Gamben • Geigen • Holzbildhauerei


Wie man ein furniertes Griffbrett herstellt

Diesen Artikel habe ich vor ein paar Jahren für den Newsletter der British Violin Making Association geschrieben, z. Z. leider nur auf Englisch

Have you ever tried to make a baroque fingerboard and when it came to veneering it the veneer always cracked? I have been making viols for a number of years and have tried all sorts of methods and this is the one I am using at the moment and which seems to work fine for me.

This is my attempt to describe how I go about making a veneered fingerboard (or tailpiece). I shall start by preparing the actual fingerboard without the veneer. Usually I have to make the radius slightly smaller than what I want to end up with, because after having veneered the fingerboard the veneer will try to straighten the curve out again, meaning that I will end up with a flatter curve on the finished item.

On most fingerboards I laminate the base or core of the fingerboard from three pieces with the middle out of quartered spruce to give it extra strength and for keeping it light at the same time. The sides can be made out of the same material as the neck ( and ideally with the grain in the same direction as on the neck), or the same as the actual veneer. The sides have to be wide enough to take the rounding of the fingerboard into the neck into consideration. The core I leave thicker to start with to avoid distortion when gluing the veneer on. After flattening the underneath I plane the sides square to this and just a little wider and longer than the finished dimension (fig. 1) Now I mark out the radius on both ends (it is not always the same radius on both ends) with a compass, making sure that the edges end up having the same height on the bass and treble side and then connect both curves on the sides. Then I use a plane to create the upper gluing surface of the fingerboard, and incorporate which ever scoop I want, ( I get the scoop by clamping the ends of the fingerboard between dogs and tighten the vice a little more so that the core bulges by the amount of scoop I want, and then supporting the middle of the core while I am planing the top surface). Next I finish the surface off with a flexible scraper and / or sandpaper on a block sanding diagonally until I get my desired surface ready to be veneered. It is important not to round the edges over, otherwise there will be a gap at the edges or the veneer might even crack at those points (fig.2).

My next step is the preparation of the veneer which I find ideally is slab cut ebony. Slab cut veneer bends more easily because of the way the medullary rays are running. If the veneer is curving one way already I shall use that side as the gluing side. After bringing the veneer to a uniform thickness of ~ 1.5 - 2 mm I finish the outside with the help of a scraperplane and a scraper. I then put the prepared core upside down on the veneer and mark out the dimensions on the veneer plus up to 1 mm all the way round, carefully cut it out and plane the sides so that they are just overhanging the core (fig.3).

Now I cut a piece of bicycle inner tube lengthwise into ~15 mm wide strips. The next step is to steam (fig.4) the outside of the veneer over a kettle or the like until it has the curve of the core (fig.5) and lay the veneer on the core and then wrap the inner tube around the two, leaving gaps in between so it can dry (fig.6). This I leave to dry for a while as I prepare an oversize counterblock for the fingerboard and get the clamps ready.

This method of steaming the veneer and letting it dry with the inner tube should prevent the veneer from trying to straighten out again and therefore distorting the fingerboard later on.

I use thick (~35 mm) black rubber foam to press the fingerboard into. For the gluing I need a thick flat piece of wood the same width as the counterblock, on top of that the counterblock then the strip of thick rubber foam, which I first wrap in clingfilm and finally the veneer and the fingerboard.

I now take the curved veneer off the core, apply the glue to the core locate the veneer and hold it in place with masking tape tightly pulled around the back of the core. I prefer to use Cascamite, because it gives me more time to line up everything properly and because I have got the feeling that the hot hideglue might make the veneer curl away from the core. Then place this upside down on to the black rubber and use clamps every ~10 cm to press the fingerboard and veneer into the foam so that it has enough pressure everywhere to press the veneer firmly onto the core and check the back of the core with a ruler for straightness and adjust the clamps accordingly (fig.7). I leave it to dry overnight.

The next day I will carefully plane the veneered fingerboard down to its final length and width and cut it to roughly the right thickness, leaving it slightly thicker to be able to adjust the elevation when it comes to gluing the fingerboard on. The only thing I have to do now is to hollow the underneath of the fingerboard where it overhangs the body and that's my fingerboard done.

I hope you find my method useful, and I would be interested to hear of your experience with veneering fingerboards.

The rubber foam I got from:

Pentonville Rubber Products Ltd, 104 / 106 Pentonville Road, London N1 9JB

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