Precision Measuring Tools

What sizes do steel scales come in?

6″ and 12

When should you replace a steel scale?

If the end is damaged or not square.

What graduations are found on steel scales?

Fractions (1/8, 1/16, 1/32, 1/64) and decimals (0.01, 0.02).

What are dividers used for?

Transferring dimensions and layout work (no direct measurement).

Name the three types of calipers.

Inside, outside, hermaphrodite.

What are calipers used for?

Measuring and comparing sizes.

What is the range for telescoping gauges?

5/16″-6″.

What are the steps to use a telescoping gauge?

Compress → insert at angle → expand to contact → lock square → remove and measure with micrometer.

How are small hole gauges used?

Expand ball to slight drag → remove → measure with micrometer.

What do thickness gauges measure?

Clearances, twist, or warp.

How accurate are thickness (feeler) gauges?

To 0.0001″.

What do radius gauges measure?

The radius of a part by comparing to a standard.

What do thread gauges measure?

Thread pitch (TPI or mm/thread), exact match required.

What dimensions can Vernier calipers measure?

Outside, inside, depth, step (some models).

Why are Vernier calipers faster than micrometers?

They cover more types of measurements with a larger range.

How do you read an English Vernier caliper?

Read bar scale (0.025″ increments) + aligned Vernier line (0.001″).

How do you read a metric Vernier caliper?

Bar = mm, Vernier divisions = 0.02 mm → add aligned value.

What are the five main micrometer parts?

Frame, anvil, spindle, sleeve, thimble.

Screw pitch of a micrometer?

40 TPI.

What is the sleeve graduation value?

0.100″ increments, split into 0.025″.

What is the thimble graduation value?

25 divisions = 0.001″ each (1 rev = 0.025″).

How does a Vernier micrometer increase accuracy?

Adds 0.0001″ (ten-thousandths).

What's the correct "feel" when using a micrometer?

Slight friction on the part.

How do you measure tube wall thickness with a micrometer?

Use a pin of known diameter inside tube, measure over pin, subtract pin diameter.

What micrometer is used for grooves/recesses?

Depth micrometer (reads backwards).

What does an inside micrometer kit include?

Head, rods (1″ each), and 0.5″ spacer.

How do you calibrate a micrometer?

Use a gauge block, adjust zero with spanner, account for temperature.

What do dial indicators measure?

Movement, runout, roundness, concentricity.

How do you set up a dial indicator?

Apply preload, zero bezel, rotate part, record max/min.

What is TIR?

Total Indicator Reading = max - min.

What does a torque wrench measure?

Torque = force × arm length.

What are the three torque wrench types?

Deflecting-beam, torsion bar, toggle/click.

What is the adapter correction formula?

TA = TW × (L + A)/L.

When is no correction needed?

When adapter (crow's foot) is at 90°.

Conversions: in-lb to ft-lb?

Divide by 12.

Conversions: in-oz to in-lb?

Divide by 16.

What happens if torque is too low?

Movement, hole elongation, thread wear.

What happens if torque is too high?

Crushed material, stripped threads → replace fastener.

What is drag torque?

Torque needed to run down a self-locking nut; must be added to final torque.

What's the correct method for multiple fasteners?

Torque in sequence and in stages (e.g., 50 → 75 → 85 lbs).