Posts Tagged ‘graduation’
More Plowden Progress
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More Plowden Progress
Graduation
Graduating hard maple can be a tough, laborious job. Besides, there is always the possibility of carving too deeply and ruining the plate. So, I try to cut the risks by creating a “map” by marking the thickness every few centimeters, and then carving the “dots” until each “dot” is about the thickness I want. Finally, I connect the “dots”, using planes and scrapers, checking for thickness as I progress.
Creating the dots. The circled numbers are already the correct thicknesses.
Checking thickness. Pretty thin plate!
Connecting the dots.
Getting there!
Grafted Scroll and Neck-Set
Once the graduations are complete, and the inside of the back plate has been scraped completely smooth, I install the label and I am almost ready to close the corpus. In this case, however, I also had decided to use the scroll I had carved, but graft a new neck to the scroll, as the original neck was too thin: so there was a good deal more work involved. Here is the grafted neck, partially shaped, with the completed back plate:
Completed back plate with neck-grafted scroll. The heel was still not shaped.
I had been anxious to complete the back plate, and had not yet set the neck. So I completed the neck and installed the fingerboard.
Fingerboard installed.
Next I set the neck, so that the angles were all correct.
Neck-set, front view. The mold is still in place.
Neck-set, side view. Notice that the neck heel has not been trimmed flush, yet.
Closing the Corpus
Then I removed the mold, and installed the inside linings on the back edge of the ribs, shaped the linings and the blocks, flattened the back of the garland, and installed the back plate. I use spool clamps and a single large spring-clamp to close the corpus. My wife thinks the spool-clamps look like old-fashioned hair-curlers.
Closed corpus with spool clamps and a spring-clamp.
Trimming the Button and Neck Heel
Once the glue was dry, I removed all the clamps, cleaned off any glue that had squeezed out of the joint, and trimmed the button and heel. The dimension from the juncture of the top edge of the front plate and the side of the neck heel (from each side) to the very center of the curve of the heel, should be right at 26 mm. You can see the two marks I laid out with a compass, testing that distance: it was still a little too high in the center of the curve, so the neck needed to be trimmed a little more.
Ready to trim the button and heel.
Purfling the Back Plate
Once the neck-heel and button were trimmed, I still had to perfect the outline of the back plate, making certain that the overhang was even all around, as much as possible. Then I laid out the purfling slot, using a purfling marker, and began incising the outlines of the slot.
Incised purfling slot. It will be corrected, and fine-tuned as I work, and look good with the purfling.
Next I cut the slot out, using a small knife and a purfling pick, then dry-fit the purfling, after bending it on the bending iron. Finally I glue it in place, using hot hide-glue.
Purfling installed, and glued in place.
Edge-Work
I marked a crest-line, about 1.6 mm in from the outer edge, then used a gouge and scrapers to carve the channel, and fair it into the plate surface. The edges were all still quite rough,and crude, so I began shaping them, using a small plane, and a half-round file, then sandpaper to get a smooth edge all around. I don’t use sandpaper much, but this is one place where it is appropriate.
Trimmed purfling, smoothed channel, and edges taking shape.
The front edges have to be finalized as well.
Finishing Process Begun
Once all the varnish preparation is complete, I brush a coat of coffee all over the instrument, to tan the wood a little, and raise the grain. When that is dry, I sand off most of the raised grain, using 400-grit sandpaper. This ensures that the grain will not raise too much during application of the spirit varnish, later. Afterward, I rub in a coat of gypsum in a coffee suspension, to fill the pores of the wood with particles of the mineral. This keeps the varnish from saturating the wood, and possibly dampening the sound.
Mineral ground drying. See how it obscures the wood? that goes away when the sealer is applied.
The sealer renders the mineral ground transparent, and it will never be visible again.
I expect that, by tomorrow, the sealer will dry sufficiently that I can begin varnishing. I am getting anxious, as the show is a week from tomorrow, and I am far from completing this instrument.
Thanks for looking.
More Progress
More Progress
Plowden Progress
Purfling and Graduation
While varnish was drying on the Titian model, I went back to the Plowden model, and began purfling the front plate and graduating the back plate:
Graduation about half done.
Graduation progress and purfling installed.
Also, I finalized the finishing process on the Titian model, and an ready to begin set-up. The pegs are trimmed, polished and drilled for strings. The nut is at the correct level and has been slotted for strings. The saddle is installed, too. The end button and soundpost were both installed quite some time ago. So, really, all that is left is the bridge and strings, and final adjustment. I don’t tend to count the tailpiece, but, as a matter of fact, it, too requires some adjustment. So does the chinrest, so I shouldn’t treat them as non-entities. The feet opf chinrests virtually never fit correctly as shipped. Tailpiece adjustment requires trial and error fitting, to get the ratio between vibrating string length and after-length (string between bridge and tailpiece fret) adjusted to a 6:1 ratio.
Anyway, here is where it currently stands. I could probably finish it tonight, but then I would be too tired to go to work in the morning…so, tomorrow will have to do. 🙂
Titian front, ready for set-up.
Titian back, ready for set-up.
Nut and pegs complete, ready for strings.
Saddle installed, ready for set-up.
So, I hope to take both of these instruments to the show in March (“Violin Tasting Event” at the Hilton Hotel, March 10th in Corvallis, OR), as well as the one in May (which used to be the Marylhurst show, but it will now be at Portland Community College, Sylvania campus: still called the Northwest handmade musical instrument show.) Anyway: lots of work left to do, in order to get ready.
Thanks for looking.
Closure and Final Scraping
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.
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!
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.
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.
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. Back view.
Full Front 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. 🙂
Thanks for looking.
Back Plates and Scrolls
Back Plates and Scrolls
Progress
Here are the back plates: the arching is complete, but the graduations are not begun…inside surface is still flat. The two scrolls have only been cut out, for the rough profile. I did lay out and drill pilot holes for the tuning pegs. That will make it easier than trying to drill them after the outer shape is completed. At this point the sides are relatively flat.
Two back plates, nearly complete: two scrolls, just begun.
Then I began cutting out all the rough outlines of the two scrolls, using a saw:
Beginning to cut out the neck/scroll combination, using a saw.
Removing the excess wood from the sides.
Cutting to the layout lines, all around the scroll, from both sides.
Continuing around the first turn of the scroll.
Cuts completed around the first turn of both scrolls.
Excess wood removed from first turn on both scrolls.
Back view with first turn wood removed.
Completing the scond turn of the scroll, using a fine-toothed pull-saw.
Second turn cuts completed.
The remaining wood will be removed using gouges, planes and scrapers, There is still a long way to go, but it does look more encouraging, this way.
Next time we will be carving the pegboxes and scrolls.
Thanks for looking.
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F-Holes and Graduations
F-Holes and Graduations
F-hole Incision and Final Arching
In my last post, I told you I would “talk about F-holes, next time”…and we are doing so. But final arching, as well as graduation have to be completed before we actually cut out the f-holes, so, first things first:
I lay out and incise the f-holes after the arching is (mostly) completed, but before beginning any graduations. (I had a few mishaps years ago, when I graduated first, and subsequently discovered that my plates were actually too thin where the f-holes were to be laid out. I learned from the error, and I check the thicknesses around my already-in-place f-hole incisions, before beginning graduation, now.)
I laid out the distance from the upper edge of each plate to where the bridge would go. That is where the inner “nicks” of the f-holes will go. I measured back from there to find where the inner edges of the upper eyes of the f-holes would go, and laid out not only that longitudinal position, but the lateral distance off center, to the inner edge of each eye. Then I repeated that process for the inner edges of the lower f-hole eyes, and I was ready to use a template to scribe in the actual perimeters of the f-holes. I simply aligned the clear plastic template (traced off the full-size photos of the original instruments) so that the inner nicks were on the bridge line, and the inner sides of both upper and lower eyes were at their correct locations. I pressed the template firmly, so that it followed the curvature of the plate, and traced with a very sharp pencil.
I try to bear in mind that the pencil line will actually be “inside” the actual footprint of the f-hole, and I will remember to adjust it later. For now, however, I incise the perimeter of both f-holes fairly deeply, so that the marks will not disappear as I complete the final arching. (In the photo below, I had also traced around the incision with a very sharp pencil, to highlight the cut, so I could see it from any angle. Otherwise it can be hard to see.)
F-holes laid-out and incised.
Final Arching
I have learned that arching is one of the most important factors in violin sound. I use two “markers” for determining the final arching.
The first: I can see that, when viewed from the side of the instrument (at least, the ones I am concerned with), the f-holes on the old master instruments appear to have the main stem nearly parallel with the plane of the ribs. I have no idea whether that is truly important as far as aesthetics, but, I have also observed that, when left to my own instinct (or lack thereof) as to proper arching, my f-holes invariably end up resembling an “S” laid on its side. So, it is a “marker” that tells me my arching is a bit “off”, if nothing else. That is why I incise the f-hole perimeters deeply enough so that I can adjust the arching to get the stems of the f-holes parallel to the rib-plane, and be fairly sure that, at least that part is better than it was before.
The second “marker” is even more mundane: I made “arching templates,” traced from the posters, so that I can actually check and see that my arching closely follows that of the old masters. It is fascinating to me, to see them drop into place, one by one, as I carefully plane and scrape away the last few “humps”. I know that many makers are convinced they do not need such a “crutch”, but I see it as only a tool. I would never claim to be able to draw a perfectly straight line by eye and hand alone, and I shamelessly use a straight-edge for such a task. Arching templates are the same thing, in my estimation. Whenever I use them, even on a plate that I thought to be very close to correct, I invariably discover that it was not as good as I thought it was.
Using arching templates and scrapers to perfect the arching contours
The truly-completed arching is not terribly different than the rough-arching I had completed before incising the f-holes, but that sort of difference can make the difference between “acceptable” and “extraordinary” sound. When I first began using such templates, I immediately got a different response from players. They said, “This one is different! Whatever you did on this one, do it again!” (Okay…will do!) So…now I do it on every single instrument, and try to make each one better than the one before.
Graduation
What we call “graduation” is simply the process (and results) of carefully carving the inside arch to match the outside arch, leaving a specified thickness between, which could all be the same, or they could vary according to some sort of deliberate scheme designed to project well, or to give superior sound in some other way. Or it could be following a “general plan,” but, beyond that, be fairly random. There are all sorts of patterns and plans.
In this case I attempted (at least in a general way) to mimic the graduations of the original old master instruments whose pattern I was attempting to follow. (In case you have not read the previous installments, these two are to be modeled after the 1715 “Titian” Stradivari instrument and the 1735 “Plowden” Guarneri del Gesu instrument, respectively.) Their graduations are pretty thin, so this is a little scary, to me. I hope it works well.
I use a gouge to rapidly carve out the rough wood, until I am approaching the proper thicknesses, but then I switch to a toothed finger-plane for rapid, but controlled, wood removal. When I am getting close enough that I am fearful of going too far, I switch to a non-toothed curved-sole finger plane and carefully bring the thicknesses down to my target measurements.
Carving rough graduations
Planing rough graduations, using toothed finger-plane
Checking graduation using shadow-lines.
Final check of graduations.
Two plates with graduation completed.
F-Holes
The F-holes are pretty much “locked-in,” now; the only thing remaining is to actually remove the wood inside the f-hole lines. The first order of business is to remove the circular portions at the upper and lower eyes of each f-hole. For this, I use a tool called an “f-hole drill”, which my grown children purchased for me a few years ago. It makes perfectly round holes, ranging in size from 5.5 mm up tp 10 mm in diameter, in 1/2 mm increments. I center a 3/32″ diameter hole in the center of the round portion of each eye, and then, using the correct bit, I insert the guide pin into that hole and gently rotate the tool to incise the hole, forst from the outside, and then from the inside, to prevent splintering, but completing the cut from the outside, so that in case any splintering does occur, it will be on the inside.
F-hole drill with cut-out plug from lower f-hole eye.
All f-hole eyes cut: ready to remove remaining wood.
Then I use a very thin, sharp knife to complete the incisions around the perimeter until the wood pops out cleanly.
Final f-hole wood removal.
Completed f-holes, ready for cleanup and final shaping.
I will continue to fine-tune the shape of the f-holes up until I begin varnishing, but, for now, they are complete.
The next thing will be the bass-bar in each top plate. The bass-bar supports the bass-side foot of the bridge, and the bass side of the plate. It is necessary in order to achieve the rich deep tones on the bass side of the violin range. So…next time: bass-bars!
Thanks for looking.
Beginning Graduation (inside carving)
Beginning Graduation (inside carving)
How Thick?
This becomes another critical issue: How thick should the plate be at any given point? I will try to follow the poster to some degree, but it was only correct for that particular instrument, with that particular set of plates. The wood I have may not be anywhere close to the same stiffness or density, so I have to get into some sort of “ball-park” range, and then start making decisions based on this wood that I am carving. How it feels, how it flexes, how it sounds when I tap on it, all make a difference in my mind, though I am aware that there are some standard thicknesses to which many makers adhere.
Others measure the vibrations of the nearly completed plates using a frequency-generator, and try for certain frequencies to make a certain set of patterns (called eigenmode frequencies, and nodal patterns, or Chladni patterns). I have tried this and couldn’t get it to work for me. Then, one day at a workshop, one maker was haranguing me that I wasn’t graduating my plate correctly, and took me out to the plate-shaker thing, and demonstrated to his satisfaction that I had it “all wrong”. I had simply followed some graduation thickness numbers given me by a master maker (who does not want me mentioning his name), so I could not tell him that. I was feeling pretty glum about the whole exchange, when he looked up and saw another maker coming in, who he considered to be an expert at testing plates. He said “Ask him! He’ll tell you!”
So, the other fellow obligingly came over and began setting up the plate-shaker, while the first guy stalked off.
I noticed that the second guy did not set it up at ALL like the first guy had done, but I kept my mouth shut. He ran through the frequencies and numbers, and finally said, “It’s perfect! Don’t do another thing to it! Install the plate!”
So, I walked back into the work area, not intending to say a word, but the first fellow was waiting for me: “Well?! What did he say??” I repeated, verbatim, the second fellow’s verdict. The first guy said “What??!! How come I got the numbers I did??” I replied, “I couldn’t tell you! I don’t know how to run that machine!” No more interference that week… 🙂
So…the point is, there are a variety of ways to achieve the goal of good plate graduation. That experience convinced me that even just following a set of established thickness values can work just fine. And, ultimately, that is probably about what I will do, on this violin.
Moving Wood
I began with a gouge, trying to get within a few millimeters of the right center thickness.
Beginning inside carving with a gouge.
Then I switched over to a toothed plane, which I find more comfortable to use. The handle on it is a modification I added to shift the pressure to the heel of my hand instead of my thumb and forefinger.
Toothed plane progress.
The normal orientation of the screw in the Ibex plane (left) has been reversed to hold the wooden handle as well as the blade.
Repairs
But then I heard a cracking sound: Not a good thing to hear when you are working on a violin. I looked the plate over and could find nothing amiss, so I went back to moving wood. Heard it again, louder. (Sigh…)
It turned out my work-cradle had broken! (What a relief!) Well, I made it 15 years ago, and it has served well, so I took the time to glue it and insert three dowels, diagonally, through the break, to hold the joint against further failure.
Repair of broken work cradle.
Work cradle construction: a heavy pine plank with a cutout to support the margin of the plate. Thin plywood surrounds the plate-edge.
Back to work:
I am aiming for about 4 millimeters in the middle, and all over, which I will refine later to the specific measurements I want. In the photo, below, reading the dial on the caliper, you can see I am nowhere close. But…I’m tired, and I’m going to call it a night. By the way, in case anyone was wondering, those jagged-looking black pencil lines around the lower corners are outlining an area that was pretty close to the right thickness already: I don’t want to touch them until I am on the home-stretch where graduation is concerned. It is VERY easy to get too enthusiastic and carve too deeply in such an area, and ruin the plate.
Long way to go!
So, next time, I hope to have the graduation complete, so I can cut out the f-holes and install the bass-bar.
Thanks for looking.
