Main Tube Bending
Introduction
A way of simplifying the Thunderbolt project is to bend the Main tube vise cutting, mitering and welding the two required angles. The process take 5 minutes and cost any where from a favor to $10.00. The best part about this is any muffler mechanics shop has the equipment to do this bending. However, this process is not without a drawback. The portion of the tube that is bent is slightly deformed. This defect appears as shown below:
Since the Thunderbolt requires a gusset that spans across both 66° and 26° angles, these blemishes can be hidden. However, the Gussets will require modification to make them fit properly.
Preparation
You need to provide a piece of 2" stock tubing that is cut to 53.3 inches in length. Using the drawings below, place marks where the bends occur. In addition, record the angle that they are to be bent.
Going Out For Bending
With your drawing (print the drawing above) and cut length of tube in hand (and $10.00 cash), visit your local muffler shop. When asked what you want, indicate that you need a tube bent in two places. Also explain that both bends are on the same plane which will makes this job very easy. Before, you commit ask for an estimate. A cost of $10.00 should more than cover this service.
Once an agreement is made, they will lead you to the Tube bending machine. The Tube Bending machine I used is built by Ben Pearson. Of course there could be numerous manufacturers that build these machines, but I'm sure the capabilities and results are the same.
The machine above uses three matched dies. The half crescent die as shown above, establishes the radius of the bend. The two straight dies provide the tube bend angle. The dies are categorized by tube diameter and bend radius.
The photo above shows the tube being situated into the bender. The mark indicating where the bend occurs, is aligned at the center between the rectangular dies.
Once the tube is in place, the desire angle is adjusted as shown above. In this example I am setting the bender for an angle of 18°.
To insure that both bends are on the same plane, a protractor is attached to the end of the tube as shown. What is not shown on this device is the bubble that indicates the rotational orientation of the tube. The protractor is attached so that either 180° or 0° is pointing directly upward.
The button is pressed and the tube begins to bend. Notice that the two rectangular dies are no longer parallel?
Viola! Here it is a completed tube waiting for final machining and welding. No, this is not me!
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