Hi All.

I've decided I wanted to try my hand at wet bending wood, so I'm planning to build a teardrop shaped bodied instrument (most likely a stick dulcimer) by soaking the wood for the sides until pliable, then forcing the wood into a jig/form that was designed around an old 8" hand-drum hoop to form the teardrop shape. I plan to document my plans and build right here in this discussion. As this is my first go at it, any constructive advice you may have is welcome. Right now I have wood for the sides clamped down and drying in the form (jig), and I need to get my design figured out on paper before I get to much further.

Well, here are a couple of photos of my first teardrop shaped side-board drying in my forming rack (jig). My forming rack is pretty crude, but I like to start simply and see where it takes me. If this minimalist forming rack doesn't hack it, I can always modify it, or build a better one from scratch. This rack is the one I built for my elliptical-shaped mountain dulcimer project. The main modification is the addition of an old skin-less hand-drum frame (hoop) around which the wet side-board is positioned and clamped down.

The sapelli wood I'm using comes in 2.2 meter length and measures 5cm (about 2") wide by 0.5 cm (about 0.2" or just under 1/4") thick. I cut a 5 foot length, soaked it for an hour in warm water. The water was originally heated to 42 degrees Celsius, but it was left to cool down as my soaking chamber (a 5 foot length of 3" wide PVC pipe, sealed on one end) has no mechanism to maintain heat for any extended period of time. So, I don't think high heat is pre-requisite for bending sapelli trim wood. But, perhaps (just maybe), heat is needed to help maintain the shape after forming (e.g. minimizing spring-back). Do you know better? I suspect I'm just building a big wooden spring and if I remove it from the rack before I have the head block attached, it will just spring back to is original (or near original) shape. Please let me know your experiences with wood bending.

Anyways, I filled the PVC pipe with the length of sapelli trim wood up with warm water in the bathtub (high tech, yes indeed!). After an hour I removed the board and kind of man-handled it into my forming rack. The wood was still pretty springy, so it took some effort to get it into the form... it wasn't like a wet noodle by any means. But it wasn't that difficult either. Once centered in place, I used a number of clamps (along with small blocks of wood to better spread the force of the clamps across the wood ) to tighten the sapelli wood ("side-board") up against half the drum hoop to help form the teardrop shape. I also added some blocks of wood as "shims" to better position the 2 ends of the side-board.

So, here is a close shot...

As is clear from these 2 photos, I did not have a clear idea of how I was going to attach the neck/head assembly (which I still need to build). To make a stick dulcimer, you need a rather long stick (neck) upon which the fretboard is mounted. As stick dulcimers are played "guitar style", the above body shape seems to be "getting in the way" of your fretting hand, making many frets difficult to reach with your fretting hand cupped around the neck. To correct this design problem some additional re-shaping of the neck will be required. Otherwise, this shape is better suited to a mountain (lap) dulcimer. Here's a couple drawings to help explain what I mean:

In the second drawing, you can see how the upper reaches of the teardrop have to be pressed downward (inward) to form a narrow "top" where the neck can be attached. This means I will have to add some more guide posts on my forming rack to form the "shoulders" that I'll need to attach the neck and head assembly to the body. Notice that these two curves will be "reverse curves" because they bend the side-board in the opposite direction from how the circular drum hoop is bending it. Also, notice how almost 3/4 of the drum hoop's circumference is now being covered by the side-board as compared to about 1/2 of the hoop in the first drawing. With a new forming-rack that implements these two reverse curves, you can bet forcing the wood to bend that much will certainly be a chore. Maybe additional soaking and/or heat application can help by making the side-board more supple.

Also a couple alternative ideas that we could explore are...

    1.) Use a smaller diameter drum hoop, say 5" or 6" instead of 8" in diameter.

    2.) Use a longer neck, usually resulting in a longer string length (VSL).

    3.) Or, perhaps some combination of these two alternative ideas.

The bridge is located 2/3s the way across the drum, but could be moved upward a couple of inches and still be well placed.This could then reduce your scale length if you were planning to increase your neck length.

Well, for now, I'm going to go with the shoulder-less (neck-less) teardrop body design. This means my target instrument will most likely be a short scale lap dulcimer. My next job will be to design and build a "head-block" to close up the teardrop and to form the frame of our sound box. I think I'll also integrate my head-block into the neck (stub) and headstock assembly. Once I'm done with this assembly, I'll mount and glue it to the side-board while the side-board is still (mostly) secured in the forming rack. So, I'll draw the plans for head-piece/neck-stub/head stock assembly now...

Okay! Back with a drawing of my headstock plans. As this first instrument will be a short scale lap dulcimer, there won't be a neck. In its place will be a fingerboard glued to the top of the sound board for pretty much entire length of the instrument. The headstock will incorporate the "head-block", a slotted "chuck of wood" that secures together the two loose ends of the teardrop shaped board to form the frame of our sound box. Here's the drawing which should clarify what I'm talking about.

Well, today, after reviewing the above drawings with machine tuners in hand, I now realize I can't do a slotted head and have the tuner knobs stick out the sides as shown above. Instead, the tuner knobs will either have to point downward like on my other stick dulcimers which feature a slotted headstock, or they'll have to point upward. I remember a few photos of slotted headstock on mountain dulcimers where the tuners were mounted upside down such that the tuning knobs rise up above the headstock, and they say it's a good way to do it as mountain dulcimers are held in the lap or sit on a table when played and tuned. Putting the tuner knobs on top makes them very accessible, but they looks ugly mounted that way (IMHO). Mounting the tuner knobs pointing downwards make them harder to reach, so that option is out. So, I think I'll change my design to a flat (no-slotted) headstock with the tuning knobs pointing out on either side as shown above. Any thoughts / advice on this matter? Well, back to the drawing board...

That's all for now...

-Rand.