Pinewood Derby Stories and Photos from Maximum Velocity
Getting Great Results with Pro-Tools - Part 1
For what are the best automobiles noted? Luxury? Probably. Power?
Certainly. Precision-built components and assemblies? Absolutely. The
engine, transmission, suspension, etc. must be manufactured to high
tolerances. There is no room for sloppy parts and assemblies.
Similarly, using precision parts is a key component of building a
high-performance pinewood derby car. Although they are significantly
simpler, the principle is the same: wheels, axles, and alignment must be
precisely machined and installed for top performance.
At one time, the average pinewood derby builder could not achieve a high
level of precision unless they had access to a machine shop. Thus, only the
fortunate few could tune up their cars with precision, and these few
typically dominated on the track. But now, with the advent of the
Pro-Tool(1) line of components, a significant level of precision can be
achieved by anyone.
Today's article will share insights into three of the Pro-Tools, while the
remaining Pro-Tools will be discussed in a future article. Much of the
material in this section was contributed by Bill Launius, the inventor and
manufacturer of the Pro-Tool line of products.
The Pro-Hub Tool is used to prepare the inside wheel hub and the wheel bore.
It has three primary functions:
1. Square the inside wheel hub to the wheel bore - This ensures that the
wheel properly mounts on a wheel mandrel, and eliminates excess plastic
flashing remaining from the injection molding process. This flashing is
readily apparent on specific BSA wheel molds.
2. Cone the inside wheel hub - This minimizes the contact patch with the car
body, thus reducing the braking effect when the wheel hub touches the car.
3. Reaming wheel bores - Some wheels are molded with a bore that is too
small for the wheel mandrel. The Pro-Hub tool will ream out undersized
But in addition to these primary functions, the Pro-Hub tool also provides
the following benefit:
4. Sizing wheel bores - The pin of the Pro-Hub tool can be used to identify
four wheels with a specific bore sizes. This is an important step in
alignment because wheels with different bore sizes, even if they are lathed
round, will not have the same measurement from tread to bore.(2) Thus, the
wheels will not sit evenly on the ground, leading to alignment problems.
5. Graphite application - The coned end of the Pro-Hub Tool can be used to
rub graphite into the inside wheel hub. Simply squirt graphite into the
coned end, slide on a wheel (hub side in) and twist.
The Pro-Hub tool now has a companion tool, the Outer Pro-Hub Tool. This new
tool is used with the Pro-Hub Tool to true the outer wheel hub to the bore.
Many pinewood derby kits, such as BSA, use nails for axles. These axles are
not manufactured to a high tolerance (they're just nails!), so they are
generally not perfectly straight. Since top-performance requires precision
parts, these axles must be straightened. Otherwise, the axle defects will
affect the speed of the car and the alignment of the car.
How do bent axles affect speed? The fastest axle/wheel combination is a
neutral position in which the wheel 'floats' back and forth between the axle
head and the car body. This minimizes friction by avoiding constant contact
with either the nail head or the car body, and ensures that the weight of
the car is evenly dispersed on the wheel bore. A bent axle will only
contact the wheel bore in limited spots, creating binding in the wheel bore,
and causing the wheel to be forced to constantly rub either the axle head or
the car body.
The Pro-Axle Press will:
1. Straighten nail-type axles - With just a hammer and firm surface, the
Pro-Axle Press will create straight axles.
2. Square the nail head - Oftentimes the nail head is not square to the
shaft. The Pro-Axle Press quickly corrects this flaw.
3. Facilitate creating a raised wheel - Three-wheel cars are faster than
four-wheel cars. One way to raise a wheel off the ground is to bend one of
the front axles upward. The Pro-Axle Press serves as a clamp to hold an
axle for a quick bend with a hammer.
Precision alignment is a critical factor for pinewood derby performance.
While methods exist to correct alignment, creating a car that requires
minimal alignment correction is the goal. A significant area that affects
alignment is axle mounting. Whether slots or drilled holes are used, the
axles must be inserted into the car parallel to each other.
The Pro-Body Tool facilitates correct alignment by serving as a drilling
guide for axle holes, or for pilot holes in axle slots. Specifically,
1. Accurate axle holes - The Pro-Body Tool places the axle holes
perpendicular to the center line of the car, thus ensuring parallelism
between the axles, front to rear.
2. Accurate placement - The Pro-Body Tool locates all of the axle holes at
the same height on the body (optionally with one wheel raised), ensuring
axle parallelism from top to bottom.
3. Minimizes drill bit deflection and run-out - The Pro-Body Tool guides the
rather thin #44 drill bit to minimize deflection due to density variance in
the wood. In addition, most drill presses have some run-out (free play in
the spindle assembly) which reduces accuracy. By using the Pro-Body tool,
run-out is minimized.
Note that Pro-Body Tools are available for various car kits including BSA,
PineCar, Royal Rangers/S&W, and Awana.
I hope that these thoughts will help in using the Pro-Tools. If you have
any tips or tricks that you have learned regarding these tools, please send
them to me and I will share them in future editions of this newsletter.
(1) The Pro-Tool line, manufactured by DerbyWorx includes: