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.
Replies
Well, I'm back from a week-long family vacation to Singapore. Nice place, had a good time. Anyways, upon my return I inspected my teardrop hoop with the back-side glued on and found that the sides warped again. This time the top edge flares outward in the "reverse curves" and "neck" areas. Had I glued on the soundboard before I left, I bet it wouldn't have warped. Lessons learned: Don't delay in gluing on both the sound board and the backboard to the teardrop hoop. Pre-make any internal pieces like the tail-block and any internal bracing, and don't go on vacation mid-build. Maybe building in a humid area is also a mistake. I think a better mold design, one that will allow you to glue on the top and bottom while the bent sidepieces are still in the mold is a good idea, too. Well, back to the drawing board.
-Rand.
Hello Rand,
I was reading through your posts again and saw the comment about the tuners. If you want the knobs on the sides of the pegbox, you could use ukulele tuners. Some people will say they are hard to keep tuned, esp. with steel strings, but I've found that placing a rubber faucet washer under the knob gives enough friction to hold them tight.
Hi Habanera Hal.
Keep the good ideas coming. I think I'll give your "uke tuners with rubber faucet washers and steel strings" idea a try when get around to retrofitting a couple older instruments that use uke tuners with uke strings. For this build, I've decided to go with my original slotted headstock and a set of tuners I normally would use with the tuner knobs pointing downward. Since doing my second "soak & bend" session with my teardrop hoop, the narrow longer neck made possible by the two reverse curves has left me thinking "stick dulcimer" rather than "mountain (lap) dulcimer". So, orienting the side-mounted tuners in my slotted headstock with tuner knobs pointing downwards seems the best way to go.
My builds all use bolts for nuts and a nut & bolt for the bridge, I guess because they work well and I'm too lazy or too impatient to craft my own. People also get a laugh at the improvised hardware. One day I'd like to figure out how to easily craft my own more professional looking nut and bridge.
I do have a pretty simple tailpiece design which I use on my neck-almost-thru designs. I use a short length of wood about 5cm long, 2.5cm wide and 0.5cm thick and attach it (glue & 2 screw) to the tail-end side of the sound box mounted perpendicular to the strings and just over the corner edge from the soundboard. Actually, before gluing on the tail piece board, I saw and file three groves into the side of the board thru which the string will run. So, after gluing and screwing on the tail piece board, be sure to clean the squeezed-thru glue from the holes so you can run your strings thru them. I usually just poke a piece of old string thru the holes, wipe-off the glue and repeat until I'm not getting any more glue. Then on the corner of the sound box around where the strings will bend over the corner I place a thin 1.5" (or so) long cut nail (I cut both the head and pointed tip off the nail). The nail in that location will keep the steel strings from cutting thru the wood of the sound box when you go to sting-up and tune the instrument. To make the nail stay in place, I cut a small 1.5" grove for it on the corner where the strings bend over, usually using a u-shaped wood gouge (tool). Before doing all this though, mark the center-line of the instrument on the sound box and tailpiece board. If a 3-stringer, string 2 should line up with the center-line. Then, depending on your desired string spacing (usually 3/8" to 1/2"), mark where the grove for strings 1 and 3 will go relative to the center-line. Then saw and file the right sized groves for the strings you plan to use. Next, pre-drill your 2 screw holes in the middle of the tailpiece board such that the 2 screws are place halfway between the outer strings and the middle string (on each side of the center-line. Hopefully, you can follow all that.
I hope this simple tailpiece design will work on this instrument design which is not a neck-thru or neck-almost-thru design. The neck is incorporated into the body frame, so I hope it can stand-up to the string tension. I was thinking I could extend the fretboard all the way down -- across the sound board and tie it into the tailpiece to add some more structural strength. Any ideas about this?
As far as adding a piezo-pup, I'm not a big fan of piezo since it picks up so much "fingering noise". There might be some secret for isolating the piezo-pup (using silicon seal and/or hot glue, etc.) such that it doesn't pickup so much "fingering noise", but I haven't figured it out. Some day I plan to do a mag-pup box guitar, but that might not happen until I get back to the States to buy more building supplies like fret wire, mag-pups, and pre-amp kits. So, maybe in September. I understand that mag-pups don't pickup finger noise, at least that's what I'm hoping.
Tomorrow (Tuesday 3/20/2012) and for the rest of the week, I'll be visiting (with my wife and young daughter) more of my extended family (in-laws), this time in Singapore. So, I will have minimal access to the Internet and won't have anymore progress to report on until after I get back. Hmmm... I should Google "Singapore" and various guitar parts to see if I can get more guitar building supplies there.
Well, that's all for now.
-Rand.
Well, last night I took my teardrop hoop off my forming rack after a 2.5 day drying time for its "second bending". Here's that photo...
I also noticed a small hair-line crack open up on the lower side of the neck (mid-board, diagonally with the grain) between where the headstock will be glued on and were I glued on that block of wood I added last night. I'm hoping that with the headstock glued on and this new block of wood added last night, the crack won't get worse. When I finish the sound box, I expect a good sanding, followed by a few coats of poly-urethane will make the crack disappear. In the mean time, I'll be watching it.
After the backboard has dried, I plan to add additional wood (which will also be soaked and formed) to the "bottom" of the teardrop to provide more wood to anchor a tailpiece and to better balance the instrument. I'll also have to finish the headstock and glue it onto the teardrop frame. This means I'll have to decide on the number of strings (3 or 4; 4 with paired melody strings). The neck is a bit narrower than I had intended, but I think I will still use a 3cm wide fretboard and allow it to overhang the sides of the neck. Maybe I can add small strips of wood to either side to fill in this overhang and better sculpt the fretboard to the neck. More grist for the mill (my mind). Well, that's all for now.
-Rand.
Hi Rand
Why not just have the overhanging fingerboard with radiused edges for comfort and forget about filling the overhang.
Hi Michael,
Good idea. I assume you suggesting to just rounding off the corners on an otherwise flat fretboard and not a radiused fretboard like on real six sting guitars. The former is easy to do, but the later would be pushing me beyond my current woodworking skill level. I prefer to keep it simple and go with a flat fretboard with rounded edges.
I was also thinking that if it was going to be a lap (mountain) dulcimer, then I could put in thicker raised fingerboard with the under board(s) narrower than the top. I could make it like a raised bridge with several piers and several spans like on my first mountain dulcimer. But since re-bending my teardrop with the reverse curves and long neck, I've been thinking "stick dulcimer".
The other concern I have is the extreme depth of the neck. It's 5.4 cm thick and fills up much of my hand even before I curl my fingers to fret chords and the like. I'm worried it will be harder to fret than most my other instruments unless I lie it down and pay it like a lap (mountain) dulcimer. You see I'm still teetering back and forth between "Is it a small lap-dulcimer?" or "Is it a stick-dulcimer?". Dimensionally, it falls between the two, and maybe if built right, it could be played either way. But, because of the string layout difference, I've got to decide which it will be.
One other problem, the headstock is also really thick around fret 1. So, I was thinking of cutting off the ends of the outer two boards of the headstock about 3 or 4cm shorter while retaining the inner block of wood. The inner block of wood and the two smaller slots should be sufficient to glue the 2 ends of the teardrop body to the headstock now that I have the spring-back tension o the teardrop hoop under control. Here's a doctored photo of what I mean...
Well, that's all for now.
-Rand.
Rand
Here are a couple of doodles it would be a shame to cut off the neck after getting this far
Michael
Hi Michael,
I like your idea about trimming the backside of the neck and then infilling it. I'm not sure if my woodworking skills are up to the task, but I'll certainly give it some more thought. I've suddenly have become busy this week and next, so my response time and the speed of this project will suffer. But, I do intend to complete it.
-Rand.
Rand -
Here's an idea for the overhanging fretboard - would be really unique: http://www.dollhouseminiatures.com/supplies/crown.htm
As to the thickness of the neck at the first fret, looking at your picture I think cutting back the two outer boards would work, but I would do it AFTER you glue the body on. Just don't spread glue on those edges - you would then have the length of the boards to apply more pressure when clamping. After the glue dries and you cut them back, you could blend them into the neck with a nice radius. If you have any concerns about the strength, you could run some dowels through the body/headstock block joint.
Hi Habanera Hal,
Unfortunately, that link seems inaccessible from China, but I can imagine what you mean... miniature crown molding. I'll see what I can come up on this side of the Pacific that can serve the same purpose. Was thinking a bamboo skewer trimmed to length might be okay. I have skewers of 2 diameters that I can play with. Hmmm... I wonder if I can soak them and roll them into spirals and other decorative shapes. Food for thought.
As far as trimming the outer two boards of the headstock, I don't anticipate clamping problems if I cut them before I glue them up as there is no more spring-back tension in the ends of the teardrop hoop now that I've glued another "block of wood" about halfway up the neck to handle the remaining spring-back (that had been already significantly reduced after my second bending which introduced a reverse curve to each side). Time for a picture, I guess...
-Rand.
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