about which board will hold the curve more, or which board will have less resistance. Any answer in the ballpark will be of great help.
Actually I’ve seen thinner boards stacked up and glued, I’m just considering that it would be easier to make a blank out of a 3" thick board, I mean cut it lengthwise, bend and glue it to the stringer, and tadaa! a blank. right? Though my fear is that the thicker board would snap if bent too much, or taking your point it won’t hold the shape.
And umm, what do you think is most efficient, a rocker table or holding the blank with sash clamps?
you are bending in the bottom rocker and then thinning the deck profile down from the curved rectangle you created
if you stick in some “springers” between the two panels
your fin boxes will have something to anchor themselves into
rocker table = an existing board you want to capture the rocker from.
stretch wrap packing tape will work but a vac bag is a better choice
use either slow curing epoxy or roo glue
you can hot wire the deck profile once you set the bottom rocker
allot of work to save some bucks
and not as long lasting as a pure hotwired from a block or molded eps blank
if you cut your outline and full perimeter high density rail bands out of xps/corecell/bluedow/precision board etc
and glue on the 1"-2" thick rail bands the same time you bend in the rocker on a table then the rocker will hold a little longer till you start shaping
if you preshape the bottom contours and then set the bottom skin to the perimeter rails when you bend in the rocker
it will not lose its rocker no matter how much you shape it because you have three sides locked in place (bottom to rail bands)
again all allot of extra work compared to juyst buying a blank
@oneula - That’s alot of options right there. Thanks!
Just to clarify, I don’t have a lot of experience with bending coz my first shape was hotwired from a block, and I think hotwiring is still the best way to go. But I’m looking into alternatives here. I already slashed ordering a blank from my options long ago coz it’s pretty expensive (shipping alone costs a wad of cash). And I could only shape one board at a time right now so I’m interested with this. But of course I’m looking into shaping a lot of boards in the future, and I’m definitely going for blocks. But for now, if this would work, then I’m good. And of course, I love hard work.
@hans - yeah, I don’t think I’m gonna go stringerless if I’m bending.
You can still hotwire these sheets if you use them vertical (so you have the glue lines showing at the deck and bottom). If you use thickened epoxy, the glue lines won’t be too visible. Or you can color the epoxy to get the appearance that there are several very thin stringers.
Just add a small amount of foam in the nose. Use the hot wire to cut the rocker and take the front piece off the bottom of the board and glue it to the top. The shape should mirror the rocker so it should work nicely.
Nice one Sharkcountry… Flat to flat is good for gluing… I’ve done the Hans way, 3"strips hot wired out of xps. I found eps not to bend very well. Good luck Mojo…
Oneula and I did all our early boards by bending EPS over a rocker template. Some templates were boards, other were rocker tables we made. If choose to bend you can do as Oneula says. I like to add wood rails as soon as possible to lock in the rocker.
Now these were all Compsand boards, so they were all skinned with a wood veneer in a vac bag. The vac bag causes all kinds of problems with rocker, so you will need a rocker table/template to hold the rocker. If you are going to glass without a skin, no problem. I have seen Charlie Price use weights when bagging skins to add or keep rocker without having a rocker table.
this is our first batch of compsands we made back in 2004 (pre Bert)
obviously we were alittle clueless back then
but such is learning
and its still a fun hobby versus a career for us
rocker tables with stretch wrap and lots of tape
this is kind of deceiving as the two on thefar right here some of the first two Marko 7’6" Jeff Johnson shape blanks I got from Jeff and Jim up at Surflight. One was skinned in mahogany and birch veneer while the other was skinned in 1/16 balsa. The one on the left is a PU blank skinned in balsa. The very fiirst Compsand I ever made it has the woven bamboo on the bottom. The four in the middle are from home made bent foam.
We use epoxy and wood veneers between the foam layers so they tend to hold the rocker for a little while. I wouldn’t wait too long though. The other thing is we keep the layers the same thickness when we do the initial bend or the rocker will be off.
I’ve done quite a few boards with thicker foam by cutting out rocker slices and gluing them together to get the width I want, but the slices were usually 6 inches thick. 3 inches will force you to have more glue lines, be sure to use a soft glue like Gorilla Glue, or shaping will be a nightmare.
If you bend the rocker in and do it right, it’s easier than shaping a clean bottom from roughly cut rocker slices. We have not tried bending the rocker in without adding something like solid rails to hold the rocker.
I have made a handful of stringerless boards from EPS, XPS and PU foam, but none have had a bent in rocker.
oneula - with vac bagging, do you still cut em for stringers or you just glass em straight away? maybe I could try it with my shortboard as the rocker table, though that’s gonna be a little ways down the road coz I’ll be doing a 7’0 Egg right now.
That being said, I’m thinking of a flatter rocker, like 3" nose 1.5" tail. Is it enough? Which bending method is advisable?
sharkcountry - I’m imagining like multiple stringers, is that what you’re suggesting?
If you have 3" thick foam you can make a board with 3" nose rocker. I just cut a board out of a 3" thick slab of XPS foam. The tail has about 2 1/2 inches of rocker the nose just about 3" The thickness is 2 1/2 "
you do know that stringers are primarily there for visual shaping purposes yah?
there’s no real strength component unless you do a triple stringer or something.
with a rocker table i precut out full rail bands out of high density foam, like corecel, precision board, or xps/blue dow the rail bands are the same thickness as the blank and have the rocker cut out usually 1’ thick. after i bag in the rocker to the flat sheets i cut out the outline and adhere the rockered rail bands to the bent in blank. You can manually build out solid wood rails at this time as well. In most cases i place a 1/8" piece of paulownia or balsa or marine ply between the light weight foam center core and higher density and “waterproof” perimeter rail. this thin piece of wood acts as the perimeter stringer and locks in the rocker. this is all allot of extra work in comparison to hot wiring a blank from a block and then attaching a thin wood sheet to the deck and bottom like what Greg calls “timber flex”.
i just build a bunch of these blanks out over a weekend and store them in temperature controlled storage locker for use later. We also premake our timberflex veneer skins with an underlayer of 2oz or 4oz cloth so the build process is simplified when you want to make a board.taping up a bunch of balsa sticks to build out a skin takes about 15 minutes so we don’t usually prebuild out the balsa panel skins and the woven bamboo is a no brainer with some tin snips. just like putting up wall paper. The idea is to have all your raw materials pre-staged so that its just like going down to the surf supplier and picking up a blank to shape. But of course shaping a purchased PU blank is the simplest and easiest of all ways to make a board. You just have to have access to those specialized suppliers.
if you use a board as a rocker table its a little more difficult but you don’t end up with a big old rocker table to store, If you go to Surflight you see rocker table after rocker table on the floor hanging on the wall etc etc.taking up allot of space.
my brother and i kind of resorted to the old surfboard as a rocker table out of space/neccesity but because we were primarily interested in copying some of our favorite old boards into longer lasting eps/epoxy/compsand versions. But that has it’s own unique problems as well if you don’t compensate for the change in materials. Also Mr.J’s ironing board apartment shaping rack was a big inspiration.
I still think the future is what Resinhead and Lillibel did with Ken over at Segway.
I wish there were operations like that at every town. Where you just design your board online and send the file off to a inexpensive CNC cutter and then pickup your shaped blank for finishing over the weekend. That seems to be the big “next thing” in my opinion, Greg wrote a post about this years ago and firewire is trying to do it. But a “pottery barn” of outlets across the country for the do it yourselfers… Kind of what your seeing in the market after Paul Jensen started doing his thing followed by Grain and now all the CAD/CNC guys selling kits and classes everywhere for hollow woodies. You can even buy a wood surfboard kit in the Grizzly catalog. Wouldn’t be surprised if Home Depot or Lowes don’t jump on the bandwagon soon.
