The Realm of the Verbal Processor

Jarvis's Ramblings

Building a Hammered Dulcimer

Back in November, my wife approached me about building something that our daughter asked for for Christmas…a hammered dulcimer. I enjoy woodworking, but building a musical instrument? That would be a stretch at best! Julie had found plans online, and pointed me towards them. After looking at it, I determined that from a woodworking standpoint, it’s basically building a box…a trapezoidal box. I can do that…and if the plans can help me precisely position the tuning pins/etc, then I could do it. Let the adventure begin!

For those who don’t know what a hammered dulcimer is, it is stringed instrument that is played by striking the strings with small wooden hammers. Our family first heard the instrument through the music of the late Rich Mullins. Here are a few links to some very talented musicians playing the instrument.

Throughout the build I took lots of pictures because I figured I would get around to writing this blog post about the build.

I took the plans from MusicMakers and then made some modifications to the frame design based on a post on the Smithsonian site by a famous dulcimer builder name Sam Rizzetta. The plans call for a simple 90 degree joint for the bottom corners. Sam uses a different joint on all four corners that is much stronger…as the strings provide tension, the joint can only get stronger. But that did involve figuring out the angles and how to best cut this without making mistakes.

Step one was to work with some scrap wood to figure out how to best go about doing the cuts before wasting the good wood. I started by just eyeballing the angles onto a scrap of plywood just to get it close.

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What that helped me figure out is that if I planned it right, every single angle of the frame would be either a 30 degree or a 60 degree angle. That meant that as long as I dialed in my table saw blade perfectly on that angle…it could cut the entire frame by just changing the height of the blade.

I then proceeded to build a full sized frame out of scrap pine. The sides of the frame (the pin blocks) were going to be 2.5 inches square, so I cut and glued some scrap 2x4s to that size. I then used them to test out the cuts before doing it for real on the good wood.

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That process helped me learn two things. First…I needed to cut both pin blocks at the same time in order for the angles to line up perfectly. Second…the miter gauge that came with my saw was simply not going to work for this…it kept slipping a little bit on the angle. So I quickly built a better 90 degree mini-sled to use for my crosscuts. I couldn’t use my regular cross cut sled because the blade on the saw was going to be angled at 30/60. This sled was made out of a block of hard maple on top and a piece of scrap bamboo flooring for the runner.

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That helped me get to this point…a solid full sized frame made out of scrap wood…and it helped me learn from a couple of mistakes on scrap wood before cutting into my maple.

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One note about the wood that I used for the actual dulcimer. The pin blocks have to be crazy strong…so very hard wood is required. (There will be 66 strings on the instrument, and one estimate said there was about 35 pounds of tension per string. That’s 2310 pounds of tension…more than a ton. If the frame isn’t strong, the instrument will actually rip itself apart under the tension.) I thought about where I could get the maple from when I remembered that when we built our house four years ago, the supplier of the stair treads sent five treads that were an inch too short…but we didn’t discover this until after we had stained them and were ready to install them. They replaced the treads, but we got to keep the five extras. Those treads are hard maple. I just needed to plane them flat, cut them to size, and glue them together. The frame was essentially free!

In cutting the frame, I ran into my first issue that I had to work around. In each of the stair treads, there was one nail that was used for holding the rounded edge on when the tread was manufactured. When I built my pin blocks, I thought I had picked sections that did not have the nail in it…I was wrong. And guess what…that nail was in a section I needed to cut out at a 60 degree angle.

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So I spent two hours cobbling together a contraption that would hold this heavy pin block at exactly a 60 degree angle so I could try to cut right next to that nail without the blade hitting it. (I did swap out to a different blade just in case!) What you see below are three clamps holding the pin block up at a 60 degree angle…and another clamp holding all of that to the miter gauge to keep it straight!

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That resulted in this cut…which actually went directly over the nail. Glad I swapped out that blade!

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The end result though is that I had a solid frame made out of maple. Due to the size and angles, I had to use a ratchet strap to clamp it when I did the final glue up. The clamps on the corners are to keep the four pieces from slipping and not lining up correctly.

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Next was to rough cut a piece of 1/4 inch plywood for the bottom and the glue/clamp it. I used 16 clamps. If you notice the front edge, I have four pipe clamps and a six inch wide piece of hard maple pulling the frame into alignment…it was slightly off, but nothing that couldn’t be fixed with some planning. Also note that there is a strap on the middle clamp that is holding the whole thing to the wall. That’s because I was concerned about the weight of the four pipe clamps pulling the whole thing off of my assembly table!

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Next was to cut and glue in the inner bracing.

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Then it was time to rough cut the soundboard out of 1/4 inch maple plywood. I also had to measure out and carefully cut the sound holes in the top before gluing it down…again with a lot of clamps.

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Up to this point, the top and bottom have been overhanging the frame. I used a flush trim router bit to trim off the excess.

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Next I needed to use my router to very carefully cut shallow grooves into the top of the soundboard that two brass bars will fit into. Those are the side bridges of the dulcimer. These two cuts were probably the most stressful of the entire build…because a mistake in one of those would mean that all of the work to this point was wasted. I practiced on scrap wood ahead of time and prayed hard before making those two cuts. They came out perfect.

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After that, it was time to build the bridges. This involved cutting out part of the plan, taping it to a board that was cut to the right size, marking the center of 33 holes, and then drilling out those holes with a forstner bit mounted in my father-in-law’s drill press. What I would later discover is that I drilled all of those holes the wrong size. The way that the forstner bits line up in the set…the label does not line up with the bit that it in front of. So instead of drilling 33 holes that were 3/4 inch in diameter…I drilled them all with the 7/8 inch bit. Which meant I had to re-do this whole section again! Ooops! I won’t make that mistake again!

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In the end, I sliced off the two bridges from that block, cut the tops to the correct angle, and cut a groove down the middle of the top for the delrin rod to go in. (The delrin rod gives the strings something smooth/slick to slide against when tuning.) Oh yeah…the bridges are made out of cherry. They look really pale and pink in the pictures, but they will darken up over time and be a very nice contrast to the maple.

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Finally, I was at the point of marking where to drill the holes in the pin blocks for the tuning pins and hitch pins. I cut apart the plan and carefully taped it into place. I also discovered that I didn’t trust my middle aged eyes enough, so I went and bought more powerful reading glasses and a magnifying glass so I could see the plans clearly! All told, there were 99 holes to mark. 66 tuning pins and 33 hitch pins.

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However…before I could drill any of those lovely holes that I marked, I had to figure out how to drill them perfectly straight. This thing is simply too large and bulky for the drill press. This led me to build this little jig which worked fantastically. This is a piece of scrap cherry that has a notch cut out of the bottom side. On the top and bottom, I glued two pieces of steel that I had on hand (steel used for joining framing). I then took that to the drill press and very carefully measured holes to be exactly the right depth from the edge to line up perfectly with the three lines of holes I needed to drill. Then I nailed a piece of scrap plywood to the side to help it line up on the edge of the frame. The two pieces of steel keep the drill bit aligned perfectly perpendicular, so I was able to use my hand drill for drill all of the holes…but I still got the accuracy of a drill press. A light shining in the hole underneath let me clearly see the marks I made above.

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End result:

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While the poly was drying on the bridges, I took time to make the hammers. I modeled them as closely as I could on the shape of the hammers I saw Rich Mullins playing in one of the YouTube videos above. The hammer itself is made out of an approximately 1/8 inch thick piece of hard maple. The handle scabs are 3/16 inch cherry. These were made predominantly with a band saw and belt sander.

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The plans called for having a long piece of delrin run the length of each bridge. I didn’t like the way that looked, and I also knew that I needed a way to mark every fourth set of strings, so I bought a piece of white delrin to use for marking those. I cut them to size and glued each one in place with a drop of super glue.

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At long last it was time to position the bridge and start stringing this thing! The way that hammered dulcimer is designed, the treble bridge (the left one) must be perfectly (and I mean PERFECTLY) positioned so that 2/5 of the string is on the left and 3/5 is on the right. What this allows is for you to play two notes on each string. On any string on the treble bridge, the note on the left side of the bridge will be a perfect fifth of the note on the right side of the bridge. So if the right side is tuned to C, then the left side will be G…all because of the perfect positioning of the bridge. I measured and marked these with tape to start with, then fine adjusted with a tuner once I had a couple of strings on the top and bottom.

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Treble bridge fully strung:

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After getting the bass bridge strung, here is the final result! Also note, that the cherry of the bridges has already started to darken up nicely just in a few days.

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Oh…and the green tape on the pins…that would be where I broke a string that I need to replace before I can complete it. I looked at the wrong note when I was tuning. I actually broke it when tuning the treble bridge and then borrowed a string from the bass bridge. I think I was supposed to be tuning that note to A3. The string didn’t take too kindly to whatever note I tried to stretch it to!

A few more pictures up close:

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And lastly…a very happy daughter! (There are lots of notes taped to the instrument right now. The strings are still stretching, so it needs to be tuned several more times before it will stabilize. Having the notes taped to it is much easier than referring back to the chart!)

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January 18, 2019 - Posted by | Uncategorized

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