ASVAB — All Questions

Steady blue-gray smoke from the tailpipe of a fully warmed engine most likely means that

• a.engine oil is being burned in the cylinders.✓
• b.coolant is leaking past the head gasket.
• c.the fuel mixture is far too rich.
• d.the air filter is badly clogged.

Oil slipping past worn rings or hardened valve stem seals burns along with the fuel and tints the smoke blue. Coolant is tempting because it also smokes, but burning coolant gives white sweet-smelling steam and a rich mixture gives black soot; the color separates the three.

Before drilling a hole in a steel plate, the layout mark is tapped with a center punch in order to

• a.leave a burr for the countersink to remove.
• b.harden the steel around the rim of the hole.
• c.keep the drill bit from wandering off line.✓
• d.clear the chips out ahead of the drill bit.

The chisel edge at the tip of a twist drill skates across smooth metal, so a punched dimple gives that point something to sit down in and the hole starts exactly on the layout mark. Chip clearing is tempting as a real drilling concern, but the flutes handle that.

A machine screw differs from a wood screw in that a machine screw

• a.has a smooth shank below a threaded point.
• b.runs one diameter, for a nut or tapped hole.✓
• c.has a tapered shank that cuts its own thread.
• d.carries a coarse thread meant for soft wood.

A machine screw is the same diameter its whole length and its thread is a standard size, so it mates with a nut or a threaded hole in metal. A tapered shank is tempting because that is the shape most people picture for a screw, but tapering is what lets a wood screw form its own thread.

The most direct way to check whether the sawn end of a board is square to its edge is with a

• a.marking gauge.
• b.bevel gauge.
• c.spirit level.
• d.try square.✓

A try square is a fixed 90 degree blade set into a stock: hold the stock tight on the edge, slide the blade against the end, and any light under the blade shows the cut is out of square. A sliding bevel gauge is tempting because it looks similar, but its blade pivots to copy any angle.

Which fastener is chosen when only one side of the joint can be reached?

• a.A hex head lag screw
• b.A blind pop rivet✓
• c.A bolt and a locknut
• d.A square head bolt

A pop rivet is set by a tool that pulls a mandrel through it, swelling the far end into a head against the back of the work, so nobody has to be behind the panel. A bolt and nut is tempting because it clamps harder, but somebody has to reach around to hold that nut still.

A split lock washer is placed under a nut in order to

• a.keep the nut from backing off from vibration.✓
• b.seal the joint against water getting under it.
• c.keep the bolt from turning inside its hole.
• d.spread the clamping load over a wider area.

The washer is split and sprung open, so tightening flattens it and drives its two sharp ends into the nut face and the work, adding friction that resists loosening on machinery that shakes. Spreading the load is tempting, but that is the job of a plain flat washer.

Radial lines stamped on the head of a bolt tell you its

• a.thread pitch in inches.
• b.overall length in inches.
• c.plating and finish type.
• d.tensile strength grade.✓

Head marks are a strength code: three radial lines mean SAE grade 5, six lines mean grade 8, and a bare head means grade 2, so more lines take more torque and more load. Thread pitch is tempting because it is also standardized data, but pitch is called out in the part size, not on the head.

A hacksaw blade used on thin sheet metal should have

• a.few coarse teeth so the chips clear faster.
• b.many fine teeth so several stay in the cut.✓
• c.long teeth so the stroke removes more metal.
• d.a wavy set so the kerf comes out narrower.

The working rule is at least three teeth touching the work at all times. A coarse blade drops one lone tooth into thin stock, and that tooth catches and strips or snaps the blade. Coarse teeth are tempting because they really do cut faster, but that holds for thick bar, not sheet.

Boards are being glued edge to edge into a wide tabletop. The right clamp for the job is a

• a.metal spring clamp.
• b.locking C clamp.
• c.wooden handscrews.
• d.pipe or bar clamp.✓

An edge glue-up needs even pressure pulled across the whole width of the panel, and a pipe or bar clamp spans several feet and draws the joints shut with a screw. A C clamp is tempting because it squeezes hard, but its throat is inches deep and it can only pinch near an edge.

Soldering differs from welding in that soldering

• a.joins the parts by melting their edges together.
• b.needs far more heat than welding does to work.
• c.makes a joint stronger than the metal it joins.
• d.joins the parts without melting the base metal.✓

In soldering only the filler alloy melts; it wets the heated surfaces and grips them as it freezes, which is why a solder joint carries far less load than the parts themselves. Melting the edges together is tempting because it sounds like joining metal, but that describes welding.

A dovetail joint is used at the corners of a drawer mainly because it

• a.can be cut faster than a butt joint.
• b.uses less wood than a butt joint does.
• c.resists being pulled straight apart.✓
• d.hides the end grain along both faces.

The flaring pins and tails of a dovetail interlock like wedges, so pulling on the drawer front cannot draw the joint open and only the other directions rely on glue. Speed is tempting, but a dovetail is slower to cut than a butt joint; that time is the price paid for the strength.

Wood stain and polyurethane varnish differ in that stain

• a.colors the wood but gives little protection.✓
• b.raises the grain so it can be cut back off.
• c.fills open grain before the first sanding.
• d.builds a hard film that resists water well.

Stain is pigment or dye carried in a thin liquid: it soaks into the fibers to change the color and the excess is wiped away, so almost nothing is left standing on the surface. A tough film is tempting because both go on with a brush, but the film is the varnish coat that follows.

An adjustable wrench should be turned so that the pulling force bears against

• a.the fixed jaw.✓
• b.the worm screw.
• c.the movable jaw.
• d.the jaw opening.

The movable jaw rides on a worm screw and is the weaker half of the tool, so the handle is pulled toward the open side of the jaws and the load lands on the solid fixed jaw. Pulling the other way pries the movable jaw wider, the wrench slips, and the nut corners round off.