KOZM Guitars - Heresy II

[Jeffkos]

Howdy,

I just wanted to introduce myself to the group here, and also share some photos of my latest acoustic guitar.

My approach to building guitars is somewhat different. For lack of a better term, I call the process “digital lutherie”.
I design my guitars on the computer, with a computer aided design (CAD) program. I then download the geometry to a program that converts the 3D geometry into G-code, which is used to orchestrate the movement of a computer controlled router, aka a CNC.

I’ve made a number of electric guitars, and this represents an exploration into the realm of acoustic guitars.

All of the bracing and stiffeners are integral – machined into the inside surfaces of the body halves.
I’m striving for a guitar that is easy on the eyes, and easy on the body – i.e., no sharp edges to dig into your arms.

Soundwise, this is only the second one I’ve built. The previous model (The Heresy 1 can be seen here: http://www.youtube.com/watch?v=0HrlcWVh3K4 ) was an attempt to duplicate the earthy-dirt and get-down funk of my very first guitar: a 1965 Sears Silvertone acoustic. The Heresy 1 has a Doug fir top, and I was surprised to find that it actually sounded very similar to the Silvertone.

The Heresy II has a slightly larger body (19” long x 14.5” wide x 3.73” deep) than the H1. Also, in an attempt to make it more expressive than the Doug fir, I went with hard maple for the front. I also intentionally added a lot of bracing – mainly to see how a super-stiff front affects sound.

Anyways, here’s a few CAD screen-shots of the guitar, and some photos of the finished instrument.

I hope to have a YouTube video up in the next few days that will hopefully give you some idea of how it sounds.



From the CAD screen - the finished guitar.








EIR bridge, pick guard and fretboard


Black walnut back, screw on (bolt on) neck.
The neck is made of mahogany, with a strip of maple down the middle.


Side view




EIR rosette


All questions, comments and critiques welcome.

Thanks a lot,

Jeff

[gitnoob]

Welcome to the forum! Very cool design, and very heretical. That CNC rig of yours must spit out a ton of sawdust.

Have you considered a conventional top and carved back? You could include some nice ergonomic features in the carved back, and the conventional top would allow you to get a more conventional tone.

Sort of like the carbon fiber builders....

[Thrillhouse]

Wow this is very cool. Do you build for others? I know you are just getting started in the acoustic thing but I'm interested.

[Tim McKnight]

Interesting design Jeff. I would question your top bracing unless the top is extremely thick and over built? The rotational force on the bridge will put a lot of torque just below the sound hole. The conventional X brace redistributes that load into the upper bout and into the sides. I would venture to say you may see some deformation below the sound hole on your design [if] it is lightly built, which should be a design consideration of a responsive acoustic guitar top.

[Tony_in_NYC]

Interesting design and guitar. How does it sound?

[mikealpine]

I went to the website and am drooling over some of the electrics. Great body shape, which shapes to the human body. Have to be a joy to hold and play.

[Jeffkos]

In case you're wondering how the Heresy II sounds, here's the link to a YouTube video that I did recently.

http://www.youtube.com/watch?v=srEhzHv30cQ

Thanks for listening...

Jeff

[gitnoob]

I like it -- an upscale little blues box.

You may hit upon the sound you're looking for (or a sound you like) using your current prototyping process, but you may end up with a LOT of prototypes.

If you want to speed up the evolution a bit, sample some tap tones of an instrument you like and target the resulting resonance frequencies in your box.

For example, thump that Larrivee below the bridge a few times and record it. Do an FFT in Audacity of the thumps. You should see a couple of strong peaks corresponding to the "main top" and "main air."

The biggest "tweak" factors will be top size/thickness, box depth, and sound hole size/location.