Pinewood Derby Wheel Inspection Gauge
Well going to bring back a fan favorite pinewood derby tool – Pinewood Derby Wheel Inspection Gauge . It measures 2 things with two different ranges. First the overall wheel diameter. The second measurement is for wheel width.
- Made of cast acrylic to bring the costs down. Durable alternative to its metal predecessor. Laser cut and engraved for smooth sanded finish.
- Comes with paper affixed to plastic to reduce premature scratches. You may leave on or remove. I like it on to be honest.
How to use derby wheel gauge for outer diameter
Wheel Diameter – Accurately and quickly verifies compliance with a 1.170 inch and 1.180 inch wheel diameter specification. Just gently attempt to slide the gauge over the wheel. If the gauge will not slide over the wheel, then the wheel complies with the specification. If the wheel almost fits into the gauge, try again at a different spot on the wheel.
A facotry width wheel will not pass through the 1.180″ channel. Any wheel that does, has been altered past factory diameters. If rules state 1.170″ is the given minimum diameter for “worked” wheels, a wheel that passes through the 1.170″ portion- fails.
The proper way is to simply “wand” the Pinewood Derby Wheel Gauge over a wheel. If the wheel is smaller than the selected diameter, the wheel will pass through without issues. If the wheel does not pass through then that means the wheel is LARGER than the selected diameters. When you try an force the tool on the wheel, weight reduced wheels have enough “give / flex” in them to actually be squeezed inside measurement thus making them fail the inspection. Improper use of the tool is why the wheel failed, not because the wheel failed.
How to use wheel measuring tool for width
This is used to determine if too much material has been removed while “truing” the edge of the wheel for concentric and for a reduction in surface area to reduce friction. A near factory width wheel will not sit flush into the .360″ portion of the wheel. If it passes through the tongs, it fails. .320″ is usually the accepted minimum width for worked wheels.
The gauge measures the overall width of the wheel including the sidewall. The tread patch is not measured by itself, as it is not easily measured on most wheels. When measuring the wheel width, measure at a point on the wheel where there is no raised lettering.
This wheel gauge is the preferred measuring guide even vs very expensive calipers for the same reason. The simply squeezing of calipers will cause incorrect measurements of weight reduced wheels.
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YouTube Video on how to use: