Building an Edge Bender
The steel edges for skis are heat tempered by the manufacturer to create a very
hard and durable metal edge. While this is great for durability, it also
makes working with edges very difficult.
In order for the edges to fit around a ski's tips and tails they
need to be bent. This can be done by hand (described in more detail in the
ski construction section) or with a
simple edge bender shown below:
The edge bender consists of a steel cylinder connected to a
rectangular steel handle. Pushing the handle forces the edge against the
cylinder to create a bend. By adjusting the bending location on the edge
you can achieve bends of various radii.
Steps to Build an Edge Bender The following outlines how to build the
edge bender shown above. Construction is relatively simple, however, a
lathe and drill press are required to accurately machine the steel. A
diagram of the edge bender is illustrated in the following.
Step 1: Gather the Following Materials
3/8" x 1" x 8" rectangular steel
4" diameter steel cylinder 2.5" in height
7/8" diameter ball bearing (2 pieces)
5/16" diameter bolt 3.5" long
5/16" diameter bolt 1" long
5/16" locknut (2 pieces)
5/16" nut (2 pieces)
Step 2: Make the Steel Cylinder The steel
cylinder provides the bending radii of the edges. We typically use
cylinders with diameters ranging 2.5" to 4" in size. For this example we
used a lathe to create cylinder with a 3.5" diameter on one side and a 4"
diameter on the other as shown below.
By flipping the cylinder on either side we are able to produce
bends of various radii.
After the cylinder has been machined to the above diameters,
drill a 5/16" diameter hole through the center. Each end of the hole will
also need a 7/8" diameter counter-bore to accept the ball bearings, which sit
flush with the cylinder's surface.
Step 3: Prepare the Handle For the handle, any rectangular
piece of steel that feels comfortable in your hand will do. This example
uses a handle that measures 3/8"x1"x8". Two sets of holes (5/16" diameter)
will need to be drilled to fit the two diameters of the cylinder made in the
previous step. Drill two holes 2.25" apart for the smaller 3.5" diameter
end and another two holes 2.5" apart for the larger 4" diameter of the cylinder.
The handle should appear as below:
4: Assembly Attach the handle loosely to the cylinder using the
3" long 5/16" diameter bolt along with a locknut and nut. The following
displays the order of assembly.
Make sure that you do not tighten the bolt and nuts completely. A small
amount of play needs to exist between the handle and cylinder in order for the
ski edges to fit through smoothly.
Step 5: Attach Pusher Bearing After the above assembly is put
together attach the pusher bearing to the handle. This bearing is the
mechanism that pushes the ski edge against the cylinder to give the edge its
bend. Use the 1" long 5/16" diameter bolt along with the corresponding
locknut and nut to attach the bearing to the handle. The nut should be
tight enough so that the bearing can roll smoothly.
That's it! Now start bending edges! Insert the edges so that the
teeth rest on the top surface of the cylinder with the rail fitting snugly
against the vertical wall.
Holding the edges in your hand give a few pushes of the handle and the bearing
should force the edge to bend around the cylinder giving a nice smooth curve.
By moving the bending location of the edge you can create curvatures of various
radii to fit the shape of your ski.
Step 6: Additional Modifications Once you start bending you
may ask how we get the really tight radii such as the curves found near the tips
of pointy skis. This is done by placing some screws into the cylinder's
top surface and simply wedging the edge in between the screws and applying some
force to create a bend.
Although the bend will not come out as smooth, some fine tuning will allow you
to create a wide array of nice looking curvatures.