Overview  The shape of a ski, i.e., the camber and the curvature in the tip and tail, is created by pressing the ski materials against a mold as shown below.  In particular, the base mold creates the shape of a ski.

A simple base mold is shown below in the picture.  The mold is made of individual ribs glued together.  Each rib is cut to a desired shape from 3/4" thick MDF material.  Notice in the design below that there are gaps between ribs.  This design was used because it was cheaper and easier to make the mold, however, the the gaps between ribs needed to be filled.  The gaps can be filled by laying two to three sheets of 1/4" masonite board over the top of the mold and nailing it in place.

Steps to Build a Mold  The following steps outline how to build the mold above.

Step 1: Mold Design:  The first step to building a mold is to decide the shape of the mold.  The mold will create the camber and curvatures of the tip and tail of a ski.  To design a mold, start by sketching out the desired profile for the mold as illustrated below in the diagram.

Determine the required running length (L) for your ski -- the running length is the distance between the tip and tail contact points.  Afterwards, decide on a maximum camber height (h) the mold should have and then connect the tip and tail contact points with an arc.  The shape of the arc can be a circle, for example.  Finally, design the tip and tail curvatures (R1 and R2 if you decide to use a constant radius of curvature).  In designing the mold profile, be sure to make the mold longer than the desired ski length (SL).  Also, take into account that a ski will relax after it is taken out of the press.  Based on experience, we have found that a ski will lose about 8-10mm of camber.  To compensate for the relaxation, we added addition camber to the mold profile design.  For our first ski press, we used a mold with 28mm of camber.

Step 2: Making Templates:  After you have sketched out the design of a profile for the mold, the next step is to draw up the design in a CAD software and then make a template.  The template will be used to cut and profile the parts of the mold.  The steps to make the template are illustrated below:

Step 3:  Cutting Mold Ribs:  The next step is to use the templates that you made for the rib and tip/tail curvature sections as a guide for cutting out parts from MDF board for form the mold.

WARNING: MDF material can be dangerous to your health if inhaled, so we recommend that you wear some sort of mask, and of course, eye protection (not shown):

Using the template as a guide, trace the shape of the pieces for the mold on MDF and then rough cut the pieces using a jig saw:

Then secure the template to each piece that was rough cut and use a router to clean up the edges so that you get smooth edges.  The key is to make all the pieces identical.

Here's what the pieces look like after they have been cleaned up using the router.  They should all be smooth and they should all have the same dimensions.

Step 4: Assembly:   Now it's time to assemble the pieces to create the mold.  First, make sure the pieces fit together:

Then assemble the pieces.  There are a number of ways to assemble the mold.  One approach is to glue all the pieces together and use clamps to hold everything together until the glue dries.  The other option is to use nails or screws to secure the pieces together.

Alternatively, you can make a mold that is adjustable, i.e., you can move the tip and tail pieces to accommodate different lengths of skis you decide to press.

Here's an example of our mold, with a couple layers of masonite board covering the top of the mold to provide a smooth surface.

NOTE: When the press is operated, the bladder can generate a significant amount of force which pushes down on the mold.  So make sure you design a mold that can withstand the forces that are generated.

Step 5:  Building the Top Mold:   After you build a base (or bottom) mold, the next step is to build a top mold.  The dimensions of the top mold is not as critical as the base mold because the top mold is simply used fill up space within the press cavity.  Also, you can use 2x4s or 2x6s to make the top mold.  Below is an example of our top mold.

Here's the base and top mold placed inside of the press structure.