The top ribs can be made of two parts and there is no need to precisely pair them as with the bottom ribs. The ensuing gap at the top should not exceed 9 mm though. See the small gap at the top underneath the top clamping block in Fig. 2 for an example. Also see the exploded view in Fig. 1 to realize by how much the top and bottom ribs extend the feathered ends of the C ribs at this point to get an idea how long you should cut them before bending.

Bending the ribs

For the bending itself the same rules as for the C ribs apply. If you need bending tips, check the chapter Bending the C ribs.
  1. Screw the four screws again in the mould again so that they rise the corner blocks about 1.5-2 mm above the surface of your workbench. Again try to put the rib stock right next to the corner blocks checking that it overlaps the corner blocks by 2 mm at the bottom and 2+ mm at the top.
  2. Cut the ribstock to correct lengths and decide the orientation of each piece, depending on the flame. With the bottom ribs, if the flame is slanted, you need to make them in two pieces to match the slant of the rest of the ribs on both sides {mirroring}.
  3. Bend the ribs. Again, for bending tips, see Bending the C ribs.
  4. Let dry.

The bottom seam

If you chose to make the bottom ribs in two parts, before gluing, you will need to make them fit as perfectly as possible. The seam must be at right angle to the bottom plane and must be aligned with the centerline of the violin.
  1. Let the ribs be clamped at the lower corner blocks (B1 and C1) and mark the center plus 1 mm at each of the two ribs.

    If you have a perfectly flat surface to rest the mould on, use a square to mark the lines where the ribs will be trimmed.
  2. Trim the ribs and check how the ends align with each other. The goal is to make a seam that is barely visible. To make adjustments, you can use a small shooting board and a block plane, your knife or a flat file.
  3. Keep aligning until the ends meet well.

The clamping

For the whole job you will need 6 C-clamps in positions marked in red, see Fig. 2.
  1. Notice the 6 clamping blocks "A1, B1, C1 and A2, B2, C2" in Fig. 1 which are made of hard wood with the sides touching the ribs following the curvature as closely as possible. Also, the sides touching the ribs are padded with something soft {ie. leather} to ensure the best contact possible without harming the ribs.
  2. Again, as with the C ribs, the red arrows in Fig. 2 denote where the clamps` action should be. Before gluing, try to clamp down the ribs in their final positions to ensure that everything sits well and that there are no gaps anywhere.

Gluing the bottom ribs
  1. Optionally, preheat the block you are about to glue to get more working time.
  2. Put some medium thickness glue on the bottom block "A1", align the left rib with the violin center and hold down with your thumb. Take the right rib along with the clamping block, position quickly to create the perfect seam, hold with both your thumbs for about 10 seconds, slide the clamping block in position and clamp down. Check that the ribs still match perfectly and that they stand firmly on the workbench overreaching "A1" block on both sides by at least 1-2 mm.
  3. The same goes for the "B1, C1" corner blocks. Put some glue on the "B1" cornerblock and running your fingers from the already glued "A1" block up to the "B1" block make sure there are no gaps between the ribs and the mould and that the rib rests on the workbench. Clamp swiftly.
  4. Repeat with the "C1" block.

Gluing the top ribs
  1. Here you can start the gluing from the upper corner blocks "B2" and "C2" going up to the top "A2" block. The procedure is otherwise the same as with the bottom ribs.

Category: Ribs