Posts Tagged ‘purfling channel’

Violin Progress

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Violin Progress

The Front Plate is Complete, except for the Bass Bar

This morning I got back to work on the scraping, and completed the outside of the front plate. The interior is also essentially complete, but still lacks the bass bar, so there is still that to do. I spent some time cleaning up the f-holes, and I am somewhat satisfied with them, but undoubtedly will do some tinkering later, just because I always do, and am never quite satisfied with them.

Front plate

Front plate

 

Back Plate Graduations have Begun

I knew I probably needed to get going on the neck, but I really wanted to begin the back plate graduations, so I started in. This is about as far as I got. I will probably complete it tomorrow, but my hands were getting tired, and I needed to do something easier for a bit.

Back Plate Progress

Back Plate Progress

 

Neck Beginning

You may recall that the neck block had been delivered to me in a trapezoidal cross-section. This is quite common, but it poses a problem for me, because, once I have the side profile of the scroll and pegbox laid out, I prefer to drill a pilot hole for each peg, using my small drill-press, so that the holes are all perpendicular to the centerline of the scroll. That is hard to do, with a sharp angled shape. So, I set my bandsaw for 1/4″, and sawed off a triangular slab from each side of the big end of the trapezoid, reversed them, and glued those slabs back onto the sides, near the thinner end of the trapezoid. I checked with my little square, to make sure I had them at an appropriate location, then clamped them home. Once the glue dries, I will square up the block, lay out the neck, drill the holes, and get going on carving the neck. Those wedges will be completely removed, long before the neck is done.

Slabs removed and rotated up to square up the neck billet.

Slabs removed and rotated up, making it possible to square up the neck billet.

 

Slabs glued and clamped.

Slabs glued and clamped. When the glue is dry, I can square the billet, and proceed with neck layout.

 

A Break-time Treat

Ann and I decided to take a break and go for a walk, as Spring seems to have arrived early. As we neared home again, a pair of Bald Eagles passed by, flying low over our place, and landing in the trees at the front of the property, on the far corner. I had never before heard eagles “chatting” with one another. It was interesting hearing their clear, high-pitched chirps, and whistles, as they “talked” back and forth.

One of them almost immediately re-located to a thicker stand of trees across the road, but the other obligingly remained in sight, preening herself, until a passing hawk began diving at her, and she, too, moved into the thicker cover. I only had my cell-phone, but I did manage to get one photo.

Eagle in the distance.

Eagle in the distance.

 

Back to Work:

Squaring the Neck Billet

Once the glue was dry, I could square the billet, by sanding or planing off excess wood. Removing those slabs had left me with a few milimeters extra on the thickness, and much more on the depth, from front to back. So, since I had tried to plane it, but it tore out badly (as curly maple frequently does) I straightened the sides using the oscillating spindle-sander, and then laid out the neck details. I have made a new neck template, but it is just thin plastic. I will eventually make a light aluminum template which will be more durable. I first laid out one side, including the locations for the peg holes. Then I drilled the 1/8″ pilot holes for the pegs and cut the profile out on my small band-saw. After that, I was able to lay out the other side, and all the rest of the details; including the width of the heel, the width of the button, the width of the neck at the nut, and the taper of the pegbox into the actual scroll.

I forgot to take photos during that step (sorry) so all I can show you is the sawing procedure I used to remove the excess wood from the scroll:

Dcroll carving, first step.

I cut tangents to the curves, down to the scroll outlines from both sides.

 

Curve sections ready to remove.

Once I have cut sections all the way around, I can easily remove those sections and begin carving.

 

I will try to complete the back plate, the bass-bar, and the neck/scroll tomorrow. If I get that far, I will feel as though I am “on the home stretch,”, as the neck-set will then be the only difficult step left to do. We’ll see, though. There may be other priorities to pursue.

 

Thanks for looking.

 

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Home Stretch for the 14-inch Viola

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On the Home Stretch Now!

The 14-inch Viola is getting closer to completion!

When I last posted, the viola was still in the spool clamps. The back plate was installed, but that was as far as I got that night.

Viola in spool clamps

Lots of promise, but not much “grace” in this picture.

 

Spool Clamps Off: Lots of Work to Do, Preparing for Purfling

So…the next step was to remove those clamps, adjust the overhangs as needed, and get on with the purfling. That sounds pretty straightforward, but there is always more to anything than meets the eye.

front view, back plate installed, button needing shaping.

Looks nice, at first glance, but take a look at the neck button (where the back plate overlaps the heel of the neck.)

 

side view viola with unfinished back plate.

Side view of the same state of the viola.

 

Back view viola with unfinished back plate.

Back view: button hidden by my hand. No purfling, and no shaping done.

 

Purfling Groove

I marked the purfling groove, using what is frequently called a “Purfling cutter“, but which is actually a marker. It has two blades that simply lay out the sides of the groove, by scribing them a set distance in from the outer edge…which is why I want the outer edge perfect, before beginning purfling. I have modified my cutter a bit, to make it work more reliably, but the link above shows the type of tool I use. I don’t think I have that brand. I can only use the marker to get within an inch or so of the corners. I lay out the corners by hand, sometimes using a frnch curve to achieve some repeatability.

Afterlaying out the groove in pencil and scribe marks, I incise the lines with a small sharp knife, then pick the waste wood from between the cuts.

Here is the completed groove:

Purfling groove and button complete

Purfling groove complete. Notice that the button is taking shape as well. The neck, too is getting slimmer, and smoother. Lotsa work…

Here is a detail shot of the groove:

Detail of purfling groove.

Detail of the purfling groove.

 

The Purfling, the Channel, and the Finish Work.

Finally I can start cutting and installing the purfling itself. I use a wood purfling, which is very brittle when dry, but bends nicely with a little moisture and a lot of heat. Once the purfling fits correctly, I lift each stip out partway, and insert hot hide glue under it, then force the strip back into the groove. Afterward, I mark the crest of the channel, and cut the channel using a sharp gouge. Finally, I use a tiny plane as well as gouges and scrapers to bring the convex curve of the plate into a fair, smooth agreement with the concave curve of the channel.

The purfling is complete, the channel is cut, and the back curve faired into the channel.

The purfling is complete, the channel is cut, and the back curve faired into the channel.

 

Purfling detail

Purfling detail: look closely, and you can see the edge-crest line in pencil.

 

side vies of viola.

It is a fairly high-ribbed viola: 35mm. I think it will sound good.

And, it is looking more and more like a viola!

Viola nearly complete

On the Home Stretch!

 

What is next? Edgework, and final scraping; coffee stain, mineral ground, sealer, and varnish…and then fittings and set-up. (The outer edgework is not even begun on the back plate.)

This is definitely as far as I am going tonight, though…. Getting too tired.

 

Thanks for looking

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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.

Thanks for looking.

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Channel cut and final arching begun

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Purfling channel and recurve begun, with final arching on the way.

Mark the crest, first

There are several ways to do this, but I used a compass, with the pencil withdrawn a few millimeters. I wanted to establish the crest of the edge about 40% of the way in from the outer edge of the plate to the edge of the purfling. In this particular case, the purfling is 5mm from the outer edge, so I set the compass for 2mm, and carefully traced all the way around the plate, so that I had a visible guide to follow with the gouge as I carved out the channel.

What gouge?

I used three different gouges: two have a curvature about like the ball of my thumb…no idea what specific sweep…one with a long handle, the other quite short. The third is a much smaller gouge I used specifically in the corners. Every few minutes I stopped and honed the gouges, or at least stropped them. You have to work very carefully to avoid tear-out in carving the channel on very curly maple. I used a rotating motion with the gouges, so that the wood and purfling was being sliced away, and was less likely to split.

What plane?

Once I had the channel cut all the way around, I switched to Ibex planes and began fairing the curve from the bottom of the channel up onto the highest areas of the plate. Occasionally I switched to a tiny flat Stanley plane to smooth out the ridges left by the curved sole Ibex planes.

It is still pretty bulgy, but looking better. All still quite rough…at this point I am more anxious to move a lot of wood than to move it smoothly. As I get closer to the final shape, I will take pains to make sure everything is smooth.

Here are a couple of pictures…not terribly clear, but I think you can see the progress.

channel and recurve cut...final arching begun

Still too high all over, but the channel is cut, and the final arching is begun.

Cello corner with channel cut and final arching begun

Same corner as before, with channel cut and final arching begun

I was getting pretty tired, so I am going to call it a night. I hope to get more done tomorrow night.

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