Archive for March, 2013
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:
Bass Bar Trimmed and finished:
And here is what it looked like after planing it to the shape I wanted it to be:
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!)
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.
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.
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.
But the f-holes are essentially complete. the next step is to install the bass-bar.
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.)
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.
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.
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.
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.
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:
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.
Here’s an end-view…doesn’t show much:
And a sort-of “3/4” side-view…trying to show the curves:
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):
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.
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:
Anyway…that’s it for tonight! The Spruce cuts very easily with a small, sharp plane. I hope to complete the arching tomorrow evening.
Cello Top Purfled and ready for Final Arching
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.
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).
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:
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:
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.
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:
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.
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?)
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?
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.
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.
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.
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.
I was getting pretty tired, so I am going to call it a night. I hope to get more done tomorrow night.