Rough Cuts
Previous lessons:
All the theoretical stuff
Things you’ll need for this
lesson:
Printed blank templates from here. This is a template without the
wheels super-imposed on the car. Print it at “actual size” so it is the right
size. If you can’t make it work, you just trace the outline of the block onto a
piece of paper. Check to see that the
templates are scaled correctly (ie, they match the block).
Ruler
Sharp pencils
A coping saw with that has a mouth that is bigger than 3.5 inches
(or a small-toothed plywood saw)
A vice clamp (recommended)
Shims to protect the wood from the clamp (eg, small plywood
squares)
WD40
A pack of extra blades if you are using a coping saw
A pencil sharpener
Popsicles
Lesson:
There are really three things that will be learned, two for the
son and one for the Dad. For the Dad, the lesson will be patience. This is the
time for your son to try, fail, and then try again. This will be a day of
failures, so you might even need to take a popsicle break or two, talk over
things during the break, and maybe even start again another day if frustration
gets too high.
The lessons for the sons will be accuracy. For some, your son will have been coddled – everything they
do is great. Sure, this is great encouragement so that they stay motivated, but
the Pinewood Derby is often one of the first experiences that good effort does
not necessarily equal good results.
The third lesson will be technique.
Today, your son will be cutting his block. Most of us do not have access to a
bandsaw. And even if we did have a bandsaw, I would not use it. A bandsaw is obviously
too dangerous for the boys to use. And if you work the bandsaw for your son,
then they never learn how to saw. This
is the day your son learns how to saw correctly.
Have your son take a piece of paper. Give him some choices of
designs, which will be a) wedge, b) plank, or c) something that will look cool,
but will be slower.
Give him the template, show him how each side corresponds to a side
of the block.
On the side profiles of the template, have him mark a dot that is on
the “front” and ½ inch from the bottom. Then have him mark a dot that is on the
“back” and ½” from the bottom. The “back” is the side where the pre-cut axle
groove is nearer to the back on the block.
Have him do it for both sides. Have him connect the front and back lines.
Is the dot exactly at ½ inch? Is the line straight? Probably not.
Start again and show him how mistakes are a natural part of this
process. Now you do this practice. Show him how to hold the ruler straight and
firmly against the paper so it does not slide. Show him why you need a SHARP
pencil to make an accurate mark. Show him how you have to angle the pencil tip
inward toward the ruler so that the mark is next to the ruler, not a bit away from
the ruler. Show him that if YOU make a mistake, you correct it or you start
over without it being a big deal that you failed.
Once the template has two straight lines on it, have him cut them
out and tape them to the block. Have him over-trace the straight lines onto the
car by pressing firmly so that the wood is marked underneath. Have him connect
the two lines on the front and back with a pencil.
Now clamp the wood block into a vice using shims to protect the
wood. I used popsicle sticks that were taped together to make a flat mat. I
used popsicle sticks because that’s what I had lying around.
You should saw a small groove on either the “front” just to start
your son off. Then have him start sawing. Show him good technique, which is to
move his arm back and forth in deliberate strokes, where the arm is tucked in
close to his side, elbow going straight back so that the saw goes straight. He
won’t be able to do it very well. As he saws, he will get off course. The saw
will bind because he won’t keep his arm straight. He will break/bend blades.
This is okay as there is room for error. Get him back on course. He will get
tired. Don’t forget to keep checking both sides so you don’t get too far off
track. When the blade binds a bunch,
spray some WD40 on the sides of the saw. And you can put a firm hand on top of
his to guide him and to make sure that he presses down on the saw as often they
are going the motion, but don’t have the strength to actually saw. This will
try your patience and his, but keep up the good work.
Phew!
