This will be a long post covering attaching the sides to the heel/tail block, radiusing the guitar sides, and installing the kerfing.

After receiving two sets of pre-bent guitar sides from LMI that were cracked, I finally received a set that will work.  Each time the problem was where the cutaway returned from going around the horn to the neck.  They bent the binding at the same time as the sides.  Even the binding was cracked at the same point, so I believe that it was a problem with either their bending jig or the heating blankets they use for the bending.  The third set looked a little dubious, too, but I went ahead and used them.

The left guitar side that does not have the cutaway matched the plans and my form quite well.  The right side, the one with the cutaway, matched well on the lower bout, through the waist, and around the cutaway horn.  But the bend does not come all the way around to run parallel to the neck.  This means that, even though I wanted to avoid doing any bending on this project, I was still going to have to set up a bending iron and test my hand at bending guitar sides.  You can see in the image below that the side needs to continue to wrap around the form to join the other side at the 90 degree corner.

A bending iron is pretty easy to make.  I used a section of 1.5″ iron pipe mounted to a piece of wood.  A propane torch is used to heat the pipe from the inside.  Spraying the piece of wood that needs to be bent with a little bit of water creates steam when it contacts the hot pipe.  This plasticizes the wood and allows it to bend more easily.  I’ve done this sort of thing in the past using a steam box to heat a large piece of wood all at once.  A bending iron allows for more localized control and to work one section of the side at a time.

It turns out that this is a lot harder than it looks.  It could be that my sides were too thick to easily bend, or that I was not aggressive enough.  Either way, I still was not able to get the side to match the cutaway on the plans.  Ultimately, I softened up the cutaway a little bit, allowing me to bring the cutaway back around to match the neck.  You can see the line I drew on the horn for the new shape of the return section of the cutaway.  This slight adjustment was all that was needed.

The next challenge was to glue the sides to the  tail and heel blocks.  These blocks connect the sides at the ends of the guitar body.  The heel block also serves as the structural attachment point for the neck.  The tail block went on easily with four clamps.  There is no need to get a perfect match where the sides meet at the tail block as this joint will be filled in with a decorative strip.

On a non-cutaway guitar body, the joint where the sides come together at the neck is usually covered up by the neck, so again there is no need to get this joint perfect.  On a cutaway guitar, this joint presents additional challenges.  First the sides do not meet at the center line of the guitar.  They actually join at a 90 degree corner where the cutaway is running parallel to the neck of the guitar and perpendicular to the center line.  This joint is often covered with a decorative strip, but I am hoping to avoid that if I can.  Also, the heel block must be shaped to match the curve of the cutaway.  I accomplished this in a two-step process.  First, I cut the heel block to width and glued it in place.  This left the side with the cutaway with almost no support.

Then, after the glue had dried, I shaped a small wedge to fill the gap between the heel block and the inside of the cutaway.  The final fit is almost perfect.

The next step involves shaping the contours of the top and back edges of the sides to match the taper and radius of the guitar body.  A guitar is usually thinner at the neck than at the tail.  Most of this taper is in the back of the guitar, leaving the top edge of the guitar fairly flat.  But since the top and back both have a slight dome in them, the sides need to match the curves of the dome.

I start by radiusing the top edge to the 28′ radius dish.  As the top edge is fairly flat, this essentially bevels out the edges and takes off some high spots.  I use a block plane to initially take down the high spots identified by laying the assembly top side down in the radius dish.

When the fit is close after block planing, the whole assembly is rotated back and forth in a truck driver motion to sand down the edges to match the curve of the radius dish.  You know when you are done sanding when a nice outline of the guitar is shown as saw dust in the radius dish.

Then the back of the guitar is tackled in a similar manner.  I start by taking the tail and heel and the sides near these blocks down just larger than final dimensions.

Next, the back of the guitar is laid into the 15′ radius dish to identify the areas where the sides need to be planed down.  I use a block plane to slowly narrow up the sides until the back sides are close to matching the curve in the radius dish.  Then the radius dish is again used to set the final radius to the back.

Finally, the kerfing is installed.  The kerfing provides the structural attachment surface for both the back and the sides.  Without kerfing, the surface area connecting the back or top to the sides would be extremely small and prone to failure.  This is a quick process involving around 90 clothes pins as clamps.  The kerfing has slots cut into it that allow it to easily bend to match the inside of the sides of the guitar.

Finally, I add some short pieces of wood to the sides to add a little bit of reinforcement.

Definitely starting to take shape!