Many years ago I made a few pinewood derby cars with a rocket-shaped fuselage. Since then, I have been asked many times if the car body was shaped on a lathe, and if so, how did I deal with the wheel struts? When I tell them that the car was hand shaped from a block of wood, they think I am kidding with them. But I soon convince them that I am being serious.
The Rocket – Extended Wheelbase
The Missile – Extended Wheelbase
Although I am not the most talented of woodworkers, I have found that with the right tools, and a good technique you can accomplish more than you would think. Oftentimes, just a little shaping (or more, as in the case of the cars above), will really set your car apart from the rest of the field. So, today we will discuss some tools and techniques for putting some pizzazz into your car.
For any car, you must first cut out the rough shape with a saw. In the case of the Missile pictured above, the body is first cut out with all sides flat and square, and initial cuts are made at the front axle strut and at the rear of the car (Figure 1).
Figure 1 – Missile After Sawing
Then the shaping begins. My preferred tool is a special wood rasp, called a “4-in-Hand” (aka, a “Shoe Rasp” or a “4-in-One” Rasp).
Figure 2 – 4-in-Hand Rasp
A rasp is a rough file; and the 4-in-Hand rasp is a combination of four rasps, a coarse and fine flat rasp, and a coarse and fine curved rasp. The flat file sections of the tool are used for creating exterior curves, while the curved file sections of the tool are used for interior curves. So, with this one tool, you can perform a wide variety of shaping operations.
For the shaping operation, the wood must be immobilized with a clamp, but the wood must be accessible on all sides. One way to accomplish this is with a combination of clamps, such as is shown here.
Figure 3 – Combination Clamping
For the Missile pinewood derby car, the coarse flat file is used to remove most of the excess wood, leaving behind a generally cylindrical fuselage. Then the fine flat rasp is used to finish up the shaping. The result is shown in Figure 4. The red color is Bondo, a car body filler which was used to fill a few spots where a saw cut was too deep.
Figure 4 – Missile After Rasp Work
After the rasp work, 60 grit sandpaper is applied to finish the shaping. Finish sanding is accomplished with 120 and 220 grit sandpaper.
Sometimes, detail needs to be carved into the car body. On the Missile car shown above, the grooved transition from the fuselage to the wider back must be created. For this type of job, I use either a small flat or triangular-shaped file. The edge of the file cuts into the wood allowing you to create the desired shape. Just be careful as it will cut into the wood very easily and quickly. Figure 5 shows the sanded version. Additional Bondo was used in a few spots.
Figure 5 – Missile Ready for Painting
A Few Tips
In building these cars, I learned the hard way that shaping the wheel struts is a bit tricky, as the wheel struts cannot take too much force (or they will break). To minimize the risk of breaking a strut, increase the strength by inserting a spare axle into each axle slot/hole. Once shaping is complete, pull the axles out with a pair of pliers (gently twist and pull).
By the way, if you are interested in making the Rocket or Missile car, complete plans are available on our web site in “Advanced Car Plans” and “Advanced Car Plans 2”.
From Pinewood Derby Times Volume 11, Issue 7
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