Tools / Measure and mark

Measure and mark

Instruments that establish length, angle, level, plumb and flatness, and the tools that transfer a measurement to the work: rules and tapes, squares, levels, gauges, calipers, micrometers and scribers.

13 tools written

• Chalk lineA cord coated with powdered chalk, kept in a case or on a reel, that is stretched taut between two points and snapped against a surface to leave a straight line. It marks lines longer than a rule or a square can reach.
• Combination squareA graduated steel blade that slides in a grooved head and can be locked at any point, the head having a face at 90 degrees and a face at 45 degrees to the blade. The head commonly carries a scriber and a spirit level, and other heads fit the same blade.
• Dial indicatorA comparison instrument in which the small movement of a contact point is multiplied through a gear or lever train and shown by a pointer on a dial. It reads how far a surface departs from a set zero, and is used to check runout, flatness, height and alignment.
• Feeler gaugeA set of thin steel blades, each ground to a marked thickness, that is slid into a narrow gap to find out whether the gap is wider or narrower than the blade. It checks small clearances such as valve tappets, spark gaps, ignition points and bearing and gear clearances.
• Folding ruleA graduated rule made of several hinged sections that fold together for carrying and open into a straight line for measuring. Hinged rules survive from the Roman period; the modern spring-jointed form that locks rigid when open is a German design adopted by Stanley in 1898.
• Framing squareA flat L of steel (now also aluminum), commonly with a 24-inch blade and a 16-inch tongue, graduated on both faces and stamped with tables for rafters, braces and board measure. It is the framer’s tool for marking right angles and laying out roof cuts.
• MicrometerA C-shaped frame with a fixed anvil and a spindle that is advanced by a precision screw, read from graduations on a fixed sleeve and a rotating thimble. A typical inch instrument reads to a thousandth of an inch directly and a vernier on the sleeve extends it to a ten-thousandth.
• Plumb bobA weight, pointed at its lower end, hung from a cord so that gravity draws the cord into the vertical. It transfers a point directly above or below another and checks that posts and walls stand upright.
• Speed squareA right-isosceles triangle of aluminum with a raised fence along one short side and scales for degrees and for rafter pitch along the others, used to lay out square, miter and rafter cuts and to guide a saw. Swanson says Albert J. Swanson, a Chicago carpenter, invented it in 1925.
• Spirit levelA straight stock carrying one or more sealed glass or plastic vials, each nearly filled with liquid so that a bubble rests at the center of the vial when the stock is level or plumb. It replaced the plumb-line level as the builder’s standard check of horizontal and vertical.
• Steel ruleA thin, flat, rigid or semi-flexible bar of steel with graduations cut or etched along its edges, used to measure short lengths and to set calipers and dividers. Brown & Sharpe says it began making steel rules in 1850.
• Tape measureA graduated ribbon of steel (earlier linen or other fabric) coiled into a case, drawn out to measure and wound back by a spring or by hand. The pocket version with a curved steel blade and a lock is the standard length measure of the building trades.
• Vernier caliperA graduated beam with a fixed jaw and a sliding jaw that carries a short second scale, the vernier, which lets the user read between the divisions of the beam. One instrument measures outside dimensions, inside dimensions and, with a depth rod, depths.