How to build an oo size acoustic guitar

[Glenn Jennings]

Hi Guys
In this tutorial I will be building an acoustic guitar oo size. With the exception of the neck wood it will be made of local woods. The neck will be made of american Walnut seeing as I still had a piece.

Meant to add this guitar is a bit of an experiment in that it will combine two differnt schools of construction. The top will have scalloped bracing as most normal acoustic guitars do but the back will be made as if for an archtop guitar which operates on an entirely different acoustic concept.
What I am hopingto create is a guitar with full bodied sound projecting the sound in the manner of both types of guitars. a hybrid if you like

Normal acoustics push the sound out in such a way that the sound spreads out very quickly and the player can hear all of the nuances of sound.

With an archtop the guitar projects the sound away from the player so that the player doesn't really get to hear all the nuances of sound the guitar has to offer. To get around this a sound hole is often cut in the side of the guitar in the top bout where it will be close to the players head. By doing this the player gets to hear most of the sound the guitar has to offer.

I hope to create an instrument that will do both so is a bit of a trial.

The format will be to make the component parts then put the whole guitar together.

Birchwood casey sealer and Tru- oil will be the finish on the guitar.

1/ The pick guard
This you can make to any shape that you might happen to like. Many are made of plastics I prefer nicely figured wood. They often have artwork applied to the taste of the maker. I make mine about 2-3mm thick. They are made to fit nicely with the purfling around the sound hole so the rosette around the sound hole has to be of the same radius to look nice.

These are easily made by just marking out the shape you want and cutting it out.

Photo of pickguard attached. This was made from American walnut the insert is made with basswood.

To inlet the basswood into the walnut I used a dremel router to cut around the profile line scribed into the wood staying about 1mm inside the line. The bulk of the wood is removed quickly that way. I then use super sharp very fine blade knives to cut the last mm of wood away cleaning the floor of the cut with a chisel.

The basswood insert has had the edge filed on a very slight ange inward toward the centre of the piece. This ensures the piece is a very tight fit in the prepared cutout as the line scribed around the piece is inside the outer edge of the insert. The basswood piece was lightly sanded to get the fit as close as possible.

The artwork was done with pyrography.

The piece is glued in with tite-bond glue.

[Glenn Jennings]

2/ The tailpiece to hold the strings

Having selected the piece of wood you want and thin it down to 8mm thick. Then mark out the selected shape onto the wood. Best way to do this is to tape the pattern to the edge of the wood then slip graphite paper underneath it and trace over the pattern and this transfers the pattern to the wood.

Take care to get the angle of the bone saddle slot and the pins centrelines correct. Mark the saddle line and the pin centres. You now have the whole pattern laid out on the wood.

Set your piece of wood up in a jig (see photo)The wood is locked in place.and can't move.Set the dremel router up so That the cutting tool runs through the centre of the marked out saddle slot. Put a block at each end to stop the travel at exactly the right spot. The router can now only move within the jig you have made for it. (see photo)

Cut the slot to the width and thickness of your bone saddle. Make cuts of up to 2mm ( the cutting tool and dremel can handle that ok.) I go down about 6mm so there is plenty of support for the saddle and plenty of bone still sticking up to trim to suit the string height when fitted to the body.

Set your wood up on the drill press with a backstop clamped in exactly the right position. I use a centre to get the exact position on one of the holes. then clamp to that position.so the wood is hard up against the back stop all the way.. Then to be sure with the wood hard up against the backstop I check each hole to be sure the centre comes down exactly on the marked hole centre. Check the pin size and pick a drill that would just fit the thinnest part of the pin at the bottom of the taper. For mine this was a 4.3mm drill. Drill a pilot hole 3mm in each of the marked hole positions then repeat with the 4.3mm drill . This helps prevent runoff of the drill bit .

NOTE in the event the drill wanders and the hole is out of line, machine a dowel to plug the hole and re-drill it. Putting a piece of wood in the drill press and just running it down to size with a file will do the job if you dont have a small lathe.

Using a tapered reamer. (any hardware store will have one they are not expensive) fit the pins to the tail piece. . Use a light touch and check often.Especially when you are getting close. When the pin is in so far that it has only 3-4 mm to go, just work it in and out a few times.This seems to polish up the hole a bit and the pin will often go right down for a nice tight fit.

NOTE Pins can vary a little in size so it pays to keep them in the right order. A piece of cardboard cut to shape makes a good holder to keep them in order. see photo.

You can now cut the piece to shape and round the edges to the desired shape. The sides i shave down to around 2-2.5mm at the outside edge. Just gives a bit of shape and a nice look.Sand it all down with 400 grit paper then rub it down with 0000 grade steel wool until it shines. Then apply sealer and finish.

NOTE only seal and finish the top of the piece the bottom needs to be clean wood to get a good glue join onto the top.

[MikeW]

Enjoying this )

[Eddy-Smiles]

Very interesting!

[joepaulbutler]

Awwwwwwwww

[Glenn Jennings]

3/ Making the neck.

The neck is crutial to the playability of the guitar. So care has to be taken in shaping the neck so that it suits the player.

The neck can be made of one piece of wood but glue ups work just as well. I am doing a glue up for this one as I wanted to make use of the piece of walnut I had. You can never have enough clamps on a glue up. See photo

The neck will be fitted with a truss rod so the neck can be adjusted. There are different types of truss rod. I go for the hot rod model as it is double acting and can be used to adjust the neck both up and down and is very thin therefore leaving more wood for strength in the neck and allowing for a lot thinner neck style that some of the other rods. 3-4 mm you think might not be much. It is when it comes to comfortable playing of an instrument.

The conection to the body will be a dovetail join and the angle of the neck will have a 1-1.5 degree downward angle from the top so that when the tension of the strings come on it it pulls up straight.

Having done the glue up the neck is marked out as per the paper pattern. See photo

First job is to router out the slot for the truss rod to fit into. I go slightly wider than the actual rod so that the rod can be packed tight in felt. This prevents any vibration producing rattles in the neck.

With the neck clamped to the bench I make a jig for the router to run in. As it turned out quite by chance by clamping a bit of wood to the back side of the neck the router cutter was in exactly the right place for the cut.

I checked the router bit at each end of the cut to ensure the cut would be correct over the full length.

As with the saddle slot I put a stop at each end of the cut to ensure there was no over run in the cutting. Routers can grab the wood at certain spots in the cut and skip forward quite quickly without warning so cutting as slowly along the cut as possible is a smart way to go.

I made the cut in about 2mm deep cuts at a time until the trussrod fit in the slot being about 1.5 mm below the top of the neck. see photo.

Some people don't bother to put a cover plate over the truss rod but getting a good bond on the fretboard is crucial so I tend to swamp the join in glue and wipe off the excess. By carefully glueing in a cover plate this ensures the excess glue from the fretboard join does not flood the truss rod slot which would likely kill the function of the truss rod. See photo


Note have added quite a bit about the style of the build which is experimental in the first post. This guitar will be a hybrid of two styles of construction.

[Just Carving]

I'm following along with your posts Glenn. The owl looks great on the pick guard.

The wood grain on the tail piece is WICKED! I couldn't imagine having to carve that piece of walnut for anything.

Thanks for sharing this process. It is immensely informative.

BobL

[joepaulbutler]

I'm trying to send your post to my son, I'm thinking they will be of interest to him~thanks for your work

[Glenn Jennings]

Hi Whittlebear
Yes that is a drop dead gorgeous piece of wood. It is an offcut from a rifle stock that I have yet to make. Was $1,250 worth of exhibition grade walnut I got from Armenia. I save every little piece of it to use in other projects. Anything that gets thrown away is too small to do anything with. some of it will be used as fret markers on the fretboard.


3/ The neck continued

Had a bit of a misshap in cutting the slope on the neck and by the time i got it all squared up I found I needed to glue on a piece to bring it back to spec. This is not a problem and will probably help with the strength of the neck and help prevent twisting.

With the glue up tidied up I marked out the headstock of the guitar and marked the machine head holes ready for drilling. I then cut the underside of the neck to profile.

Only having a small bandsaw I had to buzz one side down a bit to get it to fit in the saw. Tis had to be dead square and was spot on.

Before cutting I did a test cut on a bit of scrap to ensure that the blade was cutting at exactly 90 degrees to the work table. It was spot on so continued to cut the neck.

So The neck is now starting to take shape.

The next step is to cut the dovetail join. I do this before the sides are trimmed to size so that any minor error in cutting it which will be done by hand will appear to be significantly less when trimmed to size.

[Mark N. Akers]

Glenn, great so far, the wood and instructionals are absolutly awesome.

[yolli]

Thanks a lot Glenn, enjoying reading and stunning... GREAT

[Glenn Jennings]

Making the neck continued

With ther dovetail all marked out for cutting I set it up in the vice so the cut is vertical. This is easier than trying to compensate for things being on an angle which just doesn't feel right in the cutting.

I used a very fine bladed fret saw to make the cut and each cut was cut half way through on an angle that would have the cut down to the mark on the vertical line and 1/2 to 3/4 of the way across the horizontal line. I then turned it around and repeated the cut, finally, very carefuly finishing of the peak of the horizontal cut down until I could move the piece that I wanted cut out by hand. I then chipped out the unwanted wood and cleaned up the cut with a sharp flat blade chisel to remove the tiny bit of wood left from the cut that the saw didn't remove.

Doing it this way ensures you don't over cut the lines you have marked out and you get a good clean finish to the work.

With the dovetail cut and checked. ( It was spot on for angle.) I was very happy with the way the dovetail went It can be a real pain if you don't get it right so I only do this in good light and check everything several times before making the cuts. The next step was to trim the sides of the neck to shape on the band saw.

When doing this I cut about 1/2 to 1.0 mm away from the line so that I can ensure the correct size wont be compromised. I then sand the wood down to the to the point where there is still about half of the pencil line left. This just leaves a little wiggle room for final shaping.

To sand the sides of the headstock to ensure they are square and dead flat I hold the headstock against a perfectly squared up piece of scrap and work it back and forth on a dead flat board that has sandpaper glued to it. This prevents rounding of the edge and keeps the lines looking nice.

The next step will be to glue on the last piece of the neck heel.

Then the heel can be shaped.

Work on the neck as such stops at this point as the next step is to make the fretboard and glue it to the top of the neck. I do this before I shape the neck so that i can get a lot of clamps onto the rectangular neck and there will be no damage to the neck from clamping. Trying to do this on a neck that is already rounded is a lot more difficult.

[Just Carving]

Glenn, your work is amazing. I can see all your effort now will yield in a great guitar.

Thanks
Bob

[Glenn Jennings]

Making the neck continued

Shaped the heel of the neck today. This is always a bit of a mission to get the ballance right. Had a bit of a technical hitch when the saw cut ran off a bit on trimming one side of the heel.

This is not a major issue as the artwork I intended to place in the corner of the heel will cover the gued in Patch. Should have been more careful.

Having shaped the heel the first stage of the neck profile was cut to shape. I use 3 profile gauges over the length of the neck to get the taper right. I use chalk on the edge of the gauge to see how the fit is coming along. Sand off the high spots until I get a pretty good contact all around the gauge.

Most of the heel shaping was done with a carving knife then sanded.

[Randy]

That dovetail is Impressive work Glenn. I have issues just doing a simple one.