First, Carve a Cavity in the Pinewood Derby Car Block

It’s easiest to carve the cavity before shaping the Pinewood Derby car. Choose a location near the center of the car on the bottom to mount the circuit board. Carve out a cavity 1 1/8” wide by 2” long by ¼” deep. This is slightly larger than the board to allow some room to work and slightly deeper to allow room underneath for the extra wire.

pinewood derby block showning preferred location for installing circuit board

Trace around the circuit board on the bottom of the car block to mark the size of the hole and cut outside the line. Remove the wood to a depth (adult supervision) of ¼” with a chisel or a drill.

Use a chisel to carve the cavity

With a chisel, pound it straight down about 1/16” outlining the marked hole. Be careful near the edges so that you don’t split the wood. Then using the chisel at an angle, remove the wood in the center working with the grain of the wood. Repeat this process 3 additional times until the opening is uniformly ¼” deep (about the depth of 3 stacked nickels).

Alternatively, use a drill with a forstner bit, spade bit, or even a normal ¼” drill bit. Wrap some tape around the drill bit ¼” above the end so as not to go in too deep.  If using a spade bit make sure the tip doesn’t go through to the top of the car.  Drill out all of the wood in the cavity to a depth of ¼”. Use a small chisel or a utility knife (adult supervision) to clean up the cavity.