Earning A Merit Badge With A Pinewood Derby Photo Finish

2/4 store-bought bodies

As a boy scout properly acculturated into the DIY philosophy, [Adam] really wanted to get his hands on the new Inventing merit badge. The merit badge required solving a problem, so of course a pinewood derby instant replay system was the obvious solution.

After thinking through a few solution paths like a radio-controlled camera that follows the cars, [Adam] settled on a system that would replay the pinewood derby cars crossing the finish line.  [Adam]’s father found a cheap and readily available Playstation Eye camera that can record 60fps video for this task. [Adam]  used a laser/photodiode/Arduino setup to detect when a car was crossing the finish line. A bit of Processing code supplied by his father records the relevant 60 frames of video and plays them at 5fps on a projector for the enthralled spectators.

We suspect that a similar setup could be used if [Adam]’s den wanted to try the rain gutter regatta or oft-forgotten space derby next year. Check out [Adam]’s instant replay system after the break, or join us in the comments for the inevitable argument over who had the best pinewood derby car.


36 thoughts on “Earning A Merit Badge With A Pinewood Derby Photo Finish

  1. Awesome. As a bystander I can verify that the scouts are always blocking the view to the finish line. An instant replay of the end of the race not only eliminates arguments over who won, it greatly increases the enjoyment factor for those who elect to sit down. I’m going to put this on my project list.

  2. I am knee deep in PWD right now. I love the idea of the instant replay. If solves the issues mentioned plus gives the scouts an additional “diversion” while the next group gets ready to race, and provides the MC with commentary opportunities.

    Nicely done and a great project for the inventing MB.

  3. Many PWD track suppliers now sell timer systems that tie into racing software to automatically calculate race times and assign points/standings. We use a simple system with LEDs but will probably upgrade to such a system next year.*

    Still, this is cool. The biggest benefit is that it removes (hopefully) most human judgement and provides a cool visual for the audience. You’d be surprised how petty and combative some parents can be towards volunteers just trying to do an honest job of being fair.

    * I’ve seen an Arduino system built as an alternative. Most racing software just needs a serial dump of data (lane and times), so it’s another DIY project that can be done. It’d be awesome to have both with the system overlaying lap time onto the photo.

    1. Exactly – we use the SuperTimer 2 setup, the instant replay system was only for the enjoyment of the parents, not to judge winners or settle disputes. If anything, it lowered the number of questions from parents because they were busy watching the big screen, not questioning all the variables…

  4. The bigger problem with the PWD – at least as I saw it – was that the competition tracks weren’t fair. Four tracks, but the car in track #2 won about 80% of the time. For whatever reason, that was the smooth one.

  5. A friend of mine recruited me to build an electronic finish for a 16-track PWD he put together for Boy Scouts.

    Having actually done this, I can say I’m very impressed. And Adam’s is way cooler with photo-finish!

  6. Hmm, “Adam” Invented it huh? Or are you sure he didn’t just invent a way to get DADDY to do almost all the work… All “Adam” did was build the stand for it, DADDY wrote all the code, selected all the parts, ordered them, likely did all the soldering(a kid the age of “Adam” can safely solder with supervision) – No offense “Adam”/DADDY, but if I were your scout master I’d want to see a heck of a lot more scout effort and a lot less parent doing it for you.

    1. Don’t judge without knowing the guy personally. When I was a kid doing pinewood derby people always thought my old man was building cars for me, when in reality it was all me. Luckily I took it as the ultimate compliment and tried to shrug off accusations.

    2. He already has his Electronics merit badge (including soldering), has taken Arduino classes, and is a part of the Young Makers program at FamiLAB, our local Hackerspace (www.familab.org). If you go to our family blog (www.raisinggeeks.com), you’ll see him building lots of kits and participating in classes / events that led up to this build.

      You are correct that there was mentoring involved, and that our Scoutmaster will have to judge if he met the requirements (which are a lot more than just the working prototype). I made sure along the way to NOT decide things for him (outside of the low-level coding stuff) – it took FOREVER that way and was quite frustrating at times, but he needed to stay in control of the concept and the outcome for the very reason you mention.

      I know quite a few inventors – but few of them possess every skill needed to bring their creation to life. Inventing is a process which includes getting input and feedback from others, as well as obtaining the materials and support from others to bring your creation to life.

      1. @cz
        True, but having been personally involved in Cub/Boy Scouting, and Exploring MUCH more often than not it is as the saying goes “if it looks too good…” IOW parents helping a bit TOO much

        @sawo, Eirinn
        if you are talking about the simple statement at the end of the video that generally says Adam designed(and i assume built) the stand, nd with input from others placed/pointed the camera & sensors… no word in that about any of the wiring, selecting of the actual components used, etc

        @Ian Cole
        Like I said earlier in this comment after being in scouting for as long as i have been… Maybe I am a little quick to judge, though sadly it often does end up being like I had suspected :(

        I think it is great that he has his electronics badge and is also lucky enough to actually have a local hackerspace. and a group for young makers neither are available in a hour radius of ME last time I checked.

        I would hoe since this is just your proto-build that Adam would be more involved in coding the processing/duino code now that you knw it works.

        @Ian & Adam Cole
        Sorry if I sounded like jerk, the project is a pretty good idea.

        @Adam Cole
        Remember the mantra of many great engineers and programmers – Document, Document Document” the more you write down and document about the process the less likely someone will say you stole the idea or that somebody else did it for you.

        As an interesting side-effect of documenting stuff I have often thought of better ways I could have done it as I written down what I did (sometimes even redoing large portions of the work when I realized I could make pars significantly more efficient if I hadn’t done it the bone-headed way I did the first time :P

        Young men and women who are 14 through 20 years old (15 through 21 in some areas) check out your area for “Engineering” Explorer Posts, they are a great opportunity to learn about cool stuff in the field, possible jobs, advice on course that benefits various fields, etc… and often also throw in un stuff like field trips to technology companies, museums, and of course theme parks(a roller coaster takes a lot of engineering and they’re a blast to ride) :)

  7. Love this idea, we just had our derby this past weekend, my son won and he made the car himself. Would have loved this system in place, the very first race a parent complained that his son came in first place and the computer showed him in 4th place. I’ll definatily be building one for next year. Thanks for posting such a great idea.

  8. This is something that all parents should do, be actively engaging their children in hobby electronics. Its great time to bond with each other, and it develops their interest in science and engineering.

    My dad did this with me a lot when I was a child, and I think it is probably one of the main reasons I am studying EE.

  9. Great Job! Man the tech for the race hasn’t changed at all if that headline picture is from the race. I still remember that dragon decal and accessory set from the days when I was racing them! Wish we had photo finishes. We had alot of close races.

  10. Super work guys. As a retired Engineer and father of two boys, this is one of the best ways to help a future and cement a relationship. I revel in the memories all the projects I helped on, side by side with my boys and another, as we all grew up together! As do my boys! One a chemical Engineer / Patent Attorney, the other an Aero Engineer working on a new business project with an Ex NASA physicist.

    Is there any possibility of attaching one of the Slo-Mo’s in the video above….?
    Steve N.
    P.S. Folks. WHERE is the best place to put the weight in the PWD car, huh…?

  11. When it’s like that it’s sad. Those tpes are to be avoided if at all possible. I still hear from that other neighborhood fella that my boys and I worked with on so many projects. He learned a lot and really appreciated my being there and treating him as just another guy trying to figure things out. Sure, at times you have to steer things away from hazzard and keep the failures from coming too fast if they are not having at least some successes. There are still some partly finished projects in my basement that I didn’t steer them away from.
    Any one Want a partly finished audio board for a home made FM radio station?? or two? Or the working station 1/2 a watt – 1 mile class A radius…
    Yes, I did the detailed design and even some soldering, but all the high level design requirements were done by the boys and all the sheet metal was bent on Ralphs (dad’s)brake and rivited and drilled by the boys. It was a real team, just like I experience in Engineering on a project. The wise mentor allow mistakes to happen. Hearing “You knew that wouldn’t work, dad.” followed by a smile is one big reward. Then there’s the time Dave wanted to decompose water into H & O. Found out later, he wanted to make a hydrogen bomb! cute now.
    Working on a PWD car I said: “Well Dave. We’ve done everything we can think of to make the thing go fast. We gotta’ win. Unless there’s something we didn’t think of.”
    Son: “Like what, Pops?”
    True story.

  12. Excellent job. My son and I have been through four Pinewood Derbies – even went to district once (oddly, that was the car with the least amount of effort and sloppiest paint job – he ran out of time). Perhaps Dad did some of the lifting, but the result is way beyond what the average scout can/wants to do – Adam is commended for his work. Job well done. Wish we had one of these during our derbies.

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