Drawing Compass - History and Types of Compasses
A technical drawing tool named drawing compass is used to draw circles or arcs. This tool is also known as a pair of compasses, or simply as a compass. It can also be used for measuring distances or more precisely distances on the maps. Apart from that, drawing compasses are used in navigation, mathematic, drafting and any many other disciplines.
Materials of which compasses are made are usually plastic or metal. Drawing
compass has two parts connected by a hinge so the radius of the circle that
is drawn can be adjusted and changed. Usually at the end of one part is a
needle and at the end of another is a pencil.
First drawing compasses were found in the archeological digging of ancient
Rome. Every drawing compass before the eighteenth century didn't have a pen
but a needle instead so it scratches the surface. By the twentieth century,
drawing compasses were spread widely throughout the world.
Today, because of the development of computer aided design software or CAD
usage of drawing compasses is reduces, but it still finds its usage in
schools and colleges in teaching technical drawing and geometry.
The handle of a drawing compass is about 1.25 centimeters long, and it is
made that users can grip it between thumb and pointer finger.
Measuring compass can have two different types of legs. One type is the
adjustable leg that serves as the support for a needle, and another is a
steady immovable leg which servers for adjustments in drawing circles.
There is also a screw on a hinge which holds those two legs in position.
That hinge is also adjustable, and the compass will be more accurate if the
screw is tight. On a steady leg of a drawing compass is a needlepoint. The
function of a needle the point is to be center point of a drawn circle. The
pencil lead purpose is to draw a circle on a material. There is also a nut
that is used to adjust pencil lead to be in place.
Drawing compass can draw circles on a specific material (wood, metal,
plastic…) by putting a needle on a center of a circle that should be drawn
and rotating it around while keeping the same angle on the hinge. If the
hinge is moved, the radius of a circle can be adjusted.
Compasses can also be used for measuring distances on maps. Those compasses
are called dividing compasses, and they have two needles instead of one.
The measurement can be done by measuring how many times the fixed compass
can fit in some distance.
Types of Drawing Compasses
There are a couple of variants of drawing compass.
A beam compass is made of brass of wooden beam, and it is used for drawing
circles that are larger than those made by regular compass.
This type of compasses is the most simple by form. The scribe-compass is
used by carpenters to scribe a circle instead of drawing it.
Loose Leg Divider
These type of dividers is made of all forged steel, and it is also used to
scribe circles. Loose leg wing dividers also provide stepping off
repetitive measurements with particular accuracy.
The proportional compass (the sector) is used from sixteenth to the nineteenth
century by the military to do calculations. It is a tool consisting of two rulers which are equal length and joined by a hinge.