STEP BY STEP - 3
ASSEMBLY OF BODY
Trim rib ends to correct length.
This can be done by measurement or simply by trimming to fit inside the mold. I find this latter, more empirical method to be the easiest. While it is best that the ends of the ribs fit well, in reality the end graft will cover one joint and the neck will cover the other, so this joint will never show.
Fit Ribs into outside mold and clamp in place.
If you have done a good job of bending the sides they will fit well into the mold. If they do not fit well, it might be a good idea to touch up the bending. However minor imperfections can be corrected by simply clamping the rib to the mold. It is important that the shape of the guitar be symmetrical and that the curves be smooth and fair. I have three sets of spreaders for each mold. One for the upper bout, one for the waist and one for the lower bout. These have a threaded dowel for applying pressure and are generally all the clamping that I need.
Make end block of Baltic Birch plywood.
I make the end block of my guitars from Baltic birch plywood. This may seem to be a bit unusual for a maker who prides himself on using solid wood, but there is a good reason for this choice. Increasingly guitar players are mounting pickups in their acoustic guitars and this means that often the guitar has a long plug sticking out of the end pin. If the guitar is accidentally dropped or even set down on this the leverage is quite substantial and the end block can crack in half, which is fairly catastrophic, and difficult to repair. A plywood end block is less likely to crack. The Baltic birch plywood is very high quality and I have not noticed any effect on the sound of my guitars.
Sand end block to correct profile.
I round off the edges of the block (i.e. the face that faces the inside of the guitar. I flatten the glue surface (on some of my shapes) and sand it to the proper curvature on others.
Make neck block of mahogany.
The neck block I make of mahogany. The neck, and its attachment to the body, have a noticeable effect on the sound of a guitar and I feel that using a mahogany block is beneficial. (Of course I have no scientific tests, but this seems logical to me.)
Sand neck block to correct profile.
Like the end block, I round off the edges of the neck block and sand the gluing surface to the profile of the guitar at that point.
Glue both blocks to ribs.
Be sure that the end blocks are properly located (centered, top edge flush with ribs, etc) and clamp in place. I use Titebond for this purpose. It is a good idea to do a dry run to make sure that everything fits and that you have all the clamps you need to do the job right. Keep a couple of paper towels near by to wipe up any glue squeeze out.
Remove ribs from mold, clean up any glue and sand interior of ribs
with flap sander.
This step is part of the general effort to keep the inside of the guitar as neat and clean as the outside. I use a small flap sander in my drill press to sand the inside of the ribs, because it saves time. However, this can be done by hand.
Cut recess for end block inlay.
My end graft is a simple taper - some makers use more elaborate designs. This is purely decorative so do what pleases you. I always make the end graft a contrasting color to the sides. I also use a WBWB purfling to outline the end graft and then miter this into the purfling that is set under the binding. More about this later.
10. Cut dovetail recess.
This step is critical to the structural stability of the neck/body joint so it must be done carefully. Many years ago I had a machinist make me some matching jigs for this purpose. They are made of heavy steel and are very accurate. I use them with a router and a traditional dovetail bit. Moreover, I can adjust the jig for the body cavity to make it larger (wider - which necessarily means longer) so that I can carefully adjust the fit of the joint. Similar, but simpler jigs can be purchased from some of the luthier supply houses.
On my first few guitars I cut the dovetail entirely by hand. I laid out the taper for both the neck and the body very carefully. Then, on a table saw I cut a block of wood with one side angled at the amount that I wanted to use ((14 degrees is about right) and used that to guide my saw which was an old fashioned dovetail saw (strange that it should have that name). Worked just fine and cost nothing. No router was needed.
I cut my dovetail so that the body cavity is slightly larger than the dovetail on the neck. This necessitates the use of shims, but I find it is easier to adjust a shim than the entire neck or body cavity. That way if I make a mistake (it has been known to happen), I can simply start over with a new shim.
Linings are the small triangular strips found inside the guitar at the junction of the sides and the back (and top). They are there to provide some rigidity to the box and because without them we would be very limited in the bindings we could use - for fear of cutting away or weakening the glue joint. While some Spanish makers use small individual triangular blocks, the tradition for steel stringed guitars is that these linings are a continuous strip of mahogany, basswood or spruce. The evenly spaced cuts or slits are called kerfing and help the strips to bend around the shape of the sides. Here is how I build them. As is usually the case, there are other ways. One of which is to skip this step and purchase them from a supplier. There are probably at lease 4 or 5 that I can think of.
Select and size blocks of mahogany.
I use mahogany for my linings. To some degree this is traditional although basswood and Spanish cedar have also been widely used. One reason I use mahogany is that I generally have plenty of scrap that is properly sized. I buy planks of mahogany for my necks and rip out blocks that are 3 x 4" and the planks I buy are rarely even multiples of 4" in width. This leaves strips of wood about 28" (long enough for linings) by 3" and anywhere from 1/2 to 2 or 3 inches wide. I rip these into strips that are 10/32" thick.
2. Rip angled strips from above.
I set my table saw at a 30 degree angle, set my strips on edge and rip out
the triangular strips I use for linings. This is a lot easier (and
more economical) with the new thin-kerf saws, and the work looks better
(and there is less clean up) if the saw if either new or freshly
Trim/rip linings to correct depth.
The previous step leaves a triangular piece with a very sharp and not very even edge on the thin point. I eliminate this by another rip cut that trims off a small amount of wood, leaving a nice even edge.
Cut kerfing in strips
Elsewhere on the site there are photos of the setup I use for this. I have an old radial arm saw (my father's - which I remember him buying in 1954) that is not much good for anything else. I had several spacers made by a machinist and mounted 4 evenly spaced blades on the arbor. Using this, and an index mark to set the distance I advance the strips, I can cut the kerfing quite quickly. It is even quicker because I have the table set up to cut 4 strips at one time. I have home built guards to keep my fingers away from the blades and to hold down the strips. Even with these precautions it is a hair raising job to have my fingers so close to the blades, so I do this job only when I am rested and alert.
An important part of the set up here is that the kerfs must be the right depth. Too little and the strips won't bend around the tight curves of the waist, and too deep and the strips will shatter. Trial and error is the only way. Once I got the saw properly set up I have never needed to adjust it and I do not use the saw for any other purpose.
Glue Kerfing to ribs, carefully trimming ends and cleaning glue
The problem/trick with kerfing is to find some way to clamp the slanted kerfing to the side of the guitar. Many years ago I came up with the idea of designing some cauls which fit over the kerfing and make it possible to clamp with a simple straight clamp. There are photos HERE. I use a combination of spring clamps and small C clamps. The C clamps clamp with greater pressure so I use them on the sharp curves and alternate the two kinds of clamp on the straighter sections.
Fabricate side stiffening braces (optional)
Many makers put braces on the sides running from top to bottom of the rib. Some use a fabric for this and some use strips of thin wood. I have never found this necessary unless the wood is particularly prone to split (Ziracote comes to mind). Certainly they do not hurt anything and may possible prevent some rib cracking.
Glue and clamp side stiffening braces into ribs.
See # 2 above.
Carefully inspect and clean/sand ribs.
I believe that the inside of the guitar should be as neat and clean as the outside so this is an important step. It is not possible to do it well after the back and or top are on, so do it now. I use a small flap sander in my drill press. It can easily be done by hand.
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