How to Build a Small Car
Building a small car can be challenging, but not impossible if you have the right instructions and supplies. The best kind of small car to build if you are doing it for the first time is a small pinewood derby car because, while they're challenging to build, they'll give you a good framework by which to build something more complicated later on.
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Things You'll Need
- Basic car kit with wood block, wheels, and axels
- Paint
- Electric drillmMotor
- 120, 220, 400 grit garnet sandpaper
- Plastic auto body filler
- Wood primer
- 600 grit dry sandpaper
- Safety glasses
- Scroll saw
- Small file
- Small strip from an old t-shirt
- Tracing paper
- 3/8"x10mm tubular zinc weight
- 3/8"x10mm drill bit
- 2.3 mm drill bit
- Metal polish
- Machine oil
- Plain graphite
Instructions
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1
Come up with an idea for what your you want your car to look like. If you are good at drawing you might even draw your own design. However, if you're not or you want to look at other designs before coming up with your own, it is easy to find templates online. Draw or trace your design full-size so that you can use it when you're actually doing the building of your small car.
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2
Draw the image of your car design's profile and top onto the block of wood that came with your car kit. You can also use carbon tracing paper to get the image onto your block of wood.
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3
Using the scroll saw, cut the car shape from the block of wood following the design you drew on it.
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4
Using your drill press and a 2.3 mm drill bit, drill holes where you want the axles to be. Make sure the axle slots are square to the sides of the block, otherwise they won't have good alignment for tracking. Also be sure and put the axles into the holes to be sure that they fit and have plenty of wood beneath them.
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From the side or back of the wood block drill two or three holes of 3/8" around and 1 1/2" deep. Make sure you leave enough space to add filler. These are to put a few zinc weights to help weigh your small car down and thus give it more speed. Don't drill all the way through the wood when you do this and leave enough wood around the hole.
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6
Weigh your car on a calibrated scale. Also weigh your wheels, axles and anything else that will be a part of your car.
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7
Maneuver your car so the weight holes you drilled earlier are facing up. Add your zinc weights until the weight of your car is slightly more than 4.5 ounces (128 grams). If you aren't able to get your car to weigh this, you may have to drill an additional hole or two and add a few more zinc weights.
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8
Using the plastic auto body filler, seal up the holes that you put the weights in.
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9
Sand your wood body with 120-grit sandpaper and a wood block. Be sure and smooth the corners and edges and apply a bit more force to any flat spots while sanding. Do the same thing with a 220-grit sandpaper and then a 400-grit sandpaper. Your car body should be very smooth now.
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10
Apply the wood primer to your sanded car body. This is better than just applying the paint straight off because the wood will soak it up quickly and you'll have to apply several coats. The wood primer will save you time and paint by being the base coat.
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11
Paint your car body once the wood primer is thoroughly dry. You can paint one side at a time, or you can suspend the car from a nail or string and paint all of it at one time.
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12
Remove any burrs from the axle. Typically there are two places on the head part of the axle where there will be a mold or casting mark. Using a file, gently file down these areas.
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13
Put your axle in the drill motor chuck so that the head and 3/4" of the axle are in the open. Set up your drill so that it cannot move. Cut a 1/2" wide and 6" long piece of 600-grit dry sandpaper. Wet your piece of sandpaper with machine oil, turn on your drill and then, using the strip of sandpaper, treat the axle as though it were a shoe and you were polishing it by holding one end in each hand and moving the sandpaper back and forth. Do this until the area next to the head of the axle is smooth.
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14
Take your strip of old T-shirt or other soft cloth and put some metal polish on it, then with the drill turned on again, use a back and forth movement to polish the axle.
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15
Lubricate your wheels and axles with plain graphite. Put a bit in the axle hole of your wheel and then using the plastic auto body filler cap the other side. Carefully take the axle and put it through the wheel. Be sure and spin your wheel so that the plain graphite is distributed evenly. Repeat the lubrication process for each wheel.
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16
Attach the axles with their wheels in the holes you originally drilled for them.
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Tips & Warnings
Make sure you have your design on paper before you begin cutting out your car shape from the block of wood.
Wear safety glasses at all times to avoid any flying bits of wood while making your small pinewood derby car.
