Where my son competes in Pinewood Derby, they have pretty strict rules on what work the boys must do on their own cars.  The boys divisions have strict rules about what can and can't be done.

But THEN there is a DAD's division!   The rules for the Dad's division are as follows:
1) Weighs less than 5 ounces
2) Fits within 1-3/4" by 6-15/16"
3) Uses the wheels in the kit
4) Bring it!

Now, I am a member at TechShop (the one in RDU) - http://techshoprdu.com
I decided that I would use the opportunity to learn some new skills, and I would use the Shopbot!

Follow along for an adventure to learn what to do (and what not to do....)

Step 1: Computer Work

I had never done any 3D CAD before so I started with Google Sketchup.  I decided it would be interesting to learn, and it had the added benefit of being FREE and running on my mac.  (If Autodesk 123D had run on my mac that would have been a better choice.)

It turns out that Sketchup was NOT designed for this type of work.  I wasn't going to pay $495 for the pro version (which had solid tools.)   I should have just gone to Techshop and used Autodesk Inventor there.  (But I didn't know how to use that either, and I decided that I would just go ahead.)

Anyway, I browsed the Google 3D Warehouse and downloaded a model of a Camaro.   Then I scaled it from the full size down to the width I needed my wheelbase.  (1.5")  I deleted side view mirrors and other details (like the inside of the car).

I downloaded a free plugin that let me export STL from Sketchup.   Then I pulled it into Partworks3D (on the Techshop computers) which let me do the CAM work.  (That is the photo above.)
Do you know how to solve wheel chatter? my dad and have made 14 cars and never solved it.
<p>Probably late with an answer here but....wheel chatter is usually caused by one of few things: 1. the axles and wheel bores are not polished or lubricated enough 2. Axles are polished too much (reduced in diameter) 3. Wheel bores are enlarged usually from over-polishing. Also, your gap between the wheel hub and the body of the car should be about 0.030&quot; or the thickness of an old credit/gift card.</p>
Nice car! Any chance you would have the g-code. I have a CNC and would like to try. I use V-Carve Pro.
<p>For what it's worth, shopbot doesn't use g-code, they use some proprietary form of g-code. So what you really want is the model to load into V-carve pro. </p>
<p>Okay. Do you have the V Carve file then? Or the *.stl? Whatever file I need to use CNC.</p>
<p>I know it's late to ask this but you can't just leave us hanging: how did the car do in the race!</p>
<p>The car that was the straight block of wood where the adult spent all of the time shaping wheels and polishing axles blew away all of the other ones. I did place in the design category, but it was a ribbon and not a trophy.</p>
<p>I am making a pinewood derby car. This gave me some great ideas to do in our school CNC, but I am making it out of purple heart and I don't want to break any bits on the router. Awesome idea</p>
That should be beautiful. I look forward to seeing your creation!
5 gallon paint stiring sticks are perect for fenders, and they are the same width as the stock wheels..
Looks good, great job! I would suggest sanding it more though, it looks a little rough
agree. I just was low on time.
Just say you are going for the dimple effect...you know...like a golf ball...for speed.
I see, well good job anyways
Neat project, but doesn't that take all the fun out of a pinewood derby: carving the block yourself?
I guess it depends. I find learning new tools to be a lot of fun.
When I was a kid my brother and I had Matchbox cars called &quot;Chevrolet Astro&quot;. The look of your derby car is very reminiscent of them and brought back some fond memories.<br><br>Keep your son in scouts as long as you can. Kudos.
You sound like a typical Cub Scout DAD, always to the last minute! Looks great! Love it!

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