An electric miter saw with a carbide-tipped saw blade can be used to cut soft aluminum used for window frames. Carbide-tipped blades are the most durable blades available for a miter saw. A miter saw is able to make the precise angled cuts required for window frames by pulling the circular blade onto a piece of aluminum with a short vertical plunge.
Use a hacksaw to cut framing pieces for a metal window frame to length, if you do not have an electric miter saw. A hacksaw is strictly used for cutting metals. When using it, be sure to secure the blade with the teeth pointing forward and tighten the nut to create tension in the blade. Use steady strokes when cutting the frame, aiming the saw blade away from you. Keep the blade lightly oiled for the best performance. Be careful when using a hacksaw to cut window frames to get the corner angles right.
A tape measure and a framing square can be used along with a hacksaw to ensure the metal window frame’s corners are cut at the correct angle. The angles need to be cut to 45 degrees. After you make the cut, use a tape measure to make sure the frame side is the correct length. When all four sides are cut, use a framing square to ensure the corners of the window frame are at 90-degree angles.
Corner braces, sometimes called corner clips, are used to hold the frame together after cutting the frame pieces. The corner braces are fitted into the ends of the metal frame, holding the frame together through tension. If the pressure created by sawing the frame pieces caused them to close at the ends, you can use the flat blade of a standard screwdriver to reopen them.