SHRINKER STRETCHER MANUAL
Form Compound Curves in Metal
Eastwood Shrinker/Stretcher tools can form curves down to a 3" radius in a variety of metals: mild steel (up to 18 gauge), stainless steel (up to 20 gauge), and aluminum (up to 16 gauge). The Shrinker forms outside radius curves and the Stretcher forms inside radius curves. They are perfect for forming complicated patch pieces for such areas as rear wheel arches, dog legs, window edges, and trunk edges.
Secure the tool to a workbench. The more rigidly the tool is secured, the easier it is to use. Two holes, predrilled and tapped into the base, accept 3/8" - 16 bolts. For portability, the tool may also be clamped into jaws of a vise. The Shrinker/Stretcher, Base Mount (Item-no #28051) is designed for vise-mounted applications of the Shrinker/stretcher Set (Item-no #28053) and provides great flexibility.
Before fabricating on the Shrinker/Stretcher, bend the metal to be formed 90º on a Sheet Metal Brake (Item-no #28025), creating a maximum flange depth that is no greater than 2".
Make a template out of cardboard or a short piece of wire. Tracing the outline of the section you want to form is critical to achieving a good fit with minimal filler use.
Work the leading edge first. This "breaks down" the maximum resistance and permits easy and accurate working thereafter. For best results and maximum forming power, insert metal only halfway into the jaws. The "bunching" or "pocketing" that typically occurs when shrinking can be quickly hammered out.
Control lies in the pressure exerted on the handle while forming the metal. Move the metal back and forth until the desired radius is obtained.
The jaws of the tools are "toothed" to better grip the metal. These teeth leave slight markings, depending on the hardness of the metal, which can be removed with an abrasive cloth or wheel.
Avoid cuts and ease handling. Wear gloves durring all forming operations.
Avoid pressuring the jaws together accidentally. Remove handle when not in use.
Avoid dulling the teeth. NEVER press without a separator between the jaws. ALWAYS insert a piece of metal or other material divider between the jaws when not in use. (When you received your Shrinker/Stretcher Set, an insert was between the teeth.)
The Basic Panel Fabrication using the Shrinker/Stretcher Set
For rodders and restorers, fabricating body parts in the home shop is often the only way to go. But with the Shrinker/Stretcher Set is isn't difficult to make new panels. With good planning, you can reproduce shapes to match original contours, or design shapes limited only by the imagination.
As an example, we made a replacement headlight assembly mounting flange. Most older cars catch and hold moisture here, thus rusting out. Usually so much metal is gone that there is very little left to rescue. A new, fabricated part is the only way to go.
First, we made a cardboard template, tracing around the headlight opening. We cut a piece of steel 2 1/2" wide by 11" long, using our Rotary Bench Shear(Item-no #28034). This tool really saves the blisters you'd get from using hand shears, especially if you have a lot of metal to cut. We then bent the metal in a Sheet Metal Brake (Item-no #28025) to make a 90º flange, 3/4" wide.
The flanged section went into the shrinker/stretcher shrinking jaw. By pumping the handle firmly and moving the metal back and forth, the jaw's teeth keep drawing the metal closer and closer, creating a smooth curve. We kept checking the new piece with the cardboard template, and within minutes we had a piece very close to size.
We made some final adjustments on the car, and it fit just fine. It took a total of 15 minutes to create this mounting flange.
Compound curves can be made by working
the piece on alternating sides, when both Shrinker and Stretcher, taking care
to match work on both sides. We took an 18" by 11" piece of 20 gauge
metal and put two 1" flanges on its edges (photo 4). This technique is
especially useful when reproducing splash aprons and other large curved areas.
Clean the jaws after every job! Blowing out with an air hose doesn't do a through job. Vacuuming helps to get the fillings out. The best way to maintain the metal former is to disassemble the jaws and clean as follows:
Loosen the four (4) retaining screws to remove the jaw assembly.
Remove jaws and V-block as a single unit. Be careful, don't lose the string between the jaws.
Remove the suspension spring.
Notice how the jaws are inserted. There is a small jaw opposite a large jaw, top and bottom.
Clean the two jaws with cleaning fluid and a brush. DO NOT use a wire brush or a wire wheel.
Always brush in the same direction as the teeth, with the grooves.
Clean the V-block.
Lubricate the surface between the jaws and V-block. Reassemble.
Lift out the bottom jaws as a single unit with V-block. Clean these.
Replace jaws. Be sure you place the large jaw opposite the small jaw. when replacing the V-block, the radius corners face front.
When not in use for extended periods of time, lightly oil the jaws to prevent corrosion.
REMEMBER: Clean the jaws after EVERY job.