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Building a Partch Adapted Viola - Part 5 (How To Build It Yourself, Sensibly)

I hope this blog series has piqued the reader's interest, such that they might be spurred to do this themself. To that end, I have figured out a streamlined process for building this, which eliminates various redundancies and errors.


The instrument is quite simply a viola with a 20-inch scale length. This is preferable to a normal viola because of the greater separation between microtonal pitches, and preferable to a cello because it's cheaper and more portable. Also, it's acceptable to decorate it in attractive colors. For a luthier, the best way might be to make one from scratch. But by using an existing viola and pieces of a cello neck and fingerboard, we can both honor Harry Partch's legacy as a maverick and former hobo, and open the door for standard-issue handypersons to get in on the fun.

ADDITIONAL NOTE: This design uses the standard dovetail joint for neck attachment, conveniently provided by the donor instruments. But it is a modern convention! It is too often forgotten that Stradivarius himself glued each neck flat to the top rib, and drove three iron nails up through the neck block to hold the neck in place. Picture of a replica below by Salve Håkedal, posted to the Maestronet forums:



The benefit of the modern dovetail joint is that it's a lot easier to take apart for neck repair later, and it's just as strong. But it's also harder to do, especially if you need to alter the existing joint (which is a possibility in Steps 9 and 12-13 below). If you feel intimidated by this sort of joinery, I declare that it is perfectly OK to use nails, screws, or dowels in the neck joint instead of carving a perfect dovetail, and you can adjust the relevant steps in the process accordingly.

Without further ado, here are the steps to making an Adapted Viola. Step 0


Acquire one viola and, at minimum, one cello neck (including fingerboard). Measure the distance between the nut and bridge of the viola. Determine the difference between this length and 20 inches, or approximately 51 cm. Make a note of this amount.


There is not a hard standard for viola size, so the original scale length might easily vary between 14-15 inches, or 35-38 cm. So, in this project, you will be adding length to the viola neck in the neighborhood of 5-6 inches.


Step 1


Remove the necks (recall this video for an example technique), and remove the fingerboards from the necks. This calls for care and attention, but necks are affixed with hide glue for just this sort of situation. They will come off. The fingerboard may present more trouble and require an enormous helping of patience and perseverance, or it may just pop off without even asking.


Step 2


Some instruments have a right-angle heel on the neck, which means they have an angled neck pocket on the body; others have an angled heel, which means they have a straight neck pocket. With luck, the angles of your cello neck and viola neck will match. But if they don't, then cut the cello heel at an angle which matches that of the viola heel. Then you can trace the outline of the viola heel onto the cello heel, making sure everything is centered. This is necessary for a later step.


Step 3


Make the first part of your scarf joint by cutting the viola neck. Make absolutely sure that the cut is not skewed; it must run straight across the fingerboard surface. If you are using a table saw or miter saw/chop saw, it might help to temporarily attach the fingerboard surface to a piece of 2x4 or similar, which has been checked to assure that it's square.


The angle of the cut should be 30 degrees or less. The shallower the angle, the stronger the bond.


Step 4


Cut the cello neck at a matching angle. (If you were using a jig for the viola neck, just leave it set up and run the cello neck through it.) The cut should pass through the fingerboard surface at a distance from the heel exactly equal to the quantity from Step 0. In this way, we assure that the total neck length will give us what we need for a 20-inch scale.


Step 5

Mark the center lines of the two neck pieces, and glue them together on the matching cut surfaces. If standard cello strings are to be used, the tension will be so low that this joint should be sufficient without additional reinforcement. It is the same joint used for the pegheads of guitars, usually unreinforced even for steel-string guitars, which are under quite a bit more tension than any viola. When a scarf joint like this is clamped, it has a tendency to slide around. However, the process of sitar making showed me a neat trick: you can drill a tiny hole through the top material and partially into the bottom material, and glue in a tapered sliver of bamboo (easily sourced from bamboo barbecue or kebab skewers; or just use a toothpick). When sitars are glued up, dozens of these bamboo tacks hold the pieces in alignment as ropes are tied around them for pressure (rather than clamps). The tacks are so small that, once trimmed, they're easy to hide; and in this case, they would be underneath the fingerboard, and therefore invisible. I believe this is a better alignment solution than my drywall-screw hack. In any case, when you glue this joint (and after you trim any bamboo tacks), clamp the fingerboard surface to a surface which is known to be flat and true. This way, you will be assured that you won't need to drastically re-flatten that surface before gluing on the fingerboard.


Step 6


Cut the back side of the heel to the length--and angle!--of the back of the viola heel, where it meets the button.. The easiest way to lay this out is just to line up the bottom surfaces of the cello heel and the viola heel piece that we just cut. But make sure you don't cut into the outline of the viola heel that you traced in Step 2. The object is to avoid having to use shims in the neck pocket later; leave a small amount of extra material.


Step 7


Place a ruler against the sides of the viola neck segment, and trace their lines onto the cello neck segment. This creates a consistent taper down the whole neck. However, you will note that doing this would still leave the neck wider on the fingerboard side than it was on the heel profile we traced in Step 2.


So, you have to decide: Will you create a new heel profile that accommodates this new taper? This would simplify the shaping of the neck, but requires re-shaping the neck pocket in the body. Or will you duplicate the original heel profile of the viola, which will require you to re-taper the sides of the entire neck (or at least, curve the taper on the cello segment)? The advantage of the latter option is that you won't have to widen the neck pocket on the body, you can just clean it up and use the original dimensions. Pick your poison.

Step 8


Follow through with your choice from Step 7. Cutting these with a hand saw is challenging, and cutting these with a table saw (etc.) might require a fairly involved jig. But you can take off conservative amounts roughly with a saw, leaving a decent margin to take down with rasps and files in the next step.


Step 9


Using rasps and files, shape the neck until it feels good. You can, of course, also use chisels, whittling knives, planes, etc. -- whatever you're most comfortable with. I prefer abrasive tools rather than cutting tools, because there's less of a risk of accidentally digging in and splitting the wood along the grain. I'm sure my preference will change with continued experience. In any case, pay careful attention to the height and shape of the viola button, because those dimensions are immutable (unless you trim the button, but try not to do that), whereas the shape of the neck itself can be somewhat flexible.


Step 10


Bring the cello fingerboard down to appropriate thickness (measure the original viola fingerboard to get your dimensions for this). You can do this by making many parallel shallow cuts on a table saw--this is probably the easiest method. You could also use a router. In either case, it is helpful to leave a small amount untouched at the edges of the fingerboard, as a guide. These can then be trimmed afterward.


Step 11


Flatten the fingerboard surface that will join the neck. Beware of slightly rounding it--check it frequently by holding up a straightedge against the surface and looking for slivers of light shining through.


If your flattening tool is a piece of sandpaper affixed to a table, you might end up with a slight bulge down the center of the fingerboard surface, because of slight and uncontrollable rocking while sanding the piece. If this happens, either plane it down (carefully!), or use sandpaper wrapped around a narrow, straight, hard block to sand only the center.


Step 12


Line up the fingerboard on your neck piece and see where it falls on the body. Mark the place you wish the fingerboard to end, and cut it. This might be somewhere in the vicinity of the corners of the upper bout.


Step 13


This is really an iterated sequence of steps. You want to ensure a tight, true fit between the heel and the neck pocket, and this requires many checks and adjustments and re-checks. Extra time and care spent on this activity is well-rewarded. Once you have such a fit, then temporarily attach the fingerboard to the neck and insert it in the pocket.


By stringing up a piece of twine (and perhaps taping the bridge upright), you can see approximately how high the strings will be above the end of the fingerboard. Standard string heights for viola and cello are easily searched, and you can choose one or the other or split the difference.


If yours are too high or too low, you now know the direction by which you need to adjust the neck angle. This can be done either by differentially sanding the bottom of the heel (tricky to do without rounding, but easy to see the resultant angle), or by carefully carving away some of the base of the neck pocket (fiddly, but not terrible with a sharp chisel). Eventually, with care and attention, you will have a joint that gives you both a snug fit and the correct neck angle for proper string height.


Be aware that the string height can be brought down later by trimming the bridge. So, if you can't get a perfect angle at first, you can correct it later (up to a point).


On the other hand, if the neck is crooked--if it leans to the left or right, relative to the front of the instrument--then you're potentially quite fucked. So, spend extravagant effort getting the neck straight in that dimension, if necessary.


Step 14


Once you're getting a good dry-fit and you have the angle sorted, you can glue the fingerboard to the neck. Use hide glue -- not necessarily the kind that needs to be melted. Old Brown Glue or Titebond Liquid Hide Glue (any variety) are fine. This is because you want the option to remove the fingerboard easily later for any repairs.


After it's on, trim down the protruding sides to match the neck. Again, you can use rasps/files or planes/chisels/knives. I used a plane for this, which was easy when I had it properly sharpened--but if you do, take care not to accidentally bash the scroll with the sole of the plane. It doesn't take a lot to mar the finish, and I'm not qualified to advise on finish repair.


Step 15


Glue up the heel joint, again with hide glue and not yellow wood glue or (God forbid) a white glue like Elmer's School Glue. White glues, i.e. polyvinyl acetate, will eventually move around under pressure, and yellow glues, i.e. aliphatic resin, are impossible to remove without splintering the wood. Epoxy is even worse in that regard. Hide glue, on the other hand, is both rigid under string tension, and easily removable for repairs. Use hide glue.


You could subject the joint to a torture garden of obscure clamps and ropes and so forth, but if the sides of your joint are tight, you may only need two clamps: one on the button (put that one on first), and one on the fingerboard. The clamp on the button will anchor the neck, and the clamp on the fingerboard will rotate the neck forward slightly, pressing the base of the heel into the joint. You could also use a bamboo tack through the button to help keep everything aligned. Send me rude and hateful emails if I'm wrong.


Step 16


After the neck joint is dry, you can string up the instrument and trim the bridge to get your final target string height. (On the other hand, if your string height after glue-up is too low, you need to either order or fabricate a taller bridge. Not the end of the world!)


The following steps are un-illustrated, because they don't require much spatial imagination.


Step 17


You may want to reposition the string slots on the nut to accommodate your new, somewhat wider fingerboard. If so, carefully file new slots with needle files. Pay attention to the bottom of the nut slot, and take care to keep it the same distance from the fingerboard surface as the original. Also, if the slot is too wide for the string, it may cause buzzing when the string is played "open," so be conservative when you start the cut. Worst case, you screw up and have to fabricate a new nut. Also not the end of the world.


Step 18


Take the strings back off the instrument and finish the back of the neck. True luthiers will roll their eyes, but you can get acceptable results by doing the following:

  1. Sand the whole surface with 120, then 220, then 320 grit sandpaper. These are American grit measurements, but I'm sure there's a similar standard sequence for metric sandpaper users.

  2. Stain the heel area with something vaguely matching the rest of the instrument. Or, if you have something to hide, use black.

  3. Apply three thin layers of amber shellac, sanding lightly in between each layer. Allow time for each layer to dry, according to the directions on the can.

  4. Rub out the shellac using steel wool and a lubricant. I use Skidmore's Restoration Cream because someone gifted me a 6-ounce tub of it several years ago, and it's lovely. But you can use paste wax, or just about anything. Vigorous rubbing will take off the shellac that you don't want, such as in the middle area of the neck, and you can eventually come up with a nice gradient. If you follow the rubbing-out directions only about halfway through, you will end up with a satin finish (rather than a buffed high gloss), and that's the texture I like.

This is less time-consuming and labor-intensive than the usual oil varnish/French polish/whatever nonsense that violin makers usually do, and for the purposes of the general handyperson, it will create a pleasing effect.


Of course, you could also just spray on some clear-coat from a can.


Step 19


Mark the fingerboard! This is where you can get creative. Choose a subset of intervals you wish to emphasize. Partch's entire 43-tone set might possibly squeeze on there, but Partch himself only put on the most relevant 29 per octave. You might even prefer to mark an unjust scale--some kind of edo, Bohlen-Pierce, Carlos Alpha, or whatever!


This website is possibly the best around for calculating fret positions (which amounts to the positions of our markers). If you choose to use the 32-pitch collection that I chose, here it is in Scala format:


!QuasiPartch32.scl
!
Custom 32-tone extended Just Intonation
32
!
33/32
21/20
16/15
11/10
10/9
9/8
8/7
7/6
6/5
11/9
5/4
9/7
21/16
4/3
27/20
11/8
7/5
10/7
3/2
14/9
8/5
18/11
5/3
27/16
7/4
16/9
9/5
11/6
15/8
40/21
64/33
2/1

You can plug it into the "just (scala)" option on that webpage, and as long as you have also put in accurate dimensions for your instrument, it will just spit out a list of fret distances for you to copy. (Note that it doesn't actually need to be "just," it will read any properly formatted Scala file.) In order to get each string to display a different set of distances--instead of just transposing all the intervals from the lowest string--set the "tuning" appropriately. My strings are tuned in 5ths, so their ratios are 1/1, 3/2, 9/8 and 27/16, which would be "frets" 0, 19, 6, and 24 respectively (i.e. the ratios occupy those positions in the list). Remember that "String 1" is the highest-pitched string, not the lowest. Here's a screenshot to make this all clearer:


Once you have your distances, use a precise ruler, preferably steel, and tape the ruler securely in position while you pencil on your marks.


Step 20


Color and finish your fingerboard! As detailed in my last blog post, I used fingernail polish for my marks. But due to the fragility of nail polish, I decided to offset the color marks toward the player side of each string, such that when the string is actually pressed down, it almost always touches the wood rather than the lacquer.


You could use blotches of single colors, as I did; or double colors, as Partch did for the Chromelodeon and the Adapted Guitar; or whatever else. You could also choose other materials, such as glued-on pieces of paper, or tinted epoxy. If you were ambitious, you could carve out (with a Dremel, for the non-carpenters among us) a tiny recess for each mark, and fill it with tinted epoxy, or even actual inlay. This would be assured to never wear off, but it would take some leveling to get a smooth playing surface afterward. In any case, your own ingenuity will be your guide.


The Final Product


Here's a video of me attempting to play a tune in maqam Rast. Later, I'll see about playing/singing one of Partch's Songs of Li Po, which are after all the most important repertoire for this instrument.


If you decide to make one of these, please tell me! I would love to see how thoroughly people show me up with their beautiful instruments, and on the other hand, I would also love to marvel at others' outrageous MacGyvering. What the music world needs now is definitely at least several more Long Violas.

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