All architectural metal roofers should have a working knowledge of shrinking and stretching panels. Being able to work on radius framing will increase your overall effectiveness as a roofer and the jobs you feel comfortable bidding. The method and tools described below are common for smaller roofing projects that don’t have access to expensive panel curving machines. Manually shrinking or stretching panels using the tools below is a viable option for even the smallest roofing crew and can make a big difference for your projects outcome.
Concave panel shrinking
Here is a bay window frame that copper will be added to for a beautiful presentation. Most bay windows are curved and this produces a tricky spot for sheet metal workers who are not that familiar with curving metal.
This is what a piece of copper will look like after bending both sides up to 90° in a brake. Notice it is totally straight and will not contour to the framing. This piece of copper must be shrunk to fit.
Here is what shrinking copper looks like when being ran manually through a shrinker.
Notice the crimp marks which is “shrinking” the metal to produce the curved look.
This shows the shrinker and stretcher on its on foot powered stand. Simply put pressure on the foot pedal to bring the shrinker jaws together and start the curving process.
Notice how the copper starts to form with the curvature of the framing.
Here is the entire set up with the shrinker, stretcher, and stand. It’s smart to have 2 bodies, both the shrinker and stretcher, so that if you over shrink, you can stretch the material back, and vice versa.