Precision Measuring
Precision Measuring
• Precision – How close together or repeatable
the results are
– A precise measuring instrument will give nearly the
same result each time that it is used.
• Accuracy – How close a measurement is to the
accepted value
– For example, a balance loaded with a standard 100 g
weight should read 100 g. If it doesn’t, then the
balance is inaccurate.
Precision measuring tools are
needed for accuracy
Tools for Precision Measuring
Steel Rule
Micrometer
Tools for Precision Measuring
Digital Caliper
Dial Caliper
Reading a Dial Caliper
{
The dial caliper is a precision measuring
instrument.
The caliper’s blade graduations are
in inches and tenths (.1) of an inch.
inch
Each inch is broken into
ten, for .1 of an inch.
Reading a Dial Caliper
The caliper’s dial graduations are
in thousandths (.001) of an inch.
The reference edge
keeps track of larger
increments; the dial is for
smaller increments.
One full revolution of the pointer
on the dial equals
one hundred thousandths (.100).
Dial Caliper Parts
Inside Measuring Faces
Dial
Clamp Screw
Blade
Fine Adjustment Screw
Dial Adjustment Screw
Outside Measuring Faces
Reading a Dial Caliper
Step 1 Read inches from the blade
2
1 in. – 6 in.
Reading a Dial Caliper
Step 2 Read tenths of an inch from
the blade
2
1 in. – 6 in.
3
.0 in. -.9 in.
Reading a Dial Caliper
Step 3 Read thousandths of an inch from
the dial
2
3
2 8
1 in. – 6 in. .0 in.- .9 in. .001 in.- .099 in.
Dial Calipers Measure
• Thickness or Outside Diameter
Dial Calipers Measure
• Thickness or Outside Diameter
• Inside Diameter or Space Width
Dial Calipers Measure
• Thickness or Outside Diameter
• Inside Diameter or Space Width
• Depth
Dial Calipers Measure
•
•
•
•
Thickness or Outside Diameter
Inside Diameter or Space Width
Depth
Step Distance
Discussion Questions
• List measurement tools…
Steel Rule
Dial Caliper
Tape Measure
Meter Stick
• Explain which one of the tools listed
would be best to use and why when
measuring:
– The hallway
– Engineering Notebook
– Pencil diameter
– Height of your desk
Image Resources
Microsoft, Inc. (2008). Clip Art. Retrieved October 10, 2008, from
http://office.microsoft.com/en-us/clipart/default.aspx
Wikimedia commons (2008). Retrieved October 15, 2008, from
http://commons.wikimedia.org/wiki/ImageCaliper