[Illustration: Figure 29.--Beveling for Thin Work]
[Illustration: Figure 30.--Beveling for Thick Work]
With work less than one-fourth inch thick, this angle should be forty-five
degrees on each piece (Figure 29), so that when they are placed together
the extreme edges will meet at the bottom of a groove whose sides are
square, or at right angles, to each other. This beveling should be done so
that only a thin edge is left where the two parts come together, just
enough points in contact to make the alignment easy to hold. With work of a
thickness greater than a quarter of an inch, the angle of bevel on each
piece may be sixty degrees (Figure 30), so that when placed together the
angle included between the sloping sides will also be sixty degrees. If the
plate is less than one-eighth of an inch thick the beveling is not
necessary, as the edges may be melted all the way through without danger of
leaving blowholes at any point.
[Illustration: Figure 31.--Beveling Both Sides of a Thick Piece]
[Illustration: Figure 32.--Beveling the End of a Pipe]
This beveling may be done in any convenient way. A chisel is usually most
satisfactory and also quickest. Small sections may be handled by filing,
while metal that is too hard to cut in either of these ways may be shaped
on the emery wheel. It is not necessary that the edges be perfectly
finished and absolutely smooth, but they should be of regular outline and
should always taper off to a thin edge so that when the flame is first
applied it can be seen issuing from the far side of the crack.
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