How to achieve perfect miters

In this article, we'll show you several ways to cut 45° angles, and help you achieve right-angle miter joints that practically disappear. And we'll do it through five common approaches, moving from low-tech, low-cost methods to those that rely on power tools.

No single approach satisfies everyone's needs. Some woodworkers don't have a tablesaw, some workpieces are too long to cut comfortably on a tablesaw, and some jobs call for mitering away from the workshop. So we looked into a whole range of tools to serve every mitering purpose. You'll need to do some fine-tuning. Don't worry, we'll show you three ways to handle that task by shaving or sanding.

Miter quality: Good to poor

For $10 or so, you can buy a plastic miter box and a backsaw. The one we used gave acceptable results on narrow molding. However, with the provided saw, which has 11 teeth per inch (tpi), cutting a larger workpiece proved to be slow going. A slight amount of slop in the molded slots caused miter accuracy to vary from cut to cut. We also noticed that the cut surfaces were slightly rough.

• PROS:
• Super safe—no chance of injury or kickback.
• Very inexpensive.
• Very portable.
• You can substitute a higherquality backsaw.

• CONS:
• Stock width limited by size of miter box.
• No provision for finetuning the 45° settings.
• Clamping workpiece is awkward.
• No provision for workpiece support or stops.
• You're restricted to short saw strokes; the blade feasily can slip out of the guide slot.
• Timeconsuming.

Miter quality: Good to fair

You can buy several models of mitersaw boxes that allow the saw to pivot from one 45° detent setting to the other. They come with backsaws or frame saws. We tried out a framesaw model. It's easier to use than the plastic miter box, and the saw (24 tpi) cut slightly smoother. However, it provides no way to lock the saw at non-detent settings, and no way to fine-tune the detent settings. If you decide to buy a similar miter box, check for those options.

• PROS:
• Safe to use.
• Reasonably priced.
• Portable.
• Detents at both 45° settings.
• Clamp and stop included, but both have limited range.

• CONS:
• No provision for finetuning the 45° settings.
• Blade can flex enough to affect cut quality.
• Timeconsuming.

Miter quality: Excellent
This miter-cutting sled offers a dual-rail guidance system that rides in the miter-gauge slots of your tablesaw, and smooth-acting stops that ride in tracks. It also features a safety channel down the middle to keep your hands away from the tablesaw blade.

To build the jig, see the drawing below for the dimensions. We used Baltic birch for the base and hard maple for the other parts. Refer to the photos above for building tips that guarantee an exact fit on your saw and a pair of perfectly aligned miter fences. Use an 80-tooth crosscut blade for smooth, ready-to-glue surfaces.

To make two workpieces of equal length, start by measuring and marking your first workpiece. Miter one end of the workpiece as marked, using the appropriate fence, and then transfer the workpiece to the opposite fence. Line up the mark with the blade, slide the stop against the already mitered end, tighten it, and make the second cut. Leave the stop in place, and miter the second workpiece in the same sequence. Remember to stop your cut when the blade's highest point passes through the fence to avoid weakening the sled base.

PROS:
* Fast cuts, even in thick, hard materials.
* Combination of tablesaw and jig provides accurate, consistent, and smooth cuts.
* Makes fine trimming cuts.
* Inexpensive to build.

CONS:
* Hard to handle long workpieces.
* Dedicated to 45° cuts only.

Miter quality: Excellent to good

Mitering long pieces is much more convenient on a power mitersaw, such as the one shown above. As with the tablesaw, your first step should be to make sure the tool is aligned properly. Next, construct a permanent or temporary work support, making it as long as necessary on each side of the saw, and flush with the saw table. Install a sharp mitersaw crosscut blade, preferably one with 60 teeth and a negative hook angle. Then, with the workpiece held or clamped firmly in place, lower the blade through the workpiece slowly for a smooth cut.

PROS:
* Fast cuts, even in thick, hard materials.
* Adjustable to any angle, as well as having 45° detents.
* Good for long workpieces and repeatable cuts, if provided with suitable workstation.
* Removes tiny amounts of material if needed to fine-tune miters.
* Portable.

CONS:
* Can be awkward to cut long stock without dedicated support and fence system.
* Throws a lot of hard-to-collect sawdust into the air.
* More blade runout than a well-tuned tablesaw.

Miter quality: Excellent to fair

If you own a radial-arm saw, you face the same issues as just discussed: Accurate setup and adequate workpiece support. As with the power mitersaw, the radial-arm saw's main advantage over the tablesaw is in the handling of long workpieces. Place your workpiece flat on the table and butted against the fence, with the saw head pivoted to 45°.

PROS:
* Fast cuts, even in thick, hard materials.
* Handles long workpieces if surrounded by a flush support surface.
* Removes tiny amounts of material if needed to fine-tune miters.

CONS:
* Takes up a lot of room.
* Limited capacity when cutting 45° to the left because blade is located left of saw arm center.
* Many models have a tendency to move off the 45° setting, resulting in an imperfect cut.

You might need another tool now and then, but we suggest that you build the miter-cutting sled shown above, and rely on your tablesaw for most of your mitering work. This method offers accuracy, consistency, and control, and it's how we prefer to miter flat workpieces and molding in the WOOD® magazine shop.