How I Made a Harp

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How I Made a Harp

A log of my harp making experience

Some time during the summer of 2006 I ordered a 30x30 piece of 1/8 inch aircraft birch from the Musicmakers company to replace the soundboard of my existing 29 string harp. At the same time I ordered the hardware for the discontinued 29 string studio harp partly because orders over $100 got me free shipping, and I had always wanted to build a harp all by myself. The soundboard material cost $70 and the hardware kit cost $74. The sheet of soundboard material was big enough that I could expect to get sound boards for three 29 string harps out of it.

That fall I drew up plans using only the list of vibrating lengths for each of the strings that came with the hardware kit. I drew 29 parallel lines spaced evenly at 4 inches per octave. Then I drew a diagonal line representing the top surface of the string rib, and then I measured each string up to where its pin should go. I tried this several times, testing a few different angles for the soundboard, and in the end I most liked the curve produced by a 42 degree angle between the soundboard and the strings.

Once I had the harmonic curve and the soundboard mapped out, I drew the box and the arch and the pillar around it. Then I rolled up my plans and put them in a closet for several months.

Monday, March 12, 2007: Out of curiosity, I go to Lowes to find out how much it would cost for the lumber to build the harp I had designed. When the answer is less than $60 I decide to go back the next day and buy everything I need to make a new harp. In the mean time, I draw up a new design, using for my inspiration a drawing of the Ancient Irish Harp housed at Trinity College in Dublin.

Tuesday, March 13, 2007: at 10:00 a.m. I go shopping. I buy one 4ft x 4ft piece of 3/4 inch oak plywood, two 4in x 4ft oak craft boards, and one really long piece of oak trim to use as a string rib. I return from Lowes at 11:00 a.m. and get right to work. First I trace the pillar and arch onto the piece of oak plywood. My husband the math professor helps me figure out how to cut it using my bandsaw with the 1/8 inch blade. Now I switch to the ˝ inch blade to cut the right lengths from the oak boards for the four sides of the box. I notch the ends of both the top and bottom pieces so that the diagonal sides can fit snugly. Now I can assemble the harp. It holds together well enough that I can check the balance. I had to cut a little off the bottom corner of the pillar to get it to stand on its own.. The last thing I do is to use my router to round the edges of the soundbox boards. Then at 5:30 I decide to call it a day and make dinner before my family stages a mutiny. After dinner I take a break from cleaning the kitchen to assemble the box and trace the shape of the soundboard. I used a large quilter’s cutting board with a one inch grid all over it to help me square up the ends of the box. Then I trace the soundboard and add 1/8 inch all around. Appx. 6 hours of work today.

Wednesday, March 14, 2007: This morning I got up and tested out the stain on a scrap piece of wood. I liked it so much I decided to forgo engraving any designs on the harp. The grain of the wood was pretty enough. Most of the day I spent sanding. I did a little from 9:00 until 9:30, then came back to it about 11:30 and worked off and on (half hour break for lunch, then another half hour to teach a piano lesson) until 4:30. Using my Dremel, I smoothed all the bandsaw marks off the arch and pillar and shaped the curves. Then I used some coarse sand paper to mostly remove the Dremel marks. I had to put a little more wood putty on the edge of the arch and pillar piece due to core flaws in the oak plywood. Now it is drying. I worked about five hours on the harp today. (11 in all)

Thursday, March 15, 2007. Only two hours of work today. I did some more sanding and started routing the grooves for the soundboard and back. (13 in all)

Friday, March 16, 2007. Four hours today. I finished the routing, finding that several light passes per depth setting worked better than trying to make superfine adjustments to the depth with each pass. Routing was still awful. I cut the string ribs, and finished the fine sanding for all pieces. (17 in all)

Saturday, March 17, 2007. Today I spent about an hour and a half drawing a more accurate template for the soundboard and then staining all the pieces. Then in the evening I sanded the boards until they fit perfectly, one more hour. Two and a half hours total (19.5 in all)

Monday, March 19, 2007. Today I spent about two hours cutting out the soundboard and shaping it to fit the box. Next time I suggest to myself to cut the soundboard out, shape it perfectly, then use it to trace the back of the soundbox. (21 ˝ in all)

Tuesday, March 20th, 2007. Two and a half hours today. I routed holes for the back of the soundbox, then sanded the soundboard and the back of the box. Then I traced a new template for the pins and tuning pegs. (24 in all)

Wednesday March 21, 2007. Today I marked and drilled holes for the pins and strings, working for about two hours. I recommend doing this step BEFORE staining next time. The drill press works great, but it is hard not to scratch the wood up a bit in the process. I would have liked to sand everything down after drilling the holes, then do the staining.
The top string rib is an exception. It must be stained first.

Thursday March 22, 2007. Today I glued the string ribs to the soundboard and put three coats of polyurethane on the face of the arch where the pins and pegs are going to go. Then, when the last coat had dried enough, I banged in the pins and twisted in the pegs. I decided that it would be best to put the pins and pegs in before assembling the harp. I wanted to do the polyurethane after assembling the harp, but I realized it would be a horrible pain to work around all the pins and pegs. So I just did that one face of the arch. Last of all, I marked the string rib for drilling. About two hours of work. (28 in all) I project assembling the harp on Saturday.

Friday March 23, 2007. Three hours today! I drilled holes in the string rib, then put two coats of polyurethane on the back of the soundboard. Then I used my drafting pen to put my initials and the date and an inscription on the back of the board. I spent most of the time attaching the arch to the top of the soundbox. I used two metal braces which I covered with a piece of wood so that it would look nice. I am concerned that the connection between the pillar and the bottom of the soundbox is not strong enough. We shall see. If it goes sploop I will re-design it. Oh it will be a pain to pull out all those pins!

Saturday, March 24, 2006. The harp is assembled! I worked on it for four hours today. I tried assembling the soundbox with the soundboard and box back in place, but I needed to do some more sanding to fit all the pieces. I set the soundboard and back aside, then sanded until all the box pieces fit perfectly. Once that was done, I added the soundboard. It needed some shaving too. Last of all I added the back. At last it all fit!
Oh no, with the soundboard and back in place the balance changed! I had to sand some more off the front of the pillar so that the harp would stand up.
I used two wood screws at each corner of the soundbox, plus Gorilla Glue at all the joints. The glue was a mess and got everywhere. Maybe I will try a new kind of glue next time.
The last thing I did was to touch up the wood stain. There were scratches and chips and flakes from all the drilling and sanding to fit. I might want to stain the harp later in the process next time, but then again it is hard to stain around all the pins and pegs. How about this: Cut, sand, shape, fit, drill all the holes, and THEN stain the pieces. Also, it would work well to assemble the box entirely, screws and all, before tracing the soundboard. That way the shape of the soundboard can be super accurate. (35 hours in all)

March 26, 2007 Today I put four coats of polyurethane on the harp. I am debating whether to do more. Each coat makes the harp look goopier, but Heidi told me that many, many coats of polyurethane would make the wood stronger. I need the arch and pillar to be strong. How many coats?
Tomorrow I will do the back.
About 20 - 30 minutes per coat, so we’ll say two hours today. (37 hours in all)

March 31, 2007 I am afraid I stopped counting hours. Last week I noticed that the pillar was wobbly, so I had Russel go and buy me two more 4ft by 4 inch oak boards. These I fashioned into two support braces for the pillar, and two foot pieces to attach onto the bottom of the pillar so that the harp would still stand up. After all that time sanding down the front end of the pillar so the harp would stand on its own, I had to add the braces which changed the weight. The feet were necessary to restore the bottom end of the pillar to original shape (*sigh*). I spent several hours cutting, sanding, routing, staining and gluing. I’m better at it now, though, so it went pretty quick. I am also learning how to manage the gorilla glue.
Heidi James advised me on polyurethane. She said to wait at least 24 hours between each coat, sand carefully, be patient. The goopiness was because my coats were not drying thoroughly. My polyurethane was also too old. I bought a new, big can. After all the gluing is done I will sand carefully, clean with mineral spirits, and brush on a few more thin, thin layers. Then I will go on spring break vacation. When I come back I shall string up!

April 4, 2007. Painted a leaf design on the soundboard using wood stain. It is a lot like using very runny oil paint. I need more experience with the medium before I can get it to do what I want it to do.

April 5, 2007. As a last act before leaving on vacation, I wiped off a couple of the leaves and re-did them today. The wood stain came off pretty good so I could re-do the leaves I didn’t like.

April 9, 2007. The last coat of polyurethane went on today. Wood stain takes several days to dry if it is painted onto a non-porous surface, so it was good I had to go on vacation and take a break.

April 14, 2007. I could not stand it! I started stringing up today. At first I tuned every string to the proper pitch, but that was stressing the string rib too much so I took the tension off the strings and just installed them.

April 16, 2007. I began to tune up today. I started by tuning all the strings a fifth interval too flat.

April 17, 2007. I slowly worked the strings up to full tension today. Rough tuned to the piano (which is a bit flat itself).

April 18, 2007. Still constant rough tuning to the piano. Harp is beginning to hold pitch.

April 19, 2007. Fine tuned the harp for the first time today using the electronic tuner. Wow, it sounds good! The soundboard arched beautifully!

April 26, 2007. Harp is doing well but still goes nearly a half step flat in 24 hours. I am now tuning only once a day.

August 25, 2007. The harp is still holding together! Hooray! I only need to tune it about once a week now but it is still not settled in. The back of the soundbox has picked up a buzz. If it doesn't correct itself as the harp matures I'll try bracing it.

October 29, 2007. I took my harp to the park last Friday, sat there on the picnic blanket and plucked away while little kids rode by on their bikes and gave me puzzled and curious looks. I was so enjoying myself that I paid little heed as the middle range of my harp began to go noticeably flat. I just kept the tuning wrench handy and tuned down the top strings to match between each song.

My harp made a couple little popping sounds, but I still wasn't too concerned. It was so nice to be sitting in the damp, cool shade in a patch of green grass that I forgot what a sudden, drastic change in humidity could do to wood.

WRONK! The left side of my soundboard suddenly ripped right out of the box! Startled, I stared at it for a moment, then went for the tuning wrench. I took the tension off the strings as quick as I could, making several passes from top to bottom so that the tension would stay even as it went down. As I examined the damage it became clear that my harp had been the victim of a bad gluing job. Hardly any glue had actually come in contact with both the soundboard and the groove in the side of the box. Next time, no Gorilla Glue!

Next time, I'm using five minute epoxy. That's what we used for the repair. Russel and I worked the soundboard back in place at the park, then brought the harp home. He went to the hardware store and came back with five minute epoxy. I ran a bead of epoxy down the crack between the soundboard and the box, then worked it in with a thin piece of plastic cut from a yogurt container lid. Just for good measure I reinforced the glue job on the other side of the harp in like manner. I let it cure for over twenty-four hours, and then tuned it up starting this afternoon. So far everything seems to be holding.

My home-made harp sounds pretty good, if I do say so myself. Listen to these MP3's and hear for yourself!


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