When it comes to creating patch panels there is only so much one can do with hammers, dollies, and other common body tools. At a certain point one needs to get some specialty tools to aid in the job.
One such area is making patch panels that require a break in the metal, for instance wheelwell flanges, trunk corners, and compound doglegs. How many of you have ever tried to bend a piece of metal with any degree of break in it to flow around a curve? It didn't bend did it? In fact, what happens is it kinks and creases to the point of no return. The only way to get something like that to bend is by making a series of pie cuts. The problem here is once you get your piece made you have to go back and weld up all those pie cuts- not a small task. We think it's safe to say in situations like this the only way to make a patch panel is with a specialty tool, and in this case the tool of choice is a shrinker/stretcher.
When it comes to specialty autobody and fab tools no other name comes to mind more frequently than The Eastwood Company. They manufacture and carry an extensive line of tools to get just about any automotive job handled. Somewhere in the mix of things you will run across their shrinker/stretcher set. The Eastwood shrinker/stretcher set is designed to work with just about anything requiring the combination of a curve and an angle. The tools are designed around hardened steel jaws, specific to shrinking and stretching metal, that can form mild steel up to 18-gauge, stainless steel up to 20-gauge, and aluminum up to 16-gauge. To engage the jaws it's a simple matter of pressing down on a hand-operated press that multiplies your pressure by a leverage factor of 45. Combine all these factors and one is capable of producing curves as tight as a 3-inch radius. For convenience, both the Eastwood shrinker and stretcher comes assembled ready to work with a pre-drilled housing for easy mounting to any workbench.
To get a firsthand look at exactly how shrinker/stetchers work we ordered a set from Eastwood. Instead of mounting the set to a workbench, we also ordered an adjustable work stand from Eastwood. On a side note, Eastwood also sells a foot-operated stand compatible with the shrinker/stretcher set, and they also sell a pneumatic unit as well.
The Eastwood shrinker/stretcher...
The Eastwood shrinker/stretcher set. Both come preassembled and ready to rock. Simply secure them to a fixed position, such as a workbench, and go to town. For our set we ordered an adjustable work stand from Eastwood. This stand is nice because it can be adjusted to whatever the desired work height is, plus it is pre-drilled so it can be mounted to the floor.
The shrinker/stretcher is...
The shrinker/stretcher is color coded and labeled for its application. The yellow component is the stretcher, as indicated by the label. The way it works, the four jaws inside the housing grip the work piece, and then the left and right side pull opposite one another (noted in arrows), stretching the metal.
The blue one is the shrinker....
The blue one is the shrinker. Like the stretcher, it too has four jaws, that when engaged, grip the metal. However, unlike the stretcher's jaws that pull away from one another, the shrinker's jaws pull towards each other (noted in arrows), shrinking the metal.
Here is an inside look at...
Here is an inside look at the jaws of the tools. As you can see, inside the housing are four jaws that line up caddie corner by virtue of size, (i.e., big to big, small to small)...
...Between each set of jaws...
...Between each set of jaws is a spring. Once the lever is released, the tension is off of the jaws and the spring pushes the jaws back into the housing for the next sequence.
The shrinker/stretcher tools...
The shrinker/stretcher tools are ideal for panels that require a curve and an angle. For instance, wheelwell flanges, door frame window openings, trunk corners and the like. Which means this piece of 2-inch, 20-gauge sheetmetal broke at a 90 will be a perfect candidate.