Tube Notching 101 - Fit To Be Welded

You can use a small arbor or hydraulic press to compress the end of the tube to aid in making the weld joint a closer fit. While we do not recommend this option, it works in a pinch. While it seems quite crude in comparison to the methods mentioned previously, this procedure has its place in the fabrication of components that are not required to be of ultimate strength. In fact, we have witnessed it being used for bumper and fender mounts. If you are going to use an arbor press, make sure it is a fairly large one; otherwise, you will have to be one strong guy to compress the tube. The hydraulic press is a better option. Again, while this method works, we don't recommend it because it doesn't yield the best fit for tubes.

For the average Saturday night racer, the list of equipment required to properly notch tubes is fairly short. You may have most of the tools in your inventory right now. At the very least, from a safety and quality perspective, we recommend using a drill press if you are going to use hole saws to do the notching. If you don't have a drill press, you can purchase one at a home improvement warehouse. We've seen some nice floor-mounted drill presses on sale for under $200. This is a tool you need to have for other purposes, not just tube notching, so buying one can be a sound investment.

The drill press should be bolted to the floor, especially if you are going to be working with large lengths of tubing. Bolting the drill press down gives you greater stability, not to mention it is safer if you are not having to worry about your drill press falling over while you are notching a tube. This makes the operation much more stable and safe in all applications. Using a handheld drill is not even a viable option due to the possibility of the hole saw grabbing the work and causing some serious hand and wrist injuries. The drill press should be set to the manufacturer's recommended speed. The tools needed include the following:

* A hole saw that is the correct size for the desired radius. Hole saws can be purchased in sets or individually. Purchasing a set is preferred because it usually comes with the mandrel.
* A mandrel, which serves as the interface to attach the hole saw to the drill.
* A good vise for your drill press.
* Several clamps to hold your vise to the drill press table. The preferred method is to bolt the vise to the table. This keeps the clamps from interfering with the tube, depending on the size and shape of the tube.
* A selection of hand files to help deburr the tube after it is notched.
* Some course emery paper to dress the tube after it is deburred.

If you are going to be doing a good bit of fabricating, it may make sense to purchase a dedicated machine for notching tubing. There are tool vendors advertising within the pages of this magazine that make equipment specifically designed to notch tubing. These machines do a great job, although using them for notching only several tubes may be overkill. They are great for long-term notching, and the time required to set up and complete the notching process is quite fast, accurate, and cost effective.

When joining a tube to a section of flat stock or to a square tube, it's a simple matter of matching the surface to be welded to the flat surface. This requires a weld surface on the tube that is parallel to the surface on the flat stock or square tube. A simple hacksaw and some deburring will accomplish this.

Remember that with any static structure (in our application this is the race car, including the associated rollcage and suspension the 'cage is tying together), if we can spread the loads over a greater area, the structure will hold up to greater loads prior to reaching any point where it may yield. Those loads are the stresses that are a normal part of our sport. Just welding the tubes together may not be enough. Notching the tubes properly helps spread the load over a larger area and gives us the ability to make the welded joint stronger. It is just that simple.