This article provides a comprehensive guide on how to create and utilize a slot car donut tire cutter. Based on a design by Ken Irwin of the Cambridge Model Car Club, this simple yet effective tool allows for precise tire cutting and truing.
Design and Functionality
The slot car donut tool is a straightforward design, operable by hand or mounted in a vise. It’s used with an electric drill to cut and true slot car tires, offering a cost-effective alternative to a tire grinder. Accuracy in machining the parts is crucial for achieving precise tire dimensions.
Creating the Cutting Spike
While the hub and eccentric construction are left to the user’s machining knowledge, sharpening the crucial cutting spike is detailed. A 2mm hardened high-speed steel ejector pin, available from tooling suppliers, serves as the spike.
Grinding the spike requires a true-running Dremel or similar tool with a properly dressed grinding wheel. Concentricity is paramount for accurate scaling and consistent calibration. Cool the spike frequently during grinding to prevent overheating and softening. Polish the ground surface with fine emery paper and oil to minimize friction during cutting.
Optional Cutting Knife
An optional knife provides cleaner cuts but requires tangential adjustment to the tire after setting the diameter.
Artwork and Calibration
Printable artwork for the cutter’s scale is provided. Print it on self-adhesive paper, laminate for durability, and apply to the hub. The guide bush requires an indicator slot, best added after cutting a test tire to determine accurate placement.
Using the Cutter
Mount the donut tire and trim excess material with a sharp knife and electric drill. Set the eccentric to the desired diameter, ensuring sufficient spike or knife protrusion for cutting. Lubricate the axle and fixture hub with oil.
Attach the tire to a long 3/32″ axle secured in a drill chuck. With the hub held securely in a vise or hand, start the drill and pull it back smoothly to cut the tire in 2-3 seconds. An electric drill offers better control than a Dremel due to its torque.
Dressing and Finishing
Dress the cut tire with an emery board to achieve the final desired size and smoothness.
Conclusion
This slot car donut tool offers a practical and affordable solution for creating precise slot car tires. While requiring some machining skills, the detailed instructions and accompanying artwork make it a manageable project for enthusiasts. Remember to prioritize safety and use appropriate tools for each step. A sharp cutting instrument and a steady hand are key to achieving optimal results.
