Intro: Composite Sandwich Skateboard
This is how I made a composite sandwich skateboard. I use a much more involved version of this same process to make surfboards, but I thought the skateboard project would be a little better fit to a first-time builder. This project assumes some familiarity with the use of epoxy and fiberglass, as well as a passing knowledge of vacuum-bagging. You could absolutely do this project without any experience in either of those, it would just take a little bit of research here and online about using those techniques. None of it is rocket science, folks... Of course, neither is rocket science for that matter.
Just about everything used on this board could be substituted with something else, different foam, different wood, carbon fiber, etc... Get creative, that's what you folks here do, right?
1. 1/2' eps foam sheet (styrofoam, found at home depot) 1 lb density
2. fiberglass fabric, 4oz or 6oz. You'll probably only need a couple of yards
3. epoxy resin, shouldn't need much, maybe a quart total. I get mine from surfboard supply companies, the kind I use is called Resin Research, great stuff.
4. sheets of 1/8" balsa, available at any hobby store.
5. sheets of a pretty veneer. I used makore from ebay
6. some bits and pieces of plywood the same thickness as your sheet foam.
7. A higher density foam, backed with stiff wood, for your male mold. I used 3 lb density EPS. You could probably get away with using the blue foam from home depot, but it would be a good idea to cover it with a couple of layers of fiberglass to keep it rigid.
8. some kind of vacuum bagging system. I use the system I have for surfboards (vac pump and large nylon bags), but there are small versions commercially available that are specifically designed for home skateboard makers, Roarockit.com sells a very complete kit. You could also use a Foodsaver. There are very cheap venturi-type vacuum pumps available that attach to a home compressor, you can get them from harbor freight. You could even make a vac pump out of an old fridge compressor or use the instructable here that describes making a vac pump from a 12V tire pump. Bottom line, you need a vacuum pump, but don't let that stop you.
9. Release film, some kind of nylon plastic sheet to wrap up the project before sticking in the vacuum bag.
10. Gloves. Epoxy is sticky.
11. Denatured alcohol to clean stuff up. Epoxy is messy
Thanks to ewilhelm for letting me know its cool to mention specific products and companies here.
DO NOT! DO NOT! DO NOT! DO NOT! DO NOT! DO NOT! DO NOT! DO NOT! DO NOT! DO NOT! DO NOT! DO NOT! DO NOT! DO NOT! DO NOT! DO NOT! DO NOT! DO NOT! DO NOT!
Do NOT use Acetone to clean up Epoxy. Ever.
Do Not Use Acetone To CLean Epoxy.
Acetone gives epoxy a direct route to the bloodstream through the skin, and most instances of epoxy reactions/sensitivity in the surfboard and boatbuilding industries can be traced back to exposure to epoxy-contaminated acetone.
Step 1: Make Your Mold
I used a chunk of styrofoam in 3 pound density to make my male mold. You could really use any number of things for a mold, even another skateboard deck. I even considered using another skateboard to make a mold from plaster. Lots of options here as well.
I figured out the approximate dimensions of the skateboard I wanted, then shaped concave and nose and tail kick into the foam mold. I then covered it with some thick plastic, stretched tight and taped on, to keep the skateboard from sticking to it.
Roarockit.com sells molds, pumps, bags and veneers all together in a skateboard kit ready to go.. It might be a good way to start for someone who doesn't already have this stuff like I did.
Step 2: First Lamination
Once you have your mold made, you are ready to start sticking stuff together.
Lay out the materials by taping together a sheet of balsa strips the approximate size of the skateboard mold, maybe a little bigger. On this, place your fiberglass cloth, about the same size. Two layers would be fine.
Mix up some epoxy, probably not more than a few ounces, and work it into the fiberglass until it is all saturated. Then place the balsa sheet on the mold, fiberglass side up, and put the 1/2 foam sheet on top of that. Tape them in place on the mold with a couple of strips of masking tape, then wrap the whole thing with release film, stick it in the vacuum bag, and suck all the air out. You can see how all the layers press together and form to the shape of the mold.
Once it was under vacuum, I placed the mold over a couple of pieces of wood with a heavy weight on the center to create some "camber" in the deck. This isn't necessary for a good board, but I wanted as much resistance to my bulk as possible.
Step 3: Truck Support Inserts
You'll need solid wood for attaching the trucks.
Make sure you measure where you want your trucks very very carefully. The bigger inserts you use the more solid they'll be. Wherever you stick them, make sure you take careful notes about where they are located in relationship to the nose, tail, sides, etc.. You'll need to know where they are later.
Once I got my locations, I just routered out a couple of holes the size of the plywood chunks I was using, and fitted the plywood chunks into place. If you don't have a router, you could also just use a box knife to outline them in the foam, then dig the foam out with a screwdriver or something.
Don't worry about gluing down the truck support inserts yet.
You'll notice in the photo that the deck has "sprung back" from the mold a little, especially at the nose and tail. That's ok, that's why you use the mold for each step, by the time you vac on the last lamination, it will keep the shape of the mold just fine.
Step 4: Second Vacuum Lamination
The next lamination, this time the bottom skin of the deck, goes pretty much like the first, with one addition, you're going to attach the truck support inserts at the same time.
Get your balsa sheet and fiberglass ready as before.
I put a couple of layers of glass at the bottom of the holes for the truck inserts, same size as the holes, and cut a few pieces of glass a little bigger than the inserts to go on top.
Mix up the epoxy resin as per manufacturer's instructions, again probably not more than a few ounces. Pour a bit into the holes for the truck inserts and smear it around to saturate the glass you put down there. Then stuff the truck inserts in. Lay the small cut patches of glass over the truck inserts, and wet it out with the epoxy as well. Then wet out the layer of glass that is on the balsa skin, and flip it over on to the deck, which is on the mold already.
Then just tape it lightly to hold it all in place, wrap again with release film, tape tightly, then bag it all again and suck out the air.
A note: It is very important to pull the release film tight over the whole thing before bagging, or it can crease and fold in between lamination layers.
Again, I bridged the whole assembly and weighted the center to create camber.
Leave the whole thing in the bag, under vacuum, until the epoxy is well-cured (check epoxy directions). I did mention that in the first lamination, right? Well, you should read all the directions before starting anyway!
Did I say sorry about my cluttered garage?
Still a little springback from this lamination, but much better than before.
Step 5: Veneer!
This step is a relatively easy one.
By now you have your veneer. I used some Makore leftover from a surfboard project, but really any thin pretty veneer will work.
I just taped it together to bookmatch it, slapped some epoxy resin on it, taped it into place on the deck, and vacuumed the whole thing on the mold till cured. You can either brush the resin directly on the deck before applying the veneer, or use a layer of fiberglass between them again. I used the glass because I didn't want my fat ass breaking the board the first time I used it!
I put on the deck and bottom layers of veneer at the same time. Come to think of it, I probably could have done the same with the balsa skins, but I didn't want to push my luck first time around.
Once it's all cured, you can pull it off the mold and cut out the outline. We're going to add a 1/4" all the way around, so take that into account, but it really won't make much of a difference.
Use an old board or something to draw your outline, or just freehand it. If freehanding, use a big sheet of construction paper folded in half for your template so it will be bilaterally symmetrical after you cut it and unfold it. Symmetry is very important, otherwise why even bother?
Now (BEFORE cutting the outline) would be a really great time to use those measurements you took for the truck inserts (you did take measurements, right?) and mark out your truck locations. This is worth taking some time to get right. You haven't gotten this far without having some brains and problem-solving skills. Don't blow it all now by screwing up your truck placement.
Draw the outline on the deck, cut it with a jigsaw a little outside of the marked line, then use a sanding block to get the edges all square. The sanding goes pretty q This will be tough on the concaves to get everything square to the curved edges, but worth it.
Step 6: Attaching the Rail Material
This is kind of a "fiddly bit" as my aussie mates like to say. Or is it my brit mates? Whatever, it was kind of a pain.
The trick here is to take a sheet of 1/8" balsa and tape it along one of the rails so you can trace the shape of the rail onto it. Getting a curved and undulating shape onto a flat sheet of balsa, fun stuff. Once you get the shape drawn on, you can cut it out with a razor knife and use it as a template for the other sheets. The good news is, you only need four (two on each side) to complete the rails.
It is good if you cut them a little oversize (wide), it makes it easy to place them that way, but if there is too much sticking out it wont seat well when you vacuum bag them on.
Don't worry about wrapping all the way around the nose or the tail, we'll finish those in a next step.
Once you have the rail pieces cut out, you can glue them on with either the epoxy or foaming PU glue (elmer's ultimate, gorrila glue, etc.) . Either way. Come to think of it, if you're good with that stuff (I hate it myself), you can probably use it for most of this construction.
Anyway, get the glue or resin on the edges of the deck, and in between the layers of rail balsa, then use tape to hold them in place on the board. Wrap the whole thing with release film, and stick it in the bag again.
Once the rails are cured on, you can put on the nose and tail blocks. I made mine by clamping together a bunch of scrap balsa. Just cut the nose of the board into a slightly pointed shape, then use a sanding block to make the edges square to accept the nose blocks. I glued them on with the foaming PU glue and just used masking tape to clamp them into place.
In the last photo you can see all the rail pieces attached before sanding.
Step 7: Finishing the Rails
Then you just sand down the nose and tail blocks to get a smooth flowing outline, sand down the rail wood to get it all flush to the rest of the deck, then round everything over to get a nice radius on the edge of the board.
Fine sand everything and you're ready to glass.
In the last photo I have taped off the deck of the board in preparation of final glassing. The outside layer of fiberglass will overlap the taped off area, then when it is mostly cured the tape can be lifted and the glass can be cut with a razor right at the tapeline, giving a nice clean border.
Step 8: Glass It!
Now comes the easy part! Cover the board with a layer of fiberglass and epoxy on both sides, some extra layers of glass under the tail for durability (skid pad), then brush on a sanding coat and sand it out with some 220 grit sandpaper.
Step 9: Finish and RIDE!
Once sanded, you can spray it with some rattlecan gloss clearcoat lacquer and drill out the holes for the trucks.
You DID remember to mark the locations for the trucks, right? Because if you didn't remember to mark the trucks until the very end, you're going to give yourself a headache trying to find the right spots without ruining the board. Don't ask me how I know that.
Mount the trucks with some big ol' pimping wheels, slap on some griptape (not too much, don't want to cover up that nice finish), then go for a little ride.
Hope you enjoyed this, my first instructable. I'm interested to hear any comments or suggestions anyone has.
If you're curious about my surfboards, check me out at http://psychsurf.blogspot.com