[Originally Posted: Mar 25, 2011]

 

I have decided to call this the "boat paddle box", or simply the "paddle box" design, because of the shape of the final product. This body style is the traditional body style for stick dulcimers and was popularized by the McNally Strumstick™.  Here is a diagram of the body design that we are talking about:

Here is a photo of my first boat paddle box

instrument which I just completed:

And here (above, right) is a photo of a couple paddle shaped instruments that Kev Lloyd has built (positioned next to a McNally Strumstick for comparison). It was this photo and Kev Lloyd's plans which inspired me to try to build my own. Below I have copied Kev Lloyd's original drawings here, but have reoriented them and scaled them down for easier viewing.

 

In Kev Lloyd's drawings, the tail block is labeled "A" in the "pink drawing" above. The tail block acts as a kind of wedge, forcing the sides of the sound box aside, forming the interior space of this style of sound box. So, it seems like it should be a fairly simple sound box to build.

 

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Here are some of the initial questions (and answers) I had:

 

1.) Do we need to steam, boil or soak the two strips of wood that will become the sides of our sound box so that they will bend easily when we wedge in the tail block?

 

It turns out that you can build this box without steaming or boiling the side walls in order to bend them. However, be careful when you dry bend the side walls as they will want to shoot the tail piece out across the room.

 

2.) How important is the internal bracing in the soundboard? I have build other box instruments with 2 mm thick veneer, and have not needed to add internal bracing. If I use the same material here, would I still need to brace it?

 

So far the 2mm veneer (ply) is holding up pretty well on my new paddle box guitar without adding any bracing. A similar instrument, my square box guitar did need additional bracing under the bridge, but the width of the sound board is about 1/3 more than on the paddle box.

 

3.) The critical part looks to be the tail block. What are the angles on the tail block, especially where it contacts the side boards? My guess is 30 degrees.

 

Thirty degrees of angle looks right at the point where the side pieces intersect with the tail-piece.  I also decided to keep the tail piece "flat bottomed" so I could stand the instrument on end.

UPDATE 9/20/2012: As I build more of these instruments I've come to realize that the angle where the side boards meet the tail piece is more like 25 degrees. So, my best advice is to try to measure it (or eye-ball it as close as you can), then cut the corners of the tail piece and if any "inaccuracy" remains when you do your dry fitting, take care of it with a wood file. In most cases the angle should be around 25 or 30 degrees - nothing a bit more filing can't take care of. I usually have to do a bit of extra filing to make the two joints fit right.

Tags: A-body, boat paddle, canoe paddle, paddle box, sound box, stick dulcimer body

Replies to This Discussion

Permalink Reply by Rand Moore on March 26, 2011 at 12:44pm

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Here are my estimates as to the dimensions of a stick dukcimer based on these drawings. When I build mine, I will make the neck a bit smaller as I prefer 20" (or 50 cm) scale lengths. Do these dimensions look about right?

-Rand.

 

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Permalink Reply by Rand Moore on March 26, 2011 at 1:57pm

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Okay, I have re-calculated the dimensions for my project which will have a 50cm (approx 20 inch) scale length. Here is that drawing.

-Rand.

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Permalink Reply by Rand Moore on March 29, 2011 at 2:48am

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Here's some details on how I'll build my tail block (transom). The whole instrument, including the tail block will be built out of cherry trim wood and a lot of glue!  Here's the plan:

I think the difficult part will be rounding "the top" of the tail block. I will also have to play a bit with the angle where the side pieces meet the tail block as I'm still not exactly sure what this angle should be (should be around 25~30 degrees). Will likely mock up an instrument by clamping together the wood slats that will make up the neck and the sides of the sound box and get an estimation of the angle that way.

-Rand.

 

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Permalink Reply by Rand Moore on March 31, 2011 at 1:13am

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I have started some wood working to build the neck, side slats and tail block. I just glued it up, so I should have the framework about half done today. So, I decided to post a few photos of what I've done so far. The first photo shows the neck I laminated for this project, which includes side slats.

The side slats are 3cm wide and 0.5 cm thick. I plan to add another layer of side slats to double the sound box depth to 6cm, which is the same depth I used on my previous 2 box guitars. I'll likely do that work tomorrow. I labeled some points of interest on the photo in red. Hopefully, you can read it. Here are some more photos:

This shows a dry fit. The scale on the neck shows where my 50 cm scale length will be. The first 30cm will be on the neck and the second 20cm will be on the sound box. I plan to have 14 frets: fret 0, fret 6.5 and frets 1 thru 12.

The sound box will be 34cm long, not counting the 2cm thick tail block. The sound box will also be 18 cm wide at the tail block, so I believe the volume size of this sound box should be 4 or 5 times larger than a McNally standard Strumstick. I think that by making it large it will be easier to hold and hopefully, louder and deeper sounding.

The final photo I have today is a close up of the tail piece, showing how the side slat fits up against the tail piece. After gluing it up, a decided to reinforce the glue joint by drilling a hole and screwing in a small wood screw. The tension on the side slats is pretty great, so I was afraid the glue joint might not hold. I probably should have steamed or soaked in boiling water the side slats to shape them, but I decided I'd try the lazy way and see it the shape would hold up on its own. Without shaping it acts like a big spring, explaining why I have to clamp it down so well. It has shot the tail piece across the room several times now.

Well, that's all for now.

-Rand.

 

 

 

 

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Permalink Reply by Rand Moore on April 2, 2011 at 2:08am

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Well, today I got the basic framework of this instrument finished. I need to find some good wood (veneer) for the sound- and back boards. The last batch of 2mm veneer, which I still have, was cut in 8" strips, so I don't have any pieces long enough unless I cut it so the grain of the soundboard is at right angles to the grain of the neck, etc. So, I will likely go hunting for more scraps of veneer, this time having it cut in strips of 16". As it is supplied veneer comes as really big pieces like plywood or drywall. So, I have them cut it into more manageable sizes. Anyway, here are some photos of where I am at with this instrument.

Now that I have a chance to handle it in 3D, it looks to me like a paddle. So, maybe the name for this style of sound box is (or should be) "paddle-shape".

 

I'll be taking a few days off from instrument building as it's the Qing-Ming festival and my daughter has a couple more days off from school (so I'll be baby sitting for 4 days).

 

-Rand.

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Permalink Reply by Rand Moore on April 10, 2011 at 12:53pm

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Here are a few more photos...

Here I have glued on the 2mm veneer on top the frame to form my sound board. I have also added the sound hole. After reviewing the dimensions of my sound box and neck, I decide a 50cm scale length was too short, and so I have decided to make it 23.75" which is the same scale length as on a McNally Standard Strumstick. You can see the black mark on the sound box where the bridge should be located.

 

You may have noticed that the 2mm veneer extends up the neck to where the headstock begins. This was done so when I glue on the fretboard, there would not be a 2mm bump that the fretboard would encounter as it intersects with the body, allowing me to have a couple more frets over the body.

 

Here's a photo of the back side of the sound box. I have tried twice and failed twice to cut a backboard which will fit the back side of this 'box'. I have improved my cutting technique and am using a coping saw which splinters the wood less as compared to my hack saw. I guess I'll just have to keep at it until I get something that fits half way descent and then use filler to fix any problems. I think square boxes with box joints are a lot easier to attach sound board and back board too. On this instrument I have to kind of inlay the back board in between the side  boards and this requires a really precise cut.

In the mean time, I've started working on the headstock. It will be a slotted headstock and I'll be using a 1x3 set of open geared tuners. Still need to drill the holes for the tuners. Will likely do that tomorrow. So, that's where I'm at.

-Rand.

UPDATE 9/20/2012: After building more of these instruments, I've found the best way to cut the 2mm plywood veneer is with a large "box-cutter" style utility knife. The ones that work best are the expensive "stout" or "big handled" ones as you will need to apply a lot of pressure on the blade when you cut the plywood veneer. If all you have is a cheap flimsy box-cutter, then you will likely have better results if you use a coping saw instead.

To cut the sound-board from the piece of plywood veneer using a stout utility knife, first turn the veneer upside down and place the paddle-box frame on top the veneer to act as a kind of "cookie cutter". It's best to actually clamp the frame down over the plywood veneer as you can easily mess up your cut should the frame move relative the the veneer as you are cutting. It will take 4 or 5 passes of your utility knife to cut through the plywood veneer. Also, it's best to try to cut all the way through, rather than say cut half way through and then try to break the board along the cut. This will avoid splintering the edge of the sound board, possibly ruining and wasting the piece of plywood veneer. Also, since you are cutting all the way through, it's best to have used an old piece of plywood as your cutting surface, rather than to do it on your kitchen (or dinning room) table. This process will scratch the underlying work surface. So, you were fore-warned! Once you have all 3 sides cut, you can clean up the edges with sand paper, but don't remove all the excess wood yet. Do that after you have glued the plywood veneer to the frame. The back-board can then be cut using this same procedure.

After the sound-board and the back-board have been cut, and the rough edges sanded, you can proceed to glue them onto the frame. I usually begin with the sound-board, so that once it has dried, I can then cut the sound hole using a 1" Forstner bit. The thing about drilling holes through wood is that the underside of the wood needs to be supported otherwise the bit will splinter the wood as it breaks threw. So, once the sound-board has been glued in place (and has dried), I place the frame and soundboard over a piece of scrap wood, clamp it into place, and drill the sound hole from the inside of the sound box outward. The Forstner bit will continue to cut a bit into the scrap wood, but it will not splinter the edge of the sound hole. In the past, I have tried using a Forstner bit to drill a sound hole in completed sound boxes, but the inside edge was always rough and splintered from when the Forstner bit broke through no matter how carefully and slowly I cut. So, now I cut my sound holes early -- after the sound-board has been glued to the frame, but before the back-board has been glued into place.

In terms of locating the sound hole, I generally position about half-way between where the end of the fretboard will be and where you expect the bridge to be locate, centered along the center-line of the sound box. Because I can't see exactly how the fretboard and the strings and the bridge will be before the sound hole is cut, sometimes it is a bit off-centered. There is a tendency for these paddle-box sound boxes to be a bit unsymmetrical around the center line. More experience usually will help to eliminate these symmetry problems, and result in a better positioning of the sound hole. After the sound hole is cut, you can proceed to glue on the back-board. After it has dried, you can take a wood rasp or wood file to trim the edges of the back-board and the sound board back down the the sides of the frame. Then some sanding and you should have a nice looking sound box.

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Permalink Reply by Rand Moore on April 17, 2011 at 5:21am

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Hi All.

In my last post I said the scale length of a McNally Standard Strumstick is 23.75". I'm not sure why that number stuck in my mind, but it's wrong. The real scale length (VSL) is 22.5" and I have confirmed it by both measuring my instrument and looking at the product specs in the documentation which came with the instrument. Sorry for the misinformation. Also, I've known about this mistake for about a week now, and discovered it when I was re-measuring the nearly completed paddle box to determine optimal nut and bridge placement. That had to be decided before I could build the fretboard. My fretboard layout is based on a scale length of 22.5" to make it comparable to the McNally Strumstick, but the fret positions are based on the Stew-Mac fret calculator. They differ a bit on the two instruments. Not sure why. Likely my poor workmanship. Here are some more photos of my build:

These first two photos are of the completed headstock. The nut is just a cut bolt, and the headstock is slotted to support a 1x3 set of open geared guitar tuners. The current set of strings are strings 2, 3 and 4 from a set of six acoustic guitar strings. The next photo shows the angle and wood cut off the end of the neck to form the headstock. You may also notice that do use a fret 0 in addition to my "nut" (which really just serves to position the strings across the fretboard).

UPDATE 9/20/2012: These days, instead of using a 1x3 set of open geared tuners, I prefer to use three individual tuners (the kind with the string hole located mid-shaft). I still use a slotted head stock, but I position 2 tuners on the top (or left side of the slotted headstock) and one on the bottom (or right side of the slotted headstock). The melody string (string 1) is then routed to the single tuner on the lower (right) side of the headstock, while the two drone strings are routed to the upper (left) side of the neck. I also find that this allows me to position the tuners closer together (by placing the tuners on alternate sides), and when I hang my finished instrument on a nail in the wall, it will sit flatly (parallel) to the wall. When you have all three tuners on one side, when you hang the instrument on the wall, it will tilt the instrument outward at about a 45 degree angle from the wall (doesn't look so good IMHO).

The next photo (below) shows the fretboard, which uses real frets (as opposed to cut nail or tie-wraps, which I've used on many earlier builds). In fact, I am now out of fret wire. Will have to see if I can find a source in China. The other thing about this fretboard is it uses diatonic fret spacing as most stick dulcimers do (stemming from the tradition of Mountain Dulcimers).

Below is a shot of the body and sound board. From this angle you can see the "rather too long" heel. Next time I build one of these I want to try to shorten the heel by an inch or so to make it easier to reach the highest pitched frets.

I located the position for the bridge on the sound board by tapping on it until I heard the loudest and richest tone the box produced. From there mapped out the scale length, etc. The sound hole may be too large, as I don't feel as much air puff out when I tap the back of the box as compared to by two earlier box guitars (which use the same 2mm thick veneer (ply) for both the sound board and the back board). If you look closely at the tail piece, you can see the wire strings (string 1 & 2) cutting their way through the wood. I will likely have to replace the tail piece. Hope I can learn to build something sturdier. The tail piece is made of poplar wood colored brown. My last photos shows that it can stand on its end (flattened tail block).

That's all folks!

UPDATE: 9/20/2012:  Ever since this first instrument, I have not bothered building "deep" sound boxes by doubling the width of the sideboards. Instead my sound boxes tend to be 2.5 to 3 cm thick, depending on how wide the slats of trim wood are that I use for the sides. The resulting instruments have plenty of volume and resonance.

Also, I have found that a center core of 1" by 1" hardwood makes a nicer sounding instrument (though the neck and headstock will be somewhat heavier). This also simplifies the frame construction as all you need to glue up are the two side slats to the central core (glued up one at a time, of course), and the tail block. I have also noticed longer scale lengths sound better than short ones. So, if you are looking to build a sweet sounding instrument, try a 25" scale length with solid core head and neck.

The only problem with long scaled stick dulcimers is that if you play chordal style, many of the chords will be a long reach. You don't have this problem as much on a mountain dulcimer because players aren't also wrapping their fretting hand around the neck, so they can stretch their fingers much further. If you are a chordal player, maybe a mountain dulcimer will suite you better.

So, far the paddle-box dulcimer design is my favorite. Easy to build, Sounds good, plenty of resonance, fair volume - plenty for playing to small groups in intimate locations. If you need more volume, you can always add a piezo pickup and use it with an amplifier.

Below I have more info on more recent builds.

-Rand.

 

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Permalink Reply by moedecker on April 22, 2011 at 8:52am

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Great design, very nice. I'm gonna have to think on something this creative. Thanks for the pictures and new idea!

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Permalink Reply by Rand Moore on April 22, 2011 at 8:17pm

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Hi Moedecker.

 

I'm glad someone finds this writeup and photo interesting. Sometimes I think I'm just writing to myself. The build was easier than I thought it would be, but then I didn't bother with messy wood bending techniques like steaming the wood. A little careful "man handling", a couple strategically located nails and a bunch of clamps coaxed it into shape while gluing it up. Next time I'll try to build some kind of jig with the shape modeled into it so I can get a more symmetrical result. In the mean time I have a number of other builds I want to do, some with other shaped sound boxes (hexagonal, octagonal, circular). Just trying to improve my general wood working skills, then will re-address some om my favorite designs and try to build a higher quality instrument worthy enough to sell. My wife would like my hobby to turn into a money making enterprise. I keep telling her my skills are no where near that level.

-Rand.

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Permalink Reply by Tom Walters on April 23, 2011 at 5:35am

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Randy,

 

Thanks for your detailed notes and pictures on this.  I am thinking of building a ukulele along this lines.  I currently have a tenor fluke and it has a triangular shape and you can also stand it up  :).  I have started building a tenor uke from a kit I bought from ebay.  The sides are together with the neck and tail block and the kerfing installed.  I have started to inlay a rosette in the top and when done, I will start the bracing of the top and back.

 

I take it you are in China and don't have access to many tools or materials.  Thanks for starting this thread and for all your work on it.

 

Tom

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Permalink Reply by Rand Moore on April 23, 2011 at 6:33am

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Hi Tom Walters.

Building from a kit is a good way to get started. I should probably do the same, as they probably teach you the "proper" way of doing things. For instance, kerfing - I have never used it, but I can see it should make the instrument a lot stronger around the corners. My main limitation here in China is finding suitable materials to build with. I have standardized my last several builds on cherry wood which I buy in long strips and which is intended to be used as trim. The strips can be cut to length and glued together in different ways to form laminated necks, sides of boxes, fretboards and other structural elements (like the tail block for my paddle box gitar). So, my methods are different from many builders, but I get there in the end. And my instruments are sounding better than the cigar boxes that I used to build around. One of projects on my list is to build using a cigar box, but with a 2mm ply (veneer) sound board and (perhaps) backboard in order to see where the good sound is coming from (the sound board, backboard of sides of the box). This hobby and my writings about my projects here on CBN also gives me a cultural link to my native culture--something to help me over the feeling that I'm "stuck in China".

-Rand.

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Permalink Reply by moedecker on April 23, 2011 at 1:09pm

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We're reading it, sometimes just don't get in here for awhile. And go ahead and make them for money, hell they have a store called $99 guitars out here and people cater to it all the time. So make some CBG's and keep them at a workin' man's price level and you'll do fine, I'd like to give it a try one of these days myself but it's a balance between all the other things I do incuding playing guitar on the weekends that it's hard to produce one for myself let alone for sale. Well keep posting, I for one am paying attention and appreciate and enjoy it!! Thanks!

Rand Moore said:

Hi Moedecker.

 

I'm glad someone finds this writeup and photo interesting. Sometimes I think I'm just writing to myself. The build was easier than I thought it would be, but then I didn't bother with messy wood bending techniques like steaming the wood. A little careful "man handling", a couple strategically located nails and a bunch of clamps coaxed it into shape while gluing it up. Next time I'll try to build some kind of jig with the shape modeled into it so I can get a more symmetrical result. In the mean time I have a number of other builds I want to do, some with other shaped sound boxes (hexagonal, octagonal, circular). Just trying to improve my general wood working skills, then will re-address some om my favorite designs and try to build a higher quality instrument worthy enough to sell. My wife would like my hobby to turn into a money making enterprise. I keep telling her my skills are no where near that level.

-Rand.