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Handmade Violin, Part 7: Purfling and Completing the Plates From "Handmade Music" episode DHMM-202

The first two phases in the creation of this violin are now complete -- the curved ribs and the front and back plates. The purfling has also been added to the edges.

In this episode of DIY's five-part series on violin-making, we focus on making the violin's plates -- i.e., the top and back.

Thus far, the book-matched halves of the wood plates have been joined, the plates have been cut to shape and thinned by rough gouging, and each plate's edge has been carved to its final thickness. To finish the plates, purfling and an interior bass bar will be added.

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Purfling (figure A)serves both as visual decoration and an element to help strengthen the structure of the violin. "Purfling is a reinforcing strip," says expert violin-maker Becky Elliott, "and its main function in the violin is to prevent cracks from traveling on the edge of the plate -- which is unsupported -- into the center, where repair would be much more extensive."

The cross section shows how the purfling strips are seated in the plates (figure B).

Figure A

Figure B

A channel has to be cut half the depth of each plate to accommodate the strips. The channel is marked around the perimeter (figures C and D). Also, notice both plates are attached to the ribs temporarily. There's still plenty of work to do to the inside of the plates so they are just spot-glued to the ribs for reference while students work.

Figure C

Figure D

	Figure E
	Figure F
	Figure G

After the purfling channel is marked it's cut with a knife. The process is the same for both the front plate and the back plate. Perfling is first added at the c-bouts -- or the "waist". After each strip is cut and bent, the channels are filled with hide glue. The synthetic purfling is then set into place (figures E, F and G). It has to be seated tightly into the slot and the excess glue must be cleared. Once the C-bouts are in place each section of perfling is cut to shape and glued into the channel. The tricky part is that there are miter cuts required at each perfling joint.

The violin receives purfling on the front and back plates completely surrounding the instrument. At this point, the plates are still a little high at the purfling channel. The next step is to reduce the height with a specially shaped gouge. The height of the purfling actually brought down to slightly lower than the surface of the arch, and leaves a smooth edge. Remember that the edge has been set to final thickness, so students have to slope smoothly from the edge to the purfling channel. The cut is less than half a millimeter deep, and that will be the low point of the plate's arch. That sets the stage for the next step.

This step is called final arching, and it's done with hand-scrapers. The plates should slope upward from the purfling channel to the each plate's center. After the plates look and feel smooth, final arching is complete.

The final enhancement for the top plate are the f-holes. When it's being played, the violin actually acts somewhat as a "bellows," and the f-holes allow air movement in and out of the body of the violin. A template positions the f-holes (figure H) and a saw removes the bulk of the spruce (figure I). A knife is used to finalize the shape.

At this stage, the outside of each plate looks finished, but more work remains for hollowing the inside. The final shaping of the inside of the plates follows an established pattern that is preferred at the Chicago School. The thicknesses range from 3.2 millimeters to 2.5 millimeters, and
Becky's task is to transition smoothly from one thickness to the next. Calipers are essential here but there's also room for intuitive measurement.

Figure H

Figure I

Finally the top plate needs one more essential piece -- the bass bar. According to Becky, the function of the bass bar is to transfer the vibrations from the violin's bridge along the length of the plate. It's called the "bass bar" because it is positioned beneath the bass strings of the violin.

The bass bar begins as a piece of split spruce (figure J) which is planed down to a specific thickness (figure K). It is then fit into the plate for an exact and tight fit. It's actually fashioned so that it puts a small amount of tension on the plate.

Figure J

Figure K

As its being glued to the plate, the bar is held in position with glued-in wooden cletes (figure L) Once the bass bar is glued in place it has to be trimmed with a finger plane (figure M).

Figure L

Figure M

Figure N

When the bass bar is shaped to perfection the top plate is completely finished (figure N). The results are amazing considering this beautiful piece began as a book matched piece of spruce. But before students can celebrate a milestone, there is still work to do thicknessing the back. Thicknessing the back is done just like the top, but the difference is in the dimensions. When the back plate is finished it's glued to the rib assembly and left to dry.

RESOURCES :

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Authors: Chris Johnson and Roy Courtnall
Published by: Robert Hale & Company (1998)
ISBN: 0709058764
Order this book from Amazon.com.

Violin Making: A Practical Guide
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Publisher: Crowood Press [UK] (2001)
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Violin Making: A Guide for the Amateur
Author: Bruce Ossman
Publisher: Fox Chapel Publishing Company (1998)
ISBN: 1565230914
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Useful Measurements for Violin Makers: A Reference For Shop Use
Author: Henry A Strobel
Publisher: Henry Strobel Publisher (5th edition - July, 1989)
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The Violin Makers of the Guarneri Family, 1626-1762
Authors: William Henry Hill, Arthur F. Hill, Hill Alfred Ebsworth
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Antonio Stradivari, His Life and Work, 1644-1737
Author: William Henry Hill
Publisher: Dover Publications (2nd edition - June, 1963)
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An Encyclopedia of the Violin
Author: Alberto Abraham Bachmann
Publisher: Da Capo Press (March 1975)
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