Page 279 - Mechanical Engineer's Data Handbook

R Engineering measurements

7. I Length measurement

7.1.1 Engineer’s rule 7. I .2 Feeler gauge (thickness gauge)

These are made from hardened and tempered steel These consist of a number of thin blades of spring steel
marked off with high accuracy in lengths from about of exact, various thicknesses. They are used for
10-3Ocm with folding rules up to 60cm. They are used measuring small gaps between parts.
for marking off, setting callipers and dividers, etc.
When used directly, the accuracy is &0.25mm, and
when used to set a scribing block the accuracy is
f 0.125 mm.

I

Small engineer’s rule
Thidcnm gauge

7. I .3 Micrometers

Micrometers are used for the measurement of internal
and external dimensions, particularly of cylindrical
shape. Measurement is based on the advance of a
Folding rule precision screw. The ‘outside micrometer’ is made in a
variety of sizes, the most popular being 25mm in
0.01-mm steps. It has a fixed ‘barrel’ graduated in

Outside micrometer