Planer Core Profiler
Kam S. Leang
Date: May 07, 2005
Summary: This article discusses plans for a new core profiler
design that uses a thickness planer as the cutting element. Compared to the
traditional router-bridge method, the planer profiler can profile a wood core
much quicker while featuring greater ease of adjustability at the same time.
Description: Profiling wood cores is without at doubt the most
time consuming phase of the ski-building process. Traditionally, the
router-bridge is used for profiling because of it's versatility.
However after frequent use, one will quickly discover that the router-bridge
method isn't very efficient,
making core profiling a chore. New guide rails have to be fabricated with
every new profile design that you come up with. Also, routers tend to
create lift of the wood. This can create problems when routering thin
sections such as the tip and tail portions of the wood core (2-3mm thick).
A solution to this is to use a thickness planer to profile your cores.
The planer profile is a simple jig that holds your core on a wedge, the
angle of which corresponds to the tapered section of your core. Running this
"shimmed" core into your planer will then create the taper for your core with a
few quick passes. The design of a simple planer profiler along with
operational instructions follow.
Building a Planer Profiler A diagram of a planer profiler is
Step 1: Gather the Following Materials
Step 2: Prepare the Panels Make the panels by
simply cutting the 12" x 72" wood 2" (5cm) shorter lengthwise than your
wood core or ski lengths. For my case, I usually make skis in the
175-180cm range so my panels are cut to 170cm (67").
Step 3: Put Holding Screws In Panel To
prevent the wood core from sliding around while in the planer, use screws to
hold the core in place. Some 5/8" long screws should do the
Drill the screws into one panel until the tips just
peek out from the surface. The following picture shows how the screws
should appear in the panel.
Place approximately 20 of these screws throughout the panel.
When placed firmly onto the tips of these screws the wood core should stay in
it's place without additional help from double-sided tape, bolts, etc.
Step 4: Attach Hinges Arrange the two panels
on top of each other and connect the panels together with metal hinges.
Step 5: Make Shims To prevent the raised panel (with the
exposed screw tips) from
bending under pressure use shims for support.
Shims are really easy to make and can be cut from any leftover scrap
wood that you may have laying around. Make 4-5 shims of various sizes.
For this profiler, shims with heights of 35mm, 25mm, 15mm, and 10mm were made.
As with the panel made in step 3, screws were drilled into the shims so that
their tips were slightly exposed through one surface. These screw tips help
prevent the shims from sliding around.
That's it! Everything's done and you can start profiling
Using the Planer Profiler The planer profiler is very easy to use
and requires only a few geometry skills.
Step 1: Profile Design First select the dimensions for the
desired core profile. An example of how a core is typically profiled is
Step 2: Plane to Mid Thickness Now using your planer alone without
the profiling jig simply
run the blank wood core through until you have reached the "mid thickness"
Step 3: Set up the Planer Profiler Next set up your planer profiler
to create the tapered portions of the wood core (highlighted in red).
To set up the profiler we'll need to look at the core profile design a little
closer. In particular we'll look at the tapered section towards the
Y are known and can be calculated or measured from
your profile design in step 1.
Next, take a look at the planer profiler:
For the set up, we must set the angle of the profiler to the same angle as the
tapered section of the core.
All we have to do is make sure that the ratio of T to S is the same as Y to X.
You already have Y and X measured from your design and S is simply the length of
the panel (in this case 170cm). So to find T simply use rule of similarity to
perform the following math:
T = S*Y/X
That's it! Use calipers or a ruler to accurately measure the height of T and set
the panel into place
using the wedges.
Step 4: Plane Your Core Place your core onto the exposed
screw tips of the angled panel and tap lightly with a hammer to set into place.
Adjust the depth of your
planar accordingly and begin planing your core. You'll have to make few
passes and maybe some adjustments to your profiler to get things dialed in
Step 5: Finishing the Core Once you get used to how the jig
works profiling cores becomes a breeze making it only a 10-15 minute task
opposed to the hour or so it takes using the router-bridge method.
But there are few finishing details that need to be done. The planer puts
an extremely smooth surface to the core. You'll want to roughen up the
core with some sandpaper to increase the wood's ability to bond with epoxy.
You'll also notice that this technique doesn't create the flat plateau section
for the tips and tails. These portions can be left tapered as is or you
can simply flatten them out with your belt sander. It's a millimeter or so
thicker so it won't take much time at all. I usually just leave them