Lesson 36: DIAGONAL and STRAIGHT SCARF CORNER WELDS
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 A
Diagonal Scarf Weld
The quickest way to weld a square corner is to use diagonal scarfs,
but the resulting joint is not so strong as the straight scarf method.
Take a NEAR WELDING heat on each piece in turn and after upsetting the
ends cut them off at an angle of 45° leaving a blunt corner, like
this -
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 B
Take another heat and, using the rounded edge of the anvil, forge a
scarf on the same side of each piece, so that they pair up when laid
on top of each other at a right angle with the scarfs matching as shown
in the next illustration.
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 C
Take a FULL WELDING heat on both pieces together and lay
them on the anvil as shown.
Strike the first blow on the thick part of the top scarf so that it
welds to the thin part of the under scarf which is being chilled by
the anvil face.
Finish off with a minimum of blows so as not to reduce the thickness,
because a diagonal scarf has no surplus metal in the finished weld. |
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 D
Straight Scarf Weld
A straight scarf corner weld has greater strength than a diagonal scarf
weld, but it akes longer to prepare and make.
Take a NEAR WELDING heat on each piece in turn and upset, first quenching
the tip so that the swelling starts about 3/4"
from the end.
After upsetting take another heat and form a scarf on the edge of one
side of the bar from the end to the middle of the upset. |
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 E
Each bar is scarfed on the same side so that when one
piece is turned over and laid under the other at right angles as shown
here, the side scarf on each piece must be in contact with the upset
part of the other piece. |
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 F
Take a FULL WELDING heat and deliver the first blow on
the thick part of the top piece to weld the thin under scarf before
it is chilled by the anvil face.
Continue hammering across the thin part of the top scarf
making sure that the inside corner is welded at this heat.
Take another FULL WELDING heat and finish by hammering from the inside
to the outside of the corner. |
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 G
There is no need to forge in the superflous metal, so trim it off with
a hot chisel; ample has been allowed for the strength of the joint.
The finished welds should look like this with no reduction in section,
and a small radius on the inside corner.
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