BENDING BINDING..... AND BONDING WITH IT

INITIAL PREPARATION

The binding had already been prepared back when I was resawing the bubinga board for the back and sides. Part of it was made into bindings and the back strip/end graft. However, all the saw marks was left on and I had to do a little bit of planing to get rid of them.

The four binding strips was secured to the bench with some doublesided stickytape and planed to a thickness of just under 2mm - about the thickness of the sides. I would have liked to have had them a little thicker, just over 2mm, but this was how they ended up.

BENDING
The four binding strips was taped together to form one flat unit. They were laid as a bookmatch, two bindings facing one way and two the other. This ensured that two were bent one way and two the other.

I taped the ends and the flat bit on each side of the waist leaving all the area that was going to be bend exposed. Initially I had added taped in the middle of each of the bout for support but took them off again as the bending progressed as they hindered the heat to the bindings and wasn't all that crucial to keep the assembly together.

The purfling had one side of the sandwich jointed while the other was left with the sawmarks from the bandsaw. They were tied together the same way as the binding strips, however, their orientation was determined by the jointed and unjointed edge, the idea being that the jointed edge will be the one facing down and glued to the soundbox.

The bending was done pretty much like the sides. I felt I started to get a little more feeling for the relation between the feed rate and pressure and was able to control the bends better with more even bends and less need for correcting overbends.

The trick seemed to be to neat up the wood on the pipe, move it along and bending it while heating up the next segment. If one segment got more heat it would continue to be hot for longer and therefor continue to bend for longer, creating a sharper curve. Developing a sensitivity for this dynamic, appeared to be the key creating smooth flowing curves.

The purflings were subjected to the same treatment. However, they were considerably more plastic, to the point that it was difficult to control them. A slight touch on the bending iron and they seems to get almost gooey. I don't know if it was the glue that caused this willingness when heated up or not but they were indeed very malleable.

When the bending was done I clamped the binding and purflings into the jig I used for the sides and kept them there until they were ready to be glued on. The binding went on the side of the jig and the purflings was clamped onto small shims, the thickness of the sides, that was stuck in between the cauls and the jig, and kept there until they were ready to be glued to the body.

PLANING BINDING STRIPS

TAPED BINDINGS AND PURFLINGS

SPRITZING THE TAPED BINDINGS

BENDING BINDING STRIPS AT THE WAIST

CHECKING WAIST BEND WITH TEMPLATE

BENDING THE UPPER BOUT

CHECKING UPPER BOUT WITH TEMPLATE

BENDING THE LOWER BOUT

CHECKING PROGRESS ON LOWER BOUT BEND

FINISHED BINDINGS WITH TEMPLATE

BENDING PURFLINGS

BENT PURFLINGS WITH THEMPLATE

BINDING AND PURFLINGS IN CLAMPING JIG

FITTING THE BACK

BUILDING UP THE SPANISH HEEL

As I started to prepare the rim to receive the back, it became clear that I had taken to much off the bottom of the Spanish heel and in order for the entire surface to make contact with the back plate, it had to be build up a little.

I cut a slightly oversized 1/8" thick slice of mahogany and glued it to the heel, using the leftover as a caul against the slice and a small piece of 1/2" plywood underneath the heel. As it turned out, it was not as bad as I first thought. After the rim had been taken down to it's final height it became apparent that I could have gotten away with a slice of veneer for the last 1/2" of the tip of the heel, but it was good to be on the safe side.

Once the glued had dried I trimmed the sides and end flush with a chisel and took some of the bulk off the top with a block plane.

RADIUS SANDING THE SIDES TO FINAL WIDTH
For this I had to remove the support blocks on the solera, as they were protruding up over the rim. Instead I held the guitar in place in three places; With two clamps on the neck and with two low makeshift blocks clamped to each side of the lower bout. This provided amble stability and support for the sanding job while not getting the way.

I started by marking the final height of the sides at the heel and end block - 78.5mm and 83.5mm respectively. Two reference marks were also made on each side at the waist, not as final marks but as marks that would enable me to monitor that each side was taken down evenly.

Once all the marks were in place it was time to start the grunt work. First I sanded that entire rim with an 80 grit sanding disk and the 15' foot radius hollow form by rotating the disk and paper back and forth. The sanding left a lightly scrubbed up surface on the rim that provided a great visual reference for where the high spots were.

The disk has a selfadhering backing but I opted not to stick it in permanently, partly because I just learned that I had to ad some sort of finish to the hollow form in order for the adhesive to stick and I simply just wanted to get on with it and partly because the convenience of having the bare disc for a multitude of other purposes.

Once this was established, I continued to shave the rim down with a spokeshave and the little fence jig I used for the soundboard side of the rim. The spokeshave jig was set to about 2º, an angle that roughly fitted the sanded edge. When I had worked my way around the entire rim, which included planing the heelblock down with a blockplane, I switch to the sanding disk, sanded, measured and determined where more stock needed to be taken off and did so with the spokeshave. In this fashion the rim was slowly worked all the way down to its final dimension.

I had to be careful not to get carried away when using the sanding disk, and only use light pressure as the radiused hollow form itself was a little wobbly being only 5/8" thick. At times I resorted to holding the edge with one hand while exerting pressure down with the other hand over the center of the hollow form.

Last the rim was sanded lightly, first with 150 grit paper, then with 320 grit to remove the scratches left over from the sanding disc. A little piece of scrap spruce was used as a sanding block, and basically pressed against the rim with my thumb. This eliminated most of the danger of rounding the rim that I feared could have happened had a bigger block been used.

MARKING AND CUTTING THE BRACE NOTCHES AND FITTING THEM TO THE BACK
Fitting the back to the rim was very similar to fitting the soundboard. The main difference was that on the back I didn't have to make individual feet for the braces, but rather had to cut little notches in the linings to house the much shallower brace ends. Also, the back graft had to be trimmed to butt up against the heel and end block.

The back was laid on the rim and clamped to the end block, using a 6mm shim to raise it back above the rim at a height equal to the brace ends. The rim was then marked on each side of the protruding brace ends with a scalpel. I started by doing these marks in white pencil but found it difficult to do with precision and so switch to using a scalpel instead.

While I was at it I also scribes the braces ends to length up against the rim.

Once these marks were down, nine in total on each side, I laid a ruler on top of the assembly and aligned it with each two corresponding marks and scribed marks across on top of the linings with a scalpel. A mark was also done about 1/4" down the sides of the linings, to indicate the depth of the notches.

With a little razor saw I did two cuts for each notch on the inside of the mark, holding the saw approximately at 45º angle, ending the cut where the linings meet the sides and at the bottom of the notch. After that the waste was cleared away with a 1/8" chisel until the notch was all squared up.

Finally brace ends were trimmed to about 2.5mm inside the template, first with a razor saw and the cleaned up with a chisel and it was time to do the final fitting of the notches.

It proved to be quite a fiddly ordeal. Suffice to say that the notches didn't line up perfectly and I had a hard time determining which notches were cut slightly out of alignment, which were not, which were simply just too narrow and what not. Suffice to say, I was quite surprised to find out how tricky this part of the building process turned out to be.

Eventually I got it to a point where the braces were seated fairly nice and firmly, with only the odd gap showing here and there. Hopefully not too big a deal and if my Alhambra Luthier Model is anything to go by it's not an uncommon feature.

The depth of the notches were a little easier to deal with, and more importantly, trim to a tight fit. Here I set my calipers to the height of each brace end and used that as a reference to pare the bottom of the corresponding notch to the proper depth.

Last I cut little bevels on the ends of the braces to make room for bits of waste that hadn't been cleaned out of corners of the notches and to give excess glue somewhere to go to, other than being squeezed out in the open.

CUTTING THE BACK GRAFT TO LENGTH
The back graft also needed to be trimmed in order to fit snuggly up against the heel and end block respectively. I started with the end block. A straight edge was laid on top of the assembly, aligned with the brace notches for the lower back brace. This way it was simply a matter of butting a ruler up against the end block and measuring the distance to the straightedge to establish the length needed for the back graft to fit up against the end block.

This was done while the assembly was lightly clamped to the solera, just enough to keep it flat and in contact with the cork shim all around. If I hadn't clamped it, the body would have been tilted upwards slightly because of the neck angle.

The back graft was trimmed using chisels only. I thought of sawing it first but decided to try just to make the cut with a chisel using the polished surface of the back as a mirror to monitor the squareness of the cut. If the chisel wasn't held perfectly square the mirrored image would not be in line.

This method worked rather well, but as the cut got deeper the chisel started to crunch the work a little creating a slight peek where the cut was done. Luckily I had to trim the back graft a little further which took care of the problem, not that is was really too a big deal.

The graft was trimmed at the heel end in the same manner.

GLUING THE BACK ONTO THE ASSEMBLY
With the back held in place I was able to turn the guitar around and see the fit through the soundhole and it looked like everything was in the right place. I did a dry run with clamps as I knew that was going to be a cumbersome ordeal, more on that later.

A long bead of glued was laid on the rim and spread out with a finger tip. I tried to be a little more generous than I've been in the past as I knew the kerfed linings would provide a lot of nooks for the glue to escape into. I spread the glue to a semi transparent film that covered the rim, heel and end block completely. Cumpiano suggests doing this with two fingertips forming the glue to a little peak in the center of the rim. I tried that too, but I don't know if it made much difference in my case. It was as if the glue tended to collect towards the center of the rim anyway.

While I was spreading the glue I suddenly realized I forgot to write a little inscription to my two sons that I'm making the guitar for. And so I stopped the glue spreading and grabbed a soft pencil and wrote: "Til Frederik og Albert, fra Far, 31. marts '08" in mirrored writing while my hands were shaking and the adrenalin was rushing. Being a one-man-band, I also had to take photographs all while the glue was slowly drying. Probably not the best way to go about things, but what is done is done.

Nevertheless, I eventually got the back placed on the rim and attached the first spool clamp on the end block, next up a big Bessey bar clamp was put on the heel with the 15' radius template doubling as a caul. Then spool clamps was added at the widest place of the lower bout, then the upper bout, the waist and slowly all the spool clamps was put in place covering the entire rim.


TRIMMING THE OVERHANG
After 2 hours all the clamps were removed and it was time to trim away the overhang. I tried to do this with a chisel as I did when I trimmed the overhang of the soundboard, but it was quite difficult to work the hard bubinga. Instead I resorted to my two spokeshaves, a flat bottomed one for the bouts and a curved bottomed one for the waist area.

The blade were set so it was fully detracted at the side that was on top if the guitar body, while on the other side the blade was protruding a little. This way I virtually eliminated the danger of accidentally taking material off the sides. I started using the deep cutting side of the spokeshave and slowly moved the tool over to a finer cutting part as the work progressed.

When I was done I took the guitar off the bench and just for fun tried to hum into the soundhole to find the natural resonance of the soundbox. It ended up being an A - 110Hz or perhaps a tad sharper than that. I have read some makers aim for somewhere between a F2 and F2# - about 90Hz, but since this is 3/4 sized instrument it is not surprising that it ended up a little higher.

OOPS - A FEW MISHAPS AND A NOTE ON THE SOLERA DESIGN
Just before I was going to glue the back on I decided to trim the overhang from a 1/4" down to, well, something less. As I still had the template line showing on the inside of the back plate I quickly took it to the bandsaw and trimmed it down about an 1/8".

But when I dry fitted the back I realized that somewhere along the line (probably when I marked for the notches) things had gone a little out of whack and the back was sitting 'low' on the assembly, sticking out at the end block and being about 1/16" short at the heel.

In retrospect I should either have left the back alone or marked a new saw line while having the back in place on the rim. In itself it is not to big a deal as the mishap will eventually get evened out by the binding and purfling, though that is not really the point. I must remember that one for next time.

As I took the clamps off after the gluing I also noticed that the back had slid a 1/32" to left at the end block, something I didn't pay any attention to as I thought the fit was tight enough to hold the plate in place. Obviously not! This will have some impact on whole look of the guitar as I now have to inlay the end graft a little off center in order to align it with the back center. I just hope it won't so much that it will be noticeable to the naked eye.

I really liked the spool clamps, however, it is now apparent that I would have been much better of cutting slots for them all the way around the solera instead of just doing it for the support blocks and drilling holes for the rest. Unscrewing and screwing wingnuts on 36 spool clamps takes considerable time in context of a gluing procedure and inserting the clamps into holes from underneath the solera is no laughing matter either. Sliding them through slots, preset in size, would have made the whole process so much easier.

I think I'll have to rethink my solera for the next one.

BUILDING UP THE SPANISH HEEL

RADIUS SANDING THE RIM

SHAVING THE RIM

FINISH SANDING THE RIM

MARKING RIM FOR BRACE END NOTCHES

MARKING RIM FOR BRACE END NOTCHES

CUTTING BRACE END NOTCHES

CLEANING OUT BRACE END NOTCH WASTE

MARKING BRACE ENDS

CUTTING BRACES ENDS

PARING BRACE END WASTE

TRIMMING BRACE ENDS LENGTH FOR FINAL FIT

MEASURING BACK BRACE END DEPTH

MEASURING BRACE NOTCH DEPTH

BEVELING BRACE ENDS

MEASURING FOR EXCESS BACK GRAFT

CUTTING BACK GRAFT

PARING EXCESS BACK GRAFT WASTE

ADDING GLUE TO THE RIM

GLUING THE BACK TO THE RIM

SPOOL CLAMP CLOSE UP

TRIMMING BACK PLATE OVERHANG

THE COMPLETE SOUNDBOX

THE COMPLETE SOUNDBOX

BRACING THE BACK

CUTTING THE BACK PLATE
The back plate was first marked using the template, first one half then the other. In order to draw a saw line, a second marking was done with the pencil stuck inside a 1/4" wide brass washer, rolled around up against the template.

The back was sawed out on my bandsaw using a 1/4" 6TPI raker blade. The marking was done on the 'true bookmatched' side that eventually will be on the outside, in order to eliminated potential tearout from the saw on that face.

GLUING THE BACK CENTER REINFORCEMENT GRAFT
In Cumpiano's book he does this by lining up the back graft against a metal ruler and so I went and did the same and it worked very well. Though I think I was a little frivolous when I added the glue as the ruler ended up being heavily soiled in all of the squeeze out. But, after a couple of minutes, once the glue had set, I was able to remove the ruler and clean it up without the back graft moving and all was fine and dandy. I waited about half an hour to clean up the glue on the back itself.

For the gluing I made a 20" long caul out of some scrap walnut that I stuck to the back graft with some double sided sticky tape before gluing. The caul was about 11/16" wide, just a hair narrower than the graft and about 1/2" thick.

The graft was glued in the go-bar deck, using a 15' radius disc and a number of go-bar rods - 13 I believe. But, also of importance, the go-bars were stuck in there slight off center along the graft gently pushing the graft towards the metal ruler and thereby preventing it from slipping out of place.

CUTTING THE GRAFT PROFILE INTO A GENTLE CURVE
I have seen many different tools being used for this depending on the preferred profile and look - sanding blocks, chisels, gouges and planes.

I started off by using a block plane to cut the initial facets, but I kept having difficulties controlling it as the plane wanted to rub up against the back plate itself as the facet started to form. Soon I switched to my little bullnose plane instead. As it is a rabbet plane, the blade sits flush to the sides and I felt it gave a lot better control for faceting the edges, where the block plane kept rubbing up against the back plate. One caveat with the bullnose plane though, it had to be kept off the back plate all together in order not to mare the back plate.

Like when I did the heel carving, I started of planing a primary facet of both sides of the graft and finished the curve off with to secondary facets on either side of the primary one. This produced a gentle curved over the graft consisting of seven facets in total.

I think using facets as a great way to monitor the progress and evenness of the contour or curve you are trying to get. Using a light positioned at a low level produces a clear visual reference of the consistency and accuracy of the facets.

The graft was finished off by sanding with 320 grit paper, smoothening out the edges of the facets until one single smooth curve was present.

CUTTING NOTCHES IN THE GRAFT FOR BACK BRACES
The Torres plan I scaled down for this guitar calls for a certain positioning of the back braces. However, when I laid them out on the back I noticed that the spacing was smaller between the middle and lower brace than the spacing between the middle and the upper brace. I couldn't help but think that it looked a little odd and out of balance.

Being the vain person I am, I took the liberty to move the middle brace closer to the upper bout so these two braces were at an equal distance from the center of the soundhole. I don't know if this is going to be detrimental to anything, but, from a little bit of research I found that the spacing between the back braces to be seemingly rather random; Some keep the spacing even while others moves the middle brace closer to the upper bout, yet others again keep it closer to the lower bout. In Cumpiano's book he suggest using four braces instead of three.

I started by marking the position of the braces on the graft with a pencil. Then each brace was held in position on the marks and squared off with a engineers square held against the graft. Once the braces were in place, a mark was scored with a scalpel on either side of that brace.

With a small razor saw, cuts were done on the inside of the marks for each brace and the waste was pared down with a 1/8" paring chisel. As when the Transverse braces were trimmed to length on the soundboard, I had to be careful not the mare the back plate with the saw. As the cut progressed I gradually moved the sawing to the tip of the saw, sawing with small strokes only taking care not to keep the heel of the saw off the back, stopping just before the cut was done. The rest was taken down with a 3/4" chisel while clearing out the waste.

Finally a last fitting was done where small adjustments were performed to widen the notches here and there for a snug fit.

GLUING THE BACK BRACES

With the notches done, one last mark was made before I was ready for gluing. With a plastic drafting square a mark was made with white pencil at the template line. This was done to have a reference mark for keeping the braces square to the graft when they got glued on.

The braces were glued to the back in the go-bar deck using a 15' radius hollow form. I used 5 rods for the upper and middle braces, whereas the lower brace was glued on using 7 rods.

A note: The braces had previously been carved when I made them a while back. In retrospect I don't know if I would do that again. I think it made them more difficult to clamp in the go-bar deck. The tips of the rods had to be positioned more carefully in order not to slip off and using a caul was not really possible either. I can see why some people prefer carving them before gluing, as it may avoid problems like damaging the plate should the chisel accidentally slip and that sort of things. But, I think I prefer using cauls and I don't really mind carving the braces once they are on. Maybe another clamping method would be more suitable for the precarving approach.

SCALLOPING THE BRACE ENDS
I made a little template out of Lexan for this and used it both the mark the braces and as a reference while carving and it work quite well. I had drawn some reference lines parallel to the base that I used keep the template held aligned to the top of the brace and thus not following the radiused bottom.

The scalloped was carved with a 1/2"chisel with the belly down. On the top and middle brace they started 2" inside of the template and 2½" on the bottom brace. All of the scallops tapered down to a 1/4" at the ends.

I was quite surprised to see how much the grain in the mahogany was interlocked. Often one half of the brace, along the length, would cut fine with the grain while the other half would tear severely cutting against the it. It was quite difficult to control, but with a freshly sharpened chisel and thin slivers I was able to keep the tearout to a minimum.

Each scalloped was finished off with 320 grit sandpaper rolled onto a piece of 1" dowel.

THE LABEL
Since this guitar is a 3/4 classical size it lends itself to be played by a child, and I though what more appropriate than to have one of my sons do a drawing for it. Albert, my 4 year old, came up with a drawing of a person, me I think, playing a guitar that I thought was quite delightful (as parents do).

Kay put it all together in Adobe Illustrator and voila! the label was done. I printed it on some Strathmore Series 400 Drawing Paper, an acid free paper that is slightly cream colored and had a little bit of tooth to it.

Our Inkjet printer did the printing and that left something to be desired. The problem was that the inks bled hugely as they are water based and the glue itself contains water and when the paper absorbs it, the moisture makes it expand and buckle up. One way to remedy this is to add water to both sides and, Haha, the colors bleed.

A fellow builder had suggested using fixative to lock the inks before gluing/wetting the label. I did some test with this and found that it mostly solved the problem, but I had to literally soak the label in fixative to prevent the bleeding, and even that didn't control it 100%. Some bleeding still occured but I found that dabbing the label with tissue paper restrained it.

The label was glued in using normal yellow wood glue thinned with water. The glue was applied to the paper with my finger and once the whole surface was covered, I gently wetted the printed face with water too. This kept the label fairly flat. I held it in position for a few second and then dabbed the excess moisture off.

Despite all the care I took, the inks still ran a little and left the final appearance a little less crisp than I would have liked. But, no big deal. I wonder how it would have turned out had it been printed on a color laser printer instead. Next time........

MARKING THE BACK WITH THE TEMPLATE

CUTTING THE BACK

GLUING THE BACK GRAFT

GLUE CLEAN UP

CONTOURING BACK GRAFT IN FACETS

SANDING FACETS SMOOTH

MARKING BACK BRACE PLACEMENT

SQUARING OFF BACK BRACES

MARKING BACK GRAFT FOR BRACE NOTCHES

CUTTING BACK GRAFT NOTCHES

PARING WAIST

ADDING SQUARE REFERENCE MARKS FOR BRACES

GLUING BACK BRACES

MARKING BRACE END SCALLOPS

SCALLOPING BACK BRACES

LABELS

ADDING THE LABEL

THE LABEL ON THE BACK

THE FINISHED BACK

THE FINISHED BACK