Midi Guitar Custom Build: Continued
Custom Bridge Work: For this Midi guitar some additional routing was required. The six graph-tech, ghost system saddles that retrofit into our string-thru bridge have a hook-up wire that needs to be fed into the control cavity, and then attached to the Hexpander midi control expansion board. First the bridge is carefully prepared by marking and then center punching a spot ahead of the string hole. Then holes are drilled that are just large enough for the hexpander connector to pass thru. Other options are to pass the wire forward of the saddles and under the hum-bucker pick-up ring or to route a separate hole ahead of the bridge plate for the wires. Milling the bridge plate to allow routing the hook-up wire to pass-thru was more time consuming, but the end result is a cleaner look. However there was some difficulty in perfectly centering the holes to avoid problems with the saddle height screws. To wrap up this custom saddle installation a small channel was routed under the bridge to make room for the hook up wires.
Above: Graphtech Ghost Saddles fitted into a Stew-Mac custom bridge. On the right you can see the holes in the bridge plate with the piezo sensor wires threaded through.
Below Left: The control layout consists of one volume control and the regular pick-up three way switch. Control of the MIDI functions is handled outboard. The output jack is a Tele style cupped unit, the 13-pin midi connector comes with the Graphtech kit. On the right: The Graphtech Ghost System pre-amp with the Hexpander add-on wired in with the regular guitar controls. The Circuit board on the bottom is part of the Roland Standard 13-pin MIDI output jack.
Body Sculpting: The design calls for an ergonomic and stylish solution for the body. With that in mind the top had a slight curve carved around its perimeter, as well as having a deep belly cut and highly sculpted forearm contour. Again, there are a few ways of accomplishing this; Guitar factories rely on complex CNC routing machines which use templates and programmed patterns to consistently shape guitars out of wood blanks. Luthiers have for centuries used hand planes and scrapers to shape and sculpt wood. Modern craftsmen often use power tools and other modern conveniences to quickly remove wood.
To maintain control and assure an attractive final result a combination of hand tools and power tools were used to sculpt this guitars body. A tip from an internet guitar forum suggested using a rotary grinder to quickly remove wood. This worked well but left gouges and tended to scorch the wood. Rotary sander can also be used to rough-in shapes. The forearm and belly cut both required the removal of a lot of material. While it’s tricky, and not the safest machining operation, a band saw with the table set to a 45° angle can be used to remove most of the material. With the bulk removed, a small curved blade plane, a block plane, smaller hand plane, rough curved and flat rasps and files, as well as sandpaper held loosely and with wood blocks were all used to sculpt the bodies contours. The top was mostly carved with the small ‘violin’ plane which has a convex bottom surface and blade. It takes some skill to use planes effectively, both in set-up, sharpening, and use. Time spent practicing on scrap wood is a good idea. A detailed tutorial on using planes and other shaping tools for guitar making is best left to another article. Moving on… As the body takes shape parts can be laid out to get an idea for the look of the final guitar. There’s nothing quit like that first time all the parts come together. In this way how the instrument balances in the hand can be judged and changes made to the design if possible. It’s also a good idea to test the fit of all the parts before going ahead with the finishing process.