I designed the instrument using my past instruments and information from a few books including a book by Howie Mitchell, and the pamphlet by Sam Rizzetta as resources. Interestingly, Sam Rizzetta does not build instruments quite this way anymore, but uses the design where the sound board is laminated on as the entire upper surface of the instrument (e.g. as in the Musicmakers kit catalog). One feature I like about Sam's old design is that one CAN take the sound board off and get into the interior of the dulcimer. I think this is important for a beginning builder since one can correct any buzzing or other problems. Also if you decide you have made a mistake in the choice of sound board material, it is possible to try something else without building a whole new instrument.
Where I depart significantly from Rizzetta's plans are the interior bracing, the 'flat' upper surfaces of my pin blocks (as opposed to the beveled pin blocks in Rizzetta's pamphlet) and the fact that my keels are the same height as my pin blocks (therefore flush with the top).
WARNING!! I assume that you have one or more of the sources I indicated above (or others) and that you are familiar with the basics of building a hammer dulcimer. I don't provide enough detail here for a neophyte to make an instrument without any other instructions.
1. Lay out the instrument by carefully drawing a rectangle on the inside surface of the back which I assume will be a 2' x 4' piece of plywood. As indicated by the plans this will be a 42.9" x 20.3" rectangle.
2. Measure in the required distances (indicated on plan Figure A, 12.27" from the left upper corner and 13.23" from the right) to establish the upper corners of the trapezoid. Connect these points to the lower corners of the rectangle to draw the outline of the instrument. Draw parallel lines 2.25" to the inside of the left and right edges of the instrument to establish the dimensions of the pin blocks.
3. Draw the keels in by drawing parallel lines to the inside of the upper and lower edges of the trapezoid. The lines should be spaced the same distance as the thickness of your keel stock.
4. Draw the centerlines of the side bridges in (see plans, Figure B). These are parallel lines about .28" from the inside edges of the pin blocks. Mark the position of the treble and bass bridges by measuring from the intersection of the left side bridge centerline and the inner edges of the upper and lower keels. These measurements are actually given on plan page C. For example, the upper intersection of the treble bridge line with the upper keel is shown as 5.29" from the side bridge centerline. The rule of thumb is that the treble bridge should be located 2/5 of the distance between the side bridges (the side bridge centerlines indicated above are where your bridge caps will be if you use 0.5" wide bridges). This principle is also explained in Sam Rizzetta's pamphlet. Use this rule of thumb to double check the treble bridge position. The bass bridge position is somewhat arbitrary but I have located it where experience tells me it works well in playing.
5. Ignore my plans. Just kidding, now that you have the instrument laid out on the backboard, take your critical measurements (such as the widths to rip the pin block pieces) off your drawing and use my plans as a guide. If you want to alter the plans you can mess with them by redrawing them on the back board and transferring the measurements to your stock.
6. Make sure you have allowed for the entire length of the pin blocks when laying them out for cutting. This is indicated for the right pin block on plan Figure A. Note that the finished pin blocks are parallelograms and that the squared stock you build them from will have to be longer than one might think. If you allow for the missing 'corners' on the right hand pin block, for example, you get a length of 25.5" versus a measurement along the edge of the pin block of 24.26" inches.
7. I fabricate the sound board after assembling the frame. I rip the sound board to the proper width as measured from the finished frame (leave about 0.25" from the top and bottom keels). I then position the sound board where I want it, clamp the sound board to the top of the instrument and mark the corners where the sound board intersects the pin blocks. I draw lines to establish the angles and cut to the lines by hand with a backsaw. I do final fitting by using a sharp adjustable-mouth block plane set to a very fine cut. If you don't have such a tool you can use a 12" or so piece of wood wrapped with medium sandpaper and sand the edges selectively to get a close fit. Once the top is cut to shape, I position the sound holes where I want them to be by laying the bridge blanks on the top and putting paper cutouts of the sound holes on the top, squinting a bit, and moving the cutouts around until I get them where they seem to look best. Very scientific. Of course, sound holes are optional. Clamp the soundboard to a wood backing and use a brace and expandable bit to cut the holes. It is important to use wood to back up the soundboard when drilling because you will get tearout of you don't and the center screw on the expansion bit will need something to bite into once it is through the thin soundboard. Complete the top by gluing bracing to the underside along the upper and lower edges and gluing the bridge supports (the slats I mentioned in my email note) in place. These slats are 3/4" in width and 1/2" in depth. I mark the length of the slats after the top and bottom braces are glued to the soundboard and but the ends of the slats right up to the inside edged of the top and bottom braces. I normally use maple for the bracing but cherry, walnut or other hardwood would probably work as well. I use about a 1.25" height by 0.75" thickness for the upper and lower braces. This is illustrated in the following drawing (not to scale):
8. The treble bridge dimensions can be calculated from the backboard drawing as well. The rule of thumb, as espoused by Howie Mitchell, is that the treble bridge height is governed by the distance of the treble bridge from the left hand side bridge. The ratio is 1 to 10, i.e. the treble bridge should be 1" in height for every 10" of length between the treble bridge and the side bridge. The drawing below (not to scale) illustrates this principle. The distances A and B are divided by 10 and added to the height of the side bridge, e.g. 0.5", to derive the final shape of the treble bridge. This results in a tapered shape for the bridge:
The bass bridge dimensions are calculated from the full size drawing by drawing in the low and high points for the treble bridge and bass bridge. A CAD program can be used to good effect here as well. The principle I use is that the strings should cross midway between the bridges. I find this works well when playing flams (bounce-striking from a treble string to a bass string or vice-versa, try that on a piano!). This method of deriving the bass bridge height is illustrated in the drawing below (not to scale) :
9. If I have any original contribution to lutherie it would be the method I use to lay out pinblocks. I don't use a traditional pattern where all the tuning pin and hitch pin locations are laid out on a single piece of paper. When I decided to build an asymmetrical instrument I realized that all of the patterns available in books were useless to me because I had changed the angles of the pinblocks. I devised a method where I draw the relationship of the bass and treble courses and hitch pins to each other in a strip with registration (dotted) lines present:
I use a full scale pattern which I photocopy several times to generate enough strips. The same strip can be used for either the right or left pinblock. I cut the strips out and lay them up on the pinblocks. I stick them onto double-sided tape used for posters:
10. I drill the holes for both my tuning pins and hitch pins at about a 10 degree angle. I use nontraditional hitch pins which are #6 'trim head' wood screws with a black oxide finish. These screws are similar in appearance to drywall screws but have a smaller head. They are available from some home center stores and many of the woodworking supply catalogs list them as well. If I were to use the traditional plain steel pin type of hitch pin, I would increase the angle of the hole for the pin.
11. Beyond using your tools safely and wearing the appropriate personal protective equipment, please be careful while cutting the music wire and stringing the instrument. Music wire typically comes in rolls and the stuff can get away from you. The cut ends are needle sharp. I had a piece of #10 wire recoil on me and flick my glasses off. Missed my eye by an inch. I now wear safety goggles and leather gloves when I string one of these things up.
OK, that's about all I can think of for now. Remember that my plans are a starting point but given the 'lay-up' type of building method, one can easily make modifications and take the measurements off the full size layout. Good luck and have fun.
Copyright 1997, 1998 Thomas Price - All rights reserved
