How to Break Aluminum for Window Trim

Home repair doesn't usually involve breaking things. In the case of fitting aluminum trim around a window, however, breaking describes the procedure you need to follow in order to make trim the length you want.
Aluminum trim does not respond well to being sawed through, even with power tools. Its slightly brittle quality makes it much better suited to being scored and folded to size. Variations of this score/fold/snap technique are used on a variety of objects, among them graham crackers and postage stamps. Follow the steps below to apply this technique to aluminum window trim.

Things You'll Need

• Measuring tape or yardstick Aluminum trim Pencil Mitre box or protractor Hacksaw with metal cutting blade Counter or railing edge

Instructions

Score, Fold, Snap

1. Measure and pencil-mark the length of trim you need. A straight cut is easy. To handle diagonal cuts for edging corners, use a mitre box or protractor to get your angles precise (part of both the brittleness and the flexibility of aluminum trim means that minor corrections or trimmings are hard to do).

2. Use your hacksaw to score the trim piece. This means making a surface cut--as deep as possible but not all the way through the trim piece. Especially if your trim is ridged, concentrate on cutting through the ridges so as to make a shallow surface cut on the areas below the ridges.

3. Lay your piece of scored trim across a counter or porch railing. Line up the scoring with the counter/railing edge. Holding both pieces to avoid slippage, bend the piece extending past the counter/railing edge down as far as it will go. That's your fold.

4. Bring the extended piece back up as far as it will go. You should be rewarded with a clean snap.

5. Fold back down again if the snap didn't happen. And up again, if absolutely necessary. This repeated folding should weaken the metal enough to snap.

6. Re-score any truly stubborn areas, following the fold line carefully. Return to folding. Snap! You did it.

Tips & Warnings

• If you are new to using a hacksaw, remember that it works best as a one-way cutter. Either the push or the pull stroke is your cutting stroke--figure out which it is on a test-piece of trim and either push or pull only. Going back and forth, which is customary with a wood saw, dulls a hacksaw blade quickly.