Posts Tagged ‘bass bar’

More Progress: Plates and Scroll.

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More Progress: Plates and Scroll.

Completing the Back Plate

I continued planing away wood from the inside of the back plate until it was very nearly correct, then switched to scrapers, and completed the inside surface, so that it looks to be a smooth continuum of curves, transitioning without a ripple. The  plate will require no further attention until I am ready to install it. Unlike the front plate, I intend to install the purfling later, after I am completely sure how the garland will respond to having the mold removed (sometimes they can move, and change shape a little.)

Back Plate Graduation complete.

Back Plate Graduation complete.

 

Scroll Progress

I also continued working on the scroll. My hands were getting pretty tired, so I took a break from that. It is still quite rough, but, here’s how it looked at break time:

scroll beginning

Long way to go.

 

scroll progress

On the right path, but “miles to go before I sleep.”

 

Bass Bar Fitting

To fit a bass bar, I begin with a completed front plate, and lay out the position of the bass bar, so that the distance from the center to the bar, level with upper and lower bouts at maximum width, is 1/7th the full distance from centerline to the edge at those respective points. Usually, that means that the lower point will be about 15mm from the centerline and the upper one about 12mm (as it is in this case.) I lay out a line through those two points, and observe where it is, nearest to the bass-side f-hole. If it is too close, I “fudge” it away, a bit, trying not to change the angle. (The bass bar has to clear the f-hole.) Then I mark the two ends, 40mm away from the ends of the plate, and that is the place to fit the bass bar: the “footprint”, so to speak.

Bass bar position laid out.

Bass bar position laid out.

 

I use chalk to fit my bass-bars. I have never had a good enough eye, and a sure enough knife-hand to accurately fit a bass-bar without the use of chalk, though I have known master makers who regularly did so…perfectly. (Sorry… I’m not good enough for that.) On the other hand, I have had some nasty experiences with the residue of blue chalk mingling with the yellowish hide glue when installing a bass bar: it left a very ugly green stain…and it never completely came out. So…what to do? In the first place, I switched to pink chalk. If a little chalk is left, the glue will simply make it look a bit orange. (No problem.) But, I really don’t want chalk residue at all.

A friend showed me the paper “gauze” tape available in pharmacies. It is thin enough to completely conform to the surface of the plate, and  produce a good fit, and, it is slightly translucent, so I can see my layout lines through the tape, and keep the chalk on just the path of the bass bar. I first use a compass to mark the general shape of the bottom of the bass bar, and then trim it with a knife and a small plane. That gets me “in the ball-park,” so to speak. After that, it is chalk-fitting time.

The front plate is made of European spruce, but I chose Sitka spruce for the bass bar. There is quite a contrast in color between relatively fresh European spruce, and well-aged Sitka spruce. It actually made it a little difficult to see the pink chalk against the dark wood. But it worked.

Bass bar blank, knife-trimmed after tracing the shape with a compass.

Bass bar blank, knife-trimmed after tracing the shape with a compass.

 

paper gauze tape

This is the paper gauze tape I use for chalk-fitting.

 

Paper gauze tape and pink chalk

Paper gauze tape and pink chalk, ready to begin chalk-fitting.

 

Layout lines visible through the tape.

Layout lines visible through the tape.

 

Layout lines traced over on the tape, to make them more visible.

Layout lines traced over on the tape, in pencil, to make them even more visible.

 

Chalk on tape.

Chalk on tape.

 

Chalk transferred to bass bar

Chalk transferred to bass bar

 

The idea, in any chalk-fitting procedure, is to press the fitted part (being fitted) into the chalked surface to which it is being fit, then trim away only the portions where the chalk transferred. So, in the case of the bass bar, I need to press it into the chalked top plate, and then check the bottom of the bass bar blank, to see where to cut. I trim off the obvious spots, and try again. Ideally, every time I try, I will get a broader transfer of chalk. When the whole area gets a light dusting of chalk at one time, the fit is as close to perfect as I can get it. I remove the tape, wipe off any chalk residue, slather the hot hide glue onto the bottom of the bass bar, and clamp it home. On a good day, it takes me a half-hour. On a bad day? Don’t ask… 🙂  This time wasn’t bad, though.

Chalk-fitting complete; Dry-clamped to check fit.

Chalk-fitting complete; Dry-clamped to check the fit.

 

Tight fit

The fit is good!

 

Glued and clamped

Glued and clamped. 

More Scroll Progress

While the glue was drying on the bass bar, I went back to work on the scroll. It was looking verrry rough when I had to take a break, so it is nice to see it progressing better, now. There is still a lot to do. I have to excavate the pegbox, and cut the fluting in the volute. But this is as far as I am going tonight. I am glad to call it a night, and let my hands rest.

More scroll progress

More scroll progress: there is still a long way to go, but it is looking better.

 

Scroll partly complete.

Final status for tonight. Looking a lot better, and more encouraging to see.

 

I have other things to do tomorrow, so I may or may not get to work on the violin. At the very least, I expect I will be able to trim the bass bar to the shape I want it, but beyond that, I don’t know.

 

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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.

 

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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. 🙂

 

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More Progress on the 14-inch Viola

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More 14-inch Viola Progress

As I work by myself, I frequently fail to take pictures. I did take a few, though. (If you are impatient, you can scroll down and peek at them.)

F-holes Cut Out

I used a special tool to begin the cutting out progress: It is called an “f-hole drill”, but all it really amounts to is a specialized twin-blade hole-cutter. My children bought it for me, one year, and it has been a wonderful tool. In the first place, obviously, it is a time saver, but the biggest difference is that I can now make the upper and lower eyes of my f-holes perfectly round, to begin with, and work any special shaping in, starting from the already round holes.

I remove the waste wood from the uprights of my f-holes with a small sharp knife—many makers use a saw, and I have done so as well, but I eventually reverted to the knife. Just personal preference, I suppose.

Bass Bar

Once the f-holes are cut out and close to perfect (always allowing for later nit-picking), I install the bass bar. The bass bar is a gently-arched brace supporting the bass-side foot of the bridge. Guitars have a whole collection of similar bracing, supporting what amounts to a nearly flat (and very thin) plate. The violin family instruments depend primarily upon the compound curves of the arching to supply strength, and only need the one brace to support the bass-side bridge-foot. The other side of the bridge is supported by the soundpost, which, while it is not directly under the treble-side bridge-foot, it is very close to it, and is in a location on the treble side matching the lateral position of the bass-bar on the bass side.

I lay out the position of the bass-bar, and then use a compass to transfer the shape of the inside of the front plate to the bass-bar blank. Then I use a knife to remove most of the waste-wood, and begin checking the results against the inside curve of the front plate. When the fit is getting close to correct…close enough that it is becoming difficult to see what needs to change…I apply a strip of paper-gauze adhesive tape (available in pharmacies) to the inside of the plate, covering the bass-bar position, and I rub blue chalk into the tape. I happen to use a product sold as “sidewalk chalk;” they are big sticks of chalk, and supposedly are easy to wash off of sidewalks. But they work well for me, and the blue is high-enough contrast that I can see it easily.

I press the nearly correctly-shaped bass-bar into the chalked tape, and check to see where the chalk transferred. I cut, plane or scrape just the chalked places from the bass-bar, repeating until, finally, when I press the bar into the tape, the whole thing comes up lightly coated with chalk. Then I remove the tape, clean off any remaining chalk from both pieces of wood, and install the bass-bar, using hot hide glue and clamps. I have a specialized set of wooden clamps made for this task.

When the bass bar glue is completely dry, I remove the clamps and trim the bar to the desired shape. I make my bars a little higher than most luthiers do, in the center, but tapering to about 5-6mm high for the last few centimeters of both ends. (I will take some pictures after I remove the inside mold, so you can see the final shape.)

Edge Preparation

It is much easier to do the inside edge-work if I do it before I install the plate on the garland. So, I use a tiny finger-plane, along with round and flat files, to round the inner edge of the plate, all the way around the perimeter. I may have to do a little correction later, but I want it as close to perfect as is possible, before gluing the plate to the garland.

Installing the Front Plate

I line up the plate on the garland as accurately as I can, matching the center-line of the plate to the centerline of the garland, and then use spool-clamps to hold it in place. I was originally taught to use tiny pins to assure good placement, but eventually discontinued the practice. We know for a fact that the old masters did this, as we can see the remnants of those wooden pins in their violins, still today. Perhaps I will eventually resume using pins. For now, I do not.

Once I have the plate perfectly aligned and securely clamped, using a very thin palette knife, I slip hot hide-glue into the joint between plate and garland, and then add more spool clamps to draw the joint closed. This is a very “stress-free” way to glue plates in place. I used to experience near-panic every time I installed a plate, racing to clamp the joint before the glue gelled, but now it is a very easy and relaxed task.

Purfling

As you may remember, I have not yet installed the purfling. I wait until the plate is on the garland before purfling nowadays, because the purfling “locks-in” the location of the plate edge, and I have had problems in the past with the rib garland changing shape a little, between my tracing the plate and trying to install it. so, after gluing the plate to the garland, the first step is to double check my over-hangs, to see that they are all pretty close to the same. If I need to change them, I do so: I am free to adjust the shape of the plate to match the garland again. When the overhangs are all acceptable, I begin purfling.

Purfling is fairly simple-sounding:

  • mark the groove location
  • cut the groove,
  • fit the purfling,
  • glue the purfling,
  • mark the edge crest, and
  • cut the channel.

It sounds easy, but I still find it a hard job to do perfectly. I want my miters perfect, my bee-stings clean and sharp, and all my borders parallel. This is my 30th instrument from scratch, and I am still finding it to be challenging. Guess I am a slow learner. 🙂

Cutting the Channel

Before I begin cutting the channel I use a compass to mark a line all the way around the instrument, 1.6 mm in from the outer edge. Then, using a sharp, curved gouge, I cut my channel to that edge crest line, trying to cut the whole channel to intersect the surface of the purfling and that pencil line.

Fairing in the Channel to the Arching

Once I have the purfling completed and the channel cut, I still have to fair-in the surface of the rest of the plate to match the curvature of the channel. I do not want there to be any sudden changes; humps and hollows catch the eye of the person looking, and call into question the skill of the maker. (Besides, I think they are ugly….) I use a very sharp finger-plane to begin shaping the surface of the plate and approximating the final curves I want. Finally I use sharp scrapers to bring the curvature of the whole plate to its final shape. I use a low-angle light to cast shadows from any humps or hollows, so that I can spot them and scrape them away. At this point, the scraper has to be sharp, and I have to use a gentle touch. The changes I am making are frequently much thinner than a piece of paper.

Outer Edgework

After the whole plate is the shape I want, the last task is to shape the outer edge. I begin by using a tiny finger-plane to take the outer corners down at a 45 degree angle, then use half-round files to shape the edge all the way around, bringing the curve of the outer edge up to just intersect the edge-crest line I established earlier. I get it as smooth and even as I can, using a file, but I know when I stain the wood with coffee, it will raise the grain terribly along these edges, so I will eventually re-smooth all of them, using abrasive paper of some sort. In this particular case, I did the outer edgework after setting the neck. No special reason…that is just what I did.

Neck Set

I measure carefully, and cut the tapered mortise using a razor-saw, then use a sharp chisel to remove the waste wood of the mortise. If I do the job correctly, it works very well. I check the sides and bottom to the mortise to see that they are flat and straight, then begin attempting to fit the neck. I have already joined the fingerboard to the neck and have shaped the heel where it will join the neck-block. So, from this point forward, all the shaping and adjustment will be done to the mortise, not the neck. When I am satisfied that the fit is correct, the neck will have to be centered. straight with the centerline of the front plate, straight with the centerline of the end block (not twisted at all), and at the correct angle to place the end of the fingerboard at the right height. Also, of course, the neck has to be set so that the distance from the nut to the edge of the front plate is correct. I check and re-check, until everything works correctly. Since I set the neck before installing the back plate, I want the heel of the neck to protrude past the back end of the neck-block. I will plane it flush after the glue is dry.

Completed neck-mortise

Here is the completed mortise, cut for the neck. The outer edgework has yet to be completed. You can see the edge-crest marks.

 

ready to set the neck

The mortise is complete, and I am ready to set the neck.

 

dry-fit neck set

There is the dry-fit neck set. Notice the overhang of the heel of the neck beyond the neck-block. That will be planed off after the glue is dry.

 

dry-fit assembly

So there is the dry-fit assembly. It is starting to look like a viola!

When every measurement is correct simultneously, and the fit is tight, I remove the neck one last time and slather hot hide glue into the neck mortise. Immediately I jam the neck into place, and quickly check all those measurements again. Bingo! They are all correct, and I can relax while the glue dries! Once the glue is dry, I plane off the neck heel overhang, flush with the neck-block.

ready to remove the mold

The glue is dry, and the neck-heel overhang has been planed flush with the neck block. I am ready to remove the mold.

In this picture, I have filed the outer edge curvature already, and, though you can’t see it in this photo, I have also completed the graduations on the back plate, and have filed its inner edges, so it is ready to install. But; before I can do that, I have to remove the mold and add the back linings.

 

Ready to remove the mold.

Ready to remove the mold.

 

Dreaming of the next step!

Dreaming of the next step!

I am getting tired, though, and have some other things that need doing, so the viola will have to wait until another day to move any further toward completion.

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Progress on a 14-inch Viola

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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.

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5-String Fiddle Progress Report #5: F-holes and Bass-Bar

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F-holes and Bass-bar

F-hole Drill

We had just completed the graduation in the last post; Usually, by this point, I am beginning to see the interior of the f-holes, too, because, as you may recall, I had incised them pretty deeply. In this particular case, I could just barely see some portions. I guess they were not as deep as I thought they were.

Once the inside is complete, I finish cutting the f-holes. Many people use a jeweler’s saw, a fretsaw, or a coping saw to cut out the f-holes. I generally just use the knife, except that I do have a special tool for cutting the round upper and lower eyes. I didn’t take any photos of it this time…here is one from an earlier instrument:

f-hole drill

F-hole drill being used to cut the lower eyes on a cello.

f-hole drill and holes

F-hole drill with completed eyes and cut-out plugs.

F-holes Completed and Clean

Just getting the f-holes cut is only part of the job…they need to be clean, and smooth, and relatively symmetrical. I will keep touching them up and tweaking them until the day I begin the varnish, most likely, but here they are; close to being complete, if not completely done.

f-holes

F-holes essentially complete.

By the way, you may have noticed that on this instrument (and the last one) I purfled after installing the plates. I was taught to purfle early, but I always had trouble getting my overhang even, and my purfling parallel to the ribs. So I tried purfling after closing…works fine and looks better. Diff’rent strokes, I guess….

Bass Bar

When the f-holes are complete, and clean, I can fit the bass-bar. The bass-bar is a spruce brace supporting the bass-side of the bridge, and providing for a good sound on the low strings.

I lay out the location of the bassbar, 1/14th of the width off center, at both upper and lower bouts. It usually ends up about 15 mm off center at the lower bout and 12 mm off center at the upper bout. (Those were the exact measurements this time: the upper bout was 168mm wide and the lower was 210 mm wide. So 1/14th of each was 12mm and 15mm respectively.) When I lay the bass-bar blank along that line, the side of the blank should just about “kiss” the upper eye on the bass side. I make slight adjustments as needed to make sure it does not obstruct the f-hole at all, then scribe the line in with a flexible steel ruler and a soft pencil. The line ends 40mm from each end of the plate, so the bassbar is just under 11″ long, (and about 7mm thick where it contacts the plate, tapering to 5mm along the free edge.)

bass-bar layout

Bass-bar layout lines complete.

Chalk-Fit Trick

Then I do something a little unusual: lots of luthiers chalk-fit bass-bars…in fact, probably most of them do. I have only known one or two who can successfully “eye-ball” the thing in. But I do not like the looks of chalk-residue mixed with hide-glue, either. I can’t see the white chalk clearly enough to use it, and the others leave an ugly residue– expecially the green or blue chalks.

So… what to do? Someone, years ago (can’t recall who…probably my friend Jake Jelley), pointed out that the paper gauze tape sold in pharmacies will stick securely, you can see the line through the tape, and it holds the chalk very well. The tape (3M Micropore) is so thin and fragile that you get a very good fit, but when you take the tape off after the fit is perfect, all the chalk comes off with it. (Careful! It can pull splinters off, too!) Hey, Presto! Clean wood, and you are ready to glue in the bass bar!

Pre-Fitting the Bar

I pre-fit the bass-bar by eye, using a compass to mark the contour from both sides, then trimming with knife and plane until the fit is close.

Bass-bar pre-fit.

Bass-bar pre-fit by eye, using a knife and plane to trim the wood to a close fit. Chalk-fitting is next.

Then I apply the paper tape, darken the line on the tape as needed, and begin the chalk-fit process. It is important to learn to JUST plane or scrape away the portion of the bass bar with chalk on it, on each try. Don’t plane off whole sections…it is possible that only that one little place with the chalk was high.

paper tape for chalk fit.

There is the paper tape…you can still see my layout lines.

chalk-fitting bass-bar

Beginning chalk-fit.

chalk-fit complete

Chalk-fit complete, and tape removed. Notice the arrow on the upper end of the bar: that is to keep me from forgetting which end is which.

Final Check and Installation

I check the fit by clamping the bar in place, dry.

bass-bar dry fit

Dry fit and clamped for final check. Seems to fit acceptably…

Then I remove the clamps, and slather on the hot hide glue–carefully. I quickly re-position the bar and clamp it securely, then clean up, using hot water and a brush. The small amount of watered-down glue soaking into the wood around the bar doesn’t seem to hurt anything, so I don’t worry about it.

bass-bar glued and clamped

Bass-bar glued, clamped and brushed down with hot water.

Shaping the Bass Bar

When the glue is completely dry, I remove the clamps and shape the bar…”just so”.

sketched shape of bass-bar

The glue is dry… see the sketched-in proposed shape of the finished bass-bar. The dark area beside the bar is just a shadow, not glue.

I do not have a “scheme”, here, and I do not measure it beyond occasionally checking the center height. I am just going by feel, by eye, and by experience. I know if the bass bar is too weak, it will affect the sound of the bass string…so I err on the side of a tall bar. I am certain that many will frown upon this. I am not telling you how you should cut a bass-bar; just sharing how I handle mine.

So; I use gouges and finger-planes initially, to shape the bar, finishing up with scrapers, files, and even sandpaper. (Yes, I know…but it’s OK, honest!)

And…there’s the plate, completed and ready to install! Well…sort of….

The glue was a little too thin on one end of the bar and it popped off for about a 2″ section. So it has been re-glued and is drying.

bass-bar nearly complete

Bass-bar nearly complete. One end popped loose, and needed re-gluing.I will do a little final shaping before calling it done.

Besides, the inner edges of the plate will have to be rounded and smoothed before I can actually install it. But there are probably less than 30 minutes of work left before I can glue the front plate in place. So it’s almost done. I hope to install it tomorrow, but I have some other things to do, as well.

Some of you may wonder why I install the front plate first; I was actually taught to do the back plate first, and to install the neck last, but it finally occurred to me that I could fit the neck before installing the back plate, and before removing the mold, and get a perfect neck-set, then trim the back of the heel flush with the rib plane, and install the back last, after removing the mold and cleaning up the interior. It worked very well, so I have continued the practice. Again; different ways of doing things result from different skill-sets and different problem-solving methods. There is nothing wrong with either way. (I even knew of a fellow who set the neck before installing either plate…but I can’t see that one. On the other hand, that guy made over 1000 instruments before he died, and sold every one of them; he must have been doing something right.)

So, the next post will involve completeing the neck and fingerboard assembly, installing the front plate, and setting the neck. Could be a week away; I am going to be working a lot of overtime on my day-job, for the next several months it seems.

Later the same evening:

finished bassbar 1

Bassbar is finally complete!

bass bar side view

Side view…lighting is difficult, but you can see the profile.

Thanks for looking.

Chet

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Bass Bar installed and trimmed–F-holes refined. Edge-work begun.

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The Bass Bar is in place and trimmed. The F-holes have been refined, somewhat, and the edge-work is begun.

Bass-bar was #1 on the list!

I installed the bass-bar first thing this morning (chalk-fit to the inside of the plate in the exact location it was to be glued, then glued with hot hide glue).

Then, while the glue was drying, I went and did other things. Swept up the shop, changed the tires on my car (snow tires have to be off this weekend), and designed some display stands for the upcoming show at Marylhurst University. I had intended to begin the graduations on the one-piece cello back plate today, but after I did the tires, I was pretty worn-out, and hurting, so I decided it was time for a break, and, since the glue was dry, time to trim the bar.

Bass Bar in the rough

Here’s what the bass-bar looked like in the rough, when I took the clamps off:

Cello Bass-bar in the rough, viewed from the top.

Bass-bar in the rough, viewed from the top

Cello Bass-bar in the rough, viewed from the side.

Cello Bass-bar in the rough, viewed from the side.

Bass Bar Trimmed and finished:

And here is what it looked like after planing it to the shape I wanted it to be:

Finished cello bass-bar from front

Finished cello bass-bar from front

Finished Cello Bass-bar from side

Finished Cello Bass-bar from side

Edge-work and final prep for finishing

Although you probably really can’t tell in the photos, I have also scraped the entire plate, inside and out, under low-angle light, to get every dip and hump as smooth as can be.

Also, I began the edge-work; I first planed a small (3mm) bevel all the way around the inside edge, then rounded it with a file, to establish the inside curve of the edge. The outside will be treated the same way, after the plate is installed on the garland. It is much easier to manipulate the plate by itself, instead of the whole cello, so I want to do as much as I can before it is assembled.

I also spent time refining the f-holes; smoothing the inner edges, matching bass to treble shape, etc. That, too, is much easier before the plate is assembled with the garland.

Tomorrow I will try to graduate the back plate.

Gotta do taxes, too, though.  (Hooray for Turbotax!)

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Front Graduations Complete and F-holes Cut

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Cello Front Plate Graduation Completed

Smooth inside and out, and all thicknesses correct

It took me a couple of hours, I guess, to do the final graduation, planing and scraping the inside of the European Spruce  front cello plate to perfection (or nearly so). Here is the plate, with some pieces of willow lining stock across it, to form shadows so you can see the curves. The color is so neutral that without the shadows, the plate looks flat in photographs.

Completed graduation of cello front plate

Graduation complete!

The f-holes had been incised earlier, so all that was left to do is finish cutting them out. I used the f-hole cutter to cut the circular portions of each f-hole.

F-hole cutter in use

F-hole cutter in use

Finished result of f-hole cutter use

Finished result

Then I used a coping saw and a knife to complete the cutting. Each hole will still be refined and perfected, later, using a knife and a small file.

Cutting out the f-holes with a coping saw.

Cutting out the f-holes with a coping saw.

Finishing the F-hole shape with a knife.

Finishing the F-hole shape with a knife.

But the f-holes are essentially complete. the next step is to install the bass-bar.

Completed f-holes, ready for refinement.

Completed f-holes, ready for refinement.

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