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The Making of a Bergonzi violin

1 preparing the mould and blocks | 2 The Rib Garland | 3 Linings


The Rib Garland

My little tacked on strips have worked well for planing the short ribs. Of couse - as I said, this only works for ribs one has planed true on one face from a block. The rib pieces have now neen planed to just to just over 1mm - so still need a little finishing.

It does not seem much, but for ribs the difference between 1mm and 1.1 or 1.2mm is huge in terms of the ribs bending nicely. It also helps if they are very even in thickness. Often, the ends of the cc bouts where the curves can be tight can go thinner. Ideally, just under Imm seems right. You can see and feel the difference between 1mm and 1.1mm - without even measuring it !

Planing the ribs Some maple will plane ok, but you really need to keep a keen eye on the surface. Once that blade dulls a little it so easy to tear the curly maple. One advantage of this Veritas is the wide blade - so I can get a full rib width on a skew cut.

Mostly I tooth plane them and scrape to a final surface - but this Scottish wood seems to be ok. Ideally all ribstock should be uncut - it much easier than having to prepare both faces and you can check the run out.

Having six piece - one per bout, the lugs can be chopped off. Plenty to spare and I have two spare pieces from the same stock.


Lower Rib Join can also be a problem. You need it spot on the line of centre mould. Another problem is as soon as hot glue gets to the ends they swell and don't fit unless the two pieces are firmly held together.

The joint dry should be perfect. To position the cut I dry camp the lower corners, making sure the rib will wrap around the mould square and still have adequate overlap either side of the block. I have a special square that has a cutout that sits over the rib to check the rib is square to the mould face. Then mark the line of the join on each rib.

They are then released and the joint planed true to the lines. One has a little leeway on the final clamping of the corners. With the joint perfect it can be held firmly together with stretched electrical tape. I then cut two small strips of 0.5mm aero ply - and stitch these across the dry join spotted either end with titebond - being sure to keep the join dry and clean of any glue. The tape is stretched along the middle - the stitches either side. Clamp these and let them dry.

I then cut two small v nicks the width of the block - exactly centred on the join. This enables me to position the join on the centre line of the mould.

For clamping this block I use modified Pony ratchet clamps - the swivel heads will snap out, leaving just a small square stub end, which will fit onto the block overhang. 8 of these will fit on the top block - with four small oblong blocks, one for each pair. Once on - I replace them with small 25mm G clamps.

If you try to clamp the endblock with one large packer it tends to twist out of line with the slippery glue. This way - I can hold and see the line while attaching the first two clamps. I add a packer of the same ply between the two strips acrosss the join. The two middle block rest on the ply - the end blocks rest on the rib.

The Join is glued first - then either end is wrapped tight around and glued and clamped at the corners - checking that the rib is square - and mark the rib with pencil. Make sure it does not slide sideways when clamping the joint.

This is very much 'my way' of doing this. Many set the ribs in with the mould laid on a glass plate, packed up a mm or so - then clamp the ribs with the edges flat to the surface. The problem with this is that if the rib bends are very slightly off they want to spring the rib up - etc.

I just leave plenty of spare either side of the blocks. Its easy to trim the ribs to the level of the blocks before fitting the linings. I use this little marker a lot. The pencil scribes to the top of the spacer blocks. Sit the lower faces of the blocks on to the spacers and scribe around - easy !

The ribs are now complete and trimmed one side for the linings of the back locating face.

Geoff - Jan 01


cont...part 3