🔩 Materials, Fasteners and Shop Processes

Part 1 of 7 — Materials and Fasteners on the ASVAB

The other half of Shop Information

The Shop Information (SI) subtest covers "shop tools, building materials, and building and construction procedures" and "wood and metal shop practices." The Hand and Power Tools lesson covered the tools. This lesson covers everything else:

• Fasteners: which nail, screw, bolt, nut, washer or rivet fits the job
• Wood and building materials: hardwood and softwood, plywood, lumber sizes, framing, drywall, concrete, wood joints
• Metal and shop processes: kinds of metal, sheet-metal gauge, soldering, brazing, welding, sanding and finishing

Same clock as before

SI is not part of the AFQT, but your Auto and Shop results combine into the AS score, which appears in mechanical line scores such as Air Force M, Marine Corps MM, Navy MEC and ENG, and the Army's MM area (driven mostly by AS, MC and EI).

What these questions look like

• "Which fastener should be used to hang a heavy shelf on a hollow drywall wall?"
• "What does the d in 16d nail stand for?"
• "What are the actual dimensions of a $2 \times 4$?"
• "Which joining process melts the base metal?"
• "Which sandpaper grit is the finest?"

Nearly all of them reward one idea: every material and fastener has a job it was designed for.

🔩 Materials, Fasteners and Shop Processes

Part 2 of 7 — Nails and Screws

Nail types: read the head and the shank

Galvanized nails have a zinc coating that resists rust, so they are used outdoors and with treated lumber.

Penny sizes: the "d" is a length

Nail length is given in penny size, written with a d (16d is "sixteen-penny"). The number is a length code, not a price today.

From 2d to 10d, each penny adds $\frac{1}{4}$ inch: $\text{length} = 1 + \frac{1}{4}(\text{penny} - 2)$ inches. So a 7d nail is $1 + \frac{5}{4} = 2\frac{1}{4}$ inches.

Worked example. How long is a 9d nail? $1 + \frac{1}{4}(7) = 2\frac{3}{4}$ inches. Bigger penny number, longer nail.

Good practice: nail through the thinner piece into the thicker one. A common rule of thumb is a nail about three times as long as the thickness of the board you nail through. Clinching (bending over a nail point that pokes through) adds holding power, and toenailing means driving nails at an angle through the end of one board into another.

🔩 Materials, Fasteners and Shop Processes

Part 3 of 7 — Bolts, Nuts, Washers, Rivets and Threads

Bolts: clamp the parts between a head and a nut

Wall anchors (plastic sleeves, expansion anchors, molly bolts) work like toggle bolts on a smaller scale: they expand inside a drilled hole so a screw holds in drywall, masonry or concrete.

Worked example. A heavy mirror must hang on a drywall wall where there is no stud behind it. A plain screw would pull out of the soft gypsum. A toggle bolt opens its wings behind the drywall and spreads the weight over a large area.

🔩 Materials, Fasteners and Shop Processes

Part 4 of 7 — Wood, Lumber and Building Materials

Hardwood and softwood

The names describe the tree, not how hard the wood feels.

• Grain is the direction of the wood fibers. Wood splits easily along the grain and is strongest along its length.
• Wood shrinks and swells with moisture. Lumber that dries unevenly warps: it can cup, bow or twist.
• Pressure-treated lumber is soaked with chemicals that resist rot and insects, for ground contact and outdoor framing. Cedar and redwood resist rot naturally.

Engineered panels

Worked example. Why does plywood resist splitting better than a solid board of the same thickness? Its plies cross at right angles, so no single grain direction runs all the way through. A crack that starts along one layer's grain is stopped by the next layer.

🔩 Materials, Fasteners and Shop Processes

Part 5 of 7 — Metals, Welding, Soldering and Finishing

Ferrous and nonferrous metals

Ferrous metals contain iron. Most are magnetic, and plain ones rust. Nonferrous metals contain little or no iron.

• Galvanized steel is coated with zinc to keep it from rusting.
• Heat treating (recognition level): hardening heats steel and cools it quickly; tempering reheats hardened steel to make it less brittle; annealing heats metal and cools it slowly to make it softer and easier to work.

Sheet-metal gauge: bigger number, thinner metal

Sheet metal and wire are sized by gauge. The higher the gauge number, the thinner the metal. A $10$-gauge sheet is much thicker than a $22$-gauge sheet.

Worked example. A truck bed liner must resist dents; a heating duct just has to carry air. The liner gets a low gauge number (thick metal), and the duct gets a high gauge number (thin metal).

🔩 Materials, Fasteners and Shop Processes

Part 6 of 7 — Materials and Fasteners Test Strategy and Traps

Timing

Shop Information gives you $10$ questions in $6$ minutes, about $36$ seconds each, and materials and fastener questions share that clock with the tool questions.

• Fact questions ("What does d mean in 16d?") should take under 15 seconds. Answer, move on, bank the time.
• Number questions (penny length, board feet, actual lumber size, turns of a nut) need a quick line of scratch work. Write it; don't juggle it in your head.
• You must answer to move on and cannot return, so commit to your best answer. Treat every question as scored, since tryout items look the same.

A routine for fastener and material questions

1. What is being joined or built? Wood to wood, metal to metal, something to a hollow wall, something to concrete?
2. What does the joint need? Permanent or removable? Resist pulling out, resist vibration, sit flush, survive outdoors?
3. Pick the item designed for that job, not one that could merely be forced to work.

Worked example. "What is the best way to attach a heavy coat rack to a concrete block wall?" Joined to: masonry. Needs: strong, removable screws. Answer: drill with a masonry bit and use masonry anchors (expansion anchors) with screws or bolts. A toggle bolt is for hollow drywall; nails will not hold in block.

🔩 Materials, Fasteners and Shop Processes

Part 7 of 7 — Materials, Fasteners and Shop Processes Mastery Set

This set mixes fasteners, wood and building materials, metals, joining and finishing the way the Shop Information subtest does. Keep a test-day pace: about 36 seconds per question, with one line of scratch work for anything numerical.