Cub Scout Pinewood Derby: Building the Batmobile, Part III

This is the third and final post in a series about building a Cub Scout Pinewood Derby car that takes style cues from the Batmobile.

The first post in this series can be found here, while the second can be found by clicking here.

We left off with the chassis structurally complete, sanded, primed and painted black. The next step was to apply the decals that came with the kit; these are pretty standard dry rub decals, and were easily applied with teh blunt end of a clay shaper we had on hand. Of course, almost any blunt object will work for this purpose, ranging from a hobbyist’s burnisher to a humble, dull pencil. The kid was able to put these on with ease.

After the decals are rubbed on, they are still pretty fragile, so the next step is to take a piece of treated paper that came with the decals, and rub that paper over the decals to help prevent them from tearing or being rubbed off during handling.

The next step is applying multiple coats of gloss varnish, for two reasons: first, the varnish will seal and protect the paint and decals, and second, a gloss finish is smoother than paint, so there will be less wind resistance on the car as it travels down the track. Since placing the car on newspaper and then spraying gloss varnish wasn’t an option – the car will end up sticking to the paper, and it’s almost impossible to clean up – we improvised a pretty crude method of suspending the car in the air while we sprayed the varnish. We took a scrap of wood we were using for spraypainting and hammered a few roofing nails into it, so that all of the nail heads were about level. We placed the car on top of it and sprayed away.

After spraying multiple coats – and sanding across the woodgrain between coats  to help reduce the ridges between the woodgrains – we had a fully varnished Batmobile:

We were very pleased with the results thus far, but we did notice that our Batmobile still doesn’t have wheels. Since one of my hobbies is miniature wargaming, I decided to embark on a totally unnecessary but fun task for the wheels while I was waiting for the mutliple coats of varnish to dry. I broke out the highly-pigmented paints formulated for miniatures and the fine brushes I normally use for painting eyeballs and coat buttons on miniature soldiers, did a quick metallic drybrush on the rims to make them appear like brushed aluminum and, using some magnification, painted the raised white letters on the tire walls. While this step won’t make the car go faster, it did make it look cooler.

The next step involves tacking the wheels in place. We used a medium-sized tack hammer for the job, being careful not to mar the paint anywhere.

Now that the wheels are tacked on, it is necessary to align them so that the car will roll in a straight line for 10 feet. If a car pulls to one side or the other when it rolls, it will be grinding along the track guides as it rolls downhill on race day – something we clearly don’t want. fortunately, there is a great how-to video on the Pine Car Web site on this very topic.

One we followed the instructions in the video and had the wheels relatively aligned (we still have a slight pull to the left, but we got to a point where we just had to say it was close enough), the axles were glued in place.

Once the glue was dry, the Batmobile is basically finished. We’ll still need to add weight on race day to get it up to 5 ounces, but the car is done for all practical purposes.

The Derby is next Saturday, Jan. 14; we’ll let everyone know how the Batmobile fared in the race in next week’s posting.

Update, 11 January 2012: in case anyone was wondering, the second car we made as we were working on the Batmobile – the white Trans Am we dubbed “The Screaming Eagle” – turned out pretty well, too: