Summary

Full 3D View

Frank Kurtis was a successful designer of Indianapolis 500 race cars in the 1940s and 1950s. The 500KK was developed using the same basic architecture as his race cars.

The real thing is much prettier than what my meager design skills could produce, but this model captures most of the key features.

What is a "pinewood derby car shell"?

The pinewood derby is an event created by the Boy Scouts many years ago. Each scout is given a pinewood derby kit typically consisting of a block of wood with slots for axles, 4 wheels, and 4 nails to be used as axles. The scout (and his dad, usually) will then carve the block of wood into the shape of a car, paint it and apply stickers, install the wheels on the axles, and then race it at the "derby", which involves a sloped track with a timekeeping apparatus.

An official scout derby will usually require that the parts in the kit be used for cars entered in the derby. Other organizations (including workplaces) often hold derbies, too, and some of them require the use of the parts in the box, including the block of wood.

These "pinewood derby car shells" are intended to be used with an official derby wood block, cut down to size, along with the axles and wheels included in the kit. A printable model of the shaped wood block is provided. You can either use the printed model or use it to accurately cut an official wood block down to size.

Print Settings

Notes:

• Car body: Extensive supports are required. In Bambu Studio, I use Normal (auto) supports in Snug style. I prefer ABS for my car bodies because it sands smoother than PLA, even after using the smoothing technique described below. But PLA will work.
• I chose to paint the recessed surfaces of the front grille, to create the illusion of depth. It can be printed in all one color.
• All other parts print really easily.

Post-Printing

Just super glue all the parts together.

Note: The finish of the car in the photo was achieved by rubbing graphite powder into black gloss paint (dry to the touch). For more details, search the internet for “Mandalorian helmet graphite”.

Smoothing

This car was smoothed with 3d printing resin and baby powder. You can find videos and guides online that describe the process, but here it is in a nutshell:

• Mix 1 part resin and 2-3 parts baby powder in an opaque container (so that it can be stored without hardening due to UV exposure).
• Using a paintbrush or cotton swab, spread a thin layer of the resin/baby powder mix over the body, wherever you want to smooth print lines and gaps.
• Use a UV flashlight (a cheap one--like the kind used to harden resin finger nail polish, which you can order from Amazon or buy in the pharmacy department of Walmart) to harden the resin.
• Sand the body smooth until there are no thick layers left.
• Repeat over any areas that are still rough.

Weights

You can add tungsten weights to the holes in the rear of the body. If you plan well, and use enough infill, you can maximize the weights and end up right at 5 oz.