Last year I was part of a new startup pack and we wanted to run a Pinewood Derby. That meant we needed a track and had no money. So rather than rent one I set off to build a track as cheaply as I could. Between scrounging and some creative material selection I built a track, including electronic scoring, for about $80.
Some general pointers:
1. Minimize waste and materials overall. I used the plans from the Cub Scout How To book as a base. One 4x8 sheet of 1/2" particle board that I ripped into 4 lane sections. A few 1x4s that I ripped into 1x2s as called for in the plans.
2. For the lane guides do not even think of using lath. I started to go this way until I figured out that I had $75 worth of lath and it was all warped every which way. I picked up a 4x4 sheet of 1/4" masonite and ripped strips.
3. Buy the bulk package of screws for the lane guides.
4. Do not use blind nuts, instead drill a larger hole part way through and wedge in a normal hex nut. I bit of glue can be added as insurance that the nut does not come out.
5. The cheapest speaker wire is sufficient.
6. Scrounge whatever you can from your garage. Miscellaneous screws in particular.
An overall picture:
My starting gate used PVC pipe and rubber bands. It latches up and spring loads down. Minimize mass of this assembly to reduce momentum and avoid bounce problems:
Of course I violated the minimize rule by adding start flags The green lever is pushed down to release the gate and start the race. When the gate drops the flags drop too:
Here is the underside of the starting gate:
I got a bit carried away on the finish line I painted checkerboard on it. I also used the timer design off the net and software by James Brown. I modified the electronics to not use photo transistors and to use micro switches instead. I probably could have gotten the transistors to work... but I *KNEW* that I could get micro switches to work.
A closeup to show the switch levers at the finish:
I like modular designs, so I implemented the finish line sensors as a module that bolts to the track bottom:
The switch levers work using a cam principle to activate the switch and the switch spring to return the lever to up. The individual switch setup:
I have since replaced the popsicle stick switch levers with aluminum, the wood had durability problems. I also had some problems with the levers sticking in the down position, probably from rotating the cam over center. I added some foam as a secondary lever return spring in the track. In my latest outing this reduced the sticking down to 2 races out of 86.
This track has now been through three derbies. It got used as a secondary fun race track for a Girl Scout PowerPuff Derby. And last week it was the primary track for my new pack with 80+ boys. The part that amazed everyone is that we got through 86 races in a bit under 90 minutes. Nobody thought we could come close to being on schedule but we did [/img]
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Some of your photos are rather large and blow up the page. Can you shrink them down for better viewing?
Awana Grand Prix and Pinewood Derby racing - Where a child, an adult and a small block of wood combine for a lot of fun and memories.
Yep, I noticed the really big pictures. I have a high resolution digital camera with a large flash and I'm not afraid to use it I went through a couple of passes of shrinking them but looks like I missed one. I will shrink it this evening.
Re: track curve...
Yes the particle board does flex for the curve. It does have 16' over which to do this so the curve transition is pretty gradual. The track sections are joined together by 2 1x2s underneath with 8 1/4" bolts per joint as per the Cub Scout How To plans. This creates reasonably good joints and alignment since I have indexed all parts to go together the same every time.
I plan on using it for a 2-3 lane test track that I don't want to spend a lot of money or time on (need that for the cars) !
Thanks so much for the pictures !!!