Instructables

How to Shape a Foam Mold for Building Skateboards

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Picture of How to Shape a Foam Mold for Building Skateboards
Designing your own mold is a fun and effective way to create your own custom skateboard! With Roarockit's Thin Air Press vacuum bag technology, a builder only needs to design/shape one side of the mold. This makes the process a lot easier and more affordable than having to perfectly match a male and female side of a standard concrete or wood mold.

Here are the tools you need:

- Utility knife with a sharp long blade

- Some sort of a saw. I used a Japanese saw, but a regular saw will do.

- Rasp or a surform

- Foam sanding block - cut this from a block of foam. Make it wider than the width of the deck, and glue 100 grit sandpaper or stick grip tape to one side

- pencil or black marker

- A straight edge like a combination square or 12" ruler
 
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Step 1:

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Once you have laid out the features on your mold (concave, kick/nose tails, drops), you are ready to shape the foam to your design.

The mold can be made out of foam, mdf or other stable and shapeable materials. The denser the material, the more it will hold up over multiple pressings, but the harder it will be to shape.

Let's get started:

Set the blade of the utility knife just above the depth of the side profile line and make a series of cuts across the foam, about 1" apart.

You can see the cuts I made on the tail of the deck in this photo. Make sure you do not cut below the profile line. Using a saw cut above the profile line as shown. If you don’t have a saw, the utility knife blade will work as well, turned on it’s edge.

Remove the excess pieces of foam.

A little messy looking but don’t worry, you will be smoothing this out with the sanding block.

What are the dimensions of the mold and angles and that stuff?? I want to make my own skateboard and I don't know the dimensions.

Rockitalk (author)  nikola.bukovina1 month ago

Almost every board has a unique set of specs in regards to where a kick tail starts, ends, angle, concave, etc. The great part about making your own is the freedom to make it whatever you want! Basing it off a board you know you like is a good place to start, and you can tweak your foam mold from there.

SmashnZilla3 months ago
@Rockitalk how what do u need to make the vaccum for the press
Rockitalk (author)  SmashnZilla3 months ago

We supply a vacuum bag kit that comes with the bag and valve premade. The air is evacuated from the bag with a manually operated pump that also comes with the kit.

What kind of foam do u use
Rockitalk (author)  SmashnZilla3 months ago

We currently sell a high density polystyrene, but you can use any stable material for your one-sided mold. Foam is just easy to shape and is nice and light for shipping. Some people use mdf or solid wood for their molds as well.

BadPuns4 months ago
Cool! If I coated the foam mold in fiberglass resin, do you think it would hold up better? Or do you think it would eat through the plastic...
BadPuns BadPuns4 months ago
I mean foam, not plastic.

polyester resin eats away polystyrene, use polyurethane foam (insulation boards), i'm not sure about epoxy resins and polystyrene, but i think the epoxy doesn't affect PS

Rockitalk (author)  BadPuns4 months ago

You would have to test the resin and the foam you are using.

pixel56 months ago

Can you use polystyrene for this?

Rockitalk (author)  pixel54 months ago

Yup! We use a high density version of it, but you can make a mold out of any solid material. The denser it is, the longer it will keep its shape over multiple pressings.

kawriver1 year ago
Great Job! Quick Question: How many layers of plywood and what was the thickness?
From the pictures it looks like you might have used a Polyurethane foam sheet sandwiched into the middle.
Rockitalk (author)  kawriver6 months ago

Standard decks are anywhere from 7-9 layers of 1/16" thick veneer. It is important to start with an actual veneer as opposed to a plywood so that you can achieve accurate bends and control all of the glue lines. Foam is only used for the mold, the layer sandwiched in the middle of the finished board is a colour dyed veneer :)

sle51 year ago
Nice'! Do you have a link on how to do step 4? Let me know please :) thanks!
Rockitalk (author)  sle51 year ago
I will add one on how to use the Thin Air Press soon hopefully! We do have videos and tutorials on YouTube - http://www.youtube.com/watch?v=lnJP4hCCVsk