The bridge

The bridge, made of maple, serves the purpose of upholding the strings and transmitting the vibrations from the strings to the body of the violin. As such it must be both robust enough to withstand the pressure of the strings and light enough to transmit the vibrations freely.

Normally, you buy a bridge blank 41,5 mm wide for the 4/4 violin and carve it to get the best sound. See Fig. 1 for a typical bridge blank.

The position of the bridge is marked by the inner nicks in the f-holes. The back of the bridge should be at right angles to the top plate, the feet of the bridge should be in perfect contact with the arching. See Fig. 2. for the correct bridge position.

You also need to decide which side of the bridge is the front and which is the back and the popular advice differs on the front/back orientation of the bridge. The long medullary rays mean stiffer parallel grain which presumably should be on the back (where there is also the manufacturer`s stamp) where there is more pressure.

The bridge feet
  1. Make sure the back of the bridge is flat. Use fine abrasive paper on a flat surface and rub the back of the blank on it.
  2. Turn the bridge over and in the same manner rub its front to get the thickness of 4.7 mm at the feet. To get to the 4.7 mm at the feet faster, you can use a sharp block plane (maybe holding it in your left hand upside down, while holding the bridge with the other) but be extremely careful not to chip away any of the fine tips and of course not to cut yourself. Keep checking the thickness often as it is easy to over-thin the feet this way.
  3. Now to transfer the arching of the plate onto the bridge feet, put the bridge in its position and put a thin strip of paper or plastic (no more than 0.7 mm) on the arching, behind the feet. Take a fine pencil and with moderate pressure, transfer the outline onto the back of the feet.
  4. Now use a sharp knife and start removing the wood along the lines (always cut towards the bridge center to avoid chipping). Keep putting the bridge on the violin and work towards the back of the bridge being at right angles to the violin top. At the same time try to eliminate the gaps so that the bridge "sits" in full contact with the arching. Keep fitting until the bridge has no gaps.
  5. Get a strip of thin paper 2 x 6 cm. Take a soft graphite pencil and rub off as much graphite as possible on the paper where the bridge feet touch it. Blow off the excess graphite.
  6. Put the paper strip on the violin top where the bridge should be, put the bridge on top of it, in its proper position and move half a millimeter from side to side to rub off some of the graphite on the bridge feet. Use only moderate force to avoid bending and inaccurate imprinting.
  7. Remove wood where the graphite got rubbed on. Take your time. To remove just a tiny sliver, moisten the wood there a little. For the tiniest amounts use the knife to scrape the wood, rather than cutting it. Don't stop until the feet are in perfect contact with the top. At the inner tips of the feet, aim for about 1.5 mm in thickness.

Again, the perfectly sitting bridge has its back at right angle to the violin's top, is in full contact with it so that it doesn't rock when you lightly tap the violin body (the bridge freely resting on its feet, in its proper position).

The bridge arch
  1. Put the bridge in position with the help of two rubber bands, each band fastened to the foot at one end and to the lower corner of the back plate at the other.
  2. Sight along the fingerboard and mark its projected ends on the E and G side on the bridge. See Fig. 3 for illustration.
  3. Remove the bridge and offset the previously made marks 4.5 mm higher on the E side and 5.5 mm higher on the G side. Again see Fig. 3.
  4. Create the bridge template in Fig. 4. The template is best made of a sheet of plastic or aluminium. Print Fig. 4 out and transfer the outline onto the sheet. Cut out and refine the edges.
  5. Using the template, connect the offset points "a" and "b", as in Fig. 5. The blue dotted shape is the template here.
  6. Remove the wood from the top of the bridge down to the template line with your knife. Always cut "downhill". Retain an angle that is equal to both the front and back. Recheck with the template and use a fine file to finish the arch for now.
  7. Pare away the wood on the first 5 mm creating a taper of 1.2 mm in thickness at the top using a knife. Again, "downhill" cuts only. See Fig. 6. Finish with a file.
  8. With your Vernier caliper transfer the width of 33-34 mm onto the top of the bridge. Put it slightly to the G side as you did on the nut.
  9. Use a needle file to create shallow grooves.
  10. Fit the G and E strings to adjust their heights. They should be 4.75 mm /G/ and 3.75 mm /E/, measuring their elevation at the end of the fingerboard. Make the strings somewhat tight for the true elevation to show, but not too tight to avoid bending the top, especially if you don't have the sound post in place. File away the wood under these strings, keep renewing the grooves until you get to the numbers. Make sure you don't drift from the position.
  11. Restore the bridge arching by retracing the template and removing the wood and reshape the top to 1.2 mm again.
  12. Mark the remaining two D and A string grooves equidistantly (cca 11.5 mm width) in between the G and E grooves.

Finishing the nut

With the strings on, take a look at their distance from the fingerboard at the nut. It should be 0.8 mm for the G string and slightly less 0.6 mm form the E string. Lowering the action here will lower the string distance overall, so check again the end of the fingerboard.

The grooves should be quite shallow, only one third of the string covered, so refinish the arch of the nut accordingly.

The front of the bridge

See Fig. 7. for the final thicknesses of the average bridge. To remove wood, you can use the bridge holder and a chisel or you can just hold it in your hands paring away the wood with your knife. For thicknessing, Vernier caliper can be used or the thicknessing gauge you used in the thicknessing of the plates.

Finalizing the contour

Fig. 8. shows you where to remove wood when finalizing the contours. Be especially careful when cutting the central part of the heart as chipping easily occurs. The left and right chamfers are always cut from bottom up to avoid chipping.

Burnish the bridge using a piece of paper with a bit of dry soap.

The weight of the finalized bridge ranges usually slightly above 2 grams. See the Soundpost section for the possible relationship between the bridge and the soundpost.

Category: Setup