Back at Last

Well, I am finally back! My last post was in August, it is now December. Wow, that's a long break. The Fall semester started and I haven't been able to work on this project until now. I always underestimate how much time working for a living takes. If only I could win the lottery or the publishing sweepstakes, oh well back to this project. I can't even remember where I left off, oh yeah, I had just finished bending the sides. That was a major hurdle and the next step is putting all the body pieces together. This is where it really starts to take shape and you can see some tangible progress. Before I begin to assemble the parts there is still some finish work to do on the top and back bracing. Also, I need to make the kerfed linings. Like all the other parts you can buy these already prepared from several luthier suppliers. They are usually made from mahogany or basswood. The wood is cut in long strips approximately 1/4"x5/8" and shaped into either a traditional triangular shape or a newer radiused style. After researching both styles, I decided to go with the newer radius reverse style to add a little more stiffness to the sides. I figured my sides needed all the help they could get. Again, trying to save a little money and go with available woods that I had in the shop, I chose a scrap of some furniture grade pine that Matt had in the shop. I cut my basic strips and set up the router table with a 3/8" round over bit to make my radius top. I then set up a basic pin stop on the radial arm saw to make repeatable 1/4" kerf cuts in the strips.

Radial arm saw set up for repeated kerf cuts.

Radial arm detail. There is a hidden pin that fits into each cut slot allowing you to move the strip exactly the same amount to make each future cut the same distance apart.

Reverse style kerfed lining.

Back side showing radius.

Kerfed side of the flexible lining.

The kerfing, ready to attach to the bent side.

The finished kerfing is attached to the bent sides to give a larger glue surface to make a stronger joint between the sides and the top and the back of the guitar.

The first step in assembling the body is to attach the two bent sides together making a frame or shell to then attach the top and then finally the back. The sides are held together by a block at both the top and bottom of the guitar. These blocks are usually cut and shaped from the same wood that the neck is made from. My neck is maple so my end blocks are also maple.

The two bent sides and the end blocks in position.

As you can see the sides are long and over lap at this point. They must be trimmed square and to the appropriate length before assembling.

Detail showing end (top neck) block and over lapping sides.

Detail showing bottom end block.

Side view of sides before trimming and assembling.

Each side was carefully measured and marked for length using the plans as a guide. The sides were cut using a dovetail saw and a square clamped in place to make sure the cuts are at 90 degrees. A liberal amount of wood glue was applied to the end blocks and the sides were centered and glued to each end block

Assembled side showing the top.

Assembled sides showing the back.

The end blocks were glued flush with the top but as you can see from the photos they are short on the back side. The excess on the sides will be removed before the back is attached. As I have stated previously a flat top guitar is not flat and neither is the back. In fact the back has a significant arch from top to bottom as well as a subtle arc side to side.

The top arc is primarily created by the under bracing but it must fit perfectly to the sides, so the assembled sides must be hand sanded to fit perfectly with the top. A large sanding board is constructed and used to slowly make these adjustments.

Sanding board made from large sanding belts attached to 3/4" MDF

The side assembly is put back into the solera. A tight mold is created by sliding in the L braces and securing them with their threaded rods and wing nuts. This keeps the side assembly from moving while sanding. After the top is sanded to fit the kerf lining is attached to the sides. Wood glue is again used sparingly to avoid squeeze out and the lining is attached using spring clamps and modified close pins. The kerfed lining will be visible from the sound hole in the top so I had to take care in cleaning up the glue.

Kerf material ready to install.

Spreader clamps to put outward pressure on the sides.

Spring clamps removed showing only the vertical spreader bar.

Detail of installed kerf lining.

Detail of kerfing and end block.

Finished top kerfing.

The next step involves cleaning up the bracing on the top so it will fit on top of the sides and inside the kerfing. The bracing was left long and now has to be removed using a chisel and a dovetail saw.

Using a dovetail saw to shorten the brace.

Using a chisel to fine tune the fit.

After fine tuning the fit on the bracing more sanding must be done on the sides and kerf lining so there is a perfect joint where the top fits on to the sides.

The top is now placed face down in the solera and the assembled sides are placed on top to make sure the fit is perfect. A small amount of glue is applied to the kerfed lining on the sides and put back into position on the top. The spool clamps are put into position evenly around the top and tightened down with wing nuts. An additional wood block is clamped on top vertically with bar clamps to insure equal downward pressure. The whole assembly is left overnight for the glue to dry.

Detail of inside showing neck adjustment hole in brace.

Final clamping assembly.

Bending the Sides

The next step in the completion of the body of the guitar is the dreaded "bending of the sides." I say that because I think that I have been more afraid of this step than any other. Everything that I know about wood tells me that it's not suppose to bend and it's sure not supposed to get wet. But all the books and videos seem to reassure me that it's not a big deal. Well wer'e about to find out. In my research most of the information suggests a jig that is used to hold the bent pieces while they cool and dry. In the bending instructions on the StewMac website there is a picture of a simple two sided rack made from MDF and dowel rods. Before I start bending, I need to build something like that to hold the bent sides. I started with a piece of 3/4" MDF large enough to accommodate half the body size. I used my original template and traced the guitar shape on each side so I could place the dowel rods above and below the line to hold the bent sides between the dowels. I marked center positions above and below the traced line and drilled 3/4" holes with a forstner bit. I also cut another piece of MDF to use as the base. I glued the upright piece of MDF to the base and secured it with several biscuit joints. While the base and upright glue was drying I cut 3/4" dowel rods into 8" lengths. I put a little glue on the center of each dowel rod and inserted them into the drilled holes on the upright MDF. Simple and easy construction and it should hold two bent sides.

Finished bent side holder.

End view showing both sides.

Details showing template line.

OK, I guess I've stalled as long as I can, let's start bending. One of the first tools that my son, Brenan gave me was an electric bending iron. This is basically a pipe with a closed end mounted on a wood base. The pipe is wired with a thermostat so the pipe heats up and the temperature is controlled by the thermostat. The idea is with moisture and heat to create steam that softens the fibers of the wood allowing you to slowly bend the wood to the desired shape. Simple right. . . let's see. I literally spent hours and hours, days and days researching this process. I watched at least a dozen videos and read and re-read all my books. I finally decided to go with the instruction sheet that came from StewMac. It said to soak the wood in hot water in a shallow trough or the bath tub. It said that different woods needed to soak different lengths of time and it said that some woods didn't need to be soaked at all, just spritzed with water from a spray bottle. It suggested for maple, the easiest bending wood, that a soaking time of 30 - 45 minutes should be all right. It said and I quote, "It's hard to over-soak plain straight grained woods." I had purchased some practice bending sides from StewMac with the idea that I would practice with these and if they turned out I would just use them on this first guitar. The critical part I missed in the catalog was that these practice pieces of wood were exactly the same wood, the same thickness and width as the sides that came in their back and sides packages but not the same length. The first step before bending was to measure your template with a flexible rule or a piece of string and transfer the overall length and where the bends would be onto each side. Opps these sides were too short, dang! More delay, I decided to look locally to find some nice maple that I could resaw and sand to the right thickness for my sides rather than ordering and waiting longer for shipping. That turned out to be a great decision and was much cheaper. OK, now I am really ready to start bending. It was Friday night and I didn't have anything to do so I started with the short practice pieces and soaked one side in hot water for about 30 minutes. While the wood was soaking I clamped the bending iron to my work table and turned on the iron and set the temperature to 6, the recommended setting. I started bending at the waist as suggested and found after a few seconds on the iron with a lot of sizzling and popping the wood started to relax and I was able to bend it. I worked for a little over an hour and had difficulty in getting the tight curve at the waist. I decided to stop and start on the real thing the next morning. With the new wood I had purchased I had an extra side so, surely I could get two good bent sides out of the three pieces of wood. I started on a Saturday morning about 9:00 am. I filled my trough with about 6 inches of hot water and put my new side material in to soak for the recommended 30 minutes. I began bending about 9:30 on my first side. I worked, and worked, and worked. At about 1:00 my daughter brought me a cheese sandwich, which I ate in about three bites and continued to bend. At 3:30, I was so tired and frustrated I quit in disgust! The problem wasn't bending -- I could bend the wood easily but I couldn't get it to stay bent. The wood also looked horrible by this time. It was scorched and almost a green tint from all the water. I clamped it in my solara, not my new holder, and used every spring clamp I had to make it conform to the right shape. I hoped that when it dried it would retain the correct shape. That evening after I had recovered my composure I started looking on-line for help and answers. I found a chat forum dedicated to luthier questions and techniques. One post was asking for help and advice with exactly the same problems I was having. He was using the same wood, maple and he soaked his wood for an hour before beginning. There were at least six immediate replies with the same advise. Don't soak your wood! His response was exactly like mine. . . but the instructions said. . . Their response was unanimous, I don't care what the instructions said, don't soak the wood.  Use as little water as possible. Try a spray bottle and just mist the wood. Use an old wet towel and place it over your bending iron so the wood never touches the metal. The heat from the iron and the moisture from the towel make the steam and there is less chance of burning the wood. Sunday, I checked my clamped up piece and it had dried and it did retain the shape but it was so overworked it was fuzzy and worse it was twisted. I started over using the new technique on the last practice piece and it worked much better. I quickly decided to try the new technique on the last two pieces of maple. Between the new technique and clamping up the hot bent wood in my make shift mold I was able to get them bent. Hooray!

Bending iron clamped on the work table. The template to check progress is behind.

The pipe is thinner on the bottom for tighter curves.

First failures.

New technique with wash cloth. I thought the monogram added a touch of class.

Bending!

Trying to get the feel and technique down.

Using the stainless strap to help retain the heat and moisture for smoother curves.

Bending the tighter curve at the waist.

Clamping the hot side into the mold.

Clamped left side in mold.

Clamped right side in mold.

After the sides cooled and dried I was finally able to put them in my holder.

  What I learned, my first fears were indeed founded. It was harder than the books and videos make it out to be but with a lot of patience and the right techniques it is possible. Like most things the more you do the better you get. I will definitely build or buy solid molds for the drying forms for my next guitar rather than using the adjustable solara that I built for this one.