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The Making of a Bergonzi violin 1 preparing the mould and blocks | 2 The Rib Garland | 3 Linings | 4 The back One thing I have never done - yet ! - is cut the button off when trimming the back. This of course is pretty terminal - but one can do a 'button graft' to reclaim your expensive wedge of wood. Once the back wedge, or one piece is dead flat on the inside face, one can then mark onto it the outline of your ribs that are still glued to the mould ( below 2 ) They are not released from the mould until the back is marked. I mark them with a small washer which rolls around the edge - and a sharp but not too hard pencil. I also scribe a scratch line around the actual rib edge, which is a good back up as it does not rub off. The centre join is carefull aligned with the centre line of the upper and lower blocks. Once marked the plate is roughed around on the bandsaw - WITHOUT cutting off the button, which at this stage is left rough and oversized.
I don't cut too closely to the line as I seldom change the bandsaw blade for anything smaller than 1/2" - 4 skip tooth - which is pretty coarse. Once roughed - I glue on my locating blocks that hold the plate firmly on a board ( 4 ) - then rough gouge down to the edges and corners, essentially reducing the plate around the final edge area to about 6mm maybe.( 1 ) I then rough the plate all over with a seriously large handled gouge (one I can fit on my hip ! ) - once its sort of looking like a violin plate - I will then trim the edge. I do this now with just a small plane and a knife for the tight curves. Its trimmed just to the line - but the corners are left oversized. Its now a case of reducing the outside profile down to a finished shape. I purfle the edge after the body has been closed up, so the sinking around the edge is not finalised untill then. It needs to be sunk partially though - or its very difficult to control the arch form. This often means I am marking purfling onto a sloping edge, which you have to get used to. The advantage is that I don't have to worry about the final overhang too much, or the corner shape. These are trimmed to meet the ribs. Once I am happy with both the long and cross archings - and the edge thickness, then the plate is turned over for thickessing. I support the plate for thicknesing in a holder (5), that also serves as a finished instrument holder - either belly up or down with neck set etc. It adjusts for any size up to a large viola. I do not like to have the plate supported while thicknessing. I can then feel under with my fingers as I work the plate. Once there is some 'give' you are close. Just my way of doing things ! The thinkness of back and top are again a matter of great debate. Some would have you believe that they must be tuned to certain core frequencies - very similar to those learned religious men of old who sorted out how many 'angels were on pinheads' ! Some go by weight - fretting if they cannot get the back under 100 gms. Flex - tap tap - !!! The truth is the thicknesses of these old instruments are all over the place - so i don't think the old guys did anything too technical outside of 'feeling it'. Actually, thats pretty technical if you have brains in your hands ! I do not follow to the letter the measured thicknesses on an instrument. I think it is something one has to do 'your way' one each violin you build. Let your hands tell you its done. Many things in violin making are like that. Old makers did not force things - they worked with an old style craftsmans grace. They thought more with their muscles than their heads. The back is fairly straightfoward. As someone said - 'the back is for show, the top is for go'. |
