ASVAB Shop Information — Measuring Tools and Fasteners

Technically, a BOLT is designed to be tightened by a nut on the opposite side — it clamps two parts together through holes. A SCREW is designed to thread directly into a material (wood, metal, plastic) without a separate nut. In practical shop use, these definitions blur — 'machine screw' often refers to what is technically a bolt when used with a nut. The key concept: bolt + nut = clamping joint; screw = threads into material directly.

A level (spirit level or bubble level) contains a sealed vial of liquid with a trapped air bubble. When the surface being measured is exactly horizontal, the bubble centers between the two reference lines. Various types: torpedo level (small, used in tight spaces); 4-foot level (standard for construction); laser level (projects a horizontal laser line across a room). The plumb bob checks vertical alignment (plumb), not horizontal.

A NAIL is driven straight in (usually with a HAMMER) and holds by FRICTION; a SCREW has THREADS, is turned in (with a screwdriver/drill), grips more SECURELY (the threads bite into the material), and can be easily removed. ASVAB Shop Information tests fasteners. Screws provide stronger, more reliable holding power and can be unscrewed; nails are faster to install but hold less securely and are harder to remove cleanly. Knowing the nail-vs-screw distinction (friction vs threads, holding strength, removability) is commonly tested.

A CALIPER (vernier, dial, or digital) provides PRECISE measurement of small dimensions — including outside dimensions (like a bolt's diameter), inside dimensions, and depth — often to thousandths of an inch or hundredths of a millimeter. ASVAB Shop Information tests measuring tools. A TAPE MEASURE or YARDSTICK is for larger, less precise measurements. A MICROMETER is even more precise for very small measurements. Calipers are essential for machining and precision work. Knowing the caliper measures small dimensions precisely is commonly tested.

On a standard tape measure, the LONGEST marking between the whole-inch numbers usually represents the HALF INCH (1/2). ASVAB Shop Information tests reading measurements. The markings are graduated by length: the inch marks are longest (with numbers); the HALF-inch mark is the next longest; then QUARTER-inch marks; then EIGHTHS; then SIXTEENTHS (the shortest, most numerous marks). The longer the line, the larger the fraction. Being able to read fractional measurements on a tape measure (half, quarter, eighth, sixteenth) is commonly tested.

A flat washer spreads the clamping force of a bolt or nut over a larger area, which distributes the load and protects the surface from damage and from the fastener digging in. A lock washer (split or toothed) adds tension or bite that helps keep the nut or bolt from vibrating loose. Washers are simple but important fasteners-system components. Choosing and placing washers correctly improves the strength and durability of a bolted joint. Understanding the role of washers — load distribution and, for lock washers, resisting loosening — is part of the fasteners topic.

A square (such as a carpenter's square, try square, or combination square) is used to check and mark right angles, confirming that a corner or joint is a true 90 degrees. A level checks whether a surface is horizontal (level) or vertical (plumb); a tape measure measures length; and a plumb bob uses gravity to establish a vertical line. Matching the measuring/marking tool to the task — a square for checking 90-degree angles — is standard Shop Information content. Accurate squaring is essential for joints, framing, and layout work.

A level indicates whether a surface is truly horizontal ('level') or truly vertical ('plumb'). It works using a sealed vial containing liquid and an air bubble; when the bubble sits centered between the marked lines, the surface is level or plumb. Levels are essential for hanging shelves, installing fixtures, laying tile, and framing so that surfaces are straight and even. A tape measure handles length, and a square checks 90-degree angles. Knowing the level's job — checking for horizontal and vertical alignment — is a common measuring-tool topic on the Shop subtest.

A nail is a straight fastener driven in with a hammer; it goes in quickly and offers good resistance to shear (sideways) forces, making it common in framing. A screw has threads and is turned in with a screwdriver or drill; the threads grip the material and give much greater holding (pull-out) power and the ability to be removed and reused. Screws take longer to install but hold better in applications subject to pulling forces. Choosing nails for speed and shear strength versus screws for holding power is a practical fasteners concept on the Shop subtest.