Posts Tagged ‘scraping’

Beginning the Finish

Please share with your friends!

Beginning the Finish

Pre-varnish Scraping and Shaping

Before any finish materials can be applied, the wood has to be about as perfect as I can make it: so I scrape it to its final shape, then dampen it with coffee, to simultaneously raise any fibers that had only been flattened by the scraper blades, but not smoothly sheared off, and, hopefully, add a slight “tan” to the wood, while doing no harm.

Thus, having removed the fingerboard (which had only temporarily been installed) and having applied two coats of coffee, allowing the wood to dry between coats, and having sanded lightly, all over, with 400-grit paper, to remove the raised fibers, and any excessive “corduroy” effect, the instrument went from looking like this:

Shaping complete, but wood un-treated.

Shaping complete, but wood un-treated.

 

To looking like this:

Coffee-stained, and sanded with 400-grit.

Coffee-stained, and sanded with 400-grit.

 

Then it is time to begin the real finish: I first coat the wood with a coffee-suspension of very fine, powdered gypsum, hoping to add more color as I fill the grain with the gypsum. I vigorously rub this suspension into the wood, hoping to encourage the tiny particles of gypsum to actually settle into the pores of the wood, so as to fill them, and to slow down the absorption of varnish. It is considered undesirable, in general, to have the varnish really soak into the wood, as it tends to dampen the vibrations that make the sound. Some varnishes are more detrimental than others, but this is something I learned by reading Roger Hargrave’s notes. He is a world-class expert, so I tend to believe him that this is a good idea. I try to remove as much as I can of the excess mineral “ground” before it completely dries, rubbing hard, with a rag, but any that has settled into grain irregularities, I simply skim over, and leave it there.

So, after the gypsum has been applied, it looks more like this:

Mineral ground applied, front view.

Mineral ground applied, front view. A little darker color, and the grain is more obscure.

 

Back grain quite obscured by the gypsum.

Back grain quite obscured by the gypsum. That will clear up entirely, with the application of the sealer.

 

The sealer locks the gypsum into wherever it has been lodged, and clears the obscurity, making the gypsum completely invisible. The sealer I am using now is a concoction of pine resin, turpentine, and alcohol, with a little yellow tinting. The turpentine and alcohol evaporate, leaving the resin in the wood.

Sealed Front.

Sealed Front.

 

Sealed side.

Sealed Side.

 

Sealed Back.

Sealed Back.

 

After the sealer dries (a day or so), I begin applying the various coats of varnish: the first two or three coats are fairly yellow varnish, but after that, I begin adding the colors that will characterize the finished instrument.

Front with yellow varnish.

Front with yellow varnish.

 

Back with yellow varnish.

Back with yellow varnish.

 

From this point, forward, the instrument will become increasingly darker, leaning toward reds and browns. Ultimately, I will try to emulate the look of the 1715 “Titian” Stradivarius violin, after which this insrument is supposedly modeled. We will see how it turns out.

 

Thanks for looking.

 

 

If you found this post helpful, please share with your friends!

Closure and Final Scraping

Please share with your friends!

Closure and Final Scraping

Graduation complete

When I last posted, I was beginning the graduation process for the back plate of the Titian copy. I had a pretty busy week, but this is where it went:

Completing the graduation of the Back plate on the Titian Strad copy.

Completing the graduation of the Back plate on the Titian Strad copy.

 

Once the graduation was complete, I removed the interior form (sometimes called the “mold”) from the garland, and trimmed the blocks and linings, so that the garland and back plate could be joined. I had already flattened the back of the garland, so this was a pretty simple step.

 

Graduation complete: ready to close!

Graduation complete: ready to close!

I aligned the plate on the garland as closely as I could, dry, then began applying clamps to hold it. I adjusted the position slightly as I progressed, so that when I finally had clamps on all corners, and in the center of each bout, the position was exactly what I wanted. Then I began removing two or three clamps at a time, and slipping hot hide glue between the plate and the garland, using a thin palette knife. I quickly replaced the few clamps I had removed, and more clamps between them, so that the section was securely attached. Then I moved to the next section and repeated the process, until there was glue and clamps all the way around. I saved the neck block for last, because I intended to add that larger clamp, and it would have been cumbersome, had I used it early in the procedure.

 

Closed, clamped, and resting overnight.

Closed, clamped, and resting overnight.

I allowed the glue to dry overnight, and, in the morning, I removed the clamps and began carving the heel, and working on the edges of the back.

Closed, but a long way from done.

Closed, but a long way from done.

 

Shaping and scraping the heel.

Shaping and scraping the heel.

Finally, all the surfaces looked right, and the next step will be to remove the fingerboard, and prep the entire corpus for the varnighing process. The Guarneri copy is side-lined for the moment, which is what usually happens when I attempt to make more than one instrument at the same time. I usually get to a certain point on all of them, and then run with one to the finish, and come back for the rest. (Ah, well…at least they do get done.)

Ready for varnish prep. Front view.

Ready for varnish prep. Front view.

 

Ready for varnish prep. Back view.

Ready for varnish prep. Back view.

 

Full Front view: ready for varnish prep.

Full Front view: ready for varnish prep.

 

Full Back view: ready for varnish prep.

Full Back view: ready for varnish prep.

 

Next time, I will either talk about the varnishing preparation process, or I will follow the work on the Guarneri. Probably the varnish-prep. ūüôā

 

Thanks for looking.

If you found this post helpful, please share with your friends!

Scroll Carving

Please share with your friends!

Scroll Carving

Rough wood removal

In the last post, I demonstrated how I use a thin saw, to cut to the layout lines, so as to facilitate removal of the rough wood, preparing to carve.

Now I complete the removal of the rough wood and begin to carve.

Removal of remaining rough wood.

Removal of remaining rough wood was quite easy, because of all the saw-cuts.

Scroll-Carving

I begin to incise the outline of the eye, and carve to volute to size.

Next, I begin to incise the outline of the eye, and to carve the volute to size.

 

Trimming the scroll to the layout lines, before beginning to undercut the turns of the scroll.

Trimming the scroll to the layout lines, before beginning to undercut the turns of the scroll.

 

Starting to look like a scroll...barely.

Starting to look like a scroll…barely. I planed the cheeks of the scroll to the layout lines.

 

It is always nore encouraging when the scroll begins to take shape.

It is always nore encouraging when the scroll begins to take shape.

 

I want to complete the two instruments side by side. I have to stop and work on the other scroll.

I want to complete the two instruments side by side. I have to stop and work on the other scroll.

 

Carving the pegbox.

Carving the pegbox.

 

One scroll is nearing completion, the other is just begun.

One scroll is nearing completion, the other has just begun to take shape.

 

The next web-log post should include two completed scrolls, the installation of two fingerboards, and the setting of two necks. But perhaps that is too ambitious. The holidays seem to be a difficult time during which to get things done. (sigh…)

However, along with the graduation of both back plates, removal of the inside forms (molds) and the final assembly of the instruments, that is pretty much all that is left to do. Oh, yes, and purfling both plates on both instruments. I used to install purfling before completing the arching of the plates, but it frequently resulted in uneven plate overhang (with which I was quite disappointed) just because the purling had locked in the shape of the plates, and so, if the rib garland had changed shape at all, I was stuck. When I began purfling after assembly, the overhang problems pretty much went away.

Anyhow, that is how the project is progressing.

 

Thanks for looking.

If you found this post helpful, please share with your friends!

Final Shaping and Scraping

Please share with your friends!

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.

 

If you found this post helpful, please share with your friends!

Violin Progress

Please share with your friends!

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.

 

If you found this post helpful, please share with your friends!

Progress on a 14-inch Viola

Please share with your friends!

Continuing on the 14-inch Viola

Arching and Graduation

The outside arching for the front plate is¬†essentially complete, though there will be a lot of scraping, later on. I began the graduation (inside arching) of the front plate about the same time as I took off and “sprinted for the finish line” with the “Plowden” Guarneri-model violin (see recent posts), but all I accomplished was that the center of the plate is about the right thickness– everywhere else it was still way too thick.

So! Back to work! You can see (below) that the f-holes have been laid out and deeply incised, which allowed me to accomplish the last stage of the front arching (explained in an earlier post.) Now I need¬†to carefully carve away the interior, until all the plate is the thickness I want it to be…which varies by region, all over the plate. I have to be very careful to check certain areas with a caliper before I begin to carve, or I may¬†easily go too far and make the plate too thin. (Voice of sad experience….) The area around the lower ends of the f-holes are very likely victims of this error, so I try to check regularly, and avoid carving away too much in those areas, especially.

Outer arching small viola top

The outer arching of the small viola is complete, not counting the purfling channel.

 

Side view of small viola arching, before purfling and edgework.

Side view of the small viola’s arching, before purfling and edgework is done.

 

Inside arching of the small viola.

Inside arching of the small viola. The Graduation is¬†complete. Next, I need to cut out the f-holes, and add the bass-bar. I do realize the corners are too long…I will trim them later.

 

Coffee Stain

One thing I decided on this instrument was that I should begin the coffee staining very early, so that, if there is any distortion, due to the wetting of the wood, I can correct it before the plates go on the garland. In this photo, it is hard to see how much the grain is raised, but, those wide summer grains of the Sitka Spruce are all swelled up like corduroy!

Accentuated grain lines, due to coffee stain.

Accentuated grain lines, due to coffee stain.

I will let it dry, and then gently scrape it smooth again. The issue, here, is that the summer grain swells more than the winter reeds, but when we scrape the wood, the summer reeds compress, while the winter reeds resist the blade and are cut away. The result is that the summer reeds are already raised, even before I wet it down and deliberately raise the grain, before leveling it again.

Things remaining:

When the plate is nearly perfect all over, I will finish cutting out¬†the f-holes, and finish their edges as well as I can. I nearly always see something later that I have missed, so I just accept the fact that I will be making corrections right up until the time I begin varnishing. The same thing applies to the scroll. It will never be “perfect”, and I accept that.

I will lay out and fit the bass-bar, trying for an air-tight fit between the bass bar and the inside of the front plate. I install it using hot hide glue and clamps, but will trim it to the proper shape after the glue is dry.

After the bass-bar is fully completed, I round the inner edges of the front plate, so that it is ready to install on the garland.

Post Script:

All of the above was accomplished three weeks ago, before we left on vacation, so it should have been published then, too…but I kept thinking I would get a little more done before we left, so it simply did not happen.

We are back, and progress is once again happening, so I will post more in a day or two.

Thanks for looking.

If you found this post helpful, please share with your friends!

5 String Report #14: Final Varnish Preparation

Please share with your friends!

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.

If you found this post helpful, please share with your friends!

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

Please share with your friends!

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!”

Thanks for looking.

If you found this post helpful, please share with your friends!

5 String Progress Report #11; Back Plate Complete

Please share with your friends!

Five String Progress #11: Back Plate completed and installed.

Inside arching

The inside arching took a lot of time and energy, but it is just part of the job. Once it begins to get closer to completion it is a lot more encouraging, but initially, it is just a lot of work.

Beginning the inside arching of the back plate.

Beginning the inside arching of the back plate.

 

Bit by bit, however, the project begins to take shape:

Back inside arching in progress.

Back inside arching in progress. I made those wooden handles for my Ibex planes so I would not blister my fingers using the planes.

Graduation:

Here, you can see the curvature of the plate, but you can also see why I have to stop using the planes, relatively early, and revert to scrapers: the curly wood tears out badly under the plane.

I also have to measure the thickness over and over, using a graduation caliper, so as not to cut too deeply. This process is called “graduation”, I suppose, because the thicknesses have to gradually change from area to area. They are not entirely symmetrical, but there is a general plan and some practical limitations.

Inside graduations in progress.

Inside graduations in progress.

Scraping:

Now we work with scrapers:

Scrapers and back plate.

Scrapers cut very smoothly, and usually without any tear-out. You can make the scrapers any shape you want, but you have to keep them sharp.

 

Scraping the back plate.

Scraping can be hard on the hands: some people make handles for them. I haven’t done that yet. My thumbs get pretty tired, though.

Final inside preparation for gluing:

I almost forgot to take pictures! At this point the plate is complete, except for purfling. In the past, I have always installed the purfling before attaching the plates to the corpus,  but on this instrument I decided to try purfling after plate installation. I think I like it. I have better control of my edge over-hang in terms of both size and shape.

So: the inside edgework has been done, the label is installed, and the plate is ready to be glued in place.

Back plate ready to install.

Back plate ready to install.

Plate installation:

What I do, nowadays, is to carefully dry-fit the plate to the garland so that it is exactly the way I want it, clamping securely over all the blocks (about eight clamps in all). Then I remove a couple of clamps at a time and slip hot hide glue into the joint, wipe it down with a rag and hot water, and re-clamp that area, adding as many clamps as will fit. I work my way all the way around the plate, and never have to hurry, or suffer any fear that something will get out of alignment while I am working.

For the first four of five instruments I made, I would apply glue all the way around the garland then engage in a panicky race to get the plate aligned and all the clamps in place before the glue gelled. Not good. Usually, about that time, the phone would ring, too… (sigh…).

This way is very peaceful, by comparison, but I have learned to be less compulsive about answering the phone while gluing, too.

And here is the completed corpus, with the back plate glued in place and secured with spool clamps:

Back plate secured with hide glue and spool clamps.

Back plate secured with hide glue and spool clamps.

 

Once the glue is dry, I will be ready to begin purfling the back plate.

Thanks for looking.

If you found this post helpful, please share with your friends!