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Liquid Pinewood Derby Lube Testing

On occasion, a package arrives in the mail from a lubricant
manufacturer. Generally, the package contains a lubricant that the
company would like for Maximum Velocity to offer on our web site. I
then schedule the time to do a preliminary test to see if the lube is
worth pursuing. Typically this preliminary test is either a spin test
or a slide test (no need for track testing if the lubricant doesn't
perform well).

Late in 2008, I received one of these packages, which contained four
liquid lubes. Since the season was getting ready to start I didn't
have time to pursue testing then, so I put the lubes on the shelf and
scheduled the test for the summer of 2009.

When it came time to do the testing I read the specifications and
found that one of the lubes could react with some plastics, so that
one was scratched off the list. The other three were:

- Methyl Silicone 5 - 5.0 cSt (1) - A colorless, transparent,
nontoxic, non volatile liquid used in a variety of applications.

- Methyl Silicone 20 - 20 cSt - Same as above.

- XOil - 15.3 cSt - A transparent, colorless mineral oil, It is
generally used for lubricating measuring tools and related
instruments.

To screen these products for possible sale, they would need to be spin
tested along with the existing liquid lubes that we offer: Krytox 100
and NyOil II.

EXPERIMENT SETUP
The equipment used for spin testing was previously described in
Volume
8, Issue 6 - "Grooved Axles"

As a refresher, the apparatus consists of a machined steel ring which
is sized to fit snugly over a machined BSA wheel. The ring weighs two
ounces, which is essentially the load on a rear wheel of a pinewood
derby car.


Figure 1 - Weighted Wheel Spin Jig

After sliding the ring over the lubricated wheel-axle assembly, the
axle is mounted onto the apparatus. A length of fishing line with a
weight on one end is wound around the ring (there is a small pin on
the ring not seen in Figure 1, to which the non-weighted end of the
string is attached). On each test, the string is wound until the
weight touches the eye hook. The weight is then released and a
stopwatch is used to measure the spin time. The string is sized such
that it is released from the ring before the weight reaches the
ground.

In order to avoid lubricant contamination, two wheels were used for
each of the five lubes (ten wheels total), and one axle was used for
each of the five lubes. The reason for two wheels for each lube was
to ensure that the performance of a lube was not exaggerated or
degraded due to a "fluke" wheel. The wheels were Ultralight Speed
Wheels, which are machined inside and out. To further minimize
variance, a single mold number was used for all of the wheels.

Each wheel/axle was lubricated in the same manner (lube applied,
allowed to flow over the axle, and then blotted off). Then the
assembly was placed onto the spin jig. To break-in the lube, five
spins were given to each wheel.(2) Then five timed spins were
performed and recorded.

EXPERIMENT RESULTS
Somewhat to my surprise Methyl Silicon 20 and XOil performed quite
well in the spin tests. In fact, they both tested slightly better
than NyOil II.


Figure 2 - Spin Test Results

So, some track testing was called for. As the Methyl Silicone 20 is
rather expensive, further testing was focused on XOil. That testing
showed similar results to the spin tests.

As a result of this testing, Maximum Velocity is now offering XOil in
lieu of NyOil II.

(1) cSt stands for "centistokes", the standard for the viscosity of a
liquid. As a comparison, Krytox 100 is 4.0 cSt.

(2) Except for the Methyl Silicone 5 - in this case the fastest spin
was the first; each subsequent spin was slower.

Read More at: Pinewood Derby Times Volume 9, Issue 4

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