CNC Improves Acoustic Guitar Building

     The use of cnc in building a guitar is a game changer. The combination of machine precision used in a creative way with hand finishing craft behind it is a powerful combination. This tool has let us build a better guitar, in less time. We can repeat the some of the tasks which lets us spend more time working on a piece by hand.

     Placement of the frets, radius of the fretboard and bridge pins for scale length are derived from formulas, it is nearly impossible to get these in the exact right spot in practice. Small amounts of variance add up and contribute to a less articulate instrument. We can make these cuts with precision that ensures it’s in the exact right spot.

     The cnc has opened a new pathway for art. The interlocking wave is a signature of Portland Guitar, its creation is in the small strips of wood that are routed into waves. Many designs are possible. This is not possible by hand.

     Our split saddle bridge has many small channels, and the nut itself is at an exact angle. These are possible using small bits to get into the nooks and crannies. Since we can create multiple pieces of the same size, we can change the action with the addition of different plates.

     We can achieve a near flat fretboard with very little sanding and altering of the crowns of the frets. The fretboard is planned flat and so is the top of the neck which the fretboard sits on. These flat surfaces ensure that when the frets are pressed in they are level.

The use of the cnc has opened a wide variety of opportunities.

Here are some videos! 

This is our cnc. It’s a Laguna IQ pro ATC, we built a box for it and but acoustic batting in the sides. We’re running out of a garage in a neighborhood in Portland. So it’s important to be quiet.

One of the first places the cnc is used is on the top. We use it to route the rosette pocket, sound hole, and bridge pins.

Here is the rosette in place

One of the biggest improvements to our process is in the joins of the top and back. A single profile path can be used to put a fresh edge on our two pieces. Then they have perfect contact when glued. They are book matched when cut so the grain is symmetrical.

The heel blocks and neck blocks are also made in the cnc. The repeatability and uniform nature of these blocks allows us to create multiple necks for the same guitar with relative ease.

The artful purfling we use is an interlocking wave. Strips of wood are taped down and then routed out in bulk.

we use the cnc to make the fretboard. It allows us to put in an exact radius instead of relying on a jig. The frets are always in the same place with just the right width. It makes putting in the frets simple. We can route out pockets on the fretboard, so instead of mother of pearl dots we can include unique fretboard art.

the cnc at work

we also use the cnc to route the neck here it is doing the top

In order to level the top of the neck we running a planning path, but to get it roughly correct two machine plates are placed over our clamp with two magnets underneath , then the top of the neck can be placed level with those plates.

here it is working on the headstock. We’re able to use large metal table clamps to hold in the parts for the headstock and neck top. They also come in handy securing the head during routing of the back.

Here’s the router working on the back

The neck jig is two pieces, the bottom one is keyed into the spoiler board on the cnc bed. The top piece holds the neck. It has blocks which are keyed to the bottom board which allow it to be rotated while holding a center.

Here is work on the side of the neck

One of the last places we use the cnc is in making the nut. The precision we get in creating the right radius over the fretboard is unmatched. It lets us alter the action on these builds quickly.

If you enjoyed this article check out acoustic guitar bracing

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