Precision Measuring and Layout Flashcards
6 cards from real Millwright Certification practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 6 Precision Measuring and Layout flashcards as text
What is the purpose of gauge blocks (also known as Jo blocks) in precision measurement?
Answer: To provide exact known dimensions for calibrating instruments and setting comparative measuring devices
Gauge blocks are precision-lapped steel or ceramic blocks manufactured to extremely tight tolerances that serve as primary length standards for calibrating measuring instruments and setting comparative gauges.
How does a laser alignment system provide more accurate shaft alignment than dial indicator methods?
Answer: Laser systems eliminate reading errors, bracket sag, and provide real-time graphical adjustment guidance
Laser alignment systems eliminate human reading errors and mechanical sag, compensate for thermal growth, and display real-time correction values with graphical guidance, achieving alignment accuracy superior to dial indicator methods.
What is the correct procedure for zeroing a dial indicator before taking measurements?
Answer: Place the indicator on a known reference surface, ensure the contact is preloaded at least half a revolution, then rotate the bezel to zero
Proper zeroing requires placing the indicator plunger on a reference surface with adequate preload (at least 0.5 mm compression), ensuring the plunger moves freely, then rotating the outer bezel until the needle aligns with zero.
What is the advantage of using an inside micrometer over a telescoping gauge for measuring bore diameters?
Answer: Inside micrometers provide a direct reading without needing a transfer measurement, reducing the chance of error
Inside micrometers read the dimension directly on their own scale, eliminating the transfer step (and associated error) required when using a telescoping gauge that must be separately measured with an outside micrometer.
When performing layout work, why is a scriber preferred over a pencil for marking metal surfaces?
Answer: A scriber produces a fine, permanent, precise line that does not rub off during machining or fitting operations
Scribers produce a thin, precisely located, permanent line scratched into the metal surface that remains visible during machining, filing, and fitting, unlike pencil marks that smudge and rub off.
What is a sine bar used for in precision measurement?
Answer: Setting up or measuring precise angles using gauge blocks and the trigonometric sine function
A sine bar uses gauge blocks stacked under one roller to create a precise angle based on the formula: sin(angle) = gauge block height / center distance between rollers, enabling accurate angular measurement and setup.