Erik's Hjørne: SOUNDBOARD BRACING - FAN AND FINGER BRACES

Initially, when the fan and finger braces were prepared, I had left them oversized and partly jointed with the gluing surface planed flat, some with all surfaces square while others still had sawmarks showing from the bandsaw, but all needed to be planed to their final size, 4x5mm for the three center fans and 4x4mm for the rest.

PLANING TO FINAL DIMENSION
I fabricated a little stop from some soundboard scrap, stuck it to the bench with double sided tape, butted up against two bench dogs. I laid all the braces on the side that was jointed to the bottom or gluing face, butted up against the stop and secured to the bench with double sided sticky tape, and proceeded to plane them all down to a 4mm width, constantly monitoring the progression by carefully measuring the stack around the periphery.

Once the fans were planed to width the whole procedure was repeated, this time with their gluing surface facing downwards. The whole group was planed down to 5mm thickness and the three middle fans were removed and the rest of the stock was planed down to 4mm.

Last, the fans braces were numbered in consecutive order from 1-7 and the fingers braces 8 and 9.

TO ARCH OR NOT TO ARCH...

...... That is the question. There seems to be a great variety in how builders prepare and glue their braces. Some arch the gluing surface to match the desired dome of the lower bout, while others leave them flat and force them into the dome when they are glued to the soundboard, arguing that it will build a certain amount of tension in the soundboard that will make it more lively and responsive.

Whether this is true of not, I don't know, but I decided to go with the latter. If nothing else it saved me from arching the bottom of seven thin pieces of wood.

FITTING AND NOTCHING THE BRACES
First each brace was cut to length with a small dovetail saw.

The next thing to do was to carve out little notches so the fans would fit over the flat bridge graft and the transverse aperture grafts. I carefully marked where the notch was needed on each fan and proceeded by using a little trick I learned from Bogdanovich' book. He basically kept a few pieces of scrap from the corresponding graft that he stuck on top of the vise jaws and used them as spacers for positioning the braces in the vise, leaving them to protrude the exact thickness of the graft.

I used my patternmakers vise for this job, prepped by planing the top of the clamped jaws flat and square. I positioned the braces by having them protrude a little over the shims with only light clamping pressure, enabling me to press them down flush with a piece of scrap spruce, then clamping them fully. Once in the vise making the notch was just a matter of cutting the ends of the notches and pare the waste down flush with the vise jaws.

The two outer fans as well as the smaller finger braces on each side of the soundhole had to be notched to fit the aperture grafts of the transverse braces. This was done in a similar fashion.

These last four braces also need to have to be mitered at one end. The outer fans to butt up against the soundhole doughnut and the finger braces to butt up against the outer fans. This I did it on the shooting board using a sliding bevel set at the corresponding angle as a fence. The braces were stuck to the bevel with, you guessed it, doublesided stickytape.

GLUING THE FAN AND FINGER BRACES

Like the flat grafts, I had made a handful of clamping cauls out of 1/8" maple to distribute the clamping pressure of the go-bars a little. In hindsight I might have made them a little thicker, 3/16' or so, to facilitate this but this is how they ended up this time. Each fan was mated with a caul using double sides sticky tape and a modest film of glue was applied to the bottom of the brace.

First the fan braces went on. I started with the middle fan and worked my way out alternating from side to side, followed by clean up of the squeezed out glue on the previous fan, until all seven fans were in place.

Each fan was initially held down by hand pressure alone until the glue started to grip. Then one go-bar rod was inserted in the middle of the fan holding the brace down into the domed shape. Then a rod was added to each end and last yet another rod on either side of the middle, between that and the end rods, making up a total of five rods for each fan.

CARVING THE FAN AND FINGER BRACES
I experimented a little by using different tools, a block plane, a little shoulder plane, different sized chisels and my little flat soled Ibex finger plane. I ended up using a 3/4" paring chisel for the 'peaking' or carving the cheeks.

In Cumpiano's book he suggests holding the chisel like a pool cue when carving the cheeks, however, I found 'pinching' the edge of the chisel against the fans gave me more control. This way the fingers holding the edge functioned like a fence preventing the chisel from accidentally slipping and marring the soundboard while the other hand controlled the force as well as the cutting angle. I found a wider chisel the worked better for the particular method.

It was quite revealing how even slight changes in grain direction impacted the ease of the carving. With the grain it presented no problem, but as soon as it was against the grain, I could feel how the chisel wanted to dig in. Sometimes I ended up changing direction and started to carve from the other side, while other times it was purely a matter of taking less material of at each stroke to prevent tear out.

In the beginning I also tried to even out small irregularities from the chisel with a few strokes of the finger plane, but I eventually gave that up, partly because it was difficult to hold the plane off the soundboard and partly because the chiseling eventually got smoother as the work progressed and I started to get the hang of it.

The feathering of the end of the braces was done with a 1/4" paring chisel followed by a few strokes with the finger plane. I found the narrower chisel easier to control as the corners of the edge were less prone to dig into the soundboard once the ends started to thin out.

Once all the fans had received their preliminary carving the finger braces were glued on flat and carved in the same manner as the fans.

LAST THOUGHTS
Even though I tried to be very careful with my chisel I did mare the soundboard several places during the carving. I found the biggest problem was that curls generated by the chisel obscured my vision of the corner of the chisel closest to the soundboard and it was hard to follow when it was getting to close (or digging in). And it was virtually impossible for me to feel it when it happened as the chisel went through the soft spruce so easily.

Some builders advocate precarving the braces before gluing them as this minimizes the potential marring of the soundboard. This, I believe, is a very good idea, however, I also speculate that the clamping would have to be done with specially made cauls that would fit the pracarved profile or with something other than a go-bar deck.

FINAL PLANING OF FANS