January 19, 2012 from 6:30 p.m. to 9:00 p.m. in the CARRIBINE HALL
Most Important Tips
1. The boys and adult should
make the car together as a project! It
is not the intent that the parent show the Scout the garage door then walk
away; nor is it the intent that the boy play video games while the adult cuts
and sands. Parents should shape with the power tools and then direct the rest
of the action while showing the boy each step in building a car.
2. Have fun!
After all, this is what it is all about.
3. Know the rules. Being disqualified can be very embarrassing.
4. Safety first.
Lets not lose any fingers.
Design Tips
1. Have your son draw a design on paper then cut it out and
use it as a template. Use graph paper to make it easier for him. Draw a side
and top view on the paper by tracing around the block of wood.
2. It’s important to keep the car a full 7-inches, due to the
physics of velocity, length of travel and weight.
3. Use the full 2 3/4 inches (outside wheel to outside wheel)
that the rules give you.
4. Leave a lot of wood in the back to put in the weights.
5. Use the groove closest to the end of the block of wood as
the rear axle. Trust me, it helps. If you are interested in discussing the
physics, please e-mail me.
6. Do not make the front of the car pointed. It is hard to
set up against the starting dowels.
7. Be aware of how sensitive your electronic timers are. You
want the car to set them off at the end of the race and not before.
8. Use your imagination. Be creative. Shape has the least to
do with winning. A beaver driving a log or even a pickup truck is more
interesting than a wedge and will be just as fast. The aerodynamics of a small
block of wood doesn't mean much in thirty feet. Ideas: Hot Dog, Banana, Shark,
Watermelon Wedge, Dragster Rocket Car, Swiss Cheese Wedge with a Mouse Driver,
Ice Cream Bar, Batmobile, Carrot Ridden by a Rabbit, Police Car, Pencil, Tow
Truck, Coffin Ridden by a Skeleton, Giant Lego Car, Fire Truck, Train Engine,
Ambulance with Lights
Friction Is Your Enemy
1. Debur the wheels. Take off the flashing and seam that was
produced when the wheel was molded with a 600 grit or better sandpaper. Inside
as well as out. Sand any bumps off the wheel the sandpaper. Metal polish will
restore he gloss. Be careful not to break any rules your race has regarding
wheel modification. (Narrower wheels have less friction and are better, but
often disallowed). Don't sand too much or you'll create a flat spot. Sand by
hand not in the drill. Heat from the high speed of a drill will damage the
plastic wheel.
2. Polish the axles. First with a 400 grit if you have a
really bad spot. Then a 600 grit, and then a jewelers rouge. Finish off
with a chrome/metal polish.
3. Have only three wheels touching the track. Raise a front
one slightly. There is less friction with 3 wheels rolling than 4.
4. The head of the axle should be tapered about 15 degrees so
it rubs against the wheel less.
Wax the wheels with furniture
polish. Make sure the polish does not contain a solvent of any sort.
Lube Jobs
1. Use graphite only. Oil damages the paint and collects
dust. I'm told that the graphite works better than the new white teflon.
2. Break in the wheels by spinning them with lots of
graphite.
3. Right before check-in, fill the wheels wells with graphite
and cover with stickers like a hubcap. You can paint the 1-inch stickers in a
contrasting color. It looks great!
4. Put a small drop of white glue where the axle goes into
the car body and put powdered graphite on it there. That causes less friction
if the wheel should rub against the car body.
5. Other than the good polishing of the axles, dump the axles
and wheels in a ziplock bag with some graphite and shake them for a few days
prior to the race. That way the wheel and the axles are as slick as can be.
It's Time To Go Straight!
1. Put the axle in at a downward (5-10 degrees) angle. This
provides two benefits. The first is the only the inside edge of the wheel is in
contact with the track. This seems to make the car go straighter with less
wobble. The second benefit is that the wheel rides to the outside of the axle
and doesn't come in contact with the body. This tip is for experts only. First timers have trouble getting this right. If you have to email me to ask about
it, you shouldn't do it.
2. Axles must be in straight front to back. That is square to
the body. True the axles, don't trust the slots! If you have one, use a drill
press to ensure all axles are straight. One of the front and two of the back
should be measured to be the same height.
3. After pressing in the axles, test the car for crooked
wheels...roll it on the floor. If the wheels are on straight, the car should
roll 8-10 feet in a fairly straight line. Should the car turn left or right,
you need to tinker with the axle placement without removing them from the car
body, until it rolls straight.
4. Do not put the axles in at the top of the groove. Put them
in at the middle. This lifts the car of the track a bit more and reduces the
chance of rubbing on the center strip.
5. Glue the axles in place. Nothing is worse than having the wheel
fall off as you cross the finish line.
Once you match a wheel and axle
together with graphite, keep them together. They wear into each other as a
matched set.
Weigh In
1. Get the weight as close to the 5-ounce limit as possible. Add the last little bit of weight with
lead tape from the golf shop. This can be trimmed with scissors at the last
minute. Remember, the official scale may not weigh the same as yours.
2. Everyone has an opinion on where to put the weight. My
belief is that the weight needs to be predominantly in the rear so that gravity
can act upon the weight further up the incline and for a longer period of time.
A car with more weight to the rear generally grabs more speed down the slope.
Many suggest having the center of gravity at 1 to 11/2 inches in front of the
rear wheels. But be careful not to put too much in the rear or you'll pop a
wheelie.
3. What kind of weight? I think the melted lead is dangerous
and unnecessary. Tubular weights can be sunk in the sides; flat weights, like those
sold at hobby & council stores can be attached to the car bottom if it is
carved in a bit. Incremental weights (with pre-marked grooves) are easier to
snap off into the size you need. Some folks just use BB's, nuts & bolts,
etc., but these must be glued so that they cannot move. No movable weights or
mercury are allowed.
4. We use the round weights found at the hobby shops and
craft stores. This allows us to stick the weights out the back of the
car. We paint them and tell everyone that they are jet engines or tail
pipes. What they really do is allow us to get the weights as far back as
possible.
4. Keep the weight low on the car and in the center
(Left/Right of the car). Put the weight just in front or behind the rear wheels
for less wheel chatter.
The Finish
1. Buy a gloss finish for the car. It’s worth it. After all
that work, this is the final touch. The more coats that you put on...the
shinier your car will be. Be sure the paint is dry before putting on the gloss
coat. Some gloss products may be incompatible with the paint.
2. Sand in the direction of the
grain when smoothing and against the grain when shaping.
3. Use a sand able primer or wood
sealer. White is for light colors and grey for dark colors.
4. Water based paints dry quicker (1 hour) than oil based
paints (24 Hours).
5. Children LOVE decals. The more… the better.
Race Day-Be Prepared
1. Have extra axles and wheels on hand for last minute
repairs due to accidents.
2. Have a derby tool kit handy. It should include superglue,
sandpaper, a drill, extra screws for your weights, extra weights, and a small
screwdriver. You may not use it, but it will make you the most popular person
at the event.
3. Transport your car in a shoebox. Dropped cars are
unfortunately a too common experience.
4. Add LOTS of graphite right before check in.
5. Explain to your son that running the car along the floor
prior to the race will cause it to lose!
Race Hints
1. Have a car-building clinic after the previous months pack
meeting.
2. Use an overhead projector to display the results for
everyone to see.
3. Reserve the first row for the Scouts. The race is for
them, not the adults.
4. Sticker the cars with a number but also sticker the kids
so that they remember their number.
5. Have a test night the evening before the race when you set
up the track. Have the official scale there.
6. Use this opportunity to tell your Webelos about inertia
and gravity for their Scientist pin.
7. Use this opportunity to teach your Wolf Cubs about tools
for their badge requirements.
8. Hold a coloring contest to keep the boys occupied between
races
9. Announce that there will be adult supervised free racing
after the official races. After spending
two-three weeks building the car, the boys want to race them more than a couple
times.
10. Give the adults something to
pour their creativity into. Have a parent (sister, brother, etc.) race.
11. Invite everyone to watch the
race. Use it as a recruiting tool for future scouts.
12. Ask the Federal Highway Safety
Administration if they have crash dummy costumes that you can borrow or invite
safety speakers.