(Please note: I assembled this page late in the evening. I will add links as indicated at another time….)
Much of what has been accomplished thus far with this harp is fairly standard operating procedure in harp construction and, even though I’ve done these things many times, even so, I come up with different ideas as to how I might accomplish each task.
By definition, the string ribs are pieces of wood that are glued to the outside and inside of the center of the soundboard which support the lower end of the strings. The soundboard outer edges are attached to the soundbox, and the strings are tied in a knot inside the string rib. Here are some photos of the string rib as represented on the bronze:
These are not great photos of it, but the ribs extend all the way from bottom to top in the center of the soundboard. As you might guess, these strips of wood are rather thin, and I chose to make the outer rib of equal thickness from top to bottom (sometimes they are tapered to be thinner at the top), but I did choose to taper the width, making the top narrower than the bottom of the string rib.
It isn’t always easy to work with power tools and thin wood pieces, so here is how I chose to fashion the outer string rib for this harp. Here is the formed rib just laying atop the soundboard.
To form this rib, I began by using a quarter-round router bit to round off the one corner of a walnut board that had been carefully planed and jointed to be quite straight.
Because I wanted to taper the width of it, I rounded over only one corner of the board. Next I cut the thin strip off the board with the table saw.
Having done that, I then applied several pieces of double-sided tape to the cut edge of the board and reapplied the thin strip, leaving the unrounded edge extend past the edge of the board at the desired taper angle.
This was then run thru the table saw once again with the cutting width set just to the thickness of the board, the end result was a thin strip of wood with a top-to-bottom taper.
Before releasing my tapered piece from the board, I ran it once again thru the router to round off the newly cut corner.
The outer string rib was completed:
The next challenge is finding a system whereby one can glue the string rib to the soundboard with a solid, reliable glue joint, but without having glue come in contact with the walnut veneer adjacent to the string rib. The veneer is very thin to begin with, and to try to sand or scrape wayward glue from the veneer would surely destroy the veneer. I chose to use wide masking tape which I ran down the center of the soundboard, carefully marking the width of the string rib and where it would lie when glued. I then used a metal straight edge as a guide, and with a carpenter’s knife, made knife cuts along those lines, making cuts in the masking tape. I then peeled back the center portion of the masking tape, leaving the outermost parts of the tape intact.
As you can see on the next photo, I then widened the outer margin of the masking tape by applying a strip of blue, low-adhesive tape to the strips of yellow masking tape. I then applied glue to both surfaces, the string rib and the soundboard, and used the frame and clamps as shown below to apply pressure until the glue dried.
When the glue had dried (it is always best to do this BEFORE the glue is totally dry), I peeled back the blue and yellow tape to reveal a perfectly glue-free surface on each side of the newly-glued-on string rib.
Next came the INNER string rib which is generally more rugged than the outer string rib. Each harp string passes thru a hole in the string ribs, and it is behind this inner string rib that the lower end of each harp string is knotted. Since this rib projects into the soundbox interior, and since I make it a practice to have this rib be totally attached to the top and bottom ends of the soundbox, it is necessary that a notch be made in the top and bottom to accommodate it.
As with my most of my recent harps, I have chosen to design the inner string rib in the manner that Musicmaker’s Kits have used in the design if their “Regency” harp. It is thickest under the lowest bass string, tapering to very thin at the top of the harp. Below is the inner string rib (I chose to use oak) laying diagonally in the notch I had just cut for it.
At this stage, I glued the inner rib to the inside of the soundboard, using the same methods I have described above.
Another job that needed to be accomplished before installing the soundboard was to widen the gluing surface of the soundbox opening. This was done by installing what are called “liners” – a practice often used on guitars and other stringed instruments. The thickness of my soundbox material was 1/4 inch, so I opted to double the width by installing an additional 1/4 inch thick “liner”. Here you can see it after its having been installed:
The liners are actually two strips of wood that are the length of th soundbox that have been shaped to fit flush with the soundbox sides. Clamping them in place until the epoxy dried was rather low tech: I used common clothes pins to hold them in place for the required time.
At this point we were nearing installation time: the liners were in place, the inner and outer string ribs had been glued to the soundboard, so it was nearly time to actually install the soundboard.
One more thing needed to be done, however, before access to the inside of the soundbox was no longer possible. I use what are called “T-nuts” and stainless steel 5/16″ bolts to attach the harp base to the soundbox. I use the “T-nuts” that are attached with brads (there is a similar type that I choose not to use that come with downward projecting “points” which are simply driven into the wood).
Now it was time to install the soundboard, so I applied epoxy to the back of the soundboard:
Also to the edges of the soundbox…
Added a little extra-thick epoxy to the string rib notches:
Rolled it over on its face and applied some clamps:
I was particularly interested in seeing epoxy “squeeze-out” to be sure that I would have good adhesion around the entire soundboard:
My West System epoxy takes 4-6 hours to set up, so once that has occurred, it is time to clean up the edges of the soundboard. For this I used a combination of router trimmer, sanders, etc.
Because I was tired of balancing the soundbox with my piece of steel railroad tie to make it stand up, I decided to fashion a bit of a foot which I bolted onto the underside of the base. Having done that, here is where this project stands (literally) at the moment.