The original and the ideal

Depending on the source model, you can either use the archings as they are, or you can correct them. And why would you think Stradivari`s archings need any correction?

a) Structural deficiencies in the original creation. As it is in the case of Messiah, the top plate is unusually low /only 13.8 mm/, so not copying it verbatim and making it a little higher, 15-16 mm, is a good idea.

b) Distortions happening over time. With older instruments the wear and tear over the centuries may have caused a drop in the height of the top and bottom and subsequent distortions may occur. You don't want to copy those, you want to give your instrument a sound arch, which will withstand the ravages of time.

c) Generation loss. If you feel, like I do, that you should start with a perfect design, rather than with something that is a Nth copy of a design, think about this: 1. Concept on paper, 2. Transfer to templates, 3. Transfer into the wood, 4. Distortion over maybe hundreds of years, 5. Tracing the old instrument`s arching on paper, 6. Transfer to templates, 7. Transfer into the wood. As you can see, with your finished violin, you are as far as 7 generations away from the original concept, with every generation introducing inevitable errors.

The long arch

Take a good look at Fig. 1.

For the construction of the long arch in the back, a section of a circle can be used. For the top, you can also use a circle, with the exception of the topmost platform, which should be formed with the help of another, flatter circle /in blue/. The red lines, offset to make them more visible, denote the original arching. The highest point on both the front and the back arching is at the midpoint.

The cross arches

The cross sections of both the top and bottom plates can be derived from curtate cycloids. They create perfect curves which are very close to the ones found on many Cremonese instruments and are easily generated both by software or a simple use of a wheel, ruler and pencil. Curtate cycloids software download (mirror).

See Fig. 2. to see a typical cycloid shape overlaid on the existing cross arch in red /Messiah/.

Putting it all together

For the complete "remodeling" of the Messiah`s arches {front and back}, according to the aforementioned methods, see Fig. 3. The red curves denote the original arching, the black is the idealized form.

The total body height should be somewhere around 61-64 mm.

Making the templates

Templates, especially if this is your first violin, may be of great benefit to you. They make you work with precision you could hardly attain if you worked just by eye.

For an example of a long arch and cross arch template, see Fig. 5. These should be made of a rigid and at the same time easily workable material. Good examples here are aluminum or plastic, both in sufficient thickness, 1.5-2 mm depending on the material used.

In Fig. 5., in red, you can see the physical shape of the templates. The half templates shown here are easier done and more flexible to use than their full size counterparts and because they are short, can even be made of laminated printouts.

1. Print out the templates in Fig. 4 or photocopy the ones for your violin.
   
2. Glue the prints onto the sheet of material used for the templates {the short half templates can be quickly made of laminated paper prints.
   
3. Cut out the templates and assign a number to each.
   
   

Carving the arching

1. Mark all the positions in Fig. 6. for the cross templates so that you know where to place them during the checking. The positions "A-E" are for the cross arching templates, the "F" positions are for the long arch template.

   You can print out the positions in Fig. 6. or use those provided with the archings for your violin. If you want, you can also mark out these positions on your outline (half)template.
   

2. Mount the plate on the plate holder and fix the holder to the workbench.
   
3. First you need to make fit the long template. Use a small round thumb plane across the grain and create a sort of a plateau for the long template. When the template roughly fits, you can move onto the cross arching templates.
   
4. Now with frequent reference to the cross templates, start removing the wood using the thumb plane. Blend the different positions with one another. Be aware of the general shape of the plate. Be sensitive of the wood grain, and work with it.
   
5. When all the cross templates broadly fit, you can start with the fluting.
   
   

Fluting

Fluting creates the re-curve in the arching. It is important both aesthetically and acoustically. The re-curve helps the plate to vibrate more freely. See Fig. 7. "A" is the ideal arching based on the cycloid, "B" is the arching without the fluting, "C" is the finished cross arch.

The depth of the fluting is based on the overall height of the arch. Make only as deep a fluting as will "land" the arch at its correct final height. See Fig. 7.

The outer position of the fluting is somewhere in the middle between the purfling and the edge. See Fig. 8 for reference.

Don`t try to create the fluting in one pass, work gradually instead.

Especially with spruce, be aware of the grain and always go with it.

1. Before fluting make sure the thickness of the overhang is correct, in our case it is to be 4 mm. Go over the whole platform with your marking caliper set to 4 mm and remove any high points using your thumb plane and a file to carefully finalize the thickness.
   
2. Check the height of the arch at the center point with a caliper. Here its 18 mm. Checking with the arching template, I realize I will have to go another 2.2 mm lower to make the template fit. That's OK as the target height is 15.8 mm. The depth of the fluting therefore will be about 2 mm. See Fig. 7 for reference.
   
3. Mark a line using your pencil along the edge, half way in to the purfling. From this high point line the fluting will slope towards the purfling. See Fig. 8 for the line, here in red.
   
4. To create the fluting use a small gauge, ie. Pfeil no. 7, tilted as in Fig. 8. The gauge's tilt allows for more precise cutting, most of the time allowing you to go even against the grain, if needed.

   Make multiple precise passes, removing tiny shavings from the line down to the purfling. The deepest point of the fluting (and of the arching) is usually placed at the purfling or a little bit more in. The final shape of the fluting will be defined during the scraping.
   

5. See Fig. 8C for the extent of the fluting.
   
6. When all templates almost fit and the height of the arch is at about 1-1.5 mm higher than the final height, stop using thumb planes and move over to scrapers. For various scrapers and their sharpening see the Tools and materials section.
   
   

Finishing

1. Start cleaning up the whole surface using a scraper.
   
2. If you want, you can use a way to visualize the arches better with a marking caliper. Using a marking caliper create a number of contour lines to help you better see the irregularities in the arching. See the lines in Fig. 9 for an example. Your lines will differ based on your archings but they should flow gracefully.
   
3. Clean up the area of fluting. It is often more precise to go around the outline, touching it with your middle finger (to keep it in fixed position), while holding the scraper by the rounded tip between your index finger and thumb (kind of like holding a pen).
   
4. Clean up the whole surface again using a scraper, then use abrasive paper to create a surface as smooth as possible. (The surface will later be scraped lightly yet again to bring out the grain.)