Measurement Tools Flashcards

A metric vernier caliper main scale reads 23 mm and the vernier scale 11th line aligns. With a least count of 0.02 mm, what is the measurement?

Answer: 23.22 mm

11th vernier line × 0.02 mm = 0.22 mm added to 23 mm gives 23.22 mm.

What is the primary advantage of digital calipers over vernier calipers?

Answer: Elimination of parallax error and easier reading

Digital calipers eliminate the need to interpret vernier scales, removing parallax errors and reducing reading mistakes.

When measuring with an outside micrometer, what is 'feel' or 'touch' referring to?

Answer: The correct amount of measuring pressure applied through the thimble or ratchet

Proper measuring feel means applying consistent, light pressure — typically using the ratchet stop to prevent over-tightening.

A thickness gauge (feeler gauge) set contains blades of 0.001" to 0.025". To measure a gap of approximately 0.018", which combination is most practical?

Answer: Stack a 0.015" + 0.005" blade

0.015" + 0.005" = 0.020" — but if 0.018" exists, that's best; otherwise stacking 0.010" + 0.008" = 0.018" is most accurate.

In electrical work, a clamp meter measures current by:

Answer: Sensing the magnetic field produced by current flowing through a conductor

A clamp meter uses a current transformer (Hall effect or inductive clamp) to sense the magnetic field around a current-carrying conductor.

What is the purpose of gauge blocks (Jo blocks) in a machine shop?

Answer: To serve as precision length standards for calibrating and setting other measuring tools

Gauge blocks are precision ground and lapped to exact sizes, used as reference standards for calibrating measuring instruments.

Which tool is used to measure the pitch diameter of an external thread?

Answer: Thread micrometer with V-anvil and cone spindle

A thread micrometer has a V-shaped anvil and a conical spindle that contact the thread flanks at the pitch diameter.