Difference between revisions of "Read a Caliper"
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Calipers are measuring tools used to precisely determine the width of a gap or object, much more accurately than a tape measure or ruler. Besides digital models, which uses an electronic screen, a caliper can display the measurement on a pair of scales (vernier caliper) or on a scale and dial gauge (dial caliper). | Calipers are measuring tools used to precisely determine the width of a gap or object, much more accurately than a tape measure or ruler. Besides digital models, which uses an electronic screen, a caliper can display the measurement on a pair of scales (vernier caliper) or on a scale and dial gauge (dial caliper). | ||
| − | [[Category:Measuring and Marking Tools]] | + | [[Category: Measuring and Marking Tools]] |
== Steps == | == Steps == | ||
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#Calculate a positive zero error. If the sliding scale's 0 is to the '''right''' of the fixed scale's 0, read the measurement on the fixed scale that lines up with the sliding scale's 0. This is a positive zero error, so write this down with a + sign. | #Calculate a positive zero error. If the sliding scale's 0 is to the '''right''' of the fixed scale's 0, read the measurement on the fixed scale that lines up with the sliding scale's 0. This is a positive zero error, so write this down with a + sign. | ||
#*'''For example''', if the sliding scale's 0 is at 0.9mm on the fixed scale, write down "zero error: +0.9 mm." | #*'''For example''', if the sliding scale's 0 is at 0.9mm on the fixed scale, write down "zero error: +0.9 mm." | ||
| − | #Calculate a negative zero error. If the sliding scale's 0 is to the '''left''' of the fixed scale's 0, take the following steps:<ref>http://www.exploriments.com/Physics/Vernier_Caliper/Vernier_caliper_:_Negative_Zero_Error_/legi5MuHWL0MiHjC~giwMQ==</ref> | + | #Calculate a negative zero error. If the sliding scale's 0 is to the '''left''' of the fixed scale's 0, take the following steps:<ref name="rf1">http://www.exploriments.com/Physics/Vernier_Caliper/Vernier_caliper_:_Negative_Zero_Error_/legi5MuHWL0MiHjC~giwMQ==</ref> |
#*With jaws closed, look for a mark on the sliding scale that lines up exactly with a value on the fixed scale | #*With jaws closed, look for a mark on the sliding scale that lines up exactly with a value on the fixed scale | ||
#*Move the sliding scale so that mark lines up with the next highest value. Repeat until the sliding scale 0 is to the right of the fixed scale 0. Note the amount of distance moved. | #*Move the sliding scale so that mark lines up with the next highest value. Repeat until the sliding scale 0 is to the right of the fixed scale 0. Note the amount of distance moved. | ||
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#*Subtract the amount of distance moved from the value you just read. Write down this zero error, including the negative sign. | #*Subtract the amount of distance moved from the value you just read. Write down this zero error, including the negative sign. | ||
#*'''For example''', the 7 on the sliding scale lines up with the 5mm mark on the fixed scale. Move the sliding scale until it is further right than the fixed scale, then line up the 7 with the next fixed-scale mark: 7mm. Note that you moved a distance of 7 - 5 = <font color="blue">2mm</font>. The sliding scale's 0 is now located at the <font color="orange">0.7mm</font> mark. The zero error is equal to <font color="orange">0.7mm</font> - <font color="blue">2mm</font> = -1.3mm. | #*'''For example''', the 7 on the sliding scale lines up with the 5mm mark on the fixed scale. Move the sliding scale until it is further right than the fixed scale, then line up the 7 with the next fixed-scale mark: 7mm. Note that you moved a distance of 7 - 5 = <font color="blue">2mm</font>. The sliding scale's 0 is now located at the <font color="orange">0.7mm</font> mark. The zero error is equal to <font color="orange">0.7mm</font> - <font color="blue">2mm</font> = -1.3mm. | ||
| − | #Subtract the zero error from all measurements. Any time you take a measurement, subtract your zero error from the result to get the actual dimensions of the object. Don't forget to take the sign of the zero error (+ or -) into account.<ref>http://www.miniphysics.com/how-to-read-a-vernier-caliper.html</ref> | + | #Subtract the zero error from all measurements. Any time you take a measurement, subtract your zero error from the result to get the actual dimensions of the object. Don't forget to take the sign of the zero error (+ or -) into account.<ref name="rf2">http://www.miniphysics.com/how-to-read-a-vernier-caliper.html</ref> |
#*For example, if your zero error is +0.9mm, and you take a measurement that reads 5.52mm, the actual value is 5.52 - 0.9 = 4.62mm. | #*For example, if your zero error is +0.9mm, and you take a measurement that reads 5.52mm, the actual value is 5.52 - 0.9 = 4.62mm. | ||
#*For example, if your zero error is -1.3mm, and you take a measurement that reads 3.20mm, the actual value is 3.20 - (-1.3) = 3.20 + 1.3 = 4.50mm. | #*For example, if your zero error is -1.3mm, and you take a measurement that reads 3.20mm, the actual value is 3.20 - (-1.3) = 3.20 + 1.3 = 4.50mm. | ||
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#Adjust the jaws to take a measurement. Clamp the large, flat jaws around an object to measure an outside dimension. Insert the smaller, curved jaws into an object and expand them outward to measure the interior dimension. Tighten the locking screw to keep the scale in place. | #Adjust the jaws to take a measurement. Clamp the large, flat jaws around an object to measure an outside dimension. Insert the smaller, curved jaws into an object and expand them outward to measure the interior dimension. Tighten the locking screw to keep the scale in place. | ||
#*Slide the scale to open or close the jaws. If your caliper has a fine adjustment screw, you can use this to make more precise adjustments. | #*Slide the scale to open or close the jaws. If your caliper has a fine adjustment screw, you can use this to make more precise adjustments. | ||
| − | #Read the fixed scale value. Once you have the caliper jaws in the right position, look at the fixed scale, engraved onto the body of the caliper. Typically there is an imperial and a metric fixed scale; either one will work. Take these steps to find the first couple digits of your measurement:<ref>http://www.tresnainstrument.com/how_to_read_a_standard_caliper.html</ref> | + | #Read the fixed scale value. Once you have the caliper jaws in the right position, look at the fixed scale, engraved onto the body of the caliper. Typically there is an imperial and a metric fixed scale; either one will work. Take these steps to find the first couple digits of your measurement:<ref name="rf3">http://www.tresnainstrument.com/how_to_read_a_standard_caliper.html</ref> |
#*Find the 0 value on the smaller, sliding scale, next to the fixed scale you are using. | #*Find the 0 value on the smaller, sliding scale, next to the fixed scale you are using. | ||
#*On the fixed scale, find the nearest mark to the ''left'' of that 0, or exactly on it. | #*On the fixed scale, find the nearest mark to the ''left'' of that 0, or exactly on it. | ||
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<span id="dial"></span> | <span id="dial"></span> | ||
===Reading a Dial Caliper=== | ===Reading a Dial Caliper=== | ||
| − | #Check for a zero error. Close the jaws completely. If the needle on the dial doesn't point to zero, rotate the dial with your fingers, until the zero is beneath the needle.<ref>https://www.youtube.com/watch?v=_7-6ALptqQQ</ref> You may need to loosen a screw at the top or base of the dial face before you can do this.<ref>http://www.nefsc.noaa.gov/fsb/memos/2013/dial_calipers_revised.pdf</ref> If so, remember to tighten the screws again after you've made the adjustment. | + | #Check for a zero error. Close the jaws completely. If the needle on the dial doesn't point to zero, rotate the dial with your fingers, until the zero is beneath the needle.<ref name="rf4">https://www.youtube.com/watch?v=_7-6ALptqQQ</ref> You may need to loosen a screw at the top or base of the dial face before you can do this.<ref name="rf5">http://www.nefsc.noaa.gov/fsb/memos/2013/dial_calipers_revised.pdf</ref> If so, remember to tighten the screws again after you've made the adjustment. |
#Take the measurement. Close the larger, flat jaws around an object to measure the outside diameter or width, or insert the smaller, curved jaws into an object and expand to measure the interior diameter or width. | #Take the measurement. Close the larger, flat jaws around an object to measure the outside diameter or width, or insert the smaller, curved jaws into an object and expand to measure the interior diameter or width. | ||
#Read the scale value. The scale engraved on your caliper can be read just as you would a regular ruler. Find the value at the inner edge of your caliper's jaws. | #Read the scale value. The scale engraved on your caliper can be read just as you would a regular ruler. Find the value at the inner edge of your caliper's jaws. | ||
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== Tips == | == Tips == | ||
*Consider purchasing a digital caliper if you are having trouble reading a vernier or dial caliper. | *Consider purchasing a digital caliper if you are having trouble reading a vernier or dial caliper. | ||
| − | *To reduce the risk of errors, store your calipers with the jaws slightly apart.<ref | + | *To reduce the risk of errors, store your calipers with the jaws slightly apart.<ref name="rf5" /> Periodically remove dust and grime between the jaws by wiping with rubbing alcohol or mineral spirits. |
==Warnings== | ==Warnings== | ||
*Do not tilt the caliper when taking a measurement. If the jaws are not perpendicular to the diameter you are measuring, you will not get an accurate result. | *Do not tilt the caliper when taking a measurement. If the jaws are not perpendicular to the diameter you are measuring, you will not get an accurate result. | ||
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== Sources and Citations == | == Sources and Citations == | ||
