I started a new board last night. This will be constructed from three layers of one inch eps foam from Lowes.
I plan to make a foam copy of a wooden board that I have under way. The foam came in 4’x8’ sheets so I started by cutting each sheet in half lengthwise. This was easy because the sheets are marked with dotted lines at certain intervals. I just followed the dotted line with my japan saw:
The foam has a plastic sheet on one side and a foil sheet on the other. I left these on while cutting to help prevent breakage and then peeled them off when I was done. They came right off with no problem
Next I used the board I’m copying to dial in my rocker table. I’m using white Ehlmers glue to glue the sheets together and I want to keep this away from the rail line so it doesn’t give me problems when shaping. To do this I traced around the donor board and then trowled the glue on being careful to stay inside the lines.
Once I had all three sheets layed up I used the woody as press to clamp things down while the glue dries. I added some weight to keep things firmly pressed and used a beach towel to keep the woody from getting damaged in the process.
This will be my first board shaped from EPS.
Can’t wait to see how it feels under the planer and sureform.
Good to see a stoked board builder (who loves exploring different methods and materials)! Don't you build these boards with your kids?
Yeah I’ve gotten my two boys infected with the bug as well.
They’ve been pre-accupied with college lately so I’ve been going it alone for a while.
Schools out for the summer though so I hope to have some company in the shop soon.
I love it when there’s a line to get onto the rocker table!
I ran into a problem last night.
I've read a few times that white glue is the thing to use for gluing eps so that's what I used.
After leaving it over night, less than twenty four hours, I pulled off the weights and was surprised that everything just popped appart. the glue was still wet! I think the problem is lack of air supply for the glue to cure. I re-spread the glue and put the weights back on and plan to leave it for a couple of days this time to see if it cures. If not I'll clean it up, sand it down and try a different type of glue. Epoxy worked well on the xps blank I made. I've read that Gorilla Glue makes a version that cures white. I might try that if I can find it. It probably works out cheaper to just use epoxy though.
Another thought I had was that maybe if I had rough cut the outline before I glued up the layers it might have given air a better chance to get in there and help the glue cure.
One more thought was that maybe I should have just drizzled the glue on instead of troweling it into an even layer. Air between the drizzle lines etc...
While I wait for my "blank" to set up I've been giving some thought to stringer material.
A search here on sways turned up a few options for what to use as material but I couldn't find anything about what the properties of each material type are.
For example would pvc be stiffer/less stiff/stronger/weaker than say basswood?
I'm thinking, purely for the looks, of using a rather thick (say half inch?) light colored wood for the stringer and then making nose and tail blocks out of alternating light and dark woods and wooden glass on fins.
I don't really care much about weight. I'm used to wooden boards so no matter what I do this board will feel light to me.
Will a half inch thick stringer made from white pine or basswood, or poplar, make the board too stiff?
Is it common practice to tune the flex of a board by tuning the thickness or material of the stringer?
white glue - you mean PVA? i think a curing glue like gorilla or epoxy is a better bet than one needing to "soak" in or evapourate - i've had the same problem gluing up a few layers of foam for a race-car nose with pva
Yeah Blue, that’s the stuff. I’m debating on whether to tear it down tonight and re-do it with epoxy if its not cured or leave it sit for a couple more days. Its not I don’t have anything else to do in the mean time.
I took a few minutes to pull the weights off and check out the glue up last night.
I was surprised to see that it appears to have set up well.
I guess It just needed more time.
It was getting late but I couldn't resist drawing on the outline and cutting it out.
One thing I noticed right away is that the seems between the sheets are invisible.
When I did my xps blank like this the seems were very noticable
Next to the board I'm copying (which I built from wood):
And back on the rocker table until next time. I do this because I hope it will help train some memory into the foam.
Next step is to add a stringer.
I'm still hoping to get some feedback on that as mentioned above.
Anyone think a half inch wide wood stringer is a bad idea?
Added a stringer and started on some fins.
I decided to use pine because that's what I had. I planed it down on the joiner planer to about 3/4 inch. i know that's thick for a stringer, especially on a board this size. I did it that way because I like the way it looks. I have no idea how it will affect performance.
I also glued up the beginnings of nose and tail blocks. These will be three layers, pine, cedar, pine and will just be accents at the nose and tail.
For fins I decided to use pine again because it was the only wood I had on hand that was the right size for fin material. I'll foil these down and then add a layer or two of fiberglass to keep them from splitting.
First I cut the foam blank in half and traced one half onto the board:
Then I cut out the stringer, rough shaped it with the band saw and a block plane, and glued it up using epoxy and shrink wrap for a clamp. You can also see my nose and tail block glueing up at the same time.
And my fins also rough cut on the band saw. I copied the shape from another board.
I did use a little spackle but I guess I didn't use enough.
I was very tentative about it because I wasn't sure if it would lead to delam issues.
I used it to patch a few tearouts and some of the bigger scratches that I couldn't sand out without changing the final shape too much, then I layed a very thin coat over everything and scrapped off as much as I could. When I say "very thin" I mean about as close to nothing as I could get. And then I lightly sanded that. In the end I'm not sure I left any spackle on at all after that last sanding except for the obvious patches.
When I poured on the epoxy for the lam coat It soaked it up like a sponge. I had to mix up a second batch to finish wetting out the cloth and then a little more to do the rails.
I'm pretty sure I used way more resin than I could have if I sealed the board up better because its much heavier than I expected. Sure I used a thick stringer and nose and tail blocks but this is a EPS board and it was light as a feather before I glassed it. I wouldn't go as far as to call it heavy now but its heavier than I expected it to be.
Getting ready to glass this one soon.
I've got the shape down about as well as I hope to.
I've added a nose and tail block which are only roughly shaped at this point.
I'll have to clean those up and then make a last pass at the overall shape to bled in the blocks and fine tune my rails etc..
Then its on to glass.
Fins are pretty well foiled but still need some final sanding and tweaking. They will be glassed on.
I have a question about the final finish, before glassing.
How perfect should I try to get the surface?
Its almost impossible to get this foam dead perfect without little tear outs and pock marks.
I know that every little hole is one more place for resin to pool and add weight but won't it also increase the laminations bond?
I've considered using a coat of spackle as I've heard some do but I fear that will promote delamination.
I'd rather the board be heavier and not delam than be lighter and then have delam issues.
Here are a few pics. Note that the fins are just on with some masking tape for the sake of getting a photo.
pre nose block:
I think making your own blanks is great, true autonomy. On the rocker table, are the all threads run wild on top for a reason? Seems as though they would get in the way unless they are there for indexing. Also how was it doing the nose and tail blocks while still working on the blank? I’ve always finished the blank more or less and fitted the blocks to it, That junction where the two meet is always a pain in the a$$ for me. Nice Work.
The idea with the allthreads is that there are a second set of cross bars that are supposed to go on top of the board and then get screwed down to clamp things together.
I do that with my wood boards but didn't do it with the foam for fear of damaging it.
I could have threaded them down but was too lazy. And yeah they do get in the way.
Its a design flaw that I haven't found a way around. I need some sort of quick release so I can move them up and down easily. Threading them up and down takes too long especialy since there is all kinds of gorilla glue and epoxy gummed up in the threads because I'm a slob so you have to do each one with a wrench and a pair of pliers. That's why I end up leaving them where ever they were the last time I finished with them. The table would be more versatile if I could find a way to move them up and down easily.
Regarding the nose and tail blocks, I rough shaped them as you see them off the board and then attached them. I probably should have finished them up a bit more before I did but I got anxious to see how they looked. I haven't started working them on the board yet. I have a feeling its going to be a pain.
Roger that Squaly, thanks for clarifying. This has me intrigued, I’ve got to give it some thought on the all thread. Do you need much clamping pressure from the top? I know you must need some for the wooden boards but not the foam. Try using a Dremel with a little sanding drum in it for dialing in the nose and tail blocks.
Nice one tblank. I'll drag out the Dremel for sure!
Yeah, with the wood boards quite a bit of clamping pressure is needed depending on the thickness of the materials, amount of rocker, and build method. With foam, not as much pressure is required but its more imporant that the pressure be evenly distributed across the whole surface.
Next time around I might sandwich the foam between two layers of door skin while its on the table. That would allow me to use the allthreads and crossbars for clamping without damaging the foam and would make for more even distribution of pressure from the clamping bars.
Did a little shaping on that nose block. The Dremmel was a great idea (thanks tblank) but very unforgiving with the slightest slip and touch of the foam. In the end it was getting too late for power tools anyway so I reverted to hand tools. I found that a good way to protect the foam along the edge of the wooden block was a few strips of blue masking tape. That allowed me to be pretty agressive with the sanding block and not screw up the surounding foam. One problem that I ran into was my unfortunate choice of Gorilla glue to attach the blocks. I ran out of white glue so I used what I had. Great stuff and the bond is very strong but it left some staining where it seeped out of the seems. You can see it in the photos below. I'll have to find a way to clean this up without taking off too much foam. Maybe a good application for some light weight spackle.
The blocks came out fine, they’ll serve you well in the long run. Isn’t that where all the dings start… the nose and tail? In the future you might try plain lam resin to glue up the foam. For your blocks; at woodcraft.com they sell super glue (cyanoacrylic) with different set times and in a thicker gel formula that is easy to work with. you can put enough on to hold but no squeeze out. The dremel is good but the key is to ALWAYS keep it moving or they will dig in quickly.
Go get it wet!
Howzit tblank,FiberGlass Hi sells a glue in a spray can made for gluing foam together and it works great. I used it for gluing sandpaper to my pads that I used on fin boxes because most glues would heat up and the paper would go flying. I had to use a heat gun on the stuff when it came time to change sandpaper, wish I could remember the name and it's right on the end of my tongue. Just call themand they would know which glue I am talking about.Aloha,Kokua
Say it aint so! Howzit Kokua, You mean good 'ol Tacky has been replaced? I know 3M makes contact adhesive in spray cans that’s good stuff although the price has skyrocketed in the past year. The price went up and they shrunk the can. Got an FH shop right here in town, will give a call to Wade, Thanks. Does the glue work on styrene too?
Howzit tblank, No ,Tacky has not been replaced and I used it all the time for regular board sanding. The other stuff was for just fin boxes and fin systems that heated up the pads more. I had pads just for boxes and fin systems and pads for sanding boards. Probably had at least 2 of every pad available, 6" and 8" power pads soft to hard and 6" and 8" Ferro pads soft to hard, around 20,pads I think. Just remembered the name of the glue,Clear co was the nameand Fiberglass Hi had it. Aloha,Kokua