Playing the Angles

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This article is from Issue 97 of Woodcraft Magazine.

When 90 degrees won’t cut it

Most woodworking is all about cutting square. But to really up your game in the shop, you have to contend with angles. Picture frames, mitered boxes, chairs, or even something as simple as the wall shelf pictured on page 55 all involve non-90-degree cuts. But how do you determine the necessary angles? How do you lay them out? And how do you set up your machines to cut them accurately? Tools for working angles typically perform one or both of two functions: registering an angle, and identifying it. For example the time-honored T-bevel registers an angle by conforming to its shape. Then a protractor is used to identify the angle in terms of degrees. 

Although those two tools used in conjunction may satisfy the majority of your angled-work needs, manufacturers offer a plethora of options. As I’ll show you on these pages, some efficiently register and identify an angle in one operation. Some are better for large layouts. Some take innovative, high-tech approaches to faster, more accurate machine setups. Read on to discover the best ways to complement your particular type of work.

Up and over. T-bevels excel at laying out dovetails. Dovetail angles are frequently expressed as a ratio such as 1:6, which means six nches up for every inch over. Here, I’m using a 9" ebony and brass-handled T-bevel from I-Gaging, featuring a knurled brass knob to lock the blade.

T-bevel and protractor, hand in hand

The T-bevel, also called a sliding T-bevel or even a bevel square, is the time-tested first choice for gauging and transferring angles. This tool consists of a thick handle that locks around a thinner blade. Available in lengths from 4" to 14", an 8" to 10" model is ideal for most furniture work. To get the most from a T-bevel, pair it with a protractor to determine an angle’s measure. In practice, a protractor with a bigger scale means more accuracy and easier visibility—something to factor into your purchasing decision.

Down to a degree. Angles are frequently specified in degrees. If you know the degree, you can set your T-bevel using a protractor. This bevel gauge/protractor from I-Gaging (left) features angles from 0° to 50° with divisions every 1⁄4°. The all-metal 10" Shinwa T-bevel secures the blade with a wire bale lock at the end of the handle. T-bevels with an end lock tend to hold their setting tenaciously.

Fast Miters

To quickly set your T-bevel to 45°, register it against a precise combination square such as one made by Starrett.

Angles galore. At 0°-60°, Veritas bevel setter has a wider range than the I-Gaging model, although it’s smaller and only divides each degree in half. Its reverse side is etched with some of the more commonly used woodworking angles. The vintage Stanley T- bevel locks the blade securely with a knurled knob at the end of its handle.

Back to math class. The two protractors shown here might remind you of math class. The General model lying on the bench has easy-to-read markings from 0°-180°, but the small head makes precise settings tricky. The two-sided Sawset model features a cutaway section for your T-bevel. One side is calibrated for the actual angular measure while the obverse side (inset) notes the bisected angle as reference for setting your saw to cut a miter joint.

Hybrid angle gauging. Branded as just a protractor, this angle gauge from E-Base is more like a protractor/T- bevel crossbreed. Set its two blades along the edges of the piece in question and get the analog angle in one shot.

Beyond the T

While you can’t go wrong with adding a T-bevel (or two) and a protractor to your tool arsenal, alternatives abound. The tools shown here work similarly, but have their own unique features and solve some different problems.

All in one. For the minimalist woodworker, this handy multi-tool from Lee Valley might be all you need in your apron pocket. In addition to serving as an excellent T-bevel, it also functions as a square, marking gauge, depth gauge, compass, divider, and 12" rule. You’ll still need a protractor for measuring and setting specific angles.

Combo square add-on. Available as part of a set, or as an added accessory, a protractor head that slides on the blade of your 12" combination square adds more functionality to that tool. This cast iron head from PEC Tools fits perfectly on a Starrett rule. The protractor is graduated from 0°-180° and from 180°-0°, though the etched numbers can be hard to read. Use as shown, or slide your T-bevel through the protractor’s slot to transfer the setting.

Digital angles. This plastic/metal digital T-bevel from General features a small but readable LCD screen that indicates angles to the 20th of a degree, eliminating the need for a protractor. It is sensitive enough that setting specific angles takes a steady hand.

Bigger tools for bigger work

While an 8"-10" T-bevel will suffice for most furniture work, when it comes to laying out angles on plywood and other sheet goods, it helps to have longer tools. Some of the tools that follow are bigger cousins of those previously discussed (p. 27-29), while others are unique to the tasks involved.

Long and low-tech. This protractor from E-Base incorporates long aluminum blades that lock securely at your chosen angle. Used here in conjunction with a Starrett combo-square, it makes accurate work of laying out angles on a panel.
Long and high-tech. The 14" long, stainless steel blades on this digital protractor from I-Gaging suit it to large-scale layouts. However, despite the nicely-machined, knurled knob, this tool doesn’t lock securely. But careful use in conjunction with a long straightedge will yield accurate layout across wide sheets.

Carpentry crossover. Sold as a T-square for drywallers, this large, aluminum layout tool from Kapro has several key features that make it useful for plywood layout. Its sliding head has detents that lock it in place at 90°. But by loosening the knob you can readily pivot the head to any desired angle. It also has a built-in protractor with a few common angles such as 30°, 45°, and 60°. The head also folds parallel to the blade for compact storage.

Complementary angles. A table saw with its blade tilted to 20° will cut a 70° bevel.

Is it 90° or is it 0°?

One confusing aspect of setting up tools for angled cuts involves the gauge on the machine itself. Most table saws and miter saws—and many miter gauges—include a scale that begins at 0°, indicating the machine is set to make a 90° (or square) cut. Then as you tilt the blade (on a table saw) or pivot it (on a miter saw) the pointer will register somewhere between 0° and 45°. The I-Gaging and Veritas protractors correspond with this system, but other protractors (and many woodworking plans) refer to a square cut as 90° rather than 0°.

To compensate for this discrepancy, recall a lesson from geometry class on complementary angles (No, you won’t have to do a proof!). Complementary angles are two angles that, together, equal 90°. So if your plans call for a 70° cut, you’ll use 20° on your machine’s scale (70° + 20° = 90°). Also, understand that the angle scale on the front of most table saws only gets you in the ballpark. For precise bevel setting, you’ll need a T-bevel and protractor, a digital angle gauge, a set-up block, or even a drafting triangle.

Machine set-up

Knowing how to measure and lay out angles is only half the battle. You also need to transfer those angles to your machinery for accurate work. Some of the tools featured in this article excel at both layout and machine set up. But a couple of dedicated tools make set-ups quick and painless.

Raise and conquer. To tilt the blade on your table saw to a specific angle, raise the blade to its full height. Then set your T-bevel to the desired angle, and tilt the saw blade until it parallels the T-bevel blade. Be sure the tool handle is flat on the table and aligned with the saw’s arbor, and that its blade extends between the saw blade’s teeth. Lock the saw’s tilt control, and lower the blade to a safe height for the operation.
Making miters. To adjust a miter gauge, hold the set T-bevel against the fence and pivot the fence until the bevel’s blade is parallel to the saw blade. Keep the T-bevel’s handle flat on the saw table and extend its blade between the saw blade’s teeth. Use the same process for setting up angled cuts at the miter saw.
Magnets and technology. Possibly the fastest and easiest way to set blade tilt is with this digital angle gauge from Wixey. Simply stand the magnetic gauge flat on the saw table and press a button to zero it out. Then affix the gauge to the blade, and crank over the blade to your desired angle. Alternatively, for a 45° setting you can use a dedicated setup block (inset) or a drafting triangle.
Tilt the table. On a band saw, you can use a digital angle gauge to set the table’s tilt. Square the table to the blade before zeroing the gauge on the table. Then tilt the table as desired. 


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