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New Pinewood Derby Wheels
The
2009 pinewood derby season has brought us a new official
BSA pinewood derby wheel as shown on the right below compared to the
"old" wheel on the left.
The
wheel is lighter, has a much better outside tread
surface and has an unusual outer hub design. It
actually has a step or ledge in the outer hub (new wheel
on the right) which presents no obvious speed advantages
but does have some potential disadvantages. It
creates a second contact point on a beveled axle head
and would contact it further to the outside of the axle
head, meaning more surface contact area. With no
obvious speed advantage to the step, the predominant
speed tip for the new wheel is to get rid of the step
altogether. The Pro Outer Hub Tool seen below was
initially created to clean up the outer hub for the old
wheel but is nearly perfect for the elimination of the
step on the new pinewood derby wheel. The outer
hub tool needs to be sharpened first and that can be
easily performed with a file which we will show you
after we discuss reaming the wheel bores with the Pro
Hub Tool.
Wheel Bore Reaming
The
wheel bore, simply put, is the inside of the wheel where
the axle goes. Molded
Pinewood Derby car wheel hubs can vary in size by as
much as .01" and you must resolve this situation
to have the smoothest fit of the axle into the wheel.
The Pro-Hub Tool allows you to ream the wheel bore to
the same size or to at least select wheels from your
assortment that have a similarly sized bore radius.
This is a very important alignment tip as it allows the
car to sit evenly on all 4 wheels with equal distances
from the axle and wheel hub to the track. You will need
the Pro-Hub Tool to complete this speed tip. To perform
this procedure:
1)
Test fit
each wheel by sliding it onto the tool pin of the
Pro-Hub Tool (flat side) as shown below. If the wheel bore
is too small for the tool, use steady hand pressure and
a twisting motion to work the wheel on to the tool.
Remove the wheel and repeat 3 times.
Pro Hub Tool (Flat End)
2)
Once
completed, choose another wheel and repeat step 1.
Pro
Outer Hub Shaver
(Note: The Pro
Hub Tool is required for use with the Pro Outer Hub
Shaver)
The Pro Outer Hub
Shaver will surely become one of the most popular tools
for the 2009/2010 pinewood derby season for the
following uses:
-
Ensures accurate rotation of the wheel by
squaring the outer wheel hub to the wheel bore
for proper mounting of the wheel on the Pro
Wheel Mandrel
-
Reduces friction between the axle head and the
outer wheel hub by eliminating flaws on the
outer wheel hub and, most importantly
-
Removes the step in the outer wheel hub on the
new wheels which are a potential double friction
contact point with the axle head.
Please note
that the Pro Outer Hub Shaver is intended for use on
BSA wheels only. It is not recommended for use
on wheels made by any other manufacturer.
Sharpen the edge of the Pro Outer Hub Shaver
If
you are removing the step in the outer hub on the
"new" wheels, you will first need to sharpen the
cutting edge on the outer hub shaver. To
accomplish this step, merely file the back side of
the cutting edge with a flat file until you have
created a small angle to the back of the cutting
edge. A picture of the outer hub shaver with
the edge sharpened is shown below on the left
compared to a regular cutting edge on the right.
The specific angle is not important. You do
not need to sharpen the cutting edge of the outer
hub shaver if you are performing modifications to the
"old" wheels.
Note: The Pro Outer Hub Shaver
is available as a fully modified tool which includes
not only the above filing but a shaping of the edge
such that the outer hub is not only shaved but domed
as well. This doming effect reduces the
friction between the wheel and the axle head even
further.
Instructions for Using the Pro Outer Hub shaver
-
Remove the
protective cap from the square or flat end of
the Pro Hub shaver and
ream the wheel bores of each wheel per the
directions above.
-
Slide the Pro Outer
Hub Shaver onto the pin of the Pro Hub Tool with
the cutting edge outwards. To minimize the
risk of injury, leave the protective cap on the
coned end of the Pro Hub Tool.
-
Place a wheel onto
the pin of the Pro Hub Tool, spoke side first.
-
With one hand
holding both the Pro Hub Tool and the Pro Outer
Hub Shaver, press the wheel against the outer
hub shaver's cutting edge with the other hand. Rotate
the wheel three complete revolutions.
-
Check the outer hub
to view your progress. If you are
modifying the "old" wheels, you will not need to
make too many revolutions with the outer hub
tool to complete the process. If you are
removing the step in the "new" wheels, it will
take quite a few more revolutions to get the
outer edge of the hub even with the inner edge
of the hub and completely remove the outer step.
Continue to check your progress after a few
revolutions to make sure that you do not remove
any excess material past the removal of the
step. The finished product in either case
of the "old" or the "new" wheels should look
like the wheels shown below. The modified "old"
wheel is on the left and a modified "new" wheel
is on the right.
Note: The Pro Outer Hub
Shaver is available as a fully modified tool as well
if the above modifications appear too difficult
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