February 24, 2010 - ModGuitar Senior Editor
ModGuitar Custom Midi Guitar Build
Midi Guitar Custom Build: Continued
From a design perspective we wanted to not only conquer the elusive custom Midi controller beast but also take a stab at a few other ideas.
Design goals for a custom midi guitar:
- The body will have a carved top and be essentially hand carved to be form fitting and ergonomic including a deep belly cut and a highly contoured forearm rest area.
- The bridge will be set back toward the end of the instrument more than typically to shorten the instrument overall.
- The upper horn will extend out further ending near the 12th fret area to give the instrument balance.
- The neck pocket will be longer than normal to create a greater surface area for vibration transfer, and allow for a more conformable contoured heel.
- The volume control and switch will be installed far away from the playing area to eliminate accidentally bumping them during play.
- The headstock will have a modern look, while retaining vintage styling.
With our design goals in mind, we laid out our planes on paper, and then transferred them to our Alder blank.
The Nitty Gritty
Luthier’s Tip: When working with a body blank plan ahead by doing some (or all) of the routing before cutting the outline of the body out with a bandsaw, so that the router has a flat surface to work on.
The neck pocket is routed using a template. Then the pick-up routes and the control cavity area are also routed using templates. You can make your own custom templates, or purchase them from suppliers like Stewart-McDonald.
Cutting Out The Body: There are a number of different ways of shaping a body: band saws, jig saws, routers with templates, and sanding drums to name a few. For this project a band saw was used. A fine cut blade is installed, the guard is set a 1/4″ or so above the material. A slow and careful cut is taken, particularly around the inside corners and outside curves. The cut is made just to the outside of the pencil line. This allows for some sanding to remove cut marks, and refinement of the shape.
Above, the body shaped and rough sanded.
Luthier’s Tip: Good band saw technique is knowing when to move faster or slower as the material is fed into the blade to optimize the cut for smoothness. To slow and the wood can scorch or show chatter marks. To fast and there is a risk of getting off the ‘line’ of the cut.
Particular care is taken with the tighter curves around the upper bouts. The band saw blade can only flex so much, so there is a limit to the tightness of a curve it can cut. The risk of breaking a blade and possible injury is not worth trying to cut a small curve. The technique here is to cut sections of the curve a bit at a time, and then refine the cut using rasps, files and sandpaper if needed. With the the body shape cut out of the blank, next the edges of the body are sanded smooth and a router is used to ’round over’ the edges of the top and back. Using 120 grit sandpaper the edges are then touched up as needed.
Routing The Body: The design of this guitar calls for a string-thru the body bridge. Using the actual bridge as a guide, the location of the string channels and mounting holes are marked.
Luthier’s Tip: A common problem for those with home work shops is the availability of a drill press that has a deep enough ‘throat’ to drill precise 90° holes. A work around solution is to make a template block on a smaller drill press, and then carefully clamping the template to the body and using a portable drill to make the holes. This works, but more than likely the holes as they come through the back of the guitar will be slightly misaligned.
Once the six string channels are drilled. From the back of the guitar the holes are then counter-bored with a slightly larger drill bit to accept the sting anchor grommets. Again, this operation is best done with a drill press, but can be done by hand is absolute perfection isn’t required. A extended drill bit is then used to carefully drill a hole at an angle from the treble pick-up cavity to the control area, and then from under the bridge to the control area for the ground wire.