Spline once enjoyed a variety of commercial construction uses, which have since been replaced by modern computer designs. These days, flat spline used primarily in the installation of screens for windows and doors. The spline holds the screen tightly in the frame, but may sometime need adjustments to re-tighten the screen.
Flat spline is made with different materials such as wood, plastic, and metal. Choose your materials depending on the project that you have. For the purposes of screens, plastic is generally used as it is more flexible and weather resistant. Check your frame for two channels. One will be along the frame side and the other along the screen. The channel that is on the screen side is deeper than the frame side and this is where the spline will be installed. Do not cut your spline until you have it installed.
Take the end of the spline and press it against the channel of the screen side. Start on the one side and work your way around. Push the spline into the channel as far is it will go with the tips of your fingers. Keep the spline flat and straight as you work it in. The screen does not have to be extremely tight when you are installing the spline; at this point. Use the spline tool called a roller to get the material into the groove. Hold the frame with one hand and gently pull on the spline with the other hand to tighten it. This will ensure that the screen does get taut. Use a flat-head screwdriver to push the material into the corners working always in the same direction as the roller and never back the wheel up. Move the roller in the same direction all the time. Doing otherwise may cause bumps or the spline could dislodge from the groove. This can cause a disruption in the placement of the screen.
Place the flat spline into the groove and around the frame with your fingers, the roller and the screw driver. When this is done, cut the spline. Ensure that the spline has been tightened. Cut the spline neatly with a utility knife at the correct spot. Trim the screen using the utility knife; making straight cuts.