Sound Holes

The sound holes have a lot of different roles in the balance of the sound board (the front).
The sound produced in the box (space between the front, the back and the ribs) is being projected via the sound holes (that are commonly called F-Holes because of the F shape of the bass one).
But wood being removed at that particular point is also playing a major hole in the flexibility of the front.
Their shape, the way they are cut, where they are placed, all plays a critical role in the sound.
They also have an esthetical purpose and to emphasize this, there is a slight fluting around the
bottom wing of each sound holes.

Our tool to cut the round holes is called an F-hole cutter. The cutter is around a axle so we have to drill a first hole that can guide the cutter through.
In doing so the angle of the arching has to be respected (we don't drill perpendicular to the ground...)

The rest of the sound hole is cut with a fret saw. The one we use for cellos is a modified one made from two fret saws.

To finish the F-hole we use razor sharp knives and it take a long time and a lot of concentration.
That way way only we can assure ourselves that elegance and harmony is respected between the two.

Hollowing - part 2

 The inside of the plates too, like the outside has to be smooth.
So we use again our Thumb planes and scrappers.

Hollowing the plates - part 1

Once the archings are perfectly finished on both plates, we can start the hollowing.

We use gouges to hollow and a measuring tool called a thicknessing calliper that tells us the exact thickness  of the plate at a particular point - hence the fact that we cannot re-work the top of the plates afterwards. We follow very precise measurements for thicknessing that we have refined with our experience from existing standard measurements.

back purfling knot

This is one of my trade mark. Although (of course !) I didn't come up with such ideas, it is no longer common to see the back purfling tying into a pattern.
I did not do that on my first cello but decided to do it on all the subsequent cellos. I use a new pattern for each cello and I believe that for the longevity of the instrument, taking the purfling away from the heel [of the neck] that is a weaker part of the instrument can be a good precaution. Or maybe that's just my excuse.





For Victoria's cello I kept the design simple.
The process is otherwise the same as the rest of the purfling but it has to be executed on the finished arching.

finishing the archings

Once the purfling is in place and the fluting is finished - that is the narrow hollow running along the outline  and featuring the purfling in its deepest point - we can go back to the arching and make all the shapes flow together.
Gouges are used first and then little planes that we call Thumb Planes. These are often fascinating because of their size.

The scrappers will smooth the surface to a satin finish and a localized use will smooth out the small bumps, flats and hollows that can disturb the elegance of the arching.

Purfling - part 3

 The bending iron is used at a low temperature for bending the purfling and make sure it doesn't break.
I use a very sharp knife to get the mitres to joint in an harmonious flow. The outside of each corner is always the one which take over the inside one to assure an optical harmony. Each half of the mitre as its blacks and white cut in a way that flaters the whole mitre and ultimately the corner itself.

The gluing process is stressful because it feels like each part of the purfling should be glued all in the same time, but the glue jellify in seconds and when it does, it loses its gluing properties.

On this picture of the back, we can see the finish mitre once the purfling has been fitted, glued and cleaned up.

Purfling - part 2

 A very sharp knife, a lot of care and patience are all what we need to cut the purfling channel once it's been marked, making sure that it is not too deep as to not make the edge even more fragile rather than stronger (which is the purpose)

My purfling "pick" was designed by myself for my own technique when I was a student. I never found  the traditional pick being very practical to me, so I altered a knife into my very own purfling knife.
A levering motion allows me much more control than a pushing motion that is the principle of the pick.

Purfling - first part

The purfling is that black and white line that runs around the instrument (which is in fact an inlay of three wood veneers)
Traditionally the color might have had aesthetic purpose, but the inlay itself definitely has a higher purpose in the strength and structure of the edge - this area being very fragile at the seam (where the ribs and the plates are glued together)
While some makers rely on pre-made purfling, we have been making our own.
The black is often pear wood which has been stained with logwood chips (along with my kitchen walls), and the white can be poplar or willow.
Once the veneers are glued together, strips of 2mm are cut and each edge carefully planed.

The purfling marker is a tool specifically designed for the purpose of marking where the channel will be cut to a perfectly set distance from the edge (and following the outline, hence the care that has to brought to the latest)
I must admit our purfling marker is particularly fancy and now quite rare.
The blades are set with a bit of purfling between then and the handle rest on the outline. the screws are for setting it.
However good the marker, when comes to the corners, this will have to be drawn free hand. Where the purfling meet in the corners, this is called the mitres. It usually takes me ages before I am happy with the [imagined] 8 mitres flawing in the 8 corners, each working as a whole as well as adjusting to the slightly individual shape of each corner.

Finished outlines

This picture shows the entire outline finished on the front.

That plate will yet look very different with its fluting and the finished edges.

finishing the outlines

When the arching are "roughed" - that usually means the higher point is brought to definitive (or almost), and the rest has been given a little bit more of an arching shape, we bring the edges to the definite set height and make sure they are accurately flat. We call this the platforms. They are a reference point from which the outline of the edge will be refined to its finished form and that has to be to right angle with the platforms so the purflings and the flutings can be flowing. From this the finished arching depends a lot too.

I then finish the outlines.

The edges have an important role in the aesthetic and in the structure. They have to be strong, but they cannot be too thick, they have to be elegant, and even though the finishing of them is the last stage before the plate is glued to the ribs, it's how we treat them during the outline making that lead to what they will look like on the finished instrument. My files will be my main tool to get my edges right and square, but in the corners and the "C"s and like using a razor sharp knife to get a crisp cut in the grain.