There are three main types of caliper. Oddleg calipers are used to mark
parallel lines to an edge and if the work has two parallel edges can be used to find the
centre line. Inside calipers are used for measuring the inside diameters of tubes. Outside calipers are used for measuring the outside diameters of bars and tubes.
That's odd, I've lost my legs. Better ring
lost property.
Tip Look after your tools. If they mark and measure badly the job will come out badly.
Sometimes you find it difficult to see
marks clearly which are drawn on polished metals. For this reason a blue dye is available
which you can rub onto the surface of the metal so that any markings can be seen more
clearly.
When the work is finished the dye can be easily removed with spirit. The substance is
known as engineer's blue.