Print PDF
Favorite
Email
Step 2Building the mold
The mold is what the plywood is squashed against forcing it to take the curvy shape of the skateboard. It will be made from stacked cross sections of spruce plywood. First create a cardboard template of the mold cross sections(fig.2a) and use it to trace out 15 versions on to the spruce plywood sheets.(fig.2b) Cut out the cross-section layers then glue the layers together and squeeze with clamps,(fig.2c) wipe off the excess glue that squeezes out.
Once dry, remove clamps and use rasp or belt sander to remove any differences in the cross sections so the surface of the mold is smooth.
Mark off area for inner concave where material needs to be removed.(fig.2d)Make a template of the desired inner curve(fig.2e) so you know exactly what material needs to be removed with the rasp or belt sander.(fig.2f) Refine surface of the mold first with the coarse and then with the smooth sandpaper.
Once dry, remove clamps and use rasp or belt sander to remove any differences in the cross sections so the surface of the mold is smooth.
Mark off area for inner concave where material needs to be removed.(fig.2d)Make a template of the desired inner curve(fig.2e) so you know exactly what material needs to be removed with the rasp or belt sander.(fig.2f) Refine surface of the mold first with the coarse and then with the smooth sandpaper.
| « Previous Step | Download PDFView All Steps | Next Step » |
You just use the pink insulation foam and a hot wire cutter. If you don't have a hot wire cutter knives, and saws, will do. The foam is strong enough to resist compression once in the bag
I can't find the pics of it in the vacuum bag, but I found the compression ones. It's the same kind of mould but you only need one half for the bag.
not all these pics are from the same deck press. I just picked ones that showed it best :)
The pic of the mould is after it was used. As you can see it shows some signs of pressure but it maintained its shape. It was used again a number of times.
The second pic is the wood in the press. This shows you another way to press a deck using threaded rod as a pressure source. It's a little more cumbersome and more work than a bag.
The last pic is the board that was pressed from that mould.
I'm also curious about the differences between vacuum bagging and bolt pressing. Does one have an advantage over the other when using foam? (foam fatigue due to vacuuming is my concern)
Finally, is it a good idea to use the foam in the same way that gregy (the author of the instructable) used plywood? I want to create a decent looking concave and it seems like the method used in this instructable might be better than the method you used in that respect.
The vacum bag is a much better system than the threaded rod. It cuts your time down considerably, is easier for one man to use alone, you only need half the mold, and you get more even pressure. The foam is dense enough that it resists compression quite well. You do see some wear, and it gets worse with time, but it work very well.
As to the durability of the foam....it depends. It depends on the type of deck you wanna build. Most of the boards my buddy makes are drop down decks, like the one in the pic. The drop down creates a bit of a weak spot in the mold. Mainly because you need to use some clamps around that area even when u are using the bag. It just helps you get cleaner, sharper bends. Unfortunately it causes some extra stress and compression on the foam.
I'd say you can average about 3-5 decks per mold before it deforms too much.
Now if you were building flat decks with just some concave...you could probably get a few more presses. It all depends on what you want out of the deck.
The beauty of it is that the foam is pretty cheap so it's not a huge burden to remake a mold after a few presses. It doesn't take long to do so either.
You could use foam in the same way as he used the plywood but you wouldn't gain much for the amount of extra effort. The only reason I would think you'd wanna do that is if you had some thin, but real dense, foam and wanted to use it. Otherwise it is simpler to just lay the foam flat and cut the contour out of one piece. If you need more height glue two together. I doubt you'll put more that 2-4 inches of curve in it. If you put too much concave in the board it becomes a big trough and a little uncomfortable to stand on. If you put too much arch in it then you'll mess up your wheel base.
The plywood method makes a more durable mold but it is more labor intensive and not very adjustable. The foam is cheap, easy to work with, and you can make adjustments and corrections on it (sometimes).
For now though, I just want to thank you for helping me out.
The stuff you need for it is the rigid panel insulation. it's about 2 inches thick and comes in various sizes. It works beautifully.
Also used it to make a positive and negative for a mould that used threaded rod to provide compression. Worked beautifully like that too.
The good thing is that its 2 inches thick so it works for mostly any curve you'd want on a board. It works for a nice 2 inch drop in long boards as well. And if you need more height you just glue 2 panels together to boost you up to 4 inches.
It is a much faster and easier method than cutting this many layers of wood and sanding them to the shape.
Using a skateboard as the mold is a bad idea because it will flex when compressed, especially under the heavy compression of the vacuum, so any board you make using a skateboard as the mold is going to be warped.
To see what I mean about flimsy substances that can resist compression, find some packing cardboard used in shipping large objects - it has a honeycomb structure that resists compression extremely well. You can walk on it without damaging it, yet it is light and flimsy enough to be torn in half by hand. That stuff is made of paper, and not very much of it.
Hopefully that made sense!
If you model it using spline shapes, it's relatively easy to make variations of your deck, different sizes, etc.