Violin Making: Setting the Bass Bar in Fiona

One of the mysterious steps in violin making is setting the bass bar. There is much discussion about the bar tension, placement, and thickness; all factors that affect the tone of the final instrument. Also all factors that can not be changed after the top is glued on. Today I shaped, glued, and trimmed the bass bar in Fiona. Oh all the questions? The wondering? The acoustical samples and science. Every article I’ve read on “What makes the sound of a good violin?” Now I see and measure the details, someday I’ll understand or get a ‘feeling’ for the effects and results.

Tap Tone Test

I took tap frequency readings and weighed the plates prior to cutting the F-Holes, after cutting the F-Holes, after setting the bass bar, and now again after trimming the bass bar. After trimming the plate resonance frequency is at the same point as prior to cutting the F-Holes. The removal of wood for the F-Holes, the additional stiffness and trimming of the bass bare canceled each other the F-Holes to resolve to the same acoustical values.

Fiona, #6, is a bit lower frequency than Diana, #4. Diana had an F for the front plate and F# for the back plate. Fiona is 1/2 step lower with D# for the front and F for the back. This is also what Claude, #3, measured at. Fiona also weighs a bit less for each plate, with equivalent dimensions, which is expected with the lower frequencies. The wood has a little bit less density.

Continual Learning

As I build each instrument and record the resonate frequencies and plate weights. I can observe the effects as the building process progresses, as well as the final tonal effects on the instruments. The more I build, the more I understand. Right now I’m hypothesizing and observing.

There is a violin maker in the Maestronet blogs who used to work at the Jet Propulsion Laboratory, a Mr Don Noon. His tag line reads, “Making fiddles ain’t rocket science…  it’s much more complicated.”

Everyday, new lessons, more progress; the path to mastery

 Photos journey of setting the bass bar

Fiona with a fitted bass bar. The plexiglass brackets hold the bass bar in position while checking the fit. Chalk is spread under the bass bar, and then the bar is pressed into place, removed, and inspected for even chalk on the bar. Where its not even, the chalk and a little wood is removed until the bar fits perfectly.
Fiona with a fitted bass bar. The plexiglass brackets hold the bass bar in position while checking the fit. Chalk is spread under the bass bar, and then the bar is pressed into place, removed, and inspected for even chalk on the bar. Where its not even, the chalk and a little wood is removed until the bar fits perfectly.
Top view of Fiona's bass bar. The bar is placed in proportion to the center line of the top plate. The placement is close to the line of the G string, the lowest string on the violin. The purpose of the bass bar is to transmit the lower frequencies down to the larger 'bass' end of the violin's vibrating top plate.
Top view of Fiona’s bass bar. The bar is placed in proportion to the center line of the top plate. The placement is close to the line of the G string, the lowest string on the violin. The purpose of the bass bar is to transmit the lower frequencies down to the larger ‘bass’ end of the violin’s vibrating top plate.
High Tech bass bar clamps :-) You can purchase cast iron C clamps to span perfectly over the bass bar. I like to use the simplest technology that works. Stradivarius did not have cast iron spanner clamps, but then he probably didn't have rubber bands either....
High Tech bass bar clamps 🙂 You can purchase cast iron C clamps to span perfectly over the bass bar. I like to use the simplest technology that works. Stradivarius did not have cast iron spanner clamps, but then he probably didn’t have rubber bands either….
The under side of my bass bar clamps, wine corks. The corks are cut in half and line up with the bass bar. Without them you don't get even pressure, also the cork (or modern plastic corks in this case) provide a nice pliable surface to avoid denting the soft spruce.  Once done with the process, I celebrate by finding a new wine cork :-)
The under side of my bass bar clamps, wine corks. The corks are cut in half and line up with the bass bar. Without them you don’t get even pressure, also the cork (or modern plastic corks in this case) provide a nice pliable surface to avoid denting the soft spruce. Once done with the process, I celebrate by finding a new wine cork 🙂

Violin making: Rib Assembly on Fiona

The first steps in making Violin #6, Fiona is building the violin rib assembly. To get started we set the corner gluing blocks to the form and then gluing the ribs. It all sounds pretty simple until, like most things, you get into the details.

This first photo shows fitting the template over the form and marking the edges of the corner blocks. The insides of the corner blocks are trimmed and clued first, then the outsides of hte blocks. If you trim the outside, the point is so fragile that it will break when clamping in the C bouts, the tight middle rib pieces.

Fiona #6, triming corner blocks to fit the Strad violin template
Fiona #6, triming corner blocks to fit the Strad violin template

We test if the corner block is trimmed close enough by trying to hold a pencil line on the wooden block. If the block is the correct size the pencil will slip down the side rather than draw on the edge.

This next photo shows fitting the clamping cauls to the corners. A clamping caul is used to hold the exact curve during clamping. If the caul is not an exact reverse surface from the corner block, you will get gaps which are weak glue joints. Also the ribs need to fit, clamp and glue perfectly square, else the finished violin will not rest flat on its side, all four outer edges of the plates touching flat.

Fiona #6, Setting the glue cauls for the corners, top, and bottom blocks
Fiona #6, Setting the glue cauls for the corners, top, and bottom blocks

 

Once the cauls are all trimmed and fit, a test clamp assures that the ribs will fit tight into the corner blocks. The entire assembly is clamped up without glue with each corner seam checked top and bottom for a clean fit. Once everything is correct pencil lines are drawn on the sides and forms to show the exact position when the gluing starts.

Fiona #6, Testing Clamp fit of the ribs onto the Strad form
Fiona #6, Testing Clamp fit of the ribs onto the Strad form

If it doesn’t fit dry, it will certainly not fit in the rush of getting everything together before the hot hide glue starts to set.

Next Steps Trimming the top and bottom and gluing the rib assembly together.

 

The Making Violin #6, Fiona Started today

Sound Testing #5 Edward

With #5, Edward, playable in the white, I did a set of recordings for comparison to when Edward will have his varnish on. The recordings consist of a set of open string bowings; G, D, A, E and then a D major scale, and a three octave A major scale. The final recording is a tapping on the bridge, this measurement will provide a frequency ‘ring’ of the instrument independant of the bow and/or player skill required in the first set of recordings

Prior to making the recordings I tuned the sound post, moving it a bit forward and to the treble side. The slightest movements of the sound post had an impact on the sound of the instrument. The changes ranged from shrill to mellow, to nasal or hollow. The adjustments strive for a pleasant blend of these two scales; a tiche to the left, a tiche to the right, oh too far and a tiche back to the left. Once satisfied, then the sound test were done and recorded. I keep a set of recordings on every instrument first the tap tones taken when graduating the plates, then the instrument in the white, then when the varnish is first complete, then after a couple of months of playing. The scientific process of improvement; measure, compare, adjust, measure, compare, adjust then repeat.

The Start to Making Violin #6

These paragraphs were musings about the  process with finishing Edward, now on to the real purpose of this post: Starting to make the next violin!!!

The following photo shows the spruce and maple that will be planed, cut, glued, carved and scraped into a fine violin.

Raw wood for violin #5: top spruce billet, bottom maple billet, maple side pieces, and maple neck block
Raw wood for violin #5: top spruce billet, bottom maple billet, maple side pieces, and maple neck block

 

Wood for making Violin #5; Foreground is a jack plane fitted to a fixture to create a striking board. It is used to get a square, true edge for gluing.
Wood for making Violin #5; Foreground is a jack plane fitted to a fixture to create a striking board. It is used to get a square, true edge for gluing.

The first step is to plane the plate glue edge perfectly square and straight. The striking plane jig holds the plate flat and cuts square, then the movement across the blade will determine the straightness of hte edge.  The goal is to hold the two pieces of each plate together in front of a bright light. If any light shows through the seam, then it is not a good fit. Holding the plates together square or straight should show no light, then hold the edges a skew with the the top aligned with the bottom on one end and the bottom with the top on the other end. This will show a straight line, and no curve or angle in the cut. The finished edge will match perfectly creating a clean thin glue line in the finished plates.  An axiom in violin making; a little extra care early saves work later. Same as “Haste makes Waste.”

 

Edward #5 Setup to Play his first tunes

Today Edward, Violiln #5, was setup and played in the white. Edward was started in February of 2014. When I went to the Tuscon violin making workshop, Edward’s ribs were done and the plate edges were trimmed. Today setup was completed in the white, prior to varnishing. The reason I’m setting up Edward before varnishing is to take a set of sound recordings before and after the varnishing process. By analysing the pre and post sound samples, I’ll be able to determine what affect the varnish process has on the sound. As I complete more instruments I will be able to see how the sound developes, always making refinements for more and more quality in the instruments.

image

Edward White setup
Edward White setup

Today I played a completed Howery Violin!!!

Finally after several years of study, 2 workshops, months of trail and error varnishing; I’ve finished Diana #4. She is varnished, setup, and played!!!  Claude #3 will be completed later this week. I wasn’t content with the color and stripped him to do a second run, which came out very nice.

I will say that Diana sounds good, with more tuning of post and bridge to come, also she is easier to play than my previous instrument. Responsive, nimble, sweet tones in the upper register. I’m very happy with her and can’t wait until Tuesday when I can compare her and Claude together.

A momentous day in a multi year quest to build a violin, now to build a better and better and better one 🙂

Diana Violin #5 Diana Violin #5

 

Claude getting some color

After many false starts and learning many new things about color theory, oil painting, glazing, etc etc my violins are starting to look like violins.

 

Claude getting his color
Claude getting his color

 

 

image

 

Varnishing Beatrice

Finally at the stage of varnishing my early violins. The following photos show the varnishing stages of Beatrice my second violin.

image

This photo shows Beatrice with two coats of cold rolled linseed oil. I actually use the food grade fax oil from the health food store. Also she has two clear coats of a oil varnish and two coats of an amber/yellow colored varnish. There will be at least 6 more coats of color before she is done.

image

Varnishing the Neck

image

Putting her back into the infrared drying cabinet to cure. By using a drying cabinet I can get a new coat of varnish every day.

Day Ten of Violin Making Workshop

Today is that point where we cut holes in the front of the violin plate which we just spent 4 days making contoured, inlaid, smoothed, and very thin. We are going to draw intricately curved lines, drill four holes in the middle of the plate, cut between the holes with a jewelers fret saw, and use a free hand knife to carve squiggly lines between the holes. Any mis-step will render the painstaking work of the last 4 days a piece of firewood. Do you feel my nervousness? Today we mark and cut the f-holes, or sound holes.

imageimage

The pattern of the f-holes must be laid out very precisely, there are little nicks on the inside edges that must be 195mm from the top edge of the violin. These nicks identify the location of the violin bridge, which defines the string length and ability for a violinist to play the correct note when a finger is placed on a particular spot along a string. The top holes must be 42mm apart, which defines the width of the bridge feet, and the position of the base bar running under the G string, the lowest note on the violin. Then the bottom hole must be exactly the same distance from the nick as the top hole, but larger, and in the opposite direction. For all these precise measurements you would think that makers would have standardized the f-holes with an exact shape over the past 400 years. Sorry, no such luck, the final shape of the f-holes is ‘artistic’ it shows the variation and style of a particular violin maker.

image

Once the f-holes are cut we can locate the position of the bass bar on the inside of the plate. The bass bar provides longitudinal strength to the thin spruce top connecting the top vibrating chamber with the bottom vibrating chamber. The violin bridge will exert around 105 pounds of downward pressure on the center of the top plate (which we just weakened by cutting holes), the bass bar will help support this weight and carry the vibrations on the lower, G string, side of the bridge. This 5.5 mm thin piece of wood is contoured exactly to the inside plate. We used chalk on the plate and rubbed the wood against the chalk, then carefully (redundant word in violin making) filed the chalky high points off the bass bar until there was even chalk on the whole complex curve of the bass bar.

imageimageimage

Day Eight of the Violin Making Workshop

Days 7&8 were spent shaping the outer curves of the top and bottom plates. With the purfling done, the height of the outer edges is set. The purfling line will be gouged down with a small gouge (approx 6mm) and then a larger gouge will carry the curve into the body of the plate a bit below the edge line. This curve will then be smoothly extended to the top line of the plate.

image

This work is started with gouges, continued with finger planes, and finally finished with scrapers. Finger planes are small planes that you push with your fingers, the pushing continues for hours on various parts of the plates. Finger planes cause blisters and numb fingers by the end of the day, at least in this trainees fingers…

image

Once the outside curvature is near perfect we start the inside graduating. The graduations of the inside of the plate will go from 2.2 to 3.5 mm. This work is started with gouges, then finger planes, and finally scrapers. Once the spruce on the top plate gets down to 4.5 mm, light will shine through the plate, by holding the plate to a bright light you can see the thick and thin sections. We also measure with calipers, and use our (numb) fingers to ‘feel’ the thickness always striving for uniformity.

Below is the top plate inside graduations at about 4.5 mm.

image

 

 

Day Three of the Violin Making Workshop

Three days of learning and building. We started by making a model template out of aluminum, transfering that to a plywood mold, making and gluing top, bottom, and corner blocks,

image

 

thinning the side pieces, bending and gluing the side pieces to the mold,putting linings on the bottom side of the mold.

 

image

 

Then gluing the plates together, tracing the outlines and cutting the plates, and the final step to day was beginning the roughing out of the maple back plate.

image

 

I’m ready to sleep tonight 🙂