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
Steel Rule
Micrometer
Tools for Precision Measuring
Digital Caliper
Dial Caliper
Tools for Precision Measuring
The dial caliper is a precision measuring instrument.
The caliper’s blade graduations arein inches and tenths (.1) of an inch.
Reading a Dial Caliper
inch
Each inch is broken into ten, for .1 of an inch.
{
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.
Reading a Dial Caliper
One full revolution of the pointer on the dial equalsone hundred thousandths (.100).
Blade
Inside Measuring Faces
Outside Measuring Faces
Dial
Fine Adjustment Screw
Dial Clamp Screw
Clamp Screw
Dial Caliper Parts
Step 1 Read inches from the blade
1 in. – 6 in.
2
Reading a Dial Caliper
Step 2 Read tenths of an inch from the blade
Reading a Dial Caliper
1 in. – 6 in. .0 in. -.9 in.
2 3
Step 3 Read thousandths of an inch from the dial
Reading a Dial Caliper
1 in. – 6 in. .0 in.- .9 in. .001 in.- .099 in.
2 3 2 8
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 Tape Measure
Dial Caliper 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