Archive for November, 2015
Shaping the Double Bass Blocks
Lots of Wood to Move!
As you may recall from the previous post, the blocks on this upright bass were pretty huge, compared to what they needed to be, so there was really a lot of wood to remove.
So! A drastic need makes for drastic measures. Ordinarily, on a smaller instrument, I would use the bandsaw and oscillating spindle sander to shape the blocks, but this mold is reeaaalllly heavy (over-built, I think…oh, well, it will be removed and the bass will be normal), even though it is a soloist bass, so I can’t see trying to manhandle it around on my big bandsaw. The saw could handle it, but the table for the saw is not big enough to hold the mold steady, and I am not strong enough to just hold it up there by sheer strength…. So… what to do?
This tool (carbide abrasive disc) is something my wife bought for me a year ago (Christmas), but I had never used it much. It is called a “Kutzall”, and it tears away wood incredibly rapidly, without loading up, and without burning the wood. So I used it to remove the large rough sections, then used the plane to remove the torn surface, and finally, to shape the blocks:
Stanley #100-1/2 Squirrel-tail Plane
It was about 37 degrees, F, outside, but the sun was bright, so I worked outside.
The little plane is somewhat hard to control, because the curvature of the sole is so extreme, but, if it is sharp and if the blade is set for a very shallow cut, it works well.
The bottom block was planed entirely with a low-angle plane (also Stanley– can’t recall what number.) but it worked very well, and the bottom block was easy…I didn’t use the grinder at all on this one. So here are all the blocks, pretty close to finished:
And, here you can see the finished blocks, ready for sanding:
Homemade PVC Sanding Tool
As I mentioned earlier, the oscillating spindle sander I have would not be tall enough for these blocks even if I could manhandle the mold up onto the machine. So, I made this little sanding tool out of re-claimed PVC fittings from the “Habitat for Humanity Re-Store”, and spent more on the little can of PVC cement from the hardware store than I did on all the other materials…about $2.50 at the Habitat store. I used PVC cement to affix the abrasive cloth to the pipe, too, and bound it up with strips of plastic bag until the solvent outgassed and the cement was set.
The homemade sanding tool worked extremely well for the small corner blocks, and did very smooth work. On the neck block I used it cross-grain, holding the tool parallel to the “trough” of the curvature, and sliding it up and down the curve. It worked well, there, too, just not as perfectly as on the corner blocks. All in all, it is a very satisfying tool.
Change of Plans
You may have noticed that, though I had planned to use Willow for blocks and linings, those blocks are not willow: the corner blocks and end block are all Douglas Fir, and the neck block is laid up of three layers of clear, vertical grain Sitka Spruce. It was a matter of availability. I do have willow for the linings, and, as that in my preferred wood when I have a choice, that is what I will use. It cuts easily, bends easily, and is very pleasant to work with for both linings and blocks.
I have really felt that I was “spinning my wheels” on this project. It is large enough that I feel the necessity to work outdoors whenever possible, but the weather has not cooperated very well…it rained nearly every day for the last month. In addition, I have been struggling with a cold or some such virus. Today I was cold in the house when the thermometer read 75 degrees, so that is not normal. I finally felt a little better, this evening, and went outside for the few minutes it took me to sand the blocks, but it has been cold out, so I didn’t stay long.
Ah, well, that’s life. I’m grateful to be back on the project again.
Thanks for looking.
Resurrecting an Old Fiddle
We frequently hear the term “basket-case” in reference to one’s mental-state, but it originated in the reality of all the parts of a dilapidated mechanism or household furnishing being literally placed into a basket and delivered to a craftsperson who (it was hoped) could put it back together and make it functional.
There have been a few times when I have received such a violin…usually either having belonged to the customer’s Great Aunt, or Grandfather, or something, or a relic from their own childhood (which they are trying to hang onto.) In some cases it is worse– the customer simply acquired the instrument at a garage sale (or some similar “depository of fine musical instruments”), in pieces, and wants me to make it work.
In all of the above cases, I try to kindly explain that the labor involved will cost far more than the instrument will be worth when completed, and they must decide whether they want the instrument badly enough to pay that much to have it playable. (We are not talking about a full restoration, just bringing a dead fiddle back to life.)
In the particular situation at hand, it was a mix: The violin was coming to pieces, and was literally in a bread-bag, with the mouth of the bag tied off, to prevent the escape of any pieces. BUT, the person who brought it to me was not asking me to fix it for him…he simply offered it as a potential “project” fiddle. I gave him what he had paid for it at a junk-shop (styled “Antique Shoppe”) and tossed the bagged corpse in a box to gather dust, thinking that perhaps someday I could do a photo-story of sorts with it, in a “sow’s-ear-to-silk-purse” type of story. (Given the relative quality, I should probably edit that to say, “calico-handbag” as opposed to silk purse, but that is another matter.)
A few months ago, however, a parent contacted me, asking whether I had an “old fiddle” (full-size) for sale at a reasonable cost, to replace her daughter’s fractional size violin. Initially, I told her I did not, but upon further reflection, it occurred to me that I had the “bread-bag fiddle”. I told her exactly what it was, to the best of my knowledge (I had not opened it sufficiently to see some of the surprises), and suggested that, if I could make it a reasonable player for a price she could afford, that perhaps it would meet her expectations.
I sent her some photos, so she could see that, at least for now, it sort of “put the ugh in ugly”, and that it would never win any prizes for looks, regardless of what I did.
But–some folks like old fiddles! As it turned out, she and her family were pleased with the prospect, and told me to carry on with the “restoration.” (I repeat…this is not a true restoration, but rather a “revival” or “resurrection” of a dead or nearly-dead violin.) I had another commission going at the time, and I let them know that I could not begin immediately, but they were not in a hurry, so it was agreed that their project was next in line. I was able to begin about a month later.
The back had come loose from the ribs, partway around, and the (monstrous) lower block was separated from the ribs, as well, and (despite my best attempts) would not fit together perfectly. (sigh…)
Three of the four corners of the spruce top had missing wood, along with one lower-bout edge. One of the three had wood broken off, not just chipped or worn.
The exterior was bad enough, but when I opened the corpus I found the history, literally written on a label, and proudly claiming responsibility for the carnage within.
And, as usual, the “Tony Stradivari” label is there to confuse things further: I left it there, of course, and glued it down securely, so it would not fall out. 🙂
Here is a photo of the tail-block and loose ribs:
The “repairer-rebuilder-innovator” had removed the normal blocks and replaced them with very heavy, oversized, hardwood blocks. That was bad enough, but he had also (in response to a bass-bar crack) installed a bar at about a 20 degree angle across the longitudinal axis, rather than the 2 degree (or thereabouts) angle that is normal.
One thing to be observed, too, is the peculiar “mottled” look of the inside of the top plate, and how much fresher the wood appears here, than inside the back. From this, I see that this instrument was originally one of the very cheap fiddles for which the maker took not even the trouble of smoothing the inside of the top plate, but left it extremely rough, like chainsaw sculpture, in the knowledge that few, if any, would ever see it, whereas the back was very smooth inside, where any eye could glance inside and see the work. The “re-builder” smoothed all the rough gouge-work, removing the original “integral” bass bar (which had been carved in place, out of the same billet as the rest of the top, not carved separately and fitted to the plate), and had continued by adding the big blocks, slanting bar, etc.
How do I know? Because I have smoothed such an instrument myself, and that is how the top plate looks afterward. The areas where the most wood was removed are quite bright, whereas the places where only a little smoothing was in order are darker, showing the oxidation of the years. No harm done, there, and he did a fair job of it.
The ribs (as they came from the low-end European factory) were 2-3 times the thickness they should have been , in the upper bouts, though pretty close to normal in the lower and center bouts. There were several cracks. Some I had seen from the outside– some became obvious when I opened the box. Inside (due to inexpert top removals over the century or so of the fiddle’s existence), sufficient wood had been lost in the areas of the corner blocks that I felt it was necessary to replace wood there, as well.
First things First
Since the back was relatively undamaged, and it had to be re-secured to the blocks so that I would have a firm foundation from which to build, I reglued the blocks to the back, and
I scraped and scraped the block and ribs, to try to get the loose ribs to fit back in place perfectly, but, in the end, they still were pretty rough. I kept telling myself that this was not a restoration, just a resurrection.
I soaked loose the old, dirty glue in the center seam, and pulled it together as tightly as possible, then re-glued and clamped it. I went ahead and glued as many cracks as I could manage at the same time, wedging them in or out, as was needed to make them flush on the outside and tight, edge-to edge. I added the orange clamps as two pairs of “legs”, so that the plate could stand on edge and not twist under its own weight and that of the clamps.
As you can see, I also began replacing the corners at that time; here is how it works:
There was a third corner needing a minor wood-replacement, and a lower-bout edge worn (and splintered) off, as well. the procedure for replacement was the same in all cases.
After the glue was dry on the replaced corners, I carved and filed the new wood to match the old shape.
One lower bout had a missing edge, too, so I glued new spruce in place, and, after the glue was dry, I carved and filed it to match the original curve.
Later, I will stain the new wood to match the old, using coffee, dirt, and ash, then retouch the varnish to match the old varnish.
The bass-bar had to come out, so, after the glue had dried in the various cracks, I planed out the old bar, (and glued “cleats” on the inside along each crack) and prepared to fit a new bar. The bass-bar was going to have to be shorter than usual, as the huge end blocks crowded the normal position.
You can see that I had already begun replacing the wood missing from the inside corners: I sawed a 1 mm-thick “veneer” of clear, vertical grained spruce, glued it to the smoothed and flattened corners, and later planed it flush with the surrounding areas.
The bass-bar fitting went quite smoothly, using chalk on the inside of the top plate, and pressing the bar against the chalked area to disclose the high spots on the bar. I had it ready to glue in a pretty short time, and trimmed it the next morning, after the glue was dry.
Almost Ready for Re-assembly
Once the entire interior was smooth, with all missing wood replaced, I could start thinking about closing up the body of the violin. I re-fit and glued in place the saddle that had come with the fiddle.
Meanwhile, I had checked the back and ribs for appropriate thickness– a few areas of the back were abnormally thick, so I planed and scraped a millimeter (or so) of wood out of those areas, then even more from the upper bout ribs, where the wood was three times the normal 1 mm thickness. Perhaps it will help….
So, I was ready to close:
I dry clamped the whole corpus (body) in exactly the way I wanted it to go together, using spool clamps, just like the ones used when I was gluing the back to the garland, above.
Then, when I was sure everything was right, I heated hide glue, and, loosening a few clamps at a time, I used a palette knife to carefully insert the thin, hot, hide glue between the front plate and the linings and blocks. Then I re-applied those few clamps and repeated the process with the next few clamps until I had glued all the way around. I seldom think to take photos of thsi process, so…there aren’t any. Sorry.
Once the glue was dry, I could take off the clamps and get ready to begin final touch-up of varnish, and general polishing.
So, I spent a few evenings cleaning, and touching up varnish, so that nothing sticks out as damaged, nor as “new”. Not too shiny, but not too grubby, either. What I am attempting is “Old fiddle Chic.”
New Helicore strings because that is what the customer prefers. (Installed after the photos.)
Looks as though the bridge was a little crooked when I snapped the photos– it was straightened later, as well. 🙂
Not all of the old scars have become invisible (though some have)…some are a permanent part of this old fiddle’s character, and simply show that is has been well-loved and well-played. Future things will undoubtedly include a new fingerboard (someday) and new pegs (eventually). But for now, it is ready to sing.
The old fiddle turned out to have a rich, deep voice, and the new owners are very happy with it. I hope to hear the young lady play someday.
Thanks for looking.
Building the Double Bass Mold
Planning the Mold
I designed this upright bass mold to be collapsible and to allow me to affix the blocks to the mold with screws, so that there is no glue to have to separate later. I also wanted the mold to be slender enough from front to back that I could install the front and back linings without running into the mold, so I gave myself a 1″ clearance between the front and back faces of the mold and the front and back edges of the ribs. Since the back will taper in the upper ribs, losing two inches of depth between the middle of the upper bout rib and the top rear edge of the neck heel block, I had to accommodate that taper as well: I simply made a 2″ “step” in the mold to allow the taper to occur.
Finally, I wanted the mold to be stout enough to allow me to handle it without fear of damage. So, the construction is of 3/4″ plywood, spaced by blocks of 2 x 6 and (in the upper half of the upper bout) blocks of 2 x 4. The corner block mounts are of 1 x 6, so I do not have to use large screws to affix the corner blocks. The neck and tail block mounts are of heavier stock; 2 x 4, and removeable, to allow the mold to collapse laterally, and clear the ribs for removal.
Using the Mold Template
In the last post, I had completed the mold template, and had commented that I would use it to make the mold, and then, later, to establish the shape of the blocks. So this is how that works:
I bought two quarter-sheets of 3/4″ plywood from Home Depot. That is a pretty expensive way to buy plywood, but it solved two problems:
- I really don’t need a whole sheet of plywood, and
- Even the quarter sheets were difficult to get into my car…but not impossible.
I took the quarter-sheets home, and positioned the mold-template flush with one end of one of those sheets, and offset by two inches. I am building a collapsible mold, and I want 4″ clearance between the mold halves. I don’t need that much for mold removal, but I do need enough for my hands and forearms to reach up inside the mold and remove the screws holding the molds to the blocks. So a 2″ offset on the template will result in a 4″ gap down the center of the mold.
I traced the mold template onto the quarter-sheet, and it looked like this:
You can see that I also laid out the location and outline of the instrument blocks, the block mounts and all the spacer blocks that would become part of the mold. This took less than half of one of the quarter-sheets of plywood, so I sawed the sheets into strips, 11″ wide , and about 39″ long, and stacked them into a “sandwich” of four pieces, held together with two screws, countersunk flush with the surface. Then I sawed the whole sandwich out on the bandsaw, and smoothed the edges with the oscillating spindle-sander.
I cut all the needed blocks to complete the mold, and I was nearly ready to begin assembly.
It was tempting to take the mold quarters back apart at this point, but, fortunately, it occurred to me that I could do all my drilling at once, so things would line up, and so that I only had to drill each hole once. So I made a drill bit out of a welding rod and drilled every screw location through all four plywood quarters. (Welding rods are way too soft for most uses; they use extremely low-carbon steel for the core wire of welding rods, but it was OK for this soft plywood.)
Finally I separated the quarters, and countersunk all the screw-holes.
Assembling the Mold
I laid the mated pairs side by side, and lined up perfectly, then transferred the block locations and lines to each panel so that I could see where the blocks were to fit, on all four pieces.
Then I assembled my spacer blocks and installed them:
Once the spacers were attached with screws, the front and back were pretty stable and I could begin assembly. The back plate still needed to be cut off at the beginning of the rib taper, so it could accommodate the taper, but I began by assembling (as many as possible of) the internal members to the front plate of the mold. It turned out to be pretty easy.
Then I positioned the back plate pieces on the internal blocks and screwed it down tightly. I have used no glue in the mold, so, if I need to make modifications it will be easy to do.
The way by which I had intended to attach the upper and lower block mounts does not appear to be workable, so I will have to re-think that part. I had planned to install them on hinges, and to be able to screw down a steel bracket on one end to secure them, but it turns out that it will be too difficult to access the screws, so I will have to give it some thought and re-design that aspect of the mold.
At any rate; that is where the project stands for now.
I called the wood supplier, and they assured me that my European Spruce should show up today or tomorrow. No problem, really, but I want to get those plates joined soon. (I already have the local Big Leaf Maple in my shed, waiting to be used.) By this weekend, I hope to have the blocks installed and shaped, the front and back plates joined and the ribs cut. We’ll see how it works out.
Thanks for looking.
(P.S. : The wood showed up this evening… Good looking stuff!)