METAL BODY REPAIR - OD1653 - LESSON 2/TASK 1
are: making the cut, cracking the cut, and cutting or melting the plastic.
The first two are the most difficult, since they consist of setting up
stresses in the glass to guide the crack and applying forces that cause it
to break along the line of these stresses. Any other stresses may cause the
crack to travel away from the desired line.
Stresses can be set up by
supporting the glass on an uneven surface or by applying pressure to an edge
or corner which is unsupported.
(1) A cutting bench made of wood or steel can be used as a support.
Plywood is an ideal top for a cutting bench. The bench must be covered with
a cloth cover which is soft enough to prevent scratching, yet hard enough to
support the glass rigidly. The top of the bench should be larger than the
largest piece of glass to be cut.
For a shop that does much cutting, a
revolving pattern table is ideal.
With a revolving top, the workman can
stand in one position while cutting a door glass. As he comes to a curve in
the pattern, he rotates the table, eliminating the need for moving around
and varying the cut. Smoother cuts can be made and it is easier to get the
top cut directly above the inner cut. The cutting bench should be located
where the temperature is the most constant. Sudden temperature changes will
almost certainly result in breakage of the glass; therefore, the bench must
not be located where drafts will occur.
(2) Glass should be stored vertically in bins.
Each size should be
stored in a separate bin and labeled. A sheet of paper placed between each
sheet of glass will prevent scratching of the surface.
(3) A hardwood ruler, wider and thicker than an ordinary yardstick and
usually 60 inches long, is used as a straightedge and measuring device. A
small flange at one end may be hooked over an edge to eliminate the
necessity of holding that end. This ruler is marked in eighths of an inch.
(4) The common glass cutter has a sharp, hardened steel wheel mounted on
a pin in a steel or wood handle. Handles vary in size and length according
to requirements. They can be procured in the single or multiple wheel-type.
Diamond-tip cutters are also used by large organizations where