TOOLS : Getting a Handle on Measuring Devices

Projects built “by guess and by gosh” usually look that way and result in a nightmare of fitting and adjusting.

Here are some basic measuring tools and some hints for using them expertly:

Retractable measuring tape. Made of spring steel that rolls into a metal case, it is the most important all-around measuring tool. A useful length is 25 feet. A hook on the end of the tape catches the work piece, making long measurements a one-person job. When reading a measuring tape, twist it slightly so the markings touch the project. View the tape at a right angle to obtain an accurate reading.

Folding carpenter’s rule. Used where a rigid measuring tool is needed. Folding rules are made of wood and usually have brass hinges. Sections are 12 inches long; when unfolded, standard rules measure six or eight feet in length. The most useful style has a sliding extension for making inside measurements.

Steel rule. Neither of the above tools afford a reliable straightedge for drawing lines. For that, you can use a rigid steel rule. These come in lengths ranging from 12 to 48 inches, or you can use one of the tools favored instead by most builders and cabinetmakers--either a combination square or a carpenter’s square. A carpenter’s level also works as a straightedge.

Combination square. Consists of a metal ruler, or blade, usually 12 inches long and a shorter, sliding handle that attaches to it precisely at a right angle. Most models also have an edge that forms a 45-degree angle with the blade (useful for dividing right angles in half when fitting molding), a small built-in level, and a removable scribing tool for marking. Besides functioning as a straightedge, a combination square can be used for measuring, checking the squareness of corners, leveling horizontal surfaces, and as a depth gauge for cutouts like those needed for inlaying door and cabinet hardware.

Carpenter’s square. A large right-angled strip of metal designed for marking lumber used in house construction. Standard models have a wide 24-inch blade and a narrower six-inch blade, called the tongue.

Carpenter’s level. The most useful are two to four feet long and have three or more bubble vials to enable checking vertical as well as horizontal surfaces. As with a measuring tape, when using a level, be sure to view it at a right angle to obtain an accurate reading. Even a slight error can be significant on long surfaces.

Chalk line. For marking straight lines longer than is practical with a straightedge, use a chalk line. This is a small metal case containing chalk and 50 to 100 feet of string on a reel. Pull the string from the case, hold it taut between two points on a surface, and snap it to leave a chalk mark as a guide. The tool also functions as a plumb bob to establish a vertical line. Hang the string so the case is just above the ground; when the case stops swinging, the line is vertical.

Sliding T-bevel. Used for setting, checking and transferring angles. This adjustable gauge consists of a straight-sided wood or metal handle with a slotted metal blade connected to it at one end. The blade pivots to form any angle with the handle and locks in place. Set the angle from an existing one or match it to markings on a protractor.

Profile gauge. Records the shape of an irregular design--for instance, the contours of molding--for tracing onto a template or piece of stock. The tool has a row of movable metal or plastic pins that assume the profile of whatever object they are pressed against.