1. Tape measure. This straightforward measuring instrument is found (or at least it should be found) in every home. Stick with one primary tape for woodworking. Different tapes can sometimes have discrepancies, so designating a chief tape will keep your measurements consistent. A 16-foot tape works nicely in the woodshop, as you'll rarely measure anything beyond that length.
2. Framing square. These dedicated right angles keep projects square, especially during assembly. A large square measuring 24 by 16 inches gets the most use in cabinetry, for which perfectly square boxes are critical. Framing squares also come in handy for checking square edges on large workpieces, such as plywood and doors. Smaller dedicated squares also come in handy for tighter spaces where standard 24-inch squares cannot fit. With the help of a square, which runs a line along the workpiece opposite the piece to be attached, accuracy in nailing, screwing or stapling becomes nearly foolproof.
3. Try square. Similar to larger framing squares, try squares are dedicated right angles. However, unlike framing squares, try squares have a metal blade fastened into a wooden handle rather than single-body construction. The thicker wooden handle provides a lip on either edge of the blade, allowing the tool to rest on the workpiece more easily than its larger single-bodied counterpart.
4. Combination square. A favorite of many woodworkers, the combination square is one of the most versatile tools in the shop. In its simplest form, the combo verifies square edges and flat surfaces of workpieces. Beyond that purpose, the adjustable head of the combo is crucial for calibrating or checking machinery and laying out joinery. Because of this tool's practicality, most shops have several combination squares on hand in sizes ranging from 4 to 12 inches.
5. Sliding T-bevel. Most woodworking projects are made up of 90- and 45-degree angles, but random angles do arise, and the sliding T-bevel is there to greet them. The compassing blade of the tool matches any angle thrown its way, which can then be transferred to a workpiece or measured using a protractor (that old tool we all became acquainted with in junior high geometry class).
6. Short rule. A tape measure can be used in a pinch as a ruler, but it can be a bit clunky, especially for making critical measurements in the middle of a workpiece. A flat 6-inch ruler fits nicely in a pocket and makes meticulous measurements in 1/64-inch increments a snap. Each edge on a good ruler will offer measurements in different increments, meaning inches on one edge will be divided by eighths of an inch, and the most precise edge will be broken down into 64ths of an inch.
7. Level. The level can be a frustrating tool — not because it's difficult to work with, but because it essentially measures imperfections. Nothing is as demoralizing as assembling a table to discover a slight slant or realizing the kitchen cabinets you've installed are uneven after you've fastened them. Diligently check work with a level, and hiccups will be resolved before they become major issues.