1
2
3
4
5
6
7
8
Choosing the wood

The wood for the front plate should be as flawless as possible.
  1. Check that the wooden billets have sufficient dimensions for the violin you are building.
  2. Check for the following errors: Fig. 1., points "A-C" for possible errors.

    a) In point "A" you see an assortment of twists and warps as well as a resin streak.

    b)In "B" the growth lines are straight but the gluing surfaces have to be planed to make the lines parallel with them.

    c) In "C" you see the staining caused in most cases by oxidation. You may or may not be able to planed it off depending on location and size.

    d) In "D" everything is correct.
  3. See that the billets are correctly quartersawn, which means that the growth lines should look like in Fig. 2. when looked at from the side. (sometimes the cutting marks from the circular saw may interfere with the reading of the growth rings. Shave off the marks with you block plane to get a clear view of the rings) Making sure the wood is correctly quartered is especially important if you get the wood in precut billets where any corrections are almost impossible. Badly quartersawn wood with growth lines not going at right angle to the bottom plane is structurally much less stable.
  4. The runout is a deficiency in wood which is one of the most difficult to indicate. It happens when the cut of the wood is not in perfect alignment with the natural run of the grain. That is why the best wood with no runout should always be split rather than cut. See Fig. 3 for illustration. The red planes depict the natural grain. In "A" the natural grain is misaligned with the billet, indicating that there is a runout. If there is no runout, the billet should split through its center, along the red plane as in "B". A little runout is usually not a problem, but more of it may negatively affect the structural integrity of the wood.
  5. If you want, you can also check the growth line density. It can vary throughout the piece. Some great violins have it ranging from medium {1-1.5mm distance} at the edges of the plate to dense {0.5 mm} at the center. Dense growth lines all over usually mean denser wood which you should probably avoid. Look at the growth lines in the wood of the violin you are copying and try to find similar wood if you are aiming for similar sound.

It is also helpful to make a note of the specific gravity of the pieces you chose and better yet, make a table which will list the parameters of the woods used as you progress from one violin to the next for reference. Check the Specific gravity calculator in the Materials section. You can create a table like this one:

Violin no.WoodSourceDateSpecific gravity
1SpruceAndreas Pahler20030.41

Numbers around .42 for spruce and 0.55 for maple are considered good.

Preparing the wood

If you decide to cut the bass bar from one of the halves before joining them together, refer to the chapter on the Bass bar for the dimensions.
  1. Plane the chosen pieces flat on the bottom side, check for rock on your flat workbench.
  2. Put the pieces together and plane the upper tops to see clearly where they meet. Be careful not to remove too much wood as at the top the plates should still be thick enough to accommodate the height of the finished plate. See next Fig. 4. Make sure that the pieces put together have sufficient height both at the sides and at the projected center joint. The violin we are building here has the finished belly height of about 16 mm, so with a safety margin, the pieces should be about at least 20 mm high.
  3. Plane the sides at right angles to the bottom surface using preferably a jointer plane {no. 6 plane}. To do that, clamp one end of the piece in the vice and support the other with a block of wood to make sure the piece won`t bend while planing. See Fig. 5.

    Check the edges with a square. Both edges must be at right angles to the bottom surface along the whole length. No twist.
  4. Make sure the growth lines run parallel at the center. Make any corrections now, before you finalize the joint in the next step.
  5. Bring the two edges together and check for gaps and rock. Use a source of light positioned behind the joint to see how the surfaces match up. If the surface is a little convex (lengthwise), push down during planing a little more at the center to correct that. Special attention should be paid to the extremes, which should be in perfect contact up to the ends.
  6. Optional: Put your sash clamps in place and test clamping down the billets. The join surfaces must be in perfect contact, with no visible gap, when the billets are fully clamped. If they aren't its either you didn't prepare them well enough or the action of the clamps may be wrong. In that case, try to correct (by planing) the outer sides of the billets (those which run parallel with the gluing surfaces), to compensate.
  7. Lastly, before gluing, make two vertical marks on both pieces, crossing the joint, using a pencil. This will help you correctly align the top piece quickly and precisely when the glue starts "biting". See the two short horizontal lines in Fig. 6.

Because the wood tends to "move" with the changing humidity and temperature in your workshop, it is recommended to glue the pieces together right after you have achieved a good fit.

Gluing the pieces together
  1. Put one piece in the vice with its gluing surface up. See Fig. 7.

    You should rise the temperature in your workshop or use a heater to heat up the pieces, to prolong the working time of the glue. Do not heat up the pieces too much or unevenly, as that will cause the glue to penetrate the wooden surfaces unevenly, with very high penetration in hot areas, resulting in a starved joint. So a joint that has 30C evenly distributed is ideal.
  2. Using a larger brush, apply ample medium thickness hide glue all over the gluing surface on both the clamped piece and the other one (you are holding in your other hand) as fast as possible.
  3. Put the gluing surfaces together and rub vigorously back and forth, while still maintaining full contact of the surfaces, pressing down, squeezing out the glue. See Fig. 7.
  4. When you feel the glue starts "biting", finish the move and align the surfaces as precisely as possible (make the previously made marks meet).
  5. Optional: Let dry for 30 seconds, then carefully lay down on the prepared sash clamps and clamp down lightly as in Fig. 8.
  6. Clean up and let dry over night.

Category: Front