1, micrometer:
(1) Check the zero point before use:
Turn the fine-tuning knob D' slowly, so that the measuring rod (E) contacts the measuring anvil (A) until the ratchet makes a sound. At this point, the zero line on the movable ruler (movable sleeve) should be aligned with the reference line (long horizontal line) on the fixed sleeve, otherwise there will be zero error.
(2) Hold the ruler frame (C) with the left hand, and turn the coarse adjustment knob D with the right hand to make the distance between the measuring rod E and the anvil A slightly larger than the measured object, put the measured object in, turn the protective knob D' until the ratchet makes a sound, then dial the fixed knob B to fix the measuring rod and read the reading.
2. Calipers:
When measuring, hold the ruler with the right hand, move the cursor with the thumb, and hold the object with the outer diameter (or inner diameter) to be measured with the left hand, so that the object to be measured is located between the outer measuring claws, and when it is close to the measuring claws, it can be read. There are scales on the ruler and cursor.
Take vernier calipers accurate to 0. 1mm as an example. The minimum scale on the ruler is 1mm, and there are 10 small scales on the vernier, with a total length of 9mm, and each scale is 0.9mm, which is 0. 1mm different from the minimum scale on the main ruler.
When the measuring claws are together, the ruler body and the zero scale line of the cursor are aligned, and their first scale line is 0. 1mm, the second scale line is 0.2mm, and the 10 scale line is 1mm, that is, the 10 scale line of the cursor is just aligned with the 9mm scale line of the main ruler.
When the straightness of the object measured between the equivalent claws is 0. 1mm, the cursor should move to the right by 0.1mm. At this point, its first tick mark is just aligned with the 1mm tick mark of the ruler.
Similarly, when the fifth scale line of the cursor is aligned with the 5 mm scale line of the ruler, it means that there is a width of 0.5 mm between the two measuring claws, and so on. When measuring the length greater than 1 mm, the whole number of millimeters should be read from the scale line of the "0" line of the cursor opposite to the ruler.
Second, the reading and calculation method
1, micrometer:
(1) Read the fixed scale first.
(2) Read the half scale again. If the half scale line is exposed, record it as 0.5mm；; If the half scale line is not exposed, record it as 0.0mm；;
(3) Read the movable scale again (pay attention to the reading). n×n×0.0 1mm； ;
(4) The final reading result is fixed scale+half scale+movable scale+expected reading.
Because the reading result of spiral micrometer is accurate to one thousandth of millimeter, it is also called micrometer.
2. Calipers:
When reading, first read the millimeter integer on the scale according to the zero scale line of the cursor, that is, the integer part in millimeters. Then see which scale line on the cursor is aligned with the scale line of the ruler body. If the sixth scale line is aligned with the scale line of the ruler body, the decimal part is 0.6 mm (if there are no completely aligned lines, take the nearest alignment line reading).
If there is zero error, subtract the zero error from the above result (zero error is negative, which is equivalent to adding zero error of the same size), and the reading result is: L= integer part+decimal part-zero error.
To judge which scale line on the cursor is aligned with the scale line of the ruler, the following methods can be adopted: select three adjacent lines, such as the left line is around the corresponding line of the ruler, the right line is on the left side of the corresponding line of the ruler, and the middle line can be considered as aligned. If it is necessary to measure the average value for many times, it is not necessary to subtract the zero error every time, but only to subtract the zero error from the final result.
Extended data:
Types of calipers:
There are three kinds of calipers: vernier calipers, dial calipers and electronic digital calipers.
1, vernier caliper. A ruler-shaped hand-held universal length measuring tool based on vernier principle for subdividing readings is mainly used for measuring inner diameter, outer diameter, step and depth. When measuring, the integer part of the magnitude is read from the main ruler, and the decimal part is read from the cursor.
The principle of the cursor is to use the difference between the line spacing on the main ruler and the line spacing on the cursor to read the decimal part. There are three minimum readings: 0.02mm, 0.05mm and 0.01mm.
2. Calipers with meters. A large hand-held length measuring tool takes the pitch of a precision rack and gear as a known length, and the indicator of the corresponding scale as the amplification, subdivision and indication part. Calipers with meters can solve the reading error problem of vernier calipers. Common minimum readings are 0.0 1mm and 0.02 mm.
3. Electronic digital calipers. A length measuring tool uses capacitive grating, magnetic grating and other measuring systems to digitally display measuring instructions. The commonly used resolution is 0.0 1mm, and the allowable error is 0.03mm/ 150mm.
There are also high-precision digital calipers with a resolution of 0.005mm, with an allowable error of 0.0 15 mm/ 150 mm, and multi-purpose digital micrometer with a resolution of 0.00 1mm (this is a national patent of Anyi measuring tools, and only they can produce it), with an allowable error of 0.005 mm/50 mm.
In addition, there are various non-standard special calipers, such as hook depth caliper for measuring groove depth, gear tooth caliper for measuring gear thickness, height caliper for measuring object height, and weld caliper (weld gauge) for measuring welding quality.
Special purpose calipers: sharp claw type, irregular and unknown size measurement offset type, unequal height position size depth measurement type, depth measurement sheet type, narrow groove diameter measurement.