_MG_3073

Radio control (R/C) toys are fun, but their plastic bodies are so obviously mass-produced. To create something more interesting, I wanted to find a metal toy racer 10 inches or longer that I could transplant some R/C insides into. I soon discovered that the best candidates were all precious collectibles.

I decided to build a metal body myself and soon stumbled upon an old hobby called “tether cars,” a type of model racer that predates R/C (see Tether Cars: A Short History below). After ordering blueprints from a tether car enthusiast group in England, I learned how the old toys were made, and then ported the style to my R/C project. With a few modern adaptations, such as pop rivets instead of solder, and coil spring shocks, I built a couple of vintage-style R/C cars that would make any antique dealer jealous. Here’s my latest.

Block, Shock, and Buckle

R/C hobby manufacturers produce countless prefab parts. Some are great for combining with parts you make yourself.

Retro-RC-Racer-Illo

Sheet Metal Modeling: A Mini Primer

Sheet metal is a major component of junk everywhere, and with pop rivets and simple skills, you can turn this durable material into a model racer — or almost anything else.

TYPES OF SHEET METAL

Regular sheet metal made from steel, is very forgiving: bend it wrong, and you can just hammer it flat again and start over. Thickness varies; I use between 18 and 24 gauge. Most sheet metal is coated to prevent rust. Tin-plate steel, also called simply “tin,” has a uniform shine. Galvanized steel, coated with zinc, sports a distinctive crystallized pattern.

Stainless steel tends to be harder than regular steel, so it’s more difficult to work. If your tinsnips aren’t strong enough to get through it, try cutting with a rotary tool (Dremel).

Aluminum is lightweight and soft, easy to work, but easy to dent and scratch. Aluminum also weakens when bent in the same spot too many times. But it has a beauty unto itself, and was once even considered a precious metal.

OPERATIONS

Bending For most bends, you should use a sheet metal brake. Cheaper brakes can let the metal slip a bit, which puts the fold in the wrong place, but you can discourage this by first applying masking tape along the fold line and clamping the metal down. To bend small pieces of stiffer metal such as stainless, clamp them in a vise between wood blocks and hammer them over.

Cutting Make paper templates for all the shapes you’re cutting. Then either stick them directly onto the metal with double-sided tape, or glue them to cereal-box cardboard, cut out, and trace around them on the metal with a fine-point marker. To help anchor larger templates, cut holes in the middle and tape over them. Cut shapes out with tinsnips or a Dremel cutting wheel, but note that a Dremel can sometimes make tape melt and slide around. File or sand the edges smooth after cutting.

Drilling Center-punch holes before you drill, and use a high-quality drill bit with a sharp tip. I’ve bought some surprisingly bad drill bits, which wind up dancing around on the metal and biting in at the wrong place. Drill at 1/8″ for standard pop rivets.

Riveting Insert a rivet through your hole. For extra strength, back it with a washer on the other side. Then squeeze with the pop rivet tool. To remove a rivet, drill it out using the same 1/8″ bit you made the hole with. To test-fit a rivet, you can hold it in place temporarily with a nail.

Prototyping with Cardboard

Anything you want to make with sheet metal you can prototype first with cardboard. Just cut the pieces out, then fold and tape them together. This is an easy, fast, and cheap way of checking out a design before building.

SAFETY: Always wear eye protection and tie up your hair while working with any power tools. Wear gloves during cutting; sheet metal can be sharp.

model-craftsman-magazine

Tether Cars: A Short History

Tether cars, also known as spindizzies, are the miniature racing car hobby predecessor to the R/C era. Cars race one at a time around a circular track, tethered to a steel pipe that sticks up in the center, and accelerate with each lap. The hobby started in California in the 1930s, and back then the 10cc gas-powered cars would often exceed 50mph. Many cars looked like the midget racers (sprint cars) that were popular at the time.

Tether cars have no brakes. To stop them, the car’s owner lowers a stick, flag, or broom over the car’s path as it passes underneath. This knocks down what looks like an antenna sticking up in back, but is actually a cut-off switch for the fuel or electrical supply.

During World War II, tether car racing was put on hold in the United States, but it began flourishing in England. The British government grounded toy gas-powered airplanes and kites, fearing that spotters might mistake them for Nazi aircraft (I also wonder if they wanted to hide their near-ground radar capabilities). Then in 1942, D.A. Russell and A. Galeota published a design in the magazine Aeromodeller for a simple spindizzy powered by a 2.55cc gas engine that was originally built for model airplanes. It was an instant success, and tether car clubs soon formed all over England.

Tether cars still have a following today, with enthusiasts divided into two camps: collectors and vintage-style builders who love the aesthetics of model making, and competitive racers more interested in competition and speed records. Traditional tether cars look like real cars, but the ones that compete today at dedicated tracks in the U.S., Europe, and Australia have more abstract designs, optimized for speed. Some of these rockets-on-wheels can top 200mph. That’s fast! (But personally, I’m more interested in the artistic side.)

Plans for vintage tether cars are available in books and online (see Resources), but they’re tough to build today because some of the transmission and drivetrain parts haven’t been manufactured for more than 60 years. You can still construct the bodies, though, and I think that steering and accelerating via radio control is more interesting than running around in a circle anyway. A vintage-style tether car body with modern R/C combines the best of both worlds.