Types of Calipers

Calipers are precise measuring instruments used to measure diameter or thickness. There are three majory types of calipers. The first type is vernier calipers, which have a sliding scale along the top and bottom. The second type is dial calipers, which have a dial that displays the measurement via a pointer. The third type is electronic digital calipers, which have an LCD digital display of the measurement. Calipers can be used to measure either inside or outside dimensions, and they can have either a dial-type or digital readout. Usually, calipers can measure the inside diameter of cylinders and the thickness of breake drums and rotors. Below are the features about the different types of calipes.

The vernier caliper which named after the French man who invented it, has dual scales on its beam that show both imperial and metric measurements at the same time. Inches, tenths of an inch, and hundredths of an inch (along with centimeters and millimeters) are read directly from the scales. Thousandths of an inch (along with centimeters and millimeter) are read directly from the scales. Thousandths of an inch (and micrometers) are read from a special vernier scale and added to the larger measurement.
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Legged calipers have beams just like verniers , but they usually have a single scale. Thousandths of an inch (or micrometers) are shown on a dial similar to a watch face, which is easier and quicker to read than a vernier scale. Although most imperial dial calipers read decimal inches, you can buy models that show fractional measurements, with precision down to 1/4inch, which is a handier for most woodworking and craft projects.
Digital calipers have no scales printed on them. Turn the battery-powered caliper on and take a measurement; it displays the dimensions on a small LCD screen. Push a button and most models instantly show or convert between imperial (decimal) and metric measurements. Another button allows some digitals to be zeroed at any point, which is handy when you want to measure only how much bigger or smaller one part is than another.
Legged Calipers. There are times when you want to check the thickness of a part or compare the size of two parts, and you don’t really need to know their dimension. For example, if you want to make a new foot for a blanket chest that’s the same as the old one, who cares if they’re 3 31/32 in. thick, as long as they both end up the same size. Legged calipers (named for their shape, which resembles a person’s legs) are simple tools that check and compare parts in just that way.
Legged calipers come on two basic types: Outside calipers read a part’s outside dimensions, while inside calipers read the distance between parts or the span of a hole or slot (dividers, close cousins to legged calipers.) A caliper’s size corresponds to its maximum opening. A 4-in. pair is good for small jobs like model making. The 8-in. size is well suited to general-purpose uses, while a 12-in. pair is for large work. Lathe turners find legged calipers of all sizes useful for both wood and metal turning jobs: from sizing heads on a spindle or checking the wall thickness of a large bowl to sizing an aluminum flange or the opening on a steel socket.
Because of their shape and size, legged calipers can take readings in deeper spaces or on larger, bulkier objects than measuring calipers.