Race Car Tubing Fabrication: Part 2

Last month, we looked at the tools used to build stock cars. Most of the work will involve 0.095-wall mild steel tubing. This month we begin using these tools and showing you the techniques employed with each one.

Before embarking on a race car project, you will need the skills to use these tools. I can show you how the tools work, but you need to develop the skills through practice to use them properly. This practice can be done by yourself with the help of books such as one offered by Steve Smith Autosports, Welder's Handbook. Also, someone to work with to practice these techniques can be invaluable.

We are going to spend more time using the torch than one might think necessary. This is because the torch is basic to any other cutting and welding processes. Also, it is often improperly used.

I have taught a number of people to weld. I can have them welding and using the torch in less than a half hour. However, if they only used the welder or torch at that time and don't get any more practice for a while, later they will have trouble. One can become proficient in welding with the torch, MIG, TIG, or even the arc welder, along with the other tools, but only with practice. Skills take time to develop. Don't let this stop you. Developing these skills will give you a feeling of accomplishment. With these skills, you can build your own car. Just as important, you can repair it.

Although you won't often use the torch for welding, it is similar to any other welding process. If you can weld with a torch, you can pick up any kind of welder, anywhere, anytime, and be using it proficiently in a short time.

Select some tubing or flat steel no more than 0.095 inch thick. Install a welding tip, a No. 3 or No. 5 in the case of the Craftsman version, on the torch. Set the acetylene regulator to about 6 pounds per square inch (psi) of pressure. Set the oxygen regulator to roughly double that amount. Too much is not better. These regulator settings will need to be changed when using the cutting torch.

Before you fire it up, here are some points to know. When you turn on the acetylene bottle, open the valve only as far as you can turn it without repositioning your hand. The reason is this: The acetylene is the fuel. If anything such as a cut hose or flashback should happen, you can cut off the fuel in one motion.

What is a flashback? First, some torches have check valves to prevent this occurrence. The check valve will stop a reverse flow of gas. A flash arrester at the regulator is a good addition.

The flashback phenomenon occurs when the fire is pushed back in the tip, such as when the tip is pushed into the work where the tip outlet is temporarily sealed. Oxygen can then follow the lower pressure acetylene back down the hose. The hose will begin smoking, often accompanied by a whistling or hissing sound. This might be a good case for never having a short hose on a torch. The one thing you don't want to happen is for the fire in the hose to reach the acetylene bottle. The fire goes toward the acetylene bottle, not the oxygen. So one twist of the hand on the acetylene bottle valve stops the fuel supply process. Then shut off the oxygen.

If your torch set does not have flashback protection of some kind, I strongly recommend you get it.

With the regulators set, while wearing dark glasses, light the torch. Acetylene first, and it will get an orange smoky flame. Turn on the oxygen valve slowly, and the fire will begin to turn blue. Slowly increase the oxygen. Notice the flame takes a blue cone shape. Within the larger cone, a smaller cone will appear. Keep adding oxygen until the two cones come together. This is known as a neutral flame. Rarely will you ever need anything other than a neutral flame for any torch use, including the cutting torch.

To weld, use a filler rod, 1/16 inch in this case. Circle the flame at the spot you want to start welding. As the work piece heats up to a cherry red color in a spot about 1/4 inch diameter, be ready to touch the spot with the filler rod. The weld spot will liquefy. Now gently dip the filler rod into the molten puddle. Keep the torch moving but don't outrun the puddle. Keep dipping the filler rod into the puddle.

When the puddle is formed and the temperature is right for welding, a welder's eye will appear. This is a tiny bright dot that floats around in the puddle. This is your welding temperature gauge. Now you are a welder! Well not quite...but keep practicing.