Recycled Pinewood Derby Track and Made From Scratch Arduino Timer for Cub Scouts

This is my first attempt at an instructable, there are some missing steps that I do not have photos for, but will be willing to answer all the questions that I can. The pictures do not do this track any justice. The main ideas for the timer came from here.

As a cub scout leader, I try to make the best for my scouts. Our scout pack is always on a very tight budget, and we needed a track to hold our pinewood derby. We were given a wood 32 foot track that was in dire need of refinishing and some major work in order to get it ready for our races. The inspiration for the finished version of the track came from actual raceways. As for the timer, I had found online how to build an arduino based timer that would give us very accurate times that would also work with Grand Prix Race Manager software. The total time to refinish the track, was eight weeks with most of the work being done on weekends only. The time for the timer build was about 6 weeks, since it was our first attempt at electronics and arduino.

I would suggest getting several people to help with this project. We had six people working on this, and it still took several weeks longer than expected.

Step 1: Materials Needed

The materials needed cost us around $170 USD, this could have been more if we did not have many materials on hand or donated to us. We had to replace all the hardware on the track such as hinges and connecting bolts. I would suggest having an indoor area large enough to set the track up in its entirety to do most of the work on this project.

For the track:

A pinewood derby track (ours was prebuilt and donated to us) ( I will be building a new track from scratch and post it in the future)

4 quarts of black stain (Minwax fat drying is what we used)

vinyl decals and numbers

vinyl tape (for the lane markers)

4 quarts Polyurethane

Sand paper 40 grit to 220 grit

sanding blocks and sanders

a ton of elbow grease and patience

tack cloth

Paint brushes

For the timer: note* this will vary depending on the number of lanes your track has and the size of your timer box and how you decide to make your finish line timer*

A sheet of plywood (any thickness)

2x4x6

1x1x4

piano hinge

paint

left over polyurethane from track

vinyl decals and numbers

Arduino Uno

aluminum sheets and aluminum tape

honeycomb board or plastic

phone and Cat5 wall boxes

Phone and cat5 connectors and cable

wood screws, woodworking tools, drill, ect...

Plenty of patience

Hot glue gun, and glue sticks

cable clips

The following timer components available here:

PDT shield PCB with base components

Lane component (light source, detector and CLR) set

Place / time display (RED)

Place / time display (RED) with 20cm jumper wire or 30cm jumper wire

I2C Splitter

Start gate switch

For the software we use Grand Prix Race Manager Pro available for purchase and download here:

Step 2: Initial Assesment of Used Track and Sanding

Since this was a used track that was not sitting level, had a slight warp in it, was just poorly varnished, and a car would not make it down the track to the finish, we knew we had to first remove the varnish finish and smooth out the entire track.

The first thing was to get the track level and removing the warped areas with shims and replacing bracket boards. This meant replacing the connecting bolts, and realigning the lane guide boards. We spent the better part of three weekends, both all day Saturday and Sunday, sanding and getting all the junction points even so there were smooth transitions between the sections, and removing all the varnish. once we had the track smooth and straight we used a air gun to clean the dust off the track and then went over it multiple times with tack cloth to get it very clean.

At this time we decided where our finish line was going to be and drilled the holes for the detectors for the timer. We also went ahead and replaced the dowels for the starting gate, and made some modifications for the starting gate release mechanism.

Step 3: Staining the Track

As mentioned earlier, the inspiration for the track final look was to make it look as if it was a real raceway. So we looked at options to color the track to make it look like asphalt. To get the desired look we used scrap wood and tested paint and stain and even tried to apply scraps of vinyl. We looked into black paint which did not give us the desired look we were looking for, it gave it a ton of paint strokes and bleeds, and the vinyl would not stick properly to it for polyurethane over it. The paint also was not accepting the polyurethane properly.

So we chose to use Minwax brand black stain. Applying the first coat we applied it thin allowed it to soak in and wiped the excess off. This gave us a good base layer for our other three coats of stain. Each coat of stain that we added we added slightly thicker and allowed to soak in the wood and dry without removing. This gave us a deep rich black color before the fourth and final coat. The final coat was our thickest coat we applied. we allowed it to dry for several days before coming back to remove the excess.

Step 4: Build the Finish Line Timer Box

Due to weather, we were at a day where work on the track itself had to stop besides some light sanding to scuff up the stain to prep for the polyurethane.

So now we built the box that would house the Arduino and other electronics needed for the timer. The box was designed to house the components with giving it a bridge type feel. We first started out by building the framework by ripping a 2x4x6 in half, and making our cuts for our desired dimensions. at the base we allowed for enough room to place 1x1s on each side to make the timer fit snugly against the track. This will help in the long run of things so that all you have to do to line up the LEDs and detectors is to slide the timer housing up or down the track. It also allows an opening on the inside of the frame to run wires and allows for ventilation. Once we had the frame built we had to leave enough clearance for the cars to pass under, we achieved this by placing the tallest car we had on the track and adding two inches. I can not stress this enough be sure to check the fit of your box against your track each step. Also, make sure you are completely square with all cuts and attachments, each step of building the box. For the bottom of the box cut your plywood to fit the bottom with no gaps then with the box in place lower the bottom of the box, onto dowels put into the detector holes. Take an inkpad and cover the top of the dowels with ink, working quickly, then use the dowels to mark the holes for the LEDs. This will give you precise measurements where you need to drill your holes to where they will line up.

As you can tell by the photo we were originally just going to make the entire cabinet out of wood. We had found some sheet aluminum that would give the box some extra flair and cut it to size for the sides, and access hatch on the back and to accent the front. Which I will say made it look nicer.

Step 5: Polyurethane Time

We were fortunate to have someone that worked in auto body and paint assisting us with the build. So with his help and his ability to spray the polyurethane saved us a few weeks of work.

We took all the sections of track outside and placed them on stands in the sunlight to assist in the drying. Important note, be sure that there is no wind if you are planning on spraying the polyurethane. After each coat of polyurethane is dry we used 120 grit sandpaper to take down any runs or bumps in the polyurethane and scuffed each coat so the next coat would take to the existing coats. We applied the first four coats of polyurethane before moving onto the next step.

Step 6: Vinyl Decals

I want to apologize for not having photos of this step. Between the fourth and fifth coats of polyurethane we went ahead and added the vinyl decals. This was a tedious step but in the end it was worth it. We added decals that we had made to indicate the start and pinewood derby lettering. then using vinyl colored tape we added a green start line above the word start, white track edging, yellow lane indicators between each lane, and no track would be complete without the checkered flag finish line which we placed directly over the detector holes and just cut the decal to allow us to press the decal into the holes and access the detectors. For the yellow and white markers we assembled the track completely and ran a solid line of the vinyl tape from the top of the track to the end making sure it was straight. We then went behind with straight razor blades cutting the section junctions and folding them under. To achieve the dotted line look we took two scrap pieces of wood to the dimensions we agreed on and used them as a template to allow us to cut and remove the unwanted pieces of vinyl tape to achieve the effect.

Important note on applying these if you have never applied vinyl decals before. Use a credit card or plastic putty knife to take out the air bubbles and make them lay flat. Take your time when applying these to make sure they are straight.

Step 7: Final Coats of Polyurethane

After the tedious work of all the vinyl application, we sprayed our last two coats of polyurethane on the track to seal it. The trick here was to spray it on thick without any runs or imperfections to give it a smooth glass-like appearance. This step helped also smooth the track out and make it shine. As you can see in the photos. Now onto our timer.

Step 8: Timer Build

Next it was onto our timer build, since we had the bridge already built it was time to get down to the headache of the project. All the information of this step can be found here, including schematics and the timer code. I will apologize now for not being more indepth on this area, due to most information we used is in the links.

First thing we did was take the sheet aluminum and made all our cuts for the LCD displays, and attached our piano hinge to make the access hatch to the electronics in the back. Next we took a grinder with a brush disk and scuffed all of our sheeting to give it a brushed look, then cleaned it with alcohol. We drilled holes in one of the side panels to run our Printer cable to the Arduino for communication and wires up for our cable boxes. We then took red electrical tape and covered the edges of the LCD holes and gave an outline to our LCDs before attaching them. We wired the detectors for the track to telephone wire and a telephone jack to where it would be easily connected and disconnected to the track. Our start gate switch we ran a 30 foot cat5 ethernet cable and added a cat5 box on the track and to the timer box for easy connection and disconnect. We then hot glued our LED lights and LCD screens into the box and wired them per the schematics. To mount the Arduino and PCB inside the box we cut a piece of honeycomb, old political race sign, that would fit in the box above the LED lights and keep anything from touching them. we attached the board to standoffs to raise them off the honeycomb to reduce the risk of static. All of our wires were retained on the frame out of the way with cable clips.

We had to play with all of the wires to identify what wired communicated with what so we labeled them with basic painters tape and a marker. You will also see some notes were made on the inside of the box. After following all the steps on the website in the link above we attached the wood face to the front of the box. We then added the aluminum tape to the corners to finish off the look.

Step 9: Testing, Race Day, and Conclusion

Now that everything is complete its time to test the track. We finished the track and timer build only a day before our race day. Our testing was just hours before we started the derby. It is a good time to double check all your connections and just run a few practice runs to make sure everything is running correctly. Also I suggest taking a little mop and glow floor polish and wipe the track down on race day. It will make it shine and clean the dust off of it.

For our races we set up a playlist of songs that are all about cars, racing, and going fast and play through a PA system that I provide. I run all of this off the same laptop that the race software is being ran on. After we completed this build we had a track that after leveled and sanded would run a 4.5 second race to a track that ran 1.254 second races. We currently have the fastest track in our district and our council.

I do not have any other pictures of the finished project or of it in action but will update with more when we have the next pinewood derby.

Please let me know what you think of this project and if you build it, I would love to see pictures. Feel free to contact me with any questions, comments, or anything else. Also we are doing another track this year that we will be doing differently and will document this one much better.