Making the body cavities

Routing the pickup cavities

Make the pickup cavities 19mm (3/4") deep. With some modern single-coil pickup shapes you can use a 19mm (3/4") cutter bit for this by simply guiding the router base along a fence fastened parallel to the pickup cavity (1).

Other pickup shapes require templates for cutting out the cavity. You can either buy finished pickup cavity templates or you can make your own. These templates should be made very accurately and should be slightly larger than the cavities are to be. Corners can be drilled and tidied up with a hand saw and a file (2). Cavities for humbucking pickups are shaped according to the mounting rings used (see drawing on opposite page).

If you have got a ready-made pickguard, you can also use that as a template for making a template for cutting out the pickup cavity (3). Fasten the ready-made pickguard (which already has a suitable pickup cut-out) onto the material used for the template and rough-cut the shape of the cut-out on a drill press. Then use a small-diameter flush-trimming cutter bit with end-mounted ball bearing in a table-mounted router. This will give you a 1:1 template of the pickup cut-out. To make sure the ball bearing rides against the pickguard well, insert a sheet of veneer or a piece of cardboard under the pickguard. The cutter bit should be able to follow the whole of the outline; where this is not possible, as in the corners, some filing will have to be done later.

Cutting out rectangular pickup shapes is fairly straightforward: fasten a couple of not-too-narrow pieces of wood around the pickup cavity cover (as shown in picture 4), making sure to leave a bit of room on two of the four sides so that the pickup doesn't sit in the cavity too tight. Again pre-drilling is necessary before cutting out the cavity with a router.

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Copying an already-existing pickup cavity

The shape of the pickup cavity could also easily be copied from an already-existing guitar body by fastening the pre-drilled template on top of the cavity and then cutting out the shape with a plunge router fitted with a small-diameter flush-trimming cutter with endmounted ball bearing.

It is advisable to pre-drill pickup cavities before cutting them out (1). Again set the stop to the point of the bit. Small-radius corners or round pickup “ears” are best pre-drilled (1) using bits that have the right radius. Remove most of the remaining wood with a Forstner bit (2,3) and a chisel to keep stress on the router bit low. Then cut out the cavity using a flush-trimming cutter with shank-mounted ball bearing (4,5). The few millimeters still left due to the point of the drill bit can be routed off at the end.

Routing the control cavity

For mounting the pots and switches in a control cavity on the back of the body holes have to be drilled into the body from the front. Drill each hole with the same diameter as the thread diameter of the component fitted in it (6). After that cut a cavity for the controls from the back of the body, using a Forstner drill bit (7). It is important that you drill deep enough to allow screwing the mounting nut onto the thread. By doing so only a thin layer of wood will be left in the cavity area of the body. It is not necessary to make the whole of the control cavity bottom equally thin - the areas where no pots or switches are fitted can be made less deep (8).

Carved-top guitars require special pots with extra-long thread shaft. However, standard pots can be used if these are mounted on a plate as shown in picture (9); the plate is then simply screwed to the bottom of the control cavity. To make it possible for the plate to lie flat on the bottom of the cavity, despite its projecting mounting nuts, small recesses have to be drilled into the bottom of the cavity for these nuts.

The hole linking several pickup cavities is best drilled starting from the neck pocket (10). The link to the control cavity has to be drilled at a very flat angle (11), using a piece of veneer or cardboard under the drill shank to protect the body. Use an extralong, 6mm (1/4") drill bit for drilling these channels.

Drill the jack socket hole with a 25mm (1") Forstner bit. If you have access to a drill press, fasten the body upright and drill the hole from above. Alternatively, you can put the body in an upright position in a vise and clamp two thick pieces of wood to it as shown in picture 12. This will give you a solid surface for a stand-mounted power drill. How deep the hole has to be made depends on the jack socket used. If you don't have a drill press or a stand for your power drill, you can also drill the hole by hand as shown in picture 13. Finally, drill a smaller hole to the control cavity for the jack socket wires (14). Remember to also drill a hole from the control cavity to the bridge for the ground wire.

Routing corners

The great radius of a ball-bearing- guided flush-trimming cutter bit makes it impossible to rout tight corners.You could, however, use an ordinary 6mm (1/4") bit and carefully rout the top of the corners first and then set the bit lower so that its shank serves as a stop, although it would be better to pre-drill small radii before routing.

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