Posts Tagged ‘channel’

Final Shaping and Scraping

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Final Shaping and Scraping

The Channels and Edges

The last time I posted, the back purfling had been installed, but the back channel had not been begun, nor were the edges trimmed and rounded. I drew in the edge crest line, just as I did on the front plate, and carved the channel with a gouge, then began scraping the channel and fairing the curve of the channel up into the curves of the arching.

Beginning Channel

Beginning the channel

 

Sample corner, after preliminary scraping.

Sample corner, after gouging and preliminary scraping.

 

After I had gone over the entire instrument under a low-angle light, looking for “lumps and bumps” (any little discontinuity that will be visible under the varnish…and they all are), I wetted a cloth with black coffee, and rubbed the whole instrument down with the damp rag. This accomplishes two things: it begins to lend a very light yellow cast to the wood, and, more importantly, for now, it raises the grain, so that every little splinter that was pressed down by the scraper, instead of being severed and removed, will now stand up and be visible…easy to find and remove, using either a very sharp scraper or, eventually, a very fine abrasive. (In general, I avoid abrasives, because I am not convinced that the surface left by fine abrasives is the same as the surface left by a sharp scraper. But, as a means of smoothing between varnish coats, or just before varnishing, I feel it is viable. I also use it on the edges of the plates…especially the spruce.)

So…here is the instrument, dampened with coffee. When the coffee is dry, I will continue the smoothing and shaping process.

Coffee rubdown.

Coffee rubdown. When it dries, it will leave a pale yellow stain…very slight.

 

coffee surface

You can see the pale yellow color, and the shape of the corners. The surface actually feels rough, now, though it looks smooth.

 

Scroll with coffee dampening.

Scroll with coffee dampening. Notice the splinters on the edge of the curves.

 

Front of scroll.

Front of scroll. See how rough the wood looks…lots of scraping still to come. And maybe some abrasive smoothing.

 

Back plate with coffee stain.

Back plate with coffee stain.

 

Final Scraping of the Whole Surface

Once the coffee was completely dry, I went to one of the few places in the house where I can get a fairly dim, very low-angle light across the violin, and went over the instrument, intently searching for either rough patches or places where the smooth continuum of the arching is interrupted by a ripple, a ridge, or a bulge, etc. I want the arching to be as close to perfect as possible, and every transition from curve to curve to be flawlessly smooth.  (I have never actually achieved this level of perfection, but that remains the standard. Every time, however, after the varnish is applied, I find things I missed.)

After scraping every surface, very gently, with a sharp scraper, until all seem to be very smooth, I rub the instrument down with coffee again. Usually, this time, the grain will not raise as agressively as before, because I did not press the grain with the scrapers but just “brushed” the surface, taking off mere dust, but leaving the channels and transitions looking finished and shiny-smooth.  This is an important time to watch for anomalies of any sort, because once the varnish is applied, it is very difficult to go back and “fix” things. Several of my earlier instruments have an odd pattern of dark stripes in the upper front bass bout, following the curve of the outer edge, and adjacent to the neck. These could have been avoided by careful scraping under a low-angle light.  They remain as permanent record of my “learning curve.” (sigh…)

Here is how the instrument looks, ready to begin the finishing process:

Front plate, ready to begin finishing process

Front plate, ready to begin. (I will remove the fingerboard first.)

 

Side view

Side view.

 

Detail of Scroll.

Detail of Scroll.

 

Back view.

Back view.

 

Detail of button and neck heel.

Detail of button and neck heel.

 

Detail of Center bout, ribs and corners.

Detail of Center bout, ribs and corners.

 

As you can see, there are are a few things I will probably want to touch-up just a little more before I actually varnish, but, overall, I am satisfied that I am ready to move forward. There will always be little things I change at the last minute, but that is just my nature.

 

What’s Next?

So…the next “big” thing is to remove the fingerboard (easy to do…I only held it on there with three dots of hide glue), and then I will rub very fine gypsum mixed with coffee into the whole instrument, and rub it back off before it dries. The goal is to fill the pores, so that the varnish will not saturate the wood.

After that is dry (and it will look chalk-white), I will apply a coat of sealer (rosin dissolved in turpentine, at the moment), to lock the gypsum down, and further seal the pores. After that; varnish time!

Thanks for looking.

 

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Button and Back Purfling

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Button and Back Purfling

Trimming the Button and Heel

When I installed the back plate, the heel had been trimmed flush with the back of the garland, but the upper surface of the heel was still quite irregular, and the upper end of the button was ridiculously oversized. The excess wood made it easy for me to install a clamp, and get the back plate glued on securely. So…when I removed all the clamps, this is what it looked like:

Back plate installed; button and heel not yet trimmed.

Back plate installed; button and heel not yet trimmed.

 

Tools for completion.

Next, I will trim the button and heel, then add purfling, then scrape. These are the tools I will use.

 

Button shape.

This is roughly the shape the button will be, but a little more refined, I hope.

 

Side view of heel and butto

Side view of the heel and the button. The closeness of the camera warps the picture a little.

 

Installing the Purfling

The next thing was to scribe in the purfling slot. I used the purfling marker to scribe the double line exactly 4mm from the outer perimeter of the plate, except the corners, where I used a sharp pencil to sketch the “bee-stings” in by hand. Then I incised the lines all the way around, just barely deepening the lines, so that they are more visible, and a little easier to follow with the blade of my small knife.

Purfling slot lines lightly incised.

Purfling slot lines lightly incised.

 

Then I slice in pass after pass, trying to get the lines deep enough for the purfling I will install. I usually find that, especially on the hard maple, I have to cut the slot in two layers: the first gets about half the depth I want, and the second finishes the slot. Here is the slot at half-depth:

Purfling slot, half-depth.

It looks good, but it is not deep enough.

 

Purfling slot ready for purfling.

Purfling slot ready for purfling.

 

Back purfling installed...glue still wet.

Back purfling installed…glue still wet. 🙂

 

Front view

And the Front!

 

Back to Work!

As most of you know, I had undergone hernia surgery, just after Christmas, and had a 6″ x 8″ polypropylene mesh patch installed in my abdomen. I have been convalescing, and just this week, have finally been feeling better. So…I just received word that I will return to my work at Gunderson, Inc., tomorrow at 6AM. I think I had better call it a day, and try to get some sleep. 3:30AM comes at the same time, every morning, whether I am ready or not. I will get home sometime after 4PM, I expect. Maybe I can jump back in where I left off. 🙂

Tomorrow evening, then, I hope to complete the purfling channel and the outer edgework of both the front and back plates, and begin the final scraping in preparation for varnishing. Any little glitch, regardless of how tiny, will be very visible under the varnish. So this part has to be done with great care.

 

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Completing the Front Plate

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Completing the Front Plate

Completing the Graduations

When I last posted, I had just begun the graduations of the front plate. I got tired, and had to stop. It has been frustrating, finding how little I can accomplish, currently, before feeling exhausted. I hope I regain the strength and stamina I once had. Here is what the plate looked like yesterday morning:

Rough graduation nearing completion.

Rough graduation nearing completion.

The plate was still far too thick, but was at least looking encouraging…so I plunged in and brought the whole plate to approximately 3.5 millimeters thickness all over. This is the first time I have tried this graduation scheme. In the past I have been very particular to have one thickness in the center area, another, slightly thinner, above and below that area, and thinnest of all, out in the flanks. But, I am informed that that is not such a good plan. So…here we go!

Completed front plate interior, before f-holes and bass-bar.

The pencil is only there to cast a shadow: otherwise it is difficult to see the curvature of the completed plate.

 

Completing the F-Holes:

Once the graduation is complete, I need to finish cutting out the f-holes: I begin with a special tool called an “f-hole drill.” For years I worked without one of these little gems, but my children finally decided I ought to have one, and bought it for me. 🙂 The use of the tool is self-explanatory, and there are a wide variety of bit-diameters, for violins and violas. (I later bought another, larger one, for cello f-holes.)

F-hole drill.

F-hole drill.

 

After drilling the four f-hole “eyes,” I began cutting out the rest of the f-hole outlines, using a knife and a small saw.

F-holes.

F-holes still need to be cleaned up…but there they are!

 

Completing the Purfling Channel

Now it is time to start cleaning up the purfling channel, and fairing-in the curves, up into the arching. I began with a sharp pencil, and drew an “edge-crest” line, approximately 40% of the distance in from the plate edge, toward the purfling. Then I used a sharp gouge to remove a shallow channel across the purfling, which ended at the edge-crest. Then I used scrapers to smooth the transition between the edge of that channel and the arching curves.

Edge-crest line, and gouge, beginning channel.

Edge-crest line, and gouge, beginning channel.

 

Beginning the Channel

Beginning the Channel

 

Channel is cut: now scraping can begin.

Channel is cut: now scraping can begin.

 

Treble-side scraping is nearly complete.

Treble-side scraping is nearly complete.

 

The treble side channel is essentially complete. When I have the whole channel completed, I will flip the plate over and install the bass-bar. All along the way, I will continue to fine-tune the f-holes, until they are satisfactory. Right now they are quite rough, but my hands are tired, and I am fearful of making errors due to fatigue. So…they can wait. 🙂

 

Thanks for looking.

 

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3/4-Size Violin Completion

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Completed the 3/4-Size Violin!

I had a number of other projects going, so I neglected to maintain the website presence…the only post lately has been of another violin resurrection. But…I hope to change that.

The last post was of the neck-set on the 3/4 violin. It looked like this– but the back plate was not made, yet. Most makers complete the entire corpus, then set the neck. I complete the rib garland and the front plate, then set the neck while the inside mold is still in place. This allows me to get the neck-set perfect, and to level the back of the garland, including the back of the neck-heel, before making the plate. When I install the plate, it fits perfectly, only requiring the final trimming of the heel and button together, to establish the optimum height in the center of the curve of the heel.

Neck-set side view

Neck-set side view

Completing the Back Plate

So, the next thing was to trace the back plate, and complete it:

Corpus with back plate blank

Corpus with back plate blank

 

Beginning to carve the back archings

Beginning to carve the back archings. There is a long way to go!

 

Once the arching is complete, I cut the purfling slot

Once the arching is complete, I cut the purfling slot

 

 install the purfling, dry

Then I install the purfling, dry, to make sure everything fits correctly. That strip of aluminum is my bending strap.

Then I glue the purfling in place.

Then I glue the purfling in place.

 

Edge Crest marked

Then I mark the edge of the crest, so I know where to carve the channel.

 

channel complete

Then I carve the channel, using a gouge, and use planes and scrapers to fair-in the curves of the channel and the archings.

 

Arching and purfling complete

Here, the arching and purfling are complete…but the graduations (inside arching) are not begun.

 

Graduation

I begin by measuring the thicknesses all over the plate, so as not to run into any surprises and make the plate too thin. Then I use gouges and planes to bring all the thickness close to what I want. But, to make sure I don’t go too far, I measure and carve out small spots all over, to the exact thickness I want in each little “polka-dot”. That makes a “graduation map” that allows me to follow my plan to completion, by removing all the excess wood between the dots, thus “connecting the dots.”

There are other ways to do this. One involves a special tool, commonly called a “Strad-Spike”, because one was found among the tools of Antonio Stradivari. I have seen them and and have actually used them, but have never gotten around to building one. So…

 

graduation map laid out

Graduation map laid out.

 

Final thicknessing in progress.

Final thicknessing in progress.

 

Graduations almost completed.

Graduations almost completed.

By the way, I think it is interesting to hold the plates up to a lamp and see how much light comes through:

translucent spruce

That is a lot of light coming through that spruce plate…it is about the thinnest plate I have made.

 

translucent maple

Even the maple lets a little light through.

Closing the Corpus

Finally, to install the label and close the corpus. (I always forget to take a picture of the label…sorry.) Most makers put their label in after everything is fully completed. I used to do that, but I found it so frustrating to get a glue-coated label through the f-hole, line it up correctly and get it smoothed out on the back plate…all working through the f-hole…that I decided my labels will go in when I close the corpus; always. That means the label predates the completion by a few weeks at most, as a rule. I think one time there was a long wait,  but that was the lone exception.

Closing the corpus

Closing the corpus

 

Fully glued and clamped, using hot hide glue and spool-clamps.

Fully glued and clamped, using hot hide glue and spool-clamps.

 

Closed corpus from the back.

Closed corpus from the back.

 

Closed corpus from the front.

Closed corpus from the front. Dainty little thing, isn’t it? This is my first 3/4-size violin, and it feels pretty tiny.

 

Finishing

I removed the fingerboard so as to be able to easily access the entire exterior, for final scraping and finishing.

After that, I had a lot of “scraping and looking” to do. (Scrape and look, using a low-angle, dim light, then scrape and look some more.) When everything was as smooth as I could make it, and exactly the shape I wanted, I stained the entire violin with coffee, to get rid of the stark-white bare, new-wood look. It takes at least three coats, usually, to get the color dark enough that it will not shine through the varnish. The collateral effect is that the grain raises because of the water. So, I sand it lightly, to smooth the grain “just enough.” I want the grain to be visible in the final state, but not too visible.

Coffee stain

Coffee stain

 

Then, I rubbed in a coat of the mineral ground. I brush it on liberally, rub it in hard, with my fingers, then wipe it off as hard as I can, using a rag. When it dries, the instrument will be whiter than ever– chalk-white, all over. The first time I did this I was pretty alarmed at the look, but I had just watched Roger Hargrave do the same thing, and knew that the white mineral would completely disappear with the first coat of sealer or varnish. And it did!

Here is the violin with the sealer applied:

sealer front view

With three coats of coffee, and the dark sealer, the wood looks pretty dark. But it will look good under the varnish.

 

The back, with the seal-coat.

The back, with the seal-coat.

 

After that it was a case of applying several coats of golden varnish, then a few coats of red-brown varnish, and a final two coats of the golden stuff.

 

Front varnish nearly complete

Front varnish nearly complete

 

Back varnish nearly complete

Back varnish nearly complete.

 

front with the final coat of varnish.

There is the front with the final coat of varnish.

 

Set-up

Standard set-up, and the violin will be done! That includes the saddle and endpin, as well as re-installing the fingerboard, fitting and installing pegs, a bridge, the nut, the soundpost, tailpiece, and strings. A chinrest completes the instrument.

Bottom of the violin before the endpin

Bottom of the violin before the endpin and saddle were installed.

 

Endpin installed

Endpin installed: saddle is next.

 

Heres the plan: a rounded saddle

Heres the plan: a rounded saddle to prevent “saddle cracks”. They work because there is no sharp corner to act s a stress riser.

 

 footprint of the saddle

There’s the footprint of the saddle: no further shaping is done until I cut out the mortise in the front plate.

 

Traced saddle mortise

I traced the footprint onto the front plate, and began cutting out the mortise.

 

cut out saddle mortise

Then I cut out the mortise using sharp gouges and a small knife. Any nicks in the varnish will be retouched later.

 

The varying thicknesses of the top plate can then be traced onto the saddle itself, and final shaping can begin.

 

Saddle and endpin complete

Saddle and endpin are nearly complete. The saddle will be filed a little more, and the varnish retouch will happen later on.

 

fingerboard and pegs installed.

I reinstalled the fingerboard, and while the glue is drying, I fit and installed the tuning pegs.

 

Fingerboard and pegs complete.

Fingerboard and pegs complete. Notice the nut is also intalled.

 

Completion

Finally the little violin is complete!

 

Front view of completed 3/4-size violin

Front view of completed 3/4-size violin

 

Side view...

Side view…

 

And the back view.

And the back view.

 

finished scroll

Close-up of the scroll

Thanks for looking. Please keep in mind that the Marylhurst Musical Instrument Show will be April 29th and 3oth. If you can make it, I hope to see you there. This little violin will be there for you to test drive, along with others.

 

 

 

 

 

 

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“Beginning of the Finish”

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Finishing My Newest Violin

Introduction:

For every violin, viola, five-string fiddle, cello or double bass I build, the finishing process is nearly the same. After completing the last of the purfling, the order is as follows:

  1. Channel (the concave curve in which the purfling is nearly centered, but which must fair smoothly into all the other surfaces, concave or convex.)
  2. Final edgework (making the outer edge (and inside of the plate) curve together into the channel and arching)
  3. Varnish prep (final fairing-in of all curves and elimination of all bumps and unwanted ridges)
  4. Water-based stain (usually two or three applications)
  5. Mineral ground (one application)
  6. Seal-coat (one application)
  7. Varnish (numerous coats)
  8. All set-up issues: saddle, fingerboard, nut, pegs, soundpost, bridge, endpin, strings, tailpiece and (on the smaller instruments) chinrest.

The Channel, and Final Edgework:

I scribe a margin around the entire outer edge, usually about 1.6mm in from the outer edge. This will serve as the “limit” for the channel. I cut the channel to the desired depth, using gouges first, then small planes and scrapers,  bringing the smooth curve up to match the scribed limit. Then I file the outer edge so that it curves in from the center of the edge of the plate up to meet the scribed margin of the channel. The other margin of the channels are scraped so that they fair into the curve of the plates themselves. I true-up all my lines using scrapers, files, and very fine abrasives, and then I am ready for final varnish preparations.

On my last post, I had just completed the back purfling. That seemed a good place to “call it a night”.

 

Back purfling complete

Back purfling complete: the channel has not been started. You can see the sharp edge of the purfling in a few places.

Then I began preparations for cutting the channel, by scribing in the boundary line:

Scribed line, marking the edge of the channel.

Scribed line, marking the edge of the channel.

 

Scribed pencil lines where the channel will go at the corners.

Scribed pencil lines where the channel will go at the corners. (I didn’t use the flash on this one–that’s why the color is different.)

 

Beginning the channel cut.

Beginning the channel cut. The purfling looks cleaner, as the rough, glued edge is gone. I also began shaping the edges.

Varnish Preparations

I have a particular spot on my basement stairs, where I can get a very low-angle, not-too-bright light source, which casts shadows across the face of the instrument, and makes is easy to see irregularities. So, the last thing I do is stand there, holding the fiddle and rocking it very gradually, to see any shadows that indicate a rough spot or an irregular shape. When I find one, I gently scrape it away with a very sharp scraper. I want to move as little wood as possible at this point in the build: I already have the arching and graduation just about exactly where I want them to be. This is strictly fine-touch finish-scraping.

Some people are very particular about not using ANY abrasives. Sorry– I do use them, in a very limited way, but only at the very last part of the build. The edges of the spruce plate, for instance, are so soft that a scraper is simply too aggresive for final shaping, especially after I raise the grain with my water-based stain (strong coffee, in my case…yes, and I drink the leftover “stain.”) So I use a very fine (worn 400-grit) abrasive paper to make the edges smooth and pretty. I also use it later, between coats of varnish, to make sure that no bits of dust, splinters, etc. can spoil the next successive coat(s) of varnish.

Channel complete...no flash.

Channel and edgework complete…no flash. The wood isn’t really this yellow– we have a fairly dark house, and the sunlight filtering through makes it look this way.

 

Completed channel, with flash

Same shot of the completed channel, with flash. This is pretty close to the real color at this point.

 

Coffee Stain

I use a coffee stain because it imparts a gentle yellowish look to the wood, without doing any damage to the wood. Many people use strong tea, and I have done so. Some have a particular tea they use, for the color they want. That is fine. Some have alcohol-based, color-fast dyes to accomplish a similar result. That is OK too. I’m just telling you what I do. People have sometimes asked whether I use de-caf or regular. I love that question: I say, “Oh I always use regular, to wake up the tone!” 🙂 (Riiiight…)

Coffee stain, not fully dry yet.

Coffee stain, not fully dry yet. I used the flash on this, so the color change is real.

Mineral Ground

This is something I got from Roger Hargraves. He is a master luthier living in Germany, and he wrote an online book as he built a magnificent double bass. In it he explained why he uses a mineral ground, and what it is (it is effectively exceedingly fine gypsum dust, introduced into the wood pores in a liquid suspension. He used a very thin varnish as I recall…I used coffee, again. It dries slowly, is easily applied, and cleans up with water.) So, I apply the mixture with a brush, one area at a time, rub it in with my fingers, and immediately rub back off as much as I possibly can, using a rag. I do NOT want a thick layer of stuff on top of the wood– I want the pores themselves to be filled with the particles. I coat all areas except the “handle”portion of the neck in this manner. Supposedly it leeps the varnish from saturating the wood, thus avoiding overloading the wood with varnish and deadening the sound. Does it help? He says it does, and I know for a fact that he did it…and I saw the bass in person, last year at the International Bassists Society convention, in Ft. Collins, CO.

The ground dries chalk-white, in spite of the fact that I used coffee for the liquid. I sand it gently to remove any excess gypsum (there always is a fair amount that comes off the surface at this point). Sorry, I didn’t take a picture at this point. You’ll have to take my word for the fact that it simply looked like a chalk-white violin, with the grain and purfling quite obsecured by the dry mineral ground.

Sealer

Then I seal the violin, all except the “handle” portion of the neck. There are many things people use for sealer: Some use special commercially available preparations (I have done that, too), and some use very thin varnish, or shellac. For now, my sealer is a combination of Pine sap (yes, that sticky gunk that flows out of a cut in a pine-tree) and turpentine. The turpentine penetrates the wood very readily, taking the pine pitch with it. I allow the turpentine to evaporate off, leaving the pitch in the wood. I am of the opinion that the pitch is an OK thing in the wood, and that it seals the wood against further penetration by varnish. That’s my theory, anyway. 🙂 The mineral ground turns completely transparent under the saturation of the turpentine and pine pitch, and remains that way after the turpentine evaporates. Here is a photo of the violin with the mineral ground rendered transparent by the sealer. It will probably take a few days to get absolutely dry, (turpentine evaporates slowly) so this is the last photo for this post:

Mineral ground renedered transparent by sealer coat.

Varnish

I have used a wide variety of varnishes, but currently I am using a spirit varnish concoction. If I need more color, I use the “Transtint” dyes available in woodworking stores and online. It does not take a great deal of dye…you want to go easy on this stuff. I have considered extracting dyes from plants, etc. Never have gotten around to it. 🙂

I’ll show the varnishing process in the next post.

Thanks for looking.

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More Progress on the “Plowden-model” Violin

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More Progress: The Plowden-model looks like a violin!

Removed the Mold and Installed the Back Linings

One nice thing about this (French-style) mold is that it is easy to remove– it usually takes less than five minutes to get it out, provided I have waxed the non-glued surfaces of the mold, so there is no chance of an accidental adhesion to the ribs. I simply use a flat chisel to crack the glue loose at each block, where it is attached to the mold, and then slip my parting knife (in reality, it is an old potato knife) between the block and the mold, to make sure nothing is still adhering to the mold. After that I can slide the mold out by lifting as shown, while wiggling each individual block to make sure they are all moving evenly. The only drawback is that I have to install the back linings after the mold is removed, and the rib garland is pretty fragile. In the past, I have used a two-part collapsible mold, in the italian style (centered between the front and back edges of the ribs); but it is more difficult to remove. The only real advantage is that I can install all the linings while the corpus is still on the mold, and still get the mold out without too much trouble. I believe it does have a slightly greater tendency to leave the ribs slightly convex in the center, as well, and some people find that attractive. (I do too…. Perhaps I will eventually go back to using the Italian-style molds.)

Back before mold removal

Back before mold removal. You can see how thin and fragile those ribs are.

 

This time, the linings went in without a struggle, though, and the whole task took about 30-40 minutes. A few hours later, the glue had dried, and I was able to remove all the tiny spring-clamps, and get going on leveling the back of the garland, and cleaning up the interior.

Back linings installed,

Back linings installed, ready for shaping and smoothing.

 

Blocks and linings before shaping and smoothing.

Blocks and linings before shaping and smoothing. I had trimmed the front side of the blocks, and the front linings, before I installed the front plate.

 

Blocks and linings shaped, ready for scraping and smoothing.

Blocks and linings shaped, ready for scraping and smoothing. The blocks and linings are weeping willow…the bass bar is Sitka spruce.

 

Cleaning up the Interior

Cleaning the interior primarily means shaping the linings and blocks, after the mold is out of the way, but it also is a final opportunity to scrape any rough spots, and make any minuscule repairs. So, I put on my magnifying visor, and look things over very carefully. I use a knife to trim the linings so that they are triangular in cross-section, thickest at the edge, to suport the edge of the rib, but tapered so as to not restrict the vibrations of the middle of the ribs too much.

One thing I have to remember, at this point, is that it is also my “last shot” at the interior of the back plate, so, before I install it, I carefully check and scrape it, and, as a final “seal of approval”, I install my signed and numbered label, gluing it in place where it will be visible through the bass-side sound-hole. All my instruments are individually hand-crafted, and each ends up a signed and numbered original, not a mass-produced instrument. I’m really not interested in doing things the “factory” way.

 

Installing the Back Plate

I used to complete all the work on the back plate, including purfling and final edge-work before installing it on the garland. But I have recently altered my order of operations so that I purfle and do edgework after the plate is installed. This allows me to adjust the plate overhang boundaries, and make final decisions as to how I want things to look, before permanently locking the shape in place by installing the purfling.

I also used to “self-induce panic,” by spreading hot hide glue around the perimeter of the garland and plate, and then frantically trying to align the edges perfectly and adjust all the (25-30) spool-clamps, etc. before the glue gelled. That was a fool’s-errand, as the glue usually gels far more quickly than I could ever get everything clamped in place. The late Sam Compton shared how he applied the glue and allowed it to gel, then aligned everything at a leisurely pace, gently clamping everything in place.  Afterward, he went around the perimeter with a hair-dryer, gradually warming the plates until the glue re-liquefied. Finally, he tightened the clamps just enough to completely close the joints. Pretty clever.

I ended up clamping everything dry, then loosening a few clamps at a time, and slipping the hot hide-glue into the seams, using a very thin palette knife. That seems to work pretty well, and definitely eliminates stress. (His method probably is even better, but this is how I do things, for now.)

Back plate glued in place, using hot hide glue and spool clamps.

Back plate glued in place, using hot hide glue and spool clamps.

 

Label visible through f-hole.

Label visible through f-hole. The f-holes still will require quite a bit of smoothing.

Final Edge Shape and Purfling

Once the back is securely glued in place, I can trim the edges to exactly the shape I want, so that the overhang is matching the front plate, etc., and then begin purfling.

Front view: back plate has been installed and trimmed to size.

Front view: back plate has been installed and trimmed to size.

 

Back plate installed. Side view, before purfling and edgework.

Side view, before purfling and edgework.

 

Back plate installed and trimmed to size, before purfling and edgework.

Back view: before purfling and edgework.

I use the purfling marker to scribe in the double lines (except for the corners) where the purfling will be inlaid. I then draw in the corners very carefully. I have occasionally used a template for the corners, but it seems to not always work, since the corners are not always exactly the same. So I end up just making some layout marks to get the limits delineated, and then I draw the corners in, freehand.

I incise the purfling slot with a small, sharp knife, in three or more steps:

  1. The first pass with the knife is very shallow and light, only serving to deepen all the scribe marks.
  2. The second and third passes bring the purfling slot to the correct depth, and
  3. The last step is to use a purfling pick to remove all the waste wood between the paired cuts.

 

Purfling slot partially completed;

One-piece European maple back: the Purfling slot is partially completed; but still too shallow, and a little too tight.

 

Purfling slot complet

Purfling slot is completed… it turned out to be a little too tight: I used a tiny sharp knife to trim the tight spots, until everything fit.

I check the depth and width of the slot by inserting a small section of purfling into the slot, all the way around, until I am sure that the slot is correct. then I bend and fit the purfling strips, and make sure the fit is as exact as I can make it, terminating in the classic “bee-stings” at the corners, rather than a simple “mitered corner.”

Finally, when all is as close to perfect as I can manage, I lift each section of purfling partially out of the slot, one at a time, and slip hot, thin, hide glue into the slot, using the thin palette knife again. I press the purfling all the way down to the bottom of the slot, and allow the glue to dry before beginning the final edgework.

Back purfling completed.

Back purfling completed. Channel still needs to be cut and edgework is still untouched.

 

The Channel, and Final Edgework:

I scribe a margin around the entire outer edge, usually about 1.6mm in from the outer edge. This will serve as the “limit” for the channel. I cut the channel using gouges first,then scrapers, and bringing the smooth curve up to match the scribed limit. Then I file the outer edge to round in from the center of the edge of the plate up to meet the scribed margin. I true up lines using scrapers, files, and abrasives, and then I am ready for final varnish preparations.

We’ll talk about all that in the next post, and post pictures. I need to get this one wrapped up. I’ll show close-ups of the edges and corners next time. there is still a long way to go, but it is looking more encouraging. 🙂

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5 String Report #14: Final Varnish Preparation

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Final Varnish Preparation:

Advance warning:

An apology in advance: as I warned some time ago, I have a tendency to get out of “photography mode” and just pursue the tasks at hand, then suddenly realize that I was supposed to be doing “show and tell”. So, (sigh…) this time it will be more “tell” than “show.” But I do have some photographs of the tools involved.

Cutting the Purfling Channel

The first step in cutting the channel is to determine its boundaries. I usually use a compass to scribe a line 1.6 mm in from the raw edge of the plate, all the way around, including the corners and the ends, where the channel has to follow the purfling away from the edge. (This time I used a special tool, made by Jake Jelley, to do the same thing. I think it worked better.)

Tool for scribing the crest of the edge

Tool for scribing the crest of the edge. There is a collet-style pencil lead held in place, there.

That marks the outer edge of the channel, as well as locating the crest of the finished edge. I extend that line at the same distance from the purfling at the ends, so, at the ends I have two lines: one forms the crest of the edge, the other the edge of the channel. The dark Koa wood did not easily show the pencil mark, so I had to scribe firmly, and usually several strokes.

I then cut the channel with a sharp gouge, trying to keep it shallow, but following the scribed line all the way around. I used a larger gouge for the upper and lower bouts: a smaller one for the C-bouts.

Larger gouge for upper and lower bouts.

Larger gouge for upper and lower bout channels.

 

Smaller gouge for c-bout channel

Smaller gouge for c-bout channels

Scraping the channel and fairing the curves

Then I used scrapers to “fair in” the channel with the curve of the arching, and make sure there are no humps or hollows.

Large radius scraper

Large radius scraper (this scraper has four edges…each a different curve.)

 

Small radius scraper

Small radius scraper

 

Smaller Radius scraper

Smaller radius scraper

 

Smallest radius scraper.

Smallest radius scraper. This one has a long flat edge, a long curved edge, and both ends have a very small radius.

 

Flat scraper for final fairing-in of curves.

Flat scraper for final fairing-in of curves.

Outer edgework

Finally, I use a tiny plane and a file to shape the outer edge, curving smoothly from the scribed “crest” to the outer edge, where, hopefully, it will smoothly join the curve from the inner edge.

Planing the outer edge curve.

Planing the outer edge curve.

 

Filing the outer curves smooth.

Filing the outer curves smooth.

 

Final Neck and Scroll-Work

I also double-check the scroll and neck shape and contours. They must be scraped to perfection before I can move on. I use a template (copied from Henry Strobel’s books) to check the upper and lower shape and size of the “handle” portion of the neck, and then try for smooth transitions between the two.

Neck template

Neck template for upper and lower neck cross-sectional shapes.

 

Upper neck shape

Upper neck shape with template.

 

Lower neck shape with template

Lower neck shape with template

 

Scraping the Volute

The volute has to be scraped in both directions, otherwise the scraper will simply follow the grain and leave humps. (Ask me how I know…)

 

Scraping the transverse curve in the volute.

Scraping the transverse curve in the volute.

Final Varnish Preparation

At last I am ready for final varnish preparation. Everything has to be as perfect as I can get it, because every imperfection will definitely show up under the varnish. The tiniest blemish will show up like a neon sign once I begin the varnishing. Some people insist on only using scrapers, but at this point I feel fine about using very fine (400-grit) abrasive paper to remove the tiny blemishes.

ready to varnish

Pretty much ready to varnish. Looks pretty plain at this point, doesn’t it?

I removed the fingerboard for varnishing…it was only temporarily glued in place, originally, to aid in the neck setting procedure. While varnish is drying, I will shape the underside of the fingerboard, and lighten it, to enhance tone and projection.

After the varnishing is completed, I will glue the fingerboard permanently in place. I will also install the saddle, nut and pegs after varnishing. At that point, the violin will be essentially complete, and set-up is all that remains.

So: I’m sorry I missed the “in progress” photo opportunities, but, from here on out, it will be just progress reports in finishing. The mineral ground is next, and then the sealer.

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5 String Fiddle Progress Report #13; Completing the Purfling Weave

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Five-String Fiddle Purfling Weave

Over and Under Illusion

Some makers, especially those making violas da gamba, Lutes, etc., make much more complex purfling weaves. Some of the Celtic designs employ the technique in very sophisticated ways. The point is to make an illusion of 3-D “over and under” weave in the purfling. As far as I know it has zero effect on tone; just appearance.

Installing purfling

When I left off, last post, the purfling groove was nearly complete, but not quite: I finished picking out the last bits of wood in the “fleur de lis” areas, then went all the way around checking for depth and width.

My purfling bending “iron” is an old-fashioned solder-iron affixed to a brass cylinder with various diameters. I don’t know who made it…I got it from my friend Jake Jelley.

Purfling bending iron

Purfling bending iron: my bending strap is spiral-cut from a large energy-drink can I found at work.

Starting with the completed purfling groove, I first cut and bent the center-bout purfling strips, and inserted them into the grooves, making sure the mitered ends were all the way into the corners of the “bee-stings”, as the sharp miter-ends are commonly called.

Then I cut and bent the long upper and lower bout strips, and fitted them carefully into place, jamming them tightly into the miters at the corners, and trimming them to fit exactly at the other ends.

Dry fit lower and center bout purfling strips

Dry fit lower and center bout purfling strips

 

Upper bout purfling dry-fit

Upper bout purfling dry-fit

 

Then I began gluing the long strips in place, so that they would stay put while I installed the short ones. I tipped the center strips up and inserted hide glue in the groove, then pushed them back in place, and forced them to the bottom of the groove, so that the glue was squeezed out all the way along each strip. Then I repeated that procedure on all the upper and lower-bout purfling strips. Afterward, I could begin work on the “fleur-de-lis” designs.

Second side lower bout purfling dry fit

Fleur-de-lis design begun

 

Upper fleur-de-lis begun

Upper fleur-de-lis begun

The “Weave”:

You can see that I had to decide, initially, which strip goes “over” and which goes “under”: In reality, of course, they are all at the same level, but, choosing which gets cut off (thus looking as though it goes “under”) and which goes on through an intersection (thus appearing to go “over”) determines which way the “weave” seems to go. Once I pick a direction, I need to pay close attention to see that it continues with the “over and under” look, to make the “weave” illusion appear correctly. I also try to make both ends the same way (starting “left over right”, for instance).

Purfling weave half done

Purfling weave half done

 

Lower purfling weave complete, ready for final scraping

Lower purfling weave complete, ready for final scraping and edgework (which has not been begun.)

 

Upper purfling weave complete.

Upper purfling weave complete.

 

Purfling weave completed:

Purfling weave completed: next step will be to cut the channel.

All that is left on the back, now, is the channel, the edgework, and final scraping. We are officially “on the home stretch!”

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Front cello purfling channel cut

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Front Purfling Channel Cut: Final Arching Begun

First mark the Crest of the channel, then cut the channel!

When I first began making fiddles, it had never occurred to me that there was a specific distance from the edge that I should aim for– I just started cutting, and eyeballed the whole edge. As a result I had some very rough-looking fiddles. Now I mark about 40% (2mm, in this case) in from the outer edge, and cut my channel so that the edge of the channel hits that mark, while the top of the purfling gets trimmed back so that it is clean and smooth.

I used two gouges to cut the channel–a small one to carefully trim back the narrow lip of wood between the purfling groove and the marked crest, and a larger one to cut the rest of the channel.

Then Begin The Final Arching

Once the channel was relatively close all the way around, I began cutting the longitudinal arching down to the final level. I will not complete it tonight…I had two phone calls and a customer (future) show up, so that took up a bunch of time, and now it is getting late. Here’s what it looks like for now:

Cello Front Purfling Channel Cut

Cello Front Purfling Channel Cut

Cello Front Lower Bass Corner

Front Lower Bass Corner

Anyway…that’s it for tonight! The Spruce cuts very easily with a small, sharp plane. I hope to complete the arching tomorrow evening.

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