Chapter 5 Measurement

Objectives Measure to 1/64″ (0.5 mm) with a steel rule Measure to 0.0001″ (0.002 mm) using a vernier micrometer caliper Measure to 0.001″ (0.02 mm) using vernier measuring tools Measure angles to 0°5′ using a universal vernier bevel Identify and use various types of gages found in a machine shop Use a dial indicator Use the various helper measuring tools found in a machine shop

Introduction to Measurement Metrology Science that deals with system of measurement US Conventional units of measure Inch and foot Metric units of measure International System of Units (SI) Micrometer/micron is one-millionth of a meter

Compare Different Rules Goodheart-Willcox Publisher

The Rule Steel rule Incorrectly called a scale Simplest of the measuring tools found in a shop Many different types of rules are used to make measuring quicker and more accurate

Reading the Rule (US Conventional) Graduations Lines representing the divisions Become familiar with the rule Fractional measurements are always reduced to the lowest term Goodheart-Willcox Publisher

Reading the Rule (Metric) Most are divided into millimeter or half-millimeter graduations Goodheart-Willcox Publisher

Care of the Rule Use for measurements only Avoid laying other tools on rule Wipe steel rules with oily cloth to prevent rust Clean with steel wool to keep legible Make measurements from 1″ (10 mm) line Store separately Use with care

The Micrometer Caliper Systeme Palmer basis for modern tool Micrometer caliper – also known as a “mike” Precision tool capable of measuring to 0.001″ or 0.01 mm With vernier scale will read 0.0001″ or 0.002 mm

Outside Micrometer Measures external diameters and thickness Mitutoyo/MTI Corp.

Inside Micrometer Measures internal diameter of cylinders, rings, and slots Conventional Range can be extended Jaw-type Range limited to 1″ or 25 mm Scale graduated from right to left L.S. Starrett Co.

Depth Gage Measure the depths of holes, slots, and projections Measuring range changed by using longer spindles Measurements read from right to left Goodheart-Willcox Publisher

Screw Thread Measures pitch diameter of thread A set of thread micrometers is necessary to measure the full range of thread pitches L.S. Starrett Co.

Other Micrometers Chamfer Accurately measure countersunk holes and other chamfer-type measurements Other special micrometers are available for other applications Devised to handle nonstandard measurement tasks

Reading an Inch-Based Micrometer Each revolution of thimble moves spindle 1/40″ (0.025″) Lines engraved lengthwise on sleeve divided into 40 equal parts per inch Each line equals 1/40″ (0.025″) Beveled edge of thimble divided into 25 equal parts around circumference Each division equals 1/1000″ (0.001″)

Example of Reading Mircometer Add readings from the sleeve to the thimble 4 large graduations: 4 x 0.100 = 0.400 2 small graduations: 2 x 0.025 = 0.050 8 thimble graduations: 8 x 0.001 = 0.008 Total mike reading 0.458″

Reading a Vernier Micrometer Third scale around sleeve that will furnish 1/10,000″ (0.0001″) reading Scale has 11 parallel lines that occupy same space as 10 lines on thimble Difference between spaces on sleeve and thimble is 1/10 of a thousandth of an inch First obtain thousandths reading, then the line on vernier scale that coincides

Reading a Vernier Micrometer Example Goodheart-Willcox Publisher

Reading Other Micrometers Metric micrometer Add total reading in millimeters visible on the sleeve to reading of hundredths of a millimeter Metric vernier micrometer To the regular reading in hundredths of a millimeter, add reading from vernier scale that coincides with line on thimble

Using the Micrometer Place work in position, rotate thimble until part is clamped lightly Use very light pressure when turning the thimble Rachet stop Friction thimble Locknut

Reading an Inside Micrometer Hold tool square across the diameter of work Positioned to measure across diameter on the exact center Measure by holding one end of tool in place then “feeling” for maximum possible setting by moving the other end from left to right, and in and out

Reading a Micrometer Depth Gage Graduations on measuring tool are in reverse order than an outside micrometer Graduations under the thimble must be read, not those that are exposed

Care of a Micrometer Place and remove tool carefully for measuring Keep tool clean, wiping with slightly oiled cloth to prevent rust and tarnish Avoid “springing” Check for accuracy Place in safe location Do not “twirl” the frame Never use until machine has come to complete stop

Vernier Measuring Tools Vernier caliper can make accurate measurements to 1/1000″ and 1/50 mm Design permits measurements to be made over a large range of sizes Standard sizes Graduated beam with fixed jaw or base and a vernier slide assembly

Inside and Outside Measurements Mahr Federal Inc.

Measuring Tools with a Vernier Scale Height and depth gages Used for layout work and to inspect location of features Gear tooth calipers Used to measure gear teeth and threading tools Universal vernier bevel protractors Used for layout and inspection of angles

25-Division Vernier Scale Can be read to 0.001″ Every inch section on beam is graduated into 40 equal parts 25 divisions on vernier plate occupying the same space as the 24 divisions on the beam

Reading a 25-Division Vernier Scale Goodheart-Willcox Publisher

Reading a 25-Division Vernier Scale (Cont.) The “0” line on the vernier plate is: Past the 2: 2 x 1 = 2.000 Past the 3: 3 x 0.100 = 0.300 Plus 2 graduations: 2 x 0.025 = 0.050 Plus 18 vernier scale graduations: 18 x 0.001= 0.018 Total Reading = 2.368″

50-Division Vernier Scale Can be read to 0.001″ Every second graduation equals 0.100″ and is numbered Vernier plate graduated into 50 parts, each representing 0.001″

Reading a 50-Division Vernier Scale Goodheart-Willcox Publisher

Reading a 50-Division Vernier Scale (Cont.) The “0” line on the vernier plate is: Past the 2: 2 x 1.00 = 2.000 Past the 2: 2 x 0.100 = 0.200 Plus one graduations: 1 x 0.050 = 0.050 Plus 15 vernier scale graduations: 15 x 0.001 = 0.015 Total Reading = 2.265″

Reading a Metric Vernier Scale Principles are the same as those used for US Conventional measure Reading obtained in 0.02 mm precision Goodheart-Willcox Publisher Goodheart-Willcox Publisher

Using the Vernier Caliper Do not force on the work Slide vernier assembly until jaws nearly contact section being measured, firm but not tightly Lock clamping screw Make adjustment with fine adjusting nut Lock slide on beam Make your reading

Using a Dial Caliper Direct-reading instrument Make outside, inside, and depth measurements Lock permits tool to be used for repetitive measurements Beam graduated in 0.10″ increments Caliper dial is graduated in 100 divisions

Universal Vernier Bevel Protractor Dial Is graduated into degrees Blade Can be extended in either direction and set at any angle to the stock Can be locked against the dial Base or stock

Care of Vernier Tools Wipe with soft cloth before using Wipe with oiled cloth after use and before storage Store the tool in its case Never force the tool Use magnifying glass to make readings Handle as little as possible Periodically check for accuracy

Gages Several specialized tools Gaging Statistical quality control Checking parts with various gages Shows whether piece is made within specified tolerances Statistical quality control Handle carefully, very important tools

Types of Gages Plug gage Ring gage Used to check whether hole diameters are within specified tolerances Double-ended cylindrical – go and no-go plugs Ring gage Used to check external diameters Go and no-go gages are separate units

Types of Gages (Cont.) Snap gage Thread gage Designed to check internal and/or external diameters Adjustable, nonadjustable, dial indicator Thread gage Used to check screw thread fits and tolerances Thread plug gage, thread ring gage, thread snap gage

Gage Blocks Known as Jo-blocks or Johansson blocks Precise steel measuring standards Various sets available Used to verify accuracy of master gage Used as working gages and for setting up machining work requiring great accuracy Federal accuracy grades

Working with Gage Blocks Improper handling can cause temperature changes in the block, resulting in measurement errors Handle as little as possible, use tips of fingers When wringing together, wipe blocks and carefully slide together Separate when finished Wipe with soft cloth with oil

Dial Indicators Two types Faces available in wide range of graduations Balanced Continuous Faces available in wide range of graduations Use for centering and aligning work, checking for eccentricity and inspecting work Digital electronic are available as self-contained and remote readout units

Dial Indicators (Cont.) Goodheart-Willcox Publisher

How to Use a Dial Indicator Hand on dial is actuated by a sliding plunger Place plunger lightly against the work until the hand moves Dial face turned until the “0” line coincides with the hand As work is slowly moved, the indicator hand will measure movement

Other Gaging Tools Air gage Uses air pressure to measure hold sizes and hard-to-reach shaft diameters Especially helpful when measuring deep internal bores

Operation of Air Gage Goodheart-Willcox Publisher

Other Gaging Tools (Cont.) Electronic gage Used to make extremely precise measurements Comparison gages Laser gaging Used in communication, medical, and industrial applications

Other Gaging Tools (Cont.) Optical comparator Uses magnification for inspecting parts Optical flats Precise measuring instruments that use light waves as a measuring standard Made of quartz Shape of bands indicate the accuracy of part

Optical Flat Patterns Goodheart-Willcox Publisher

Other Gaging Tools (Cont.) Thickness (feeler) gage Pieces or leaves of metal manufactured to precise thickness Ideal for measuring narrow slots, setting small gaps, determining fit between mating surfaces, and checking flatness of parts in straightening operations Screw pitch gage Used to determine pitch or number of threads per inch on a screw

Other Gaging Tools (Cont.) Fillet and radius gage Used to check concave and convex radii on corners or against shoulders Use for layout work, inspection, and template when grinding form cutting tools Drill rod Used to inspect hole alignment, location, and diameter

Helper Measuring Tools Tools which are not direct reading Calipers Makes internal and external measurements of 1/64″ (0.4 mm) Distance must be measured with steel rule Require considerable skill

Helper Measuring Tools (Cont.) Telescoping gage Intended for use with micrometer to determine internal dimensions Small hole gage Used to measure openings too small for telescoping gage