Dent in sound board… Help please

  • Participant
    Joanne McMullan on #254891

    Hi, I have a 34 string celtic harp that my dad built for me. It has a sitka spruce soundboard. Last night while I was tuning it my harp key fell out of my hand and hit the soundboard putting a dent in it. I’m concerned that this will weaken the soundboard. Can anyone offer any advice? Firstly, will it weaken the soundboard? Secondly, how can i repair/reinforce /secure it off it has weakened it? This is the third soundboard my dad has put on my harp. He is not in a position to replace it again so I’m very concerned at what has happened.

    Participant
    hearpe on #254896

    It’s hard to say not seeing the soundboard, but I was musing on this topic just last night tuning my Limrick steel string harp that is rather unstable and now appears to have more of a bend to the soundboard.

    Urethane may protect your soundboard- a coat gives a piece of wood a great deal more strength, and as my Limerick Clarsach has great volume and tension, both because of the steel strings, I’m considering using some clear coat urethane on one or both sides.

    If volume is an issue- a strengthening such as that will cut the volume a slight bit. I’ve either painted or urethaned several harp string support pieces- the reinforcement behind the soundboard the strings run through, and it has cut down on the sound board bowing without discernable difference in timber, I think partly because it is a piece involved in transmission of sound to the box and not the actual sides of the box.

    Just a thought- might by the box some time if the board is cracked, but probably cut volume to some extent. A dent you can also fil with repeated applications using artist brushes right where the dent is then- the dent will still be there- it just won’t show then.

    • This reply was modified 6 days, 21 hours ago by hearpe.
    Participant
    charles-nix on #254898

    Not to be a smart a**–but of course it weakens it–you knew that already, or you wouldn’t have asked. Whether it weakens it enough to matter or not depends on how thick the soundboard is, how big and deep the dent is, and where the dent is, and how much string tension you have. Any attempt at repair/strengthening will stiffen the soundboard and change the sound of the harp.

    The question that jumps out at me is “why have you had three soundboards already?” Over how long? Were they each damaged? If the design is simply too weak to begin with, has that been improved with each iteration?

    The second question that jumps out is if you are using a rubber coated tuning key. That’s not a sure prevention, but it helps.

    There are ways (steaming) to raise dents in wood. It won’t help with the strength, though, only the appearance. It is critical to know what the finish on the soundboard is, and how to touch it up afterward. It is not for an amateur to attempt.

    There are several harp technicians on this list. Good photos from different angles showing the details of the dent will help greatly.

    Participant
    hearpe on #254899

    Here is a 1933 Supertone guitar I got last summer. The top was rather compromised and wouldn’t hold it’s shape as much as I’d hoped after straightening and urethane. The only choice I had-outside of using very light strings, was to keep filling in some top bow with urethane. It finally worked pretty well. The guitar ids originally small bodied and it doesn’t have great volume still- but it’s an 88 year old guitar I got for $58 delivered and a cool antique. If you enlarge and look closely to the right of the soundhole, you’ll see the urethabe is rather caked there. I really need to sand it smooth again there, but it’s filling a rather large warp. My Supertone collection L to R: 1933, 1938 and 1941.

    • This reply was modified 6 days, 21 hours ago by hearpe.
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    Participant
    Biagio on #254906

    It is possible to strengthen a sound board by applying thin fiberglass on the inside but this is usually a job for an experienced technician. IMO polyurethane would not provide appreciable strength but I could be wrong. Would have to see some data. Follow the logic…..

    After drying, urethane acts as a thin plastic which under stress expands in all directions. One would have to put down a very heavy layer – 20 coats or more – for that to have any strengthening effect and at that only on the surface. Not exactly what one wants to do on a harp sound board.

    Note to Hearpe: Musicmakers have changed some of their string charts so I am not sure what you might have. But I can assure you that if the sound board fails due to string tension it will be at the sides where the board is slid into shallow slots, not from failure of the board itself. That is made from 5 layers of Finnish birch laminate for a 3mm thick board. One could practically jump up and down on the stuff and not break it.

    Participant
    Sylvia on #254926

    I have nothing to offer but sympathy.
    I dropped a tuning key on the soundboard of a new Princess Louise 23 at the University when I was young.
    My hands were cold, and it just flew.
    I reported it right away to my teacher. The dent in the soundboard stayed.
    My teacher had done an internship at Lyon-Healy when he was younger. Later, when I bought my own harp, I noticed that the tuning key had rubber on it…no metal was exposed to dent soundboards. I’ve always believed he was the one who asked LH to start making them that way…so if you have a padded tuning key, I may have had something to do w/it.

    Participant
    balfour-knight on #254934

    Good for you, Sylvia! My tuning keys have rubber on them, thanks to you.
    HARP HUGS,
    Balfour

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