This could hardly be considered a wood carving but since it is made from wood and this is my blog: So it qualifies!
It was recently decided that my wife and I would have Grandkid duty for
a couple of days in the early part of June while our daughter is working. They live in another town so we have been
thinking about the types of things that we could/should take with us to
entertain two 7 years olds and two 8 year olds for long stretches of time. One of the things that we came up with was a
pinewood derby set. Any race track design
carried with it an additional requirement: it had to have the capability to be
disassembled for transport.
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| Four Completed Cars Ready to Race |
I started with the cars.
I went to my favorite hobby store with the intent to buy four Official Cub Scout Pinewood
Derby car kits. As it turns out, doing that wasn’t as easy as it might have seemed it would be.
I was there in late April only to discover that the “official Pinewood
Derby Racing Season” was over and that all of the “regulation” car kits had
already been pulled from the shelves and stored for next year. All that remained on the shelves were the fancy, to say
nothing of expensive, brand name kits. Some
of these kits cost as much as I had hoped to spend for the entire set…and that
was just for one car!
They did, however, still have sets of official Pinewood
Derby wheels on the shelves so I snatched up four sets and went home. Fortunately, Basswood is something that I got
a lot of, so I figured that I would just design and build my own cars.
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| Note the track alignment pins protruding from the tops of pylons |
Visions of fancy race car designs danced in my head as I drove home but after a quick sobering walk around the block I realized that to
show up with four different cars was only to ask for problems as far as which
kid got which car. I decided that it was
a better idea to make them all exactly the same. I settled on a relatively bland 1930s,
open cockpit, retro race car design and made four cars as identical as I could. Their mother specifically requested
that no “kid painting” be involved…hmmm…Gee, I wonder why. :-) So, I sprayed them with a coat of
polyurethane and we purchased some details so that the kids could personalize
them.
I thought about the track for quite some time and finally
decided that 3 pieces of ¼” Luan underlayment (15” x 48”) connected end to end
would make a reasonable race track. Easy
to assemble and transport. I built 3 pylons of progressively lower heights to
support the race track.
Each pylon has a
set of dowel pins sticking out of its top to lock the track sections
together. I added a tab to the underside
at the upper end of each track section to force it to be flush with the next
higher track section to minimize the chance of a bump where two sections meet. The idea works “pretty well”, but not
perfectly. You do have to run your
fingers over the seam to make sure that everything lines up correctly and
adjust things accordingly.
I ripped down a number of ¾” wide strips from the same Luan
sheet and glued them to the track sections to form the lanes. If I was to do this over again, I would either
use something thicker or glue down a second strip on top of the first one,
because the cars “can” still jump the rail.
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| Track and Pylon Details |
I made the pylons out of more pieces of the Luan glued together
with blocks in the corners for strength.
I used thicker pieces of pine along the inside edges at the end of each
pylon to give the alignment dowels something substantial to be glued to. The original Pylon heights were 6”, 4” and 2”
with about a ¼” slope (in the direction of travel) to the top.
I had done some preliminary testing to see how
much height I would need to give the cars a decent starting speed to make it a real
race. At first, it seemed that a 6” high
starting pylon to be plenty high enough.
But, after completing the entire course I discovered that I really
needed another 4” or so at the top to really get the cars moving at a speed
that a 7 or 8 year old would like. So, I
build a four sided box with a rabbit around the inside for the original first pylon
to sit down into. Fortunately, because
the track is relatively flexible, I discovered that the other two pylons could
remain unaltered. This 10+ inch high
starting point sends the cars off at a nice, exciting speed.
I used polyurethane on the track sections and used some red,
white and blue spray paint to give the pylons a little added flair.
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| Starting Gate |
The starting gate is partially my design but the concept is
based on a “how-to video” that I found on the making a Pinewood Derby race
course. The design uses a main shaft (a piece
of ½ plastic pipe) to hold four short pieces of ¼” dowel that stick up through
the track, one in each of the four lane of the track. Each car is positioned on the track with its
nose resting against one of these car retaining pins.
The main shaft is mounted to the underside of the top
section of the track using 5 blocks of wood.
A ¼” dowel runs through the support blocks to act as a “stop” for the car
retaining pins after the gate has been released.
One end of the main shaft has an elbow and a short piece of
pipe that form a handle used to “cock” the mechanism. The other end has a small cylindrical collar
fastened to it.
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| View of Underside of Starting Gate |
The gate release is a short section of ½” dowel that sits in
a short length of plastic pipe. The gate
release is locked into a hole on the perimeter of the collar by a spring
located in the base of the pipe. When
the gate release is retracted, the main shaft, which is rubber band powered, is
released and rotates forward. Each of
the dowels snaps down through its slot in the track, releasing all four cars
simultaneously, auto-cross style.
The rubber band used to
“power” the starting gate is looped over the car retaining pin in the second
lane (going l-to r) and is stretched to the retainer under the track near the
top edge.
Operation of the Starting Gate
How Well Does it Work? You be the judge! Yeah, there was a bit of bumper cars goin' on there:-)
