Aluminum-framed screens are popular features of ready-made window units because they look good for many years, hold the screen mesh tight and are easily removable. Another useful, though little-know, attribute of aluminum-framed screens is that they're easily made-to-order in the home workshop. If you've ever wanted to build custom-made screens but didn't know where to start, look no farther.
Anatomy of an Aluminum-Framed Screen
The drawing here shows the main parts of a typical aluminum-framed screen. It's based on a factory-painted extrusion (typically available in white or brown) that has a lot of interesting features. First of all, its hollow shape is made to accept preformed 90-degree aluminum or plastic corner clips that can be used to hold any four-sided frame together. Another feature is the narrow channel found in one of the outside faces. This channel is made to accept a flexible strip of rubber or foam called a spline. The spline is pushed into the channel over top of the actual screen mesh during installation. The mesh is not only held firm by the spline, but the action of it sinking down into the aluminum channel automatically tightens the mesh for a sag-free installation.
Shopping for Supplies
Screen-making supplies aren't common items on hardware store shelves, but that doesn't mean you can't get them. The best place to start looking is at a shop specializing in screen repair. If you're making a lot of frames you'll have no trouble dealing with wholesalers carrying screen supplies. Large, national building supply outlets also list screen materials in their catalogues, but they may have to order them in for you. Aluminum frame extrusion is typically sold in 12-foot lengths, corner clips by the piece and spline by the foot off a roll. Mesh is also sold off rolls of a fixed width, typically starting at 24-wide and working up.
Cutting and Assembling the Frames
What makes aluminum-framed screens so easy to build in the home workshop is a little-known fact about how to cut the frame members. Most people are surprised to find that any carbide-tipped saw blade is quite capable of cutting the soft aluminum extrusions used for screen frames. (Aluminum downspout and eaves trough is also made of the same kind of metal and can be cut in the same way.) A chop saw is the ideal power tool for cutting screen frames because it's so well-suited to producing the 45-degree mitres required. Just to be safe, though, use an older carbide blade that you don't mind wearing out a little faster than normal. Although I've cut lots of aluminum screen frames without any saw blade trouble, I wouldn't risk my finer blades on the job. You could also cut screen frame material with an ordinary hacksaw, though you'd have to be careful to get the corner angles right. A fine blade will give a smoother cutting action.
The most important thing about cutting aluminum on any kind of power saw is the need to wear safety glasses and to keep everyone away from the cutting area.
The aluminum cuttings that are produced are very sharp and they can fly quite far. Workshop eye-safety is always an important consideration, but it's even more vital when working with aluminum.
Cutting aluminum screen frames is simply a matter of measuring the length and width required, then cutting the four side frame members as needed. Don't forget to make your frames slightly smaller than the opening they'll fit into to allow easy installation and removal -- 1/16 to 1/8 clearance on all sides is ideal. Some designs of corner clips extend slightly beyond the ends of the extrusions they fit into, increasing the effective length of the frame's sides once everything is assembled. Take a close look at the clips you're using and make adjustments to the lengths of your frame members accordingly.
You'll soon learn that corner clips are designed to fit into the aluminum frame extrusions with enough friction to hold them in place. This friction alone is almost always enough to hold the frame together, but if your frames don't hold together reliably, squirt a small blob of silicone caulking into the ends of the frame extrusions before assembly. Once dry, it'll hold things together, yet still allow you to take the frame apart later for repairs.
Mesh Selection and Installation
There are two kinds of window screen mesh available: aluminum and fiberglass. Fiberglass is the option I prefer because it combines low cost, good looks (it's dark colored and hard to see) with great flexibility that makes installation easier. Fiberglass mesh is also quite tough and lasts a long time. The technique for installing mesh on a new screen frame is the same as that for replacing damaged mesh on an old screen.
Begin by cutting a piece of mesh that's about 1 1/2 longer and wider than the inside dimensions of your screen frame. Place the frame on a large, flat surface with its spline channel facing up and lay the mesh on top. The object here is to orient the mesh so it's parallel to the sides of the frame and to preserve that orientation as the spline is installed and mesh pulled tight. This is easier than it sounds because the mesh is stretchable and can veer out of alignment as you work along one side. Steering the installation of mesh is all about pulling it one way or the other with your hands in that area that's just in front of the point at which the spline is being pushed into place. Take a length of spline material in your offhand and a wide-bladed stubby slot screwdriver in you dominant hand and begin to push the spline into the extrusions slot with the mesh underneath. You'll immediately see how this action draws the mesh down and acts to tighten it as installation progresses. Continue to work your way around the frame, always being conscious to keep the squares of the mesh parallel to the sides of the frame. When you've splined your way back to the starting point, cut the spline to length so it butts tightly against the end you began with. Use a fresh utility knife blade to trim away the excess mesh that extends beyond the spline. That's it!