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 bores.
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 Pro-Outer Hub Shaver. 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.
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:
Pro-Outer Hub Shaver Tool
Pro-Wheel Shaver XT
The Pro-Tools are available at Maximum Velocity.
(2) If the lathed wheels are mold-number matched, such as those by Maximum Velocity, then the bore sizes are the same, so wheel matching is not required.
From Pinewood Derby Times Volume 4, Issue 6
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