![]() ![]() This is because on a miter saw, a 90° cut, relative to the fence, reads 0° on the saw’s miter scale. ![]() However, the bisected 88° angle is not accomplished by cutting each miter at 44° on the miter saw, but at 46°, the complement of 44. For example, an 88° corner is tighter than 90°, and the two-degree variance is best accommodated by adjusting the two pieces that meet at the miter by one degree each. The tool makes the task easier, because adjusting miters for out-of-square conditions is confusing. Tune the miter to fit with a razor-sharp low-angle block plane. Find the true angle with a construction protractor or a bevel gauge. I like the Pro Site because it shows the bisecting angles for out-of-square corners. If I’m trimming old work or trimming doors or windows someone else installed, I check the jamb corners with a Starrett Pro Site protractor. If I am casing doors or windows that I installed, I know the miters will be 45°, because when I install doors and windows I take the time and effort to make the head jamb and side jambs perpendicular, resulting in 90° corners where the head and side casing meet. ![]() A negative hook angle creates a less aggressive but cleaner-cutting blade.Īn alternate top bevel (ATB) tooth pattern reduces chipping and tearout. It’s also important to have a decent stand that holds your saw securely and supports long stock. With a slow feed rate, a sharp, high-quality blade on a well-tuned saw will produce glass-smooth cuts in hardwoods. I prefer full-thickness blades over thin-kerf versions because they deflect less, resulting in more-accurate cuts, especially with hardwoods. On my miter saws, I use negative hook angle ATB blades with 80 to 100 teeth. Assuming the casing is not warped, a saw that’s properly tuned will cut the pieces so that they have tight, coplaner corners. Cut four equal-length pieces with 90° corners, and then arrange the pieces into a four-sided frame. Test your saw’s setup by making a small picture frame with casing. Set the bevel by squaring the blade perpendicular to the saw’s table. Use a square to ensure the blade is exactly 90° to the fence. Make sure the table is flat from front to back and side to side.Ĭheck that both sides of the fence are aligned with each other. You can learn how to adjust the fence and set the pointers with help from the owner’s manual, which can be found online if you’ve tossed it. Finally, make sure the miter pointer and bevel pointers read zero when the sawblade is perpendicular to the fence and saw table. ![]() Then use a straight edge to check that both sides of the fence are coplaner. Use a straight edge to check the rotating miter table is in plane with the nonmoving part of the saw table. Miter saws need sharp, high-tooth-count blades and to be properly tuned to cut cleanly and accurately. Here are some other ways I prevent opened miter joints for better-looking casing and fewer callbacks. CA glue may dry quick, and a few drops make a great clamp, but the joint is brittle and doesn’t hold long-term. The end-grain glued joint is strong and has a lot of surface area so it keeps the miter from spreading. It might sound obvious, but a good first step is to glue your miters with wood glue. I know because I’ve been a carpenter for three decades now, and I see which techniques work and which don’t. It might seem an impossible task, but with the right tools, techniques, and casing styles, you can make mitered joints that stay tight forever. When the mitered joints are tight, it shows that the carpenter is skillful and indicates a higher quality of construction throughout the house.Įven the tightest miters can open weeks or months after the trim is installed as the moisture content of the wood changes seasonally. Most casing patterns are designed to turn corners with tight, coplaner miters. Maybe more than any other finish-carpentry detail, the casing on doors and windows shows the skill of the carpenter who did the work. With annotated illustrations, this guide discusses the type of blade to use and how to accurately set up the miter saw, considerations for back beveling and front beveling, best ways to fine-tune out-of-square corners, and more. Synopsis: Carpenter Brian Campbell lists seven techniques for achieving mitered joints that won’t open over time. ![]()
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