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Back to Part Two
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If an old component such as the fiberglass wheel pant at top right is available, it can serve as a pattern
for shaping a handmade duplicate. However, one does not hammer the new metal to shape by holding it
against such a pattern. |
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Experience with sheet aluminum tells one the size, shape and number of pieces that can most readily be
hand-hammered and English-wheeled to shape and then welded together. When each piece is being
shaped, it is frequently held against the pattern object to see where and how much it needs further
shaping. |
When heated, the flux used for welding aluminum develops spots that glow very brightly, and the light
contains rays that can harm the eyes of a person who does much welding. Over the years a variety of glass
types have been used in aluminum welding goggles.
None had a really good combination of resistance to heat and breakage combined with ray control capability
and a clear view of the work being done. In 1989 Kent's firm developed and patented a new welding goggle
glass that has superior eye protection qualities. We have already noted that some special
aluminum-working tools are expensive. Some idea of the truth of this is obtainable from noting that a
piece of this glass measuring 2 inches by 4.25
inches sells for over $100.00. But as one's eyes are so important, the protection this glass affords is worth the
price.
See the TM 2000 glasses
White has learned many things in his years of aluminum work. For a long time he had problems teaching some
students to weld. They just couldn't seem to pick up the knack of heating the metal just right. He
finally realized that the usual method of testing eyes for depth perception did not work well for the
short distances between eyes and work typical of aluminum welding. By fitting inexpensive reading glasses
of suitable diopter inside welding goggles, the poor close-range depth perception of these problem
students was overcome, and they then learned to weld effectively.
Most sheet aluminum airplane components having compound curves must be made up from two or more pieces of
metal. After each has been formed into the required shape, they are welded together to form the unit as a
whole. The pieces are all blocked into proper relative position and welded into a single unit. To start
the welding, white tack welds them together. Me does this by using the sensitive little Meco torch to get
very small molten spots every inch or two.
In effect, the pieces are stitched lightly together. This holds them in proper position relative to one
another and also does much to keep the assembly as a whole from warping as the final seam welding
progresses.
Another obscure but useful thing he has learned is that it's very important to remove aluminum welding flux
residue promptly, using a stainless steel brash and hot water. Bits of flux residue remaining on the work
can "erupt" some weeks later and mar a beautiful paint job
The word "planishing" is much used in aluminum forming work. It means to smooth up a metal surface by gentle
hammering. This is where the "slapper" tool is much superior to hammers. Where the nose of a hammer will
cause dents, the polished surface of a slapper works so as to push down high spots and therefore, at the
same time, to bring up low spots, while at the same time not denting the metal. One of White's
publications, the 16-page book-let
Repairing Aluminum
contains a useful coverage of the shrinking technique. The six-page pamphlet
Using the Slapper
gives a good sense of how this tool works and is to be used.
The photos that follow convey a general idea of how three different airplane components were shaped from
sheet aluminum. As far as we are aware, this is the first time any aviation magazine has brought its
readers how-it's-done information of this kind. Enjoy!
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