Archive for the ‘Cello build photo-essay’ Category

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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Graduation Progress

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Carving the Inside of the Front Cello Plate

 

All with planes, this time.

I probably should have used gouges, but the planes are so easy to control and the spruce is so easy to carve, that I chose to use these three planes: (I may still use gouges to get the areas around the end block platforms correct.)

Carving inside of cello top plate

Carving inside of cello top plate: Two hours work, and not done.

As you can see, the plate is not yet done, but I was pretty tired to start with, today, and now I am even more so.

Cello front plate with tools

Cello front plate with tools

Keeping the Goal in View

Here is how deep the graduations are, so far. I hope to have the thickness of the whole center area at about 5.5mm, fading to 4mm up the center on both ends, and 3mm on the upper and lower “flanks”, for lack of better word.  Right now the center is 6mm, and the areas up the center are still about 7mm…the areas out in the skirts are way too thick, still: 10-12mm. It takes a fair amount of care, graduating a cello plate: I have to stop every few minutes and check the thickness with a dial caliper, to avoid making the plate too thin.

Depth of partial graduation--correct in center; unfinished elsewhere.

Depth of partial graduation–correct in center; unfinished elsewhere.

Perhaps I will have it finished and ready for the bass bar by Tuesday. Tomorrow is busy, and I will work late Monday, so…probably Tuesday. That’s OK: it will give my hands time to recuperate.  They are pretty worn out…and that one-piece maple cello back will be much tougher to carve.

I did, however, complete the refinishing of the viola I built back in November. It looks pretty nice, now. So I will have that for the show, as well.

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Front and back plates fully arched, f-holes incised

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Final arching is complete

Low-angle light and Scrapers

Today I used low-angle light to reveal all the humps and hollows, and used scrapers to bring all of them to a smooth continuum of curving wood.

“Flat F-holes”

Once I had the front plate fairly smooth, I laid out the f-holes, and incised them deeply. My reason for doing this is that every single instrument I have made, the arching proved to need correction, as revealed when I laid out the f-holes. Invariably the arching was too “puffy” around the lower ends of the f-holes, so I had to re-carve that area. Finally it occurred to me that if I cut the lines in, they would remain visible as I carved, and I would not have to lay them out over again. That turned out to work pretty well, so now I routinely assume I will have to correct the arching, and I incise the f-holes, then view the plate from the side: what I am aiming for is that the general shape of the f-hole will seem to lie in a plane parallel to that of the ribs when the instrument is assembled, rather than describing a lazy “S” from the side.

Here is an example from an unfinished viola, from several years ago:

Flat F-hole

Flat f-hole

It is not something “exact”, but more of a general impression. One way or another, it allows me to see when my arching is not right, and correct it.

So, here is the top plate with the f-holes incised. I will finish cutting them out after the inside carving (graduation) is nearly complete.

Cello Front Plate with f-holes incised

Cello Front plate with f-holes incised

Here’s an end-view…doesn’t show much:

End View of Cello Front Plate

End view of Cello Front Plate

And a sort-of  “3/4” side-view…trying to show the curves:

3/4 view of cello front plate

3/4 view of Cello Front plate

Here’s a close-up of the c-bout with the f-hole incision (I used a special f-hole cutting tool to incise the circular parts):

Cello C-bout with incised f-hole

C-bout with incised f-hole

Annnd the back plate: (still may be a bit puffy in spots…I will work on it more later. Right now my hands are hurting from all the scraping) That’s all for today! I’m worn out.

Side view one-piece Cello back plate

Side view one-piece Cello Back plate

End-view of one-piece cello back-plate

End view of one-piece cello back plate

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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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Cello top purfled– ready for final arching

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Cello Top Purfled and ready for Final Arching

Fresh Purfling

Here is the cello top, freshly purfled, hot hide-glue still wet. Tomorrow night I will try to complete the final arching and lay out the f-hole perimeters.

I had some distractions tonight, but that is life. Life is what happens while you are trying to complete your projects and plans. Embrace it or fight it, that is simply how it is.

This spruce has very pronounced winter grains, which were hard to cut smoothly for the purfling slot, but the plate rings like a big bell if you tap on it. I think it will probably be a very good cello.

Freshly Purfled Cello Top

Freshly Purfled Top

Anyway, tomorrow evening when the glue is dry, I will cut the channel and begin finalizing the arching. If I get it close, I will try to get the f-holes laid out and outlined. After that it will be time for graduation of the plate (carving the inside arching).

Press on!

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Cello top rough-arched, ready to purfle

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The Cello top is rough-arched, and ready to purfle.

All thicknesses are approximately correct

The European Spruce top, from International Violin Co., carves easily, but is quite crisp, too. I reduced the top to 24mm thick, using an abrasive planer, then reduced the edges to 5.5mm, using an Ibex plane, modified to take a wooden handle.

Poor Man’s Scrub Plane:

Here is the tool, from a year ago, when I was working on a different cello:

Modified Ibex plane with wooden handle

Modified Ibex plane with wooden handle.

This tool allows me to apply much more force, and cut deeper, faster.  Sort of a “poor man’s scrub-plane”. Once the edges were close to the 5.5mm line, I switched to a 10mm Ibex plane and shaved the edges of the spruce right down to the line.

And here is the result of about two hours’ work:

Rough-arched plate ready for purfling

The edges are 5.5mm…the middle is 24mm. I will finish the arching after the purfling is complete.

Ready for purfling

The cello top is ready for purfling. Tomorrow I will begin the purfling, and complete it on Friday, I hope. Then I can complete the arching, trace the f-holes, and start making this thing look like a cello.

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More progress on the back plate– beginning the front plate

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One-piece Cello Back progress; Cello top beginning

Low-angle Light Reveals Lumps

Remember I said that the cello back was ready for scrapers and low-angle light? Well, here is what low-angle light reveals:

low angle light & lumps

Low-angle light, illuminating lots of lumps. (Fun to say, but a pain to smooth out.)

Pretty rough-looking, huh? But that low-angle light is what reveals the lumps so that they can be planed or scraped away. Some of those lumps are big enough that I intend to use a small plane to reduce them before scraping again.

Saturday, I joined the top plate halves. The notches in the ends and center were to accommodate clamps. I had worked the mating edges as smooth and flat as I could get them (it seemed perfect, but looks can be deceiving), and then heated the two surfaces with my heat gun until they were uncomfortably warm, slathered on the hot hide glue, and presented one half to the other, rubbing them under pressure, to get the glue to run out the edges. Then I clamped each end firmly, and finally applied two bar clamps in the center notches.

I was fearful that the joint might not have been good, but today I took the clamps off and had a look. All is well! Here are the two plates (front and back) together. Notice how much nicer the back plate looks in normal light? That is why you never trust the looks of the arching until you have checked under low-angle light.

One-piece back with front billet

One-piece back with front billet

Front and back plates, inside to inside

Front and back plates, inside to inside

I was curious how close the front and back of the garland might be, in terms of shape (they almost never are exactly the same), so I traced around the back plate in blue ink, and then checked it against the actual garland. (Oops. No, that will not be good enough… see the blue line in the photo below?)

Using a slice of aluminum pipe and a ball-point pen to trace the shape of the cello front plate from the garland.

Using a slice of aluminum pipe and a ball-point pen to trace the shape of the front plate from the garland.

So I re-traced in black ink, directly off the front side of the garland, using the section of aluminum pipe to maintain the overhang distance. See the difference?

Front and back are not exactly the same.

Blue line is traced from the back–black is from the front of the garland.

So, I cut the plate out on the black line, leaving the corners just a little long, so I could work on them more carefully, later. Here is the result.

Front plate cut out with saber-saw

Front plate cut out with saber-saw

Front plate ready for arching

Front plate ready for arching

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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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Cello Back freshly purfled

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One-piece Cello back purfling complete.

Narrow (violin-style) purfling, like the original

Today I completed the back plate purfling. Though this is a cello, I purfled it with violin-style purfling, as it was pointed out to me by Jacobus van Soelen that the original instrument (1712 Davidov Stradivarius) had narrow purfling, like a violin, not the wide purfling I used on my first cello (and which I actually like to use on violins and violas, as well.) I just like the eye-catching appeal of the larger purfling as a rule. In this particular case, I must concede that the wood is so beautiful that it really does not need additional “eye-candy”.

The job starts with layout and measuring

Last night I laid out the corners, and marked the whole purfling channel using a purfling marker (sometimes called a purfling cutter— but I only use it for marking– I use a knife to actually cut out the slot for the purfling).

Then cutting and fitting

This morning I incised the whole purfling slot, using a small, home-made knife, and then cleaned the waste wood out of it with a purfling pick.

While I fitted purfling into the slot, and carefully fitted the corner miters, the glue-pot was heating up.

Gluing the purfling

When all the purfling seemed to fit correctly, I tipped each center-bout purfling strip up out of its respective slot, so that it pivoted up and out on the two corner miters, but left the ends in the slots, unmoved. I slipped hot hide-glue (quite thin) into the slot, using a palette knife, brushed hot water to flow the glue, and pressed the purfling strip back into the slot, forcing it deep into the groove with a special tool. (Sometimes I use my purfling pick for that job. Today I remembered that I have a plastic wheel on a sturdy handle,  actually designed for forcing the rubber trim into screen window frames. It worked perfectly. :-)) Then I repeated the above process for the upper and lower bouts.

If I start toward the middle of a section of purfling, and work toward the ends, the glue is forced along under the purfling, and squirts out along the edges and, finally, out the ends, and the miters. The result is that all of the piece has adequate glue, even if some spots had been a little skimpy. Then I brushed more hot water to re-flow the glue, and wiped off the excess with a rag.

So– here is the completed back, ready for final arching, and for having the edge channel cut, etc. It will look pretty rough until the gouge slices along the channel, and trims that excess glue and damaged fibers off the top of the purfling strip. Then it will look very nice. (Purfling isn’t only for looks, by the way, on violins– it also helps stop a split from the edge from moving up into the plate…supposedly.) Anyway, this is how it looks for now:

Completed purfling on one-piece cello back, before carving the channel.

The channel still needs to be cut, but the purfling is complete.

Lower treble cello-back corner, freshly purfled

Lower treble corner, freshly purfled

The next step will be to mark an edge margin all the way around, locating the crest of the finished edges, after which I can use a gouge to carve the channel, and begin the final arching.

But, for today, I have a bow to re-hair, so this is as far as I am going with the cello.

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