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Measurement and Measuring Instrument Mata Kuliah : Perbengkelan Dosen : Supriyanto, S.TP, M.Kom
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English System? The English system of measurement grew out of the creative way that people measured for themselves. Familiar objects and parts of the body were used as measuring devices. For example, people measured shorter distances on the ground with their feet. They measured longer distances by their paces (a "mile" was a thousand paces). They measured capacities with common household items such as cups, pails, and baskets. The word gallon comes from an old name for a pail.
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English system In the English system the fundamental units of force, length, and time are expressed in the standard units of foot, pound, and second. Unlike the metric system, the English system has no common multiplier and the subdivisions of the units of measurement bear no common relation to each other.
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Unit of Legth 12 inches = 1 foot 3 feet = 1 yard 5 ½ yards = 1 rod (16 ½ feet) 16 ounces = 1 pound 2000 pounds = 1 ton (short) 2240 pounds = 1 ton (long)
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. LINEAR EQUIVALENCE Conversion Factors English to Metric 1 inch = 1 foot = 5,280 feet = 1 mile = 2.54 centimeters (= 0.254m) 0.3048 meters (= 304.8mm) 1.34 kilometers Metric to English 1 centimeter = 1 meter = 1 kilometer = 0.3937 inches 3.280 feet (= 39.37 inches) 0.746 miles (= 3,280.84 feet)
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High accuracy, low precisionLow accuracy, high precision Akurasi dan Presisi Akurasi tingkat kedekatan pengukuran terhadap nilai yang sebenarnya Presisi ukuran kedekatan dari masing-masing hasil pengukuran yang dilakukan secara berulang.
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Measuring Systems Metric system based on the meter Most common units in the automotive industry are the centimeter and millimeter Millimeters are used to express close tolerances of engine measurements Metric system is based on divisions of ten
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Metric System Such units as length, volume, and mass are easily converted to the next higher denomination by using the simple multiplier, 10.
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Units of Length 10 millimeters = 1 centimeter 10 centimeters = 1 decimeter 10 decimeters = 1 meter 1000 meters = 1 kilometer Units of Weight 10 milligrams = 1 centigram 10 centigrams = 1 decigram 10 decigrams = 1 gram 1000 grams = 1 kilogram 1000 kilograms = 1 metric ton
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Rulers Simple tools to measure straight-line distances where tolerances are not a major factor May be USC or metric Can be made of metal, plastic, or wood Typical rulers are 6 inches or 12 inches
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Feeler Gauge (pengukur celah) Kaliper celah adalah alat ukur yang biasa digunakan untuk memeriksa jarak-jarak yang kecil atau ukuran celah-celah diantara dua permukaan. Celah yang sempit membutuhkan alat ukur tak berskala Alat ini dipakai secara luas dalam bidang pemesinan, fitting dan otomotif. Contoh penggunaannya adalah untuk menyetel pisau mesin frais atau memeriksa kelonggaran katup pada mesin.
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Tapes The most common method of obtaining simple measurements of length is by the ruler or tape A ruler may be graduated into feet, inches, or fractions thereof. Rulers and tapes used in engineering work are most frequently made of metal and the fractions of inches may be graduated to subdivisions as small as 1/64 or 1/100 of an inch. Care should be exercised in using metal rulers and tapes, especially if extreme accuracy is required. The margin of error due to expansion or contraction of the instrument from changes in temperature can be considerable.
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Jangka Sorong : Calipers Calipers. Engineers and machinists frequently use calipers to secure accurate measurements of inside and outside diameters.
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Bagian – bagian Jangka Sorong
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Cara membaca Carilah panjang benda yang diukur dengan jangka sorong jika pada skala utama dan skala nonius tampak sebagai berikut : Lingkaran Biru : 5, 3 “sekian” cm, sekian akan kita dapatkan di lingkaran “merah” Lingkaran Merah : 5 Jadi hasilnya = 5,35 cm
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Contoh Penggunaan Mengukur Blok Silinder
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Micrometer
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Micrometers Engineers frequently rely on the micrometer caliper to obtain measurements accurate to 1/1000 of an inch. This instrument is particularly useful for measuring relatively short lengths and the diameter of journals or cylinders. The common commercial micrometer consists of a frame; an anvil, or fixed measuring point; a spindle; a sleeve, or barrel; and a thimble. The spindle has threads cut 40 to the inch on the portion that fits inside the sleeve. The thimble fits over the end of the sleeve, and rotating the thimble turns the spindle.
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Bagian – Bagian Mikrometer
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Skala Lihat pada skala utama, lihat skala yang tepat ditunjuk atau tepa di sebelah kiri skala putar. Angka tersebut dalam mm Lihat angka pada skala putar yang segaris dengan garis melintang di skala utama. kalikan angka itu dengan 0,01 Tambahkan angka yang sobat dapat di angka satu dan angka 2. Selesai.
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Micrometers Micrometer Calibration In order to measure accurately, the micrometer must be accurate itself Extreme temperatures can affect accuracy
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Inside Micrometers
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Telescopic Gauges Used with outside micrometers to measure inside diameters Various lengths and T-shaped Extensions are spring-loaded Leg has a rotatable handle to lock extensions in place Once gauge is removed, measure with outside micrometer
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Telescoping gages
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Depth Micrometers
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Small Hole Gauges To measure small holes Gauge is straight with a screw handle on one end and a split ball on other Handle is turned to expand ball Removed and measured with a micrometer
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Small Hole Gauges
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Pressure and Vacuum Measurements Pressure Gauges Measure amount of pressure applied to a closed, sealed system Fitted into pressure line with appropriate fittings
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Summary Most common measurement system in United States is the United States Customary or the English system Base USC measurement is the inch Base metric measurement is the meter Use proper measuring tool for the job
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