Control LIne Aerobatics-2011/09

126 MODEL AVIATION
Setting up shop
[[email protected]]
Control Line Aerobatics Bob Hunt
Also included in this column:
• Straightedges
• Triangles and angle finders
• Circle templates
• Combination square
IT’S TIME to revisit my “shop setup”
series.
Sometimes the most mundane things can
prove to be among the most important
things as well. Such is the case with
measuring tools and straightedges in model
building. Certainly these devices are not
nearly as interesting as, say, a hand grinder,
a scroll saw, or even a sanding block, but in
many cases they prove to be the tools that
make the biggest difference in achieving an
accurate, well-built model.
Throughout the years, without realizing
it consciously, I’ve acquired a variety of
measuring tools and straightedges. Many
have been gifts from friends who know of
my penchant for, and love of, such tools.
Most are just conversation pieces, but a few
have become building staples, although
these are the more “normal” of their type.
Into this mix I’ll also throw drawing tools
and templates.
My first precision tools were drawing
tools that my step-grandfather gave me
when I was roughly 8 years old. He and my
grandmother lived three streets away from
my family, and I would visit them almost
daily.
It became a ritual for me to spend the
weekends there, and I was royally spoiled
by both of them. My step-grandfather, who
was known to me as “Poppy,” was quite
wealthy and had made his fortune from his
A flexible plastic ruler can be pushed into
concave areas for precise line scribing or
cutting. Here it is being used to lay out the
rib locations in a Lost-Foam Wing Fixture.
Left: A thin, flexible metal
straightedge makes trimming
foam-core wing sheeting quick
and easy. Note how the
straightedge follows the
contour of the wing allowing
for an accurate cut.
Two useful building tools
are a combination square
(L) and an angle finder.
better at drawing, and was delighted when he
presented me with a full set of genuine
Dietzgen drawing tools! I knew they were the
real thing, because they were the same tools
that I watched the designers use at his factory.
I still have that set 54 years later, and it is
still intact and complete. It is among my most
treasured possessions. Poppy also built a
small drawing board for me on which to do
my drawings.
Soon after that I began designing and
large dental-supply business. By the time I
came on the scene, he had semiretired from
the business, but he kept a close eye on it and
went to his factory every business day to read
the mail, sign checks, and such.
I went with Poppy on many occasions to
his factory. There were many drawing boards
on which the designers drew plans for new
products. I was intrigued by their work and
spent much time watching them design
things. I must have driven them crazy with
my myriad questions.
I started to draw cars and airplanes in the
evenings that I spent at Poppy’s house, and he
would carefully look at each one and
comment on how much better each was than
the one before. I knew that I was getting
Above: Measuring tools and
straightedges are some of the
most important modelbuilding
tools and are often
overlooked. Building quality
models requires a variety of
tools and the knowledge of
how to use them.
09sig4.QXD_00MSTRPG.QXD 7/22/11 11:55 AM Page 126
building small gliders, and again Poppy paved
the way to success by buying me proper
measuring and cutting tools. I owe him a great
deal, and I just wanted to share that story
because I believe that his interest in my
modeling passion, and those tools, are a huge
part of the reason that I build straight,
accurate models to this day. I’ll never forget
his kindness, his generosity, and his guidance.
Straightedges: The ubiquitous straightedge
may be the most useful tool in your shop. It
can be used for many things in model
building, but most often it is employed to cut
a straight line in a piece of balsa.
I never use a factory edge on a piece of
balsa. I’ve found that balsa can have stresses
in it that will relieve and cause a “bow” when
a piece is cut from a sheet without first truing
the factory edge. In fact, I routinely trim both
edges of a fresh sheet of balsa before
attempting to cut from it a model part.
Most of the time, and particularly with
thicker pieces of balsa (1/4-inch thick and
greater), I feel that a band saw does a much
better job of relieving stress in a sheet of balsa
search bar and you will be surprised how
many options there are.
Be aware that a precision 36-inch
straightedge will cost anywhere from $50
to $150. A 48-inch precision straightedge
will cost substantially more! Believe me, it
will be money well spent.
My father had a full machine shop, and
in it he had a precision press shear. He
made several very nice straightedges on it
for me many years ago, and I still use them
to this day. I am considering buying a new
48-inch straightedge, however, and I
expect to pay upwards of $200 for it!
You will also find much use for a
flexible metal straightedge, especially
when working on a curved wing surface.
Again, a Web search for “precision flexible
metal straightedges” will yield a lot of
sources. Be prepared to spend a few
shekels to get a good one.
My son, Robby, found an excellent use
for a flexible metal straightedge. When cap
stripping the ribs on a built-up wing, he
wanted to ensure that even pressure was
applied all along the length of the cap strip
than does edge trimming with a knife.
However, I do use a knife on thinner pieces
of balsa (1/32- to 3/16-inch thick pieces).
If you choose to use the band saw
method, you will still need to draw a pen
line on the balsa to follow while cutting. If
you opt to use the knife method, you will
need an accurate straightedge against which
to cut.
If you saw or knife-trim the edge, you
will then have to true it with a sanding
block. I use the long PermaGrit blocks that I
have mentioned in a previous column for
this chore. I check that trued edge against
the straightedge to insure that it is indeed
accurate before use.
You can purchase fairly good
straightedges from your local Home Depot
or Lowe’s Home Improvement stores, and
many of the mail-order hobby concerns also
offer good modeling straightedges. But, to
ensure that your work is as perfect as
possible, I suggest purchasing a precision
straightedge. Sources for these can be found
by searching the Web. Type the phrase
“precision metal straightedges” in you
while the medium CA glue cured.
He first cuts the cap strip to fit with a
very slight interference fit to the LE and TE.
He then sands the edges of the cap strip to
ensure that they are smooth and even. Robby
applies CA glue to the rib onto which the
cap strip will be installed and puts the cap
strip in place on the rib, making small pencil
marks on the adjacent LE and TE sheeting at
the center of the rib to aid in aligning the cap
strip properly atop the rib.
Robby quickly sands the points at which
the cap strip butts against the LE and TE
using a professional-type emery board. The
sanding dust serves to help fill any tiny gaps
between the LE or TE and the cap strip. He
then quickly places a flexible metal
straightedge on top of the cap strip and
applies pressure on the straightedge to
ensure that the entire length of the cap strip
is adhered to the rib. The result is a perfectly
attached and blended cap strip.
Of course, the main use in my shop for
metal straightedges is trimming the edges of
1/16-inch thick balsa wing sheeting when
making up wing skins for the commercial
foam cores and foam wings that I produce.
I also use and recommend clear plastic
straightedge/rulers that have embossed lines
that allow you to use the straightedge/ruler
as a square when laying out parts. The
embossed lines are 90° to the edges of the
straightedge/ruler. I use these a lot when
laying out Lost-Foam Wing fixtures. They
are flexible enough to be forced into the
concaved wing cradles and allow the
drawing of accurate rib alignment lines on
the foam.
I prefer the plastic straightedge/rulers
made by the C-Thru Ruler Company. I use
the 18-inch long, two-inch wide units that
are graduated in eighths (Part Number B-
85). These rulers are getting hard to find in
the local marketplace, because CAD
drawing has pretty much taken over.
Fortunately you can order directly from the
company online.
While researching C-Thru’s website for
the availability of this product, I was pleased
to find that the company makes a wide
variety of plastic and metal straightedges,
measuring tools, and templates that are
perfect for our use. I recommend that you go
128 MODEL AVIATION
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to the site and take a look at all of their
products and try to envision how to
incorporate them into your building.
Triangles and Angle Finders: You will find
myriad uses for both see-through plastic
triangles and metal triangles in model
building. Again, search the Web for these
tools and purchase the ones that make sense
for your particular building practices. I have a
number of each type in a wide variety of
sizes.
Another great tool for modeling is a
standard angle finder. You can find these at
your local hardware store or home
improvement store. I find this tool invaluable
for finding and then duplicating an angle. I
use it more than I ever thought I would.
Circle Templates: Another useful tool is a
circle template. There will be many times
when you will need to layout and cut holes in
plywood doublers to reduce weight. I have
several sizes of circle templates as well as a
number of ellipse templates that I use for this
purpose.
These templates and many of the other
tools mentioned will serve double duty when
you get on the drawing board to design that
new “world beater.”
Combination Square: One last item that you
should own is a combination square. I have
several including a high-quality one that I use
solely for marking square ends on pieces of
wood for cutting.
I also have a few good-quality
combination squares that I use to actually
sand against with a sanding block to square
pieces of balsa. I know that many will cringe
about that use of this tool, but it works for me
and I find that each square will last several
years without losing accuracy. Eventually the
sandpaper will erode the metal bar away
enough so that the square is no longer, well,
square!
Reading about mundane measuring,
layout, and cutting tools is not as exciting as
reading about flying, but if you obtain and
learn to use a wide variety of these tools, your
airplanes will be more accurate and will fly
better. And, that is exciting!
Till next time, fly Stunt! MA
Sources:
The Home Depot
(800) 466-3337
www.homedepot.com
Lowe’s Home Improvement Center
(800) 445-6937
www.lowes.com
C-Thru Ruler Company
(800) 243-8419
www.cthruruler.com
Precision Aerobatics Model Pilots
Association
www.control-line.org