Why projects call for a miter saw
A miter saw drops a blade through a board at a set angle, which makes it very good at two things: square crosscuts and repeatable angled cuts. When a project has many parts that must be the same length, or many corners that must meet cleanly, the saw’s fence and angle scale do the work that would otherwise take careful marking and handsawing. It is best at short to medium boards. It is not the tool for ripping long boards or for cutting wide sheets.
Trim and molding
Baseboard, casing and window trim. These are the classic miter saw jobs. Outside corners are usually mitered, and inside corners are often cut so that one piece is coped over the other, but many people also miter inside corners. Door and window casing needs matching pieces cut square or at an angle. Trim carpentry also uses many hand tools besides the saw.
Crown molding. Crown sits at an angle between wall and ceiling, so cutting it is a puzzle of compound angles. Some saws can cut it with the molding laid flat using bevel and miter settings together, and others cut it standing against the fence. Practice on scrap first, because mistakes are expensive with long pieces. Walls that are not perfectly square are common, so test-fit before committing.
Chair rail, wainscot caps and picture rail. Long runs of trim with repeated joints around a room.
Frames and boxes
Picture frames and mirror frames. Four 45-degree miters make a square corner. Matching the length of opposite sides matters more than almost anything else, and a stop block gives you that.
Shadow boxes and display cases. The same principle applies to deeper frames. Corners can be glued and reinforced with splines or small fasteners. The problem of miter joints that gap is mostly about angle error and fit, and small errors add up quickly across four corners.
Window and door frames for sheds, cold frames and garden projects. Simple frames from lumber can be cut square at consistent lengths.
Face frames for cabinets. Rails and stiles are cut to length with square crosscuts, and the pieces need to match closely to produce a flat, square frame.
Repeated-angle and repeated-length projects
Decks, railings and stair parts. Balusters, rail sections and deck boards need many cuts of the same length, and angled cuts where rails meet posts or stair stringers. Treated outdoor lumber often has a coarse, wet surface that dulls blades, so a sharp blade is useful.
Picket fences and trellises. Pointed or angled tops on pickets, and repeated lengths for slats.
Shelving and furniture parts. Shelves, aprons, stretchers and legs of identical size. Angled legs on benches and stools are cut with a bevel or miter setting.
Hexagon and octagon shapes. Planter boxes, small tables and decorative frames use repeated angles. The angle depends on the number of sides. Each joint is split evenly between two pieces, so a regular six-sided shape needs 30-degree miters (the corner is 120 degrees) and a regular eight-sided shape needs 22.5-degree miters (the corner is 135 degrees). Test on scrap, since small errors multiply with every side.
Setting up for accuracy
- Check the saw first. Set the blade square to the fence and the table, and confirm that the 0-degree and 45-degree detents are accurate with a reliable square. Saws can come out of adjustment from handling and use, which is part of why regular accuracy checks are worth doing.
- Use a stop block for repeated lengths. Clamp a block to the fence or an auxiliary fence, push each piece against it, and every cut matches. Do not use the cutoff piece between the blade and the stop, since the offcut can bind and kick.
- Support long boards. A board that sags past the table changes the cut. Use roller stands, a sacrificial extension or a workbench to hold the far end at the same height as the table.
- Mark the cut side. The blade removes material, called kerf, so decide whether it takes the line or sits beside it. The saw kerf is often about an eighth of an inch, though blades vary.
- Choose a blade for the job. Finer tooth counts give smoother results in trim and molding, and lower counts cut faster in framing lumber. The blade often affects cut quality as much as the saw does, so it is worth knowing the common saw blade types.
- Cut slowly through the stroke. Let the blade reach full speed, lower it smoothly and let it stop before lifting.
Safety
A miter saw can injure quickly. Wear eye and ear protection, and a dust mask. Keep your hands well clear of the blade path, and clamp the piece when it is short or awkward, because a held piece can be pulled by the blade. Never cross your arms over the blade, and do not reach behind it. Wait for the blade to stop before moving the work. Unplug the saw before changing the blade or making adjustments, and use the guards as the manufacturer describes. Follow your specific model’s manual, since details differ. This is general information, not professional training.
Is it the right tool?
If most of your projects involve trim, frames or repeated lengths, a miter saw makes them faster and more accurate than a hand saw. If you only need a few cuts, a handsaw and a miter box or a circular saw with a speed square can do an acceptable job, though with more effort and less accuracy.