The Mitertite™ system cuts and fastens mitered casing joints. The patented system from Collins Tool Company uses a single pocket screw perpendicular to the joint driven through the edge of the mitered casing, as shown at the bottom of its assembly plate in the left picture above. One of the keys to the system, shown in its carrying case in the right picture above, is its Micro Fence that fits to your chop saw and makes the saw’s 45° setting actually 44.9°, splaying out the legs of a pre-assembled casing. When the casing is installed, the legs are pulled in and the inside of the miter is compressed. They claim this prevents the joints from opening when the wood either dries out or takes on moisture. The stretch clamps, shown in the top of the case, are another key to the system: They keep the inside corners under pressure as you’re moving the casing assembly for installation.
At $297 it’s not inexpensive, but if you do a lot of trim and finish carpentry it may be worth it. The complete system includes the assembly plate, the Micro Fence, three stretch clamps, a hex-shank 3/8″ bit with hex holder and driver, a plug cutter with guide bushing, enough screws for “two average size houses,” an owner’s manual, and a carrying case.
Tools Of The Trade magazine has a first test review here. Collins Tool has a video of the system at the link below.
Mitertite™ [Manufacturer’s Site]