Short-Scale Tenor Guitar

Introduction

This is my first real design, and it's still a work in progress. 

It's a four string tenor guitar. All parts are 3D printed, except:

• a set of standard guitar tuners.
• nylon or gut strings.
• a 12 ¼ inch double-action truss rod (I used this one) 
• A couple of m3x20 bolts and hex nuts for solidly bolting the neck to the body.
• Fretwire. (I don't like 3d printed frets, so the model is made with slots sized for standard guitar fretwire.)

Strings

Currently, this needs to use nylon strings; if you use metal strings, the body will warp.  In a future version, I'll probably work in a slot for a carbon fiber rod, because it'll sound a lot better with metal strings.

Printing

I printed this in PLA, and I think it's the best material for it. In my experience, there would be tiny adhesion gaps - and any gap has a major effect on the sound. PETG is just too flexible.

I'll update this as I make changes.

Assembly

• For the most part, it should be pretty obvious. 
• All of the large parts - the neck, body, and fingerboard - are split to be printable on a MK4, and they have studs and sockets to fit together. Each of the split parts should be glued, with either cynoacrylate, or epoxy.
• Insert the trussrod into the neck, with the hex socket in the opening in the headstock. 
• Glue the fingerboard to the neck. You should line up the bottom edge of the fingerboard (the part that doesn't have any fret lines) with the edge of the neck heel.
• Wrap the neck and fingerboard in rubberbands to hold the fingerboard in place while the glue sets. 
• Glue the nut to the neck right above the top of the fingerboard.
• Mount the tuners into the holes in the headstock.
• Attach the neck to the body. It should fit into the slot in the body. Then run a couple of m3 bolts through the back of the neck-heel into the holes in the body's screwblock.  (I designed it with slots for hex-nuts, but found that the size I made the holes forces the bolt to cut threads into the plastic when it's screwed in, and that's more than enough strength.
• Mount the strings, and set the bridge under them. You'll need to adjust the bridge position a bit to get the intonation to work correctly. It should be 18 inches from the top of the fingerboard to the bridge.