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People have been building boats about a million years longer than they
have been building trucks so there is no reason why we can’t learn
something useful from the boat builders.
A very useful thing we can learn is an easy method for making parts
fit unusual shapes. The method I want to show you is called fitting
by back-measuring and by using your head you can apply this method to
almost any shape. It would be
useful for building sub boxes, building hood scoops, shaping a bumper to
the contours of the fenders—anything.
The
first step is to get a board to use as a pattern, ¼” plywood works
well, and roughly shape it to within an inch around the inside or outside
of the area where you need to fit a part. Here I am doing an inside
fitting. An outside fitting is no different except the pattern might be U
shaped to loosely fit over a transmission hump for a console or around a
window pillar to make a gauge pod—for example, or L-shaped if you were
going to pick up the contours of a fender to make a bumper look like it
belongs on your truck.
Level
the pattern on the exact plane that the part will fit. It doesn’t have
to be level with Mother Earth, unless that’s what you need. For
instance, a console over a transmission hump could be angled away at
45-degrees so you could see the gauges.
What I am doing here is forming a seat to go into the bow of a
small boat.
Next
you need a sharp stick of maybe 4-6” length—you’ve been playing with
sharp sticks since you were so high so this should be easy.
The stick should be more or less straight along one side and it
needs a notch cut into it, as mine has.
What
you are going to do with your sharp stick is very simple. Place it flat on
the pattern, touch it to truck, boat, whatever, and draw along the stick
carefully until the notch stops your pencil or sharpie. Make a thicker
mark in the notch. Keep doing
this all over the place. In straighter place you don’t need very many
lines and marks. In places where the shape is rapidly changing, make lots
of lines and marks.
The
lines can cross each other and go any which way—it doesn’t matter. The
lines are simply pointing at a spot off of the edge of your pattern and
they can point from anywhere on the pattern. Just make sure you can find
the marks at the end of the lines you are drawing. Once you have enough
lines to pick up the shape, remove the pattern and go find a piece of
material large enough to make the finished part with.
In
this case, I found a big piece of scrap and decided that if I cut away
everything that didn’t look like a bow seat, I would end up with a bow
seat. The way you decide which pieces don’t look like your finish part
is to place your measuring stick along the lines you drew, align the mark
on the line with the notch on your stick and at the very point of the
stick, mark the material. You
are going to do what you did on your truck, boat, whatever, just in
reverse.
Again,
align the notch, mark, stick, line…
And
mark the point of the stick onto the material. Do it, obviously,
everywhere there is a line and mark.
After you have it all done you will have a whole bunch of points
marked around, or inside, of your pattern.
Your pattern is no longer necessary. Now you get to play that
childhood favorite—Connect the Dots. I usually just sketch it in but I’ll show you a way that is
a little better for long, smooth curves—say you are fitting Batmobile
fins to the bedsides of your ranger.
Take
little nails and pound them into the marks that you made. Bend a thin
stick around the outside of the nails using other nails or weights to hold
the stick. Draw inside the stick. On the parts you are going to sketch you
can do a nice job of making a smooth curve if you keep your eye a couple
of marks ahead of where the pencil is and draw in short quick strokes.
Now, using a tool suitable for what you are going to cut, remove
all the bits that don’t look like what your are building.
Here
is the part ready to by puttied and taped into place. Using this method of
fitting it takes about ten minutes to shape a part. Your pattern does not
have to be very pretty at all. You can use your imagination to expand on
this simple way of fitting things.
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