- - AGRICULTURE CORE CURRICULUM - - (CLF2000) Advanced Core Cluster: AGRICULTURAL MECHANICS (CLF2150) Unit Title: MEASUREMENTS ___________________________________________________________________________ (CLF2153) Topic: CALIPERS AND MICROMETERS Time Year(s) 3 hours 1 / 2 / 3 / 4 ___________________________________________________________________________ Topic Objectives: Upon completion of this lesson, the students will be able to: Learning Outcome #: (C-2) - Measure objects correctly, using calipers and micrometers. (C-4) - Differentiate between U.S. Customary and metric measurement units (in linear, area, and volumetric measurements). Special Material and Equipment: 0"-1," 1"-2," and 2"-3" micrometers, one 0-25 mm micrometer, inside and outside calipers, object to measure References: Cooper, Elmer L. (1987). AGRICULTURAL MECHANICS: FUNDAMENTALS AND APPLICATIONS. Albany, NY: Delmar Publishers. Phipps, Lloyd J., & Reynolds, Carl L. (1990). MECHANICS IN AGRICULTURE (4th ed.). Danville, IL: Interstate Publishers. Evaluation: Quiz by instructor. TOPIC PRESENTATION: CALIPERS AND MICROMETERS A. Calipers 1. Definitions a. Calipers are instruments used to measure the diameter or thickness of an object. b. Both inside and outside calipers are used. 1) Inside calipers measure inside distances such as the diameter of an engine cylinder. 2) Outside calipers measure the outside of round objects such as pipes. Inside Caliper Outside Caliper _ _ ( ) ( ) / \ / \ /===\<|--0 /===\<|--0 / \ / \ || / \ || | | || / \ || \ _ / ||_____________|| (_) ---------------' 2. Reading Calipers a. Many economical calipers are not direct-reading measuring tools but require a separate rule or scale to measure their settings. 1) Such calipers are used as measurement transfer tools similar to small-hole and telescoping gauges. 2) They transfer the internal measurement of an engine part to a micrometer caliper for precision reading. b. More expensive calipers have their own dimension scales. c. A slide caliper (vernier caliper) is a direct-reading measuring instrument used to make fast, accurate measurements. c. To measure very small distances, some calipers use a dial. B. Micrometer Calipers 1. Definition and Parts Identification a. The micrometer caliper is a direct-reading, precision measuring tool, which can measure to .001 inch. 1) Micrometers come in various sizes for different size objects. 2) They are very delicate and are ruined if dropped. b. To use the micrometer properly, the mechanic should be able to identify its parts. Sleeve Ratchet Stop Lock Nut | | Anvil Spindle | | __________.-------------. | | | __________________/__\ \ \ | .--._ ____/ \ \\ \ 0___1__\ 20\ \ \___ () |_) ()____) | || | ''''''''|__ | | |__| || | \_/__//__/_________/15 / / / || | Frame || = | \ /_________/ / || | | || | "------------" || \ | // / | \\ \ _______// / Thimble \\ / \\___________/ 2. Using and Reading a Micrometer a. To measure with a micrometer, place the object to be measured between the anvil and the spindle. 1) Screw the spindle until it touches the object. a) Do not screw the spindle so tight that it clamps onto the object being measured. b) Excessive pressure on the object will ruin the micrometer. 2) Read the micrometer. b. To read the English micrometer, the following steps should be followed. 1) Identify the frame size of the micrometer being used and write down the smallest number of inches that can be read. a) If the micrometer has a 1-to-2 inch frame, write down 1.000 in. b) The one inch is already given since the anvil and the spindle can be no closer than one inch. 2) List the number of tenths of an inch (hundred thousandths) indicated by the largest number visible on the sleeve. 3) Count the number of lines easily visible between the last tenths marking and the thimble then multiply the number by .025. 4) Locate the line on the thimble that matches the horizontal line on the sleeve and write its number down in thousandths of an inch. 5) Total the values in steps 1 - 4. Example: _____________ /23 ___________________/_ 22 (Framesize = 2 to 3 in) \ \ _ 21 \ 0 1 2 3 \ _____ 20 Framesize: 2.000 in |___|___|___|___|__|_ 19 Number of 10ths | ||||||||||||||||_ 18 on Sleeve: 0.300 in / | | | | | | | /_ 17 Lines on Sleeve: 0.050 in /___________________/_ 16 Thimble Reading: 0.019 in \____ 15 Total: 2.369 in \14___________ c. To read a metric micrometer, a mechanic should take the following steps: 1) Identify the frame size of the micrometer being used and write down the smallest number of millimeters that can be read. 2) List the number of millimeters indicated by the largest number visible on the sleeve. 3) Count the number of lines (above the horizontal line) easily visible between the last number on the sleeve and the thimble, and add .05 mm to the total if a line below the horizontal line is visible between the last upper millimeter line and the thimble. 4) Locate the line on the thimble that matches the horizontal line on the sleeve and multiply its number by 0.01 mm. 5) Total the values in steps 1 - 4. Example: _____________ / _________________________/_ (Framesize = 0 to 25mm) \ \ _ \ 0 5 \ ___25 Framesize: 0.00 mm | |___|___|___|___|___|__|_ Sleeve: 5.00 mm | | | | | | | | | | | | ||_ Lines on Sleeve: 0.50 mm / /_ Thimble Reading: 0.24 mm /_________________________/_ Total: 5.74 mm \___20 \_____________ _________________________________________________________ ACTIVITY: 1. Use both English and metric micrometers to measure the same objects and compare the readings. 2. Take transfer measures of a small engine cylinder with an inside caliper and measure the caliper setting with a micrometer. 3. Measure various valve stems and rods with a micrometer. _________________________________________________________ 6/27/91 OLR/tf #%&C