Shortly before Christmas, David, the son of a teacher-friend of mine, after seeing and playing one of my paddle-box dulcimers, said he'd like a "Flying V" dulcimer (a flaming red one). So, from this suggestion came idea for this project.
So, this first attempt at a Flying "V" shaped instrument would be based upon my "standard" 50cm VSL paddle-box dulcimer design, but will include a "V" shaped tail-block as opposed to the simple "flat bottom" one used on my standard design. Here is a modified diagram showing you what I've been thinking...
After studying this initial drawing I decided I would have to elongate the body because the "V" shaped tail-block was cutting too much into the interior space of the sound box. So, I decided to push the "V" shaped tail-block out such that the center "tip" of the "V" would start where the old style straight (flat bottomed) tail piece would normally end. The resulting design is shown here:
This updated drawing is based on a Flying V frame that I just made up and then measured to create this drawing. My Flying V Dulcimer will have a 50cm scale length (VSL). When I measured the scale length from the nut down to the sound box, I found the bridge should be located about 10cm from the "tip" of the "V". And the sound hole should be located about another 8cm closer to the neck.
I decided that I will use a solid hardwood core neck with two long slats of sapelli wood glued on to either side of the neck. So, the neck will be built using a 40cm x 2.5cm x 2.5cm length of beech wood with two strips of sapelli trim wood measuring 86cm x 2.5cm x 0.5cm.
The "V" shaped tail-block is made of two 6" lengths of 2.5cm x 2.5cm beech wood. The two pieces were cut at 45 degrees and butt joined, then reinforced with a brass angle bracket. The part of the above drawing which really isn't to scale is the thickness of the wood used for the "V" shaped tail block. It should be about 1/3 thicker.
Here some photos of the parts that go into building the Flying V frame:
These two photos show the "V" shaped tail block from two different angles. The lower shot shows the brass metal angle bracket that re-enforces the joint. In building it, I managed to twist off one of the brass screw heads when tightening it down. So, to fix the problem, I drilled out a second hole and put in a larger steel wood screw. The heads of the screws don't sit down level with the bracket because the bracket is being used "backwards" from its normal application (the other side has the countersunk holes to receive the flat head screws). But, since this ugliness will be hidden inside the sound box, I didn't really care and left them this way.
This photo shows a dry fitting of my Flying V frame parts. I originally cut the two sapelli sides to 90cm. But after fooling around with the pieces, I decided to cut off 4cm from both sides. This will make them 86cm long, as documented in my second drawing above. My regular 50cm VSL dulcimers end with a flat bottom about where the tip of the "V" tail-block is seen in this photo, so the sound box is a little larger than my standard box length- and perhaps width-wise, but it will only be 2.5cm deep (what I call a narrow profile model).
This photo shows a modified jig or form which should help hold my pieces in place when I glue them up. The form was designed originally for a 45cm VSL paddle box, but I modified it for use on this project. In the end, it was still too short for my application and so I resorted to other means to hold by pieces together during glue-up. If your build one of these, I recommend building the form first. I've used them on past builds and they make gluing together parts a lot easier, and especially of a "V" shaped tail block which proved to be difficult to glue-up to the frame. Next time I will definitely build a new form, one long enough for this instrument design.
After getting the tail-block built I also drew up this drawing showing length measurements and angles:
After getting the pieces built and making sure they fit well, I went ahead and glued them together. Here is a photo showing the resulting Flying V frame:
After gluing together the frame, I rough cut the backboard (i.e. the side opposite the sound board) and later glued it onto my Flying V frame, clamped it down, let it dried. After it dried I took a wood file and filed down the excess wood along the edges. Here's a series of photos related to those steps:
Prepping the plywood veneer: First I cut a piece of plywood veneer large enough to for the soundboard and the backboard, without wasting too much wood. In this case, two pieces approximately 7.5" by 20". I used the frame as a template and drew with a pencil an outline of the frame, then I turned the frame around and used it again as a template to draw the outline for the second piece. Then I cut the board into two pieces at a slight angle, allowing me to minimize wastage a bit more.
Next, I clamped the frame over the first piece of plywood veneer as close as possible to where I drew the outline. The frame would serve as a cookie cutter. I then used a thick-handled utility knife (like a box cutter but with a big comfortably sized handle, as you can see in the photo) and cut the plywood veneer to the approximate size of the frame (a little bigger, the excess will be filed off later). I then applied wood glue to the frame and positioned the frame over the plywood veneer cut-out and I clamped it down, making sure the frame stayed in position over the cut-out. With clamping complete, I wiped up excess glue using wet-wipes. I let it dry for about 90 minutes. Here's a photo of the frame clamped to the cut-out made while waiting for the glue to dry:
The white plastic bag under my work piece is just to keep any excess glue I miss from drying and sticking the work piece to my work surface. The following two photos show the frame with backboard glued on:
So, my Flying "V" is longer and narrower than my standard paddle-box. The "V" shaped tail-block would have cut too far into the sound box if I tried to make them both the same length, so instead, I elongated the sound box so that the tip of the "V" would begin where the standard straight tail-block of the paddle-box would normally end.
Today I went to work on the sound board, rough cutting the piece of plywood veneer into the approximate shape of the frame using the frame as a template and the utility knife. It takes about 4 passes of the utility knife to cut all the way through the plywood veneer. I then drew a center-line down the middle of the rough cut piece of veneer and marked where I wanted the bridge to go and where I wanted the sound hole to go. I then drilled out the sound hole using a hole cutting bit. I think it was 7/8" if I recall right. I then applied glue to the frame, put the sound board into place and clamped it down as shown in this next photo:
After clamping things down and wiping up excess glue, I waited 90 minutes and then release the clamps. I then took a wood file and filed off all the excess wood from the edges of the sound board. The I wiped down the Flying V "corpse" with a wet wipe to remove excess saw dust and to add a bit of color to the wood. Then I took the following photos:
You also might notice that the sound hole is located about 1/8" to 1/4" too far to the right. I'm not sure how this error crept in, but it did. My best working hypothesis is that I used the "tip" of the "V" cut in my rough cutout as one of two points to draw my center-line. But this point was off because of how I rough cut the "V" in the sound board. On these box-cutter like utility knives, the blade is not mounted in the middle of the handle, but to one side. When I made the rough "V" cut, I cut from the center of the "V" out, then I reversed the direction of the knife to cut the other side of the "V". So, one side was cut close, and the other side was cut maybe an extra 1/8" to 1/4" inch too wide, and this mistake messed up my assumption that the second center-point would be the middle "tip" of the "V". Live and learn...
Anyway, that's where I'm at. Tomorrow, I'll start on the headstock. First I'll cut down the front face of the head stock by maybe 1/8" to 3/16", then I will cut a slot in the middle using my method of drilling series of holes 1/4" apart, then use wider and wider drill bits to enlarge the holes until the holes almost join, and then use a chisel to rough cut the slot, then wood rasps, wood files and sandpaper to clean up the slot. If I can do all that in the next day or two, I'll be doing real good.
That looks incredible. Makes me want to build one. I didn't see any kerfing inside the box, are you worried about the top coming loose?
Nicely done, Rand. Great write-up, too, as usual.
To address your question, Wormil...
On all my home-made-box guitars (dulcimers) I have never used kerfing, and never had a problem with the top or bottom coming loose. I use modern white carpenter's glue or TightBond to glue my pieces together, and the walls are 0.5cm thick. I even got mad when I screwed-up one of my paddle-box dulcimer builds and beat the hell out of it, but the joints held. So, I don't really see a need for kerfing. But on finer instruments built using traditional methods (ultra thin materials and hide glue, etc.), then maybe kerfing is needed. I don't know because I never have used real kerfing; but on my first mountain dulcimer, I did glue on small cuts of wood and placed them every 4" or so to insure it wouldn't come apart.
Well on traditional instruments they need the kerfing because they router back the top for purfling and binding. I just assumed that such a thin joint would need reinforcement but maybe not, I'll give it a try sometime.
Yes, I forgot about the routing required for doing the binding. That would certainly weaken the joint and necessitate the use of kerfing. None of my instruments are so fancy as to have a binding treatment done to the edges. "Perfling?" I don't even know what that is. I guess I should look up that term.
Okay, now I know what perfling is. It's an extra, usually contrasting band of material inlayed along the binding for additional gaudiness. If anyone wants to know more, check out this link.
I haven't used binding or purfling either, someday I want to try though.
Nice job, Rand! I mean - both the instrument and documentation.