Fig. 6. Tracing the neck heel contours onto a full-pocket maple shim.

Crafting a shim. Use a hobby saw to cut out a rectangular piece of wood that’s slightly wider and a bit longer than the neck pocket. Begin by tracing the neck heel onto your rectangular piece of maple (Fig. 6). Next, using the 80-grit sandpaper or a belt sander, trim the wood along the neck-heel line. Frequently check your progress to assure a close fit (Fig. 7).

Fig. 7. Checking how the shim fits into the neck pocket.

When you’ve shaped the shim so it sits securely inside the neck pocket, trim off any excess length. Using the rear edge of the neck pocket as a ruler, mark the trim line on the shim, remove the extra wood with the hobby saw, and then sand the edge smooth.

Fig. 8. Using a pencil to mark the bottom of the shim before sanding it into a subtle wedge.

Once the shim fits the neck pocket, the next step is to shade its entire bottom with a pencil (Fig. 8). This will help you know where to sand and how much material to remove.

Fig. 9. Getting ready to sand the shim to its proper thickness and angle.

Next, place the shim on the belt sander—make sure it’s turned off—with the shaded side face down. Lay your sanding block on top of the shim with the 80-grit paper against the wood (Fig. 9).