View Shopping Cart
All Products
How to Check the Roundness of Your Pinewood Derby Car Wheels
Pinewood Derby Wheel Roundness Gauge
Your Pinewood Derby car will be faster if you use round wheels but most wheels are not round. . Use this tool to select the fastest wheels for your car..
Instructions
- Cap - Used to move the Stem up and down.
- Bezel - Rotates the dial to zero the needle.
- Clamp - Locks the Bezel.
- Hex Nut - Adjusts the position of the Gauge.
- Contact Point - Contacts the wheel to be measured
- Wheel Pin - Holds the pinewood derby wheel
This gauge should be set up correctly before use. The Contact Point should extend 1/4" past the wheel tread as shown in this picture. Place a wheel on the Wheel Pin and slide it next to the Contact Point. If the Contact is not 1/4" below the outside diameter of the wheel, adjust it as described in the next step.
The Contact Point should extend a quarter inch below the wheel surface when fully extended with no wheel on the pin. To adjust the Contact Point position, loosen the hex nut with the provided Allen wrench and move the gauge up or down to the proper position. Lightly tighten the hex nut (if too tight, the Stem Housing will warp causing inaccurate readings).
The Contact Point should be riding on the right edge of a wheel when the wheel is on its left most position on the Wheel Pin (the spokes side of the wheel should be facing left). If this is not the case, loosen the Wheel Pin Nut and use a screwdriver to adjust the Wheel Pin position. Tighten the Nut when done.
The optional Wide Tip replaces the ball tip that is included in the wheel gauge. The Wide tip measures the full width of the wheel thread in one pass so it simulates the track surface and eliminates the need to reposition the wheel to check different parts of the tread.
To check the roundness of a wheel, slide the wheel on the pin with the spoke side of the wheel facing to the left. Raise the contact point by pulling on the cap so that the wheel can slide under the contact point. Rotate the wheel until you find the lowest point as indicated on the dial. Rotate the Bezel until the needle is pointing at 0. This is your reference point. The indicator reads .001 inches per division.
Rotate the wheel while watching the dial on the gauge noting its maximum deviation from 0. Slide the wheel to the right slightly and rotate again. Repeat until all of the wheel tread has been measured. The ultimate goal is that the needle doesn't move as you rotate the wheel. The more a wheel is out of round, the more the wheel will bounce as it rolls.
If you have access to extra wheels, use the gauge to find four wheels with the least amount of deviation.
If you purchased the optional Wide Tip, install it by unscrewing the black ball tip (you may need to use a pliers to gently unscrew it). Then replace it with the Wide Tip.
Adjust the wheel pin so that the Wide Tip is centered on the wheel. Now, one rotation is all you need to check the roundness of the wheel.
