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, 0.1mm.
② Calipers with gauges. 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.
Calipers have four main functions, as follows:
A. outside diameter measurement (lower/outer measuring claw), B. inside diameter measurement (upper/inner measuring claw), C. step distance measurement (left head), D. depth measurement (tail depth needle)