How Compass is made and How Compass Works?

Basic compass has a magnetic needle which is aligned with North-South, windrose that displays the cardinal directions - North, East, South and West, and box that holds everything together. The compass indicates to magnetic north of the Earth because the magnetic needle of the compass aligns itself to one of the lines of the Earth's magnetic field.

Iron needles that are made from iron ore, coke, and limestone; heated, rolled and cut into shape of needle are placed into an automated turntable where North end of the each needle is sprayed with red paint and the South end is sprayed with white paint. At the same time the needles are exposed to strong electromagnet which magnetizes them permanently. The paint is dried naturally or in oven, and the needles are sent to be assembled with the box.

Boxes are usually made from plastic that is melted and injected into molds of the desired shape. Box is usually marked so it shows directions of the world. In the beginning, when the compass appeared for the first time, only marking was that of the North. Later compasses were marked with North, East, South and West. After that, in China compass card was divided into 24 equally spaced points, while in Europe it was divided into 32. Names of these points of the European compass are (clockwise): North, North by east, North-northeast, Northeast by north, Northeast, Northeast by east, East-northeast, East by north, East, East by south, East-southeast, Southeast by east, Southeast, Southeast by south, South-southeast, South by east, South, South by west, South-southwest, Southwest by south, Southwest, Southwest by west, West-southwest, West by south, West, West by north, West-northwest, Northwest by west, Northwest, Northwest by north, North-northwest and North by west. Modern compasses can also be marked in 360-degree system while military are marked in angular mils. Box also has a vial that holds the needle on the pivot and lets it rotate freely. Cheap compasses most commonly have a steel pivot, but the best compasses have jeweled pivots in order to resist wear and to last longer. Needles are placed in the box and the box is closed. Needles are balanced during manufacture needle will be level, eliminating needle drag which can give wrong reading. For ship compasses, correction for errors is done to negate deviation caused by iron and steel in structure and equipment of the ship. Similar process is done in the airplanes with compass deviation card mounted permanently above or below the magnetic compass on the instrument panel.

Parts of the most common transparent orienteering compass are: transparent base plate, housing that is airtight and which holds moving parts of the compass and fluid in which they are immersed, magnetic needle that does all the work, orienteering arrow that can be rotated and that works as a sort of memory for a direction, orienteering lines which are used to orientate a map, bearings that go around the compass housing and are also used for orienteering and a magnifying glass for reading.