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.
Four Completed Cars Ready to Race |
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.
Note the track alignment pins protruding from the tops of pylons |
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.
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.
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.
Track and Pylon Details |
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.
Starting Gate |
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.
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.
View of Underside of Starting Gate |
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:-)
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:-)