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  1. #1
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    Jan 2021
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    Default 31 String Gothic Harp

    Hi All,

    I have just joined the forum after finding it whilst looking for advice on laminating hardwood. Other projects I have done are on the G'day Mate welcome folder if anyone is interested (Hi from Canberra).

    This project is a Musicmakers 31 String Gothic Harp. I bought the plans and hardware kit in December and have been digesting the plans and sourcing some specific tooling before I start. As of today I committed to the project by cutting templates for the main parts out of 3/4 ply and making a table saw sled for cutting the tapered and angled sides of the sound box.
    My timber choice is Silky Oak for all of the hardwood choices. The plans and musicmakers website have a great discussion on the benefits of using good ply for the sound board so in this case I am going to use Aircraft standard birch ply. I have some beautiful Silky Oak from Monaro timbers here in Canberra and have yet to order the ply.

    My first question for the experts....I need to laminate the neck and was wondering about the glue used. In building my boat I used West epoxy for laminating the stem and rudder so I am comfortable in using that product. But I really don't want to use it in this case unless it is the best option. I have original titebond wood glue and as this is an indoors instrument I think that should be ok. There is up to 1000lbs of pressure on the neck apparently so I obviously want to get it right. I am more than happy to listen to all opinions. The neck and pillar will be 1 1/2 in when finished and I think I will use three layers of timber to maximise grain direction and aesthetics.

    Mark
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  3. #2
    Join Date
    Nov 2004
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    Millmerran,QLD
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    Mark

    Unfortunately, for you, I don't know the answers to your question, but as the harp has great appeal I will watch the build with interest. Don't despair, I am sure others here will be able to assist with your gluing question.

    With your boat building experience I expect you already know to sand and prepare the surface and glue as soon as possible afterwards. Also wiping the surface with acetone prior to gluing assists too.

    Regards
    Paul
    Bushmiller;

    "Power tends to corrupt. Absolute power corrupts, absolutely!"

  4. #3
    Join Date
    Feb 2007
    Location
    blue mountains
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    Default

    Hi Mark,
    I will also be watching along with this build as it sounds really interesting. I have not tried to make a harp but am aware of the musicmakers kits from getting general information for other instruments. Had a quick look at what they say on glue. They say titebond or a good marine epoxy so as you have experience with the epoxy I think its good to go. My mind would be more at rest with epoxy for something under constant string tension.
    Regards
    John

  5. #4
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    Jan 2021
    Location
    Canberra
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    Default

    Thanks for replying Paul, John,I will try and keep progress moving along so as not to bore people, plus my wife is harassing me for this project and when I finish it I can start on a "proper" woodworking bench. Like most I just have to fit it in between family, work, and life.I still haven't settled on the glue question. Watching a couple of professionals on you tube and they are using two part epoxy so maybe Wests epoxy may be the go. It just isn't the most pleasant stuff to work with, but then building a boat I had to use a lot more of the stuff than I expect I ever will again. There is a significant twisting action on the neck but all forces are steady and constant so I am not concerned with the brittleness of the epoxy as I would otherwise. More concerned about the layout of the grain and getting the joints right there. Mark

  6. #5
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    Jan 2021
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    Canberra
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    Good Morning, I just wanted to post something to show some life.

    Work on the harp is slow going and mainly a combination of making plywood templates and making a couple of sleds for various bits and pieces.

    My stated timber choice was wrong sorry. I was looking at Silky Oak and about to buy it and that stuck in my head but what I actually got was spotted gum. I also got some blackbutt as a middle lamination but as it turned out the timbers were almost identical when sanded and a trial varnish applied. So what to do - I had some really nice Sapele left over from my music stand and being a red wood it was perfect so that is what I have gone with - Sapele sandwiched between spotted gum.

    I also have gone with West epoxy for the laminations. I spent most of this weekend with my chemists hat on reacquainting myself with the product and testing in small batches to make sure the glue had not gone stale. I haven't really used it since I finished my boat and at the time I said I never would again as it is sticky messy volatile stuff that blunts all my tools....but it is strong!

    Anyway last night I laid up the pillar blanks and bit the bullet and slopped on some epoxy and as usual wishing I had more clamps. When building the boat I made about 30 plywood planking clamps but they were made to be functional rather than long lasting so I could have used them again now. I will just have to keep building up my stocks as I get more into this hobby.

    The neck stack photo demonstrates how distracted I can be when it comes to procrastinating over epoxy use - I wanted a sharpening station of some sort so started to transfer this old government standard tv stand into a mobile sharpening point. I will make some draws and cupboards for it next but fine woodworking it isn't...but again it will be very functional.

    So that is that. I will glue up the remaining parts tonight and work on them over the coming week after work. On the weekend I will start the sound box.

    Mark
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  7. #6
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    Jan 2021
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    Canberra
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    Had a reminder of how hot a exothermic reaction can be with epoxy - melted the cup and brush before I realised. If I hadn't finished with the laminating then I would switch to the slower curing hardener. but the layups went ok.

    Every spare space taken with clamps but I still would have preferred to get more on if I could find room.
    Somewhere in the picture under the clamps is the neck, shoulder, and neck extension.
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  8. #7
    Join Date
    Feb 2007
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    blue mountains
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    I use paper plates to mix up epoxy. Being wide and shallow there is a lot less heat buildup.
    Regards
    John

  9. #8
    Join Date
    Nov 2004
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    Millmerran,QLD
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    70
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    Quote Originally Posted by orraloon View Post
    I use paper plates to mix up epoxy. Being wide and shallow there is a lot less heat buildup.
    Regards
    John
    John

    For small quantities I use the aluminium tops from discarded wine bottles.

    Regards
    Paul
    Bushmiller;

    "Power tends to corrupt. Absolute power corrupts, absolutely!"

  10. #9
    Join Date
    Feb 2007
    Location
    blue mountains
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    Default

    The paper plates are only when its a decent amount so as to avoid it getting too hot. A tip I picked up back when I was doing archery bows. For small bits I use just about anything that comes to hand and not plastic.
    Regards
    John

  11. #10
    Join Date
    Jan 2021
    Location
    L.A
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    5

    Default

    It takes time to find the ideal laminating wood for the harp soundbox. but you need to find a super hardness toughness one. The sound intonation will be lost if the eye buckle on the soundbox is unstable.

  12. #11
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    Jan 2021
    Location
    Canberra
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    I have had a break from all woodwork due to a treatment of Efudix on my face - amazing how abrasive sawdust is to a red raw face....

    I started up again today and completed the shoulder, feet, base and sides.

    For the shoulder it is laminated from 4 layers of spotted gum. It took me three goes to get the shape right as I took the plans as gospel and shouldn't have as it turned out. I also had a bit of trouble with trying to sequence the cuts as it wasn't as simple as straight cuts then curves as the whole piece seems to be one big curve - just in all different directions. Also the plans only had one set of measurements for two edges and not the other. There is a warning written on the plans that after years of copying the lines may be out a bit but after ensuring all accurate cuts and angles the braces as per the plans would be about 1/2 inch short so just as well I am checking everything a couple of times.

    The sides have one side 90 degrees and the other 86 degrees. To complicate a bit further there is a rebate all round on the inside face that has a 4 degrees shoulder on the sides and 6 degrees on the ends. Also there are three brace rebates on each side with a 6 degree edge 1/4 inch deep sloping forward from the inside face. phew....
    The make this successfully I made a simple sled allowing me to hold the angled sides dead straight - worked like a charm and the time spent on the sled was well worth the sleepless nights trying to work it out in my head.
    I have also included a photo of the brace rebate to show what I can't explain properly.
    Up to now I have secured the base and shoulder in place and will work on the braces tomorrow. I have had the ply delivered and it is being stored flat on the floor in the sewing room so I am not too popular on that front but she knows how much it cost so is not complaining too much.

    I am happy with the timber selection. It is a floor harp which is just as well as the frame is really heavy. I am confident with my grain alignment and some test pieces I have tried to destroy have broken well away from the glue lines so all good there. I think that if there is any failure it won't be in the timber choices more than likely in the soundboard which I am following precisely as directed in the plans. The only thing left to buy is the edging which I will commit to soon, just after I find a gothic looking decorated pattern to complement the style of harp.

    Trust all are well and chipping away at projects.

    Mark
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  13. #12
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    Canberra
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    So I have just attached the soundboard and thought I had better update the progress.

    The back of the sound box went on fine, the final attachment going too fast to enjoy it.

    IMG_1073[1].jpgIMG_1074[1].jpg

    The back is all according to the plans - each of the holes has a pair of braces on the inside which serve no purpose other than to provide some extra bracing to the holes that will be used to gain access to the strings.

    Then for the inlay. I thought long and hard about how to do this - the plans just call for inlay tape over the seam but I didn't want a raised edge so I bought a dremmel router base and bit and routed in .72mm to allow the slightest of proud fitting inlay. The end result came up really well and I am happy - except the veneers are so thin I think I am playing with fire when it comes to sanding everything flush. No power sanders here and I have stopped all sanding now until I do the final sand on the whole box.

    IMG_1087[1].jpg

    The soundboard is a bit more complicated. Apart from the actual shape there is a stiffener on the inside - also 3mm birch plywood - and a hardwood spine on the outer face. The whole sandwich is then drilled with 31, 1/8" holes for the strings. There is also a notch at the bottom where the pillar will slot into the sound box. This is a future problem for me as the plans again didn't match the instructions and as I went off the plans the notch is about 1/2" too short. I have a solution already for that little curly. It is frustrating that the instruction booklet was written as an accompaniment for a kit harp so there is a mismatch - but I won't try and palm off my lack of clarity before undertaking a process. The second photo is off the trial fit before final gluing.

    IMG_1088[1].jpgIMG_1094[1].jpg

    The final set up was to cut some scrap pieces to sit on top of the braces to give the soundboard the required shape. The strings will keep the shape once the scrap is removed. These had to have the same curve on them plus be 1/8" shorter to allow for the stiffener on the back of the soundboard.

    IMG_1095[1].jpg

    Then it was final sand and dust, and as per tradition with instruments I signed the inside of the base before attaching the soundboard with cauls, glad wrap, lots of clamps and of course titebond.

    IMG_1096[1].jpg

    Which brings me up to date.

    The next step will be to route out the soundboard inlay grooves in a couple of days as I really want the glue to set completely. Once the grooves are at the right depth I will put in tacks with some epoxy all round the soundboard as a bit of insurance against the string tension. Then it will be final sanding and spray finish which I am still researching - but leaning towards a water based polyurethane sprayed on. If anyone has any other suggestions I am really keen to hear them as I have never spayed before and I don't want to shy away from it.

    Mark.

  14. #13
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    Jan 2021
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    Canberra
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    So the ongoing saga....

    I last posted that the soundboard was on but unfortunately there was about a 20cm spot that sat proud and I had to carefully scrape that bit out and redo it today. I had clamps on it for a couple of days to help it sit and it was relatively drama free to do.
    In the meantime I routed out the other side for the inlay and glued that in. The silky oak tears fairly easily so there is one or two spots that have to be sanded out but it is not a problem as the plans say to round the corners aggressively and this will hide most defects. The photo is just the tools of the trade. I find I use the little veritas plane more than the Dremel as it makes mistakes slower generally.

    IMG_1100[1].jpg

    A job I have been putting off for a while is making the hardwood dowel and groove in the neck for the neck soundboard joint. The is a floating joint with only the strings holding it together. It allows the harp to be disassembled if need be just by loosening the strings. The dowel I made from a 1 inch square piece of Sydney Blue Gum ( I think) Very red and heavy anyway. Good old YouTube had a tutorial on making a 1 inch dowel with nothing more than a 1/2 round over bit on the router and it was as easy as...
    To get the groove in the neck however was more tricky. It would not sit on my router table and the guide plates for my routers were all too big because of the neck curves. In the end I made a very rough but stable neck extension and router fence and very slowly made the groove over about 10 passes. The photo may not be very clear sorry. The piece in the centre is the actual neck. The piece closer to the camera with the clamp is an extension piece designed to stop the neck twisting over under the string tension. It has now had a lot of bulk taken off everywhere except the bottom surface to blend into the neck.

    IMG_1101[1].jpg

    So not helping myself I put the pieces together to have a look at the fit between the pillar and the neck as that will be my next job after the soundboard veneer. The fit is actually really good and there will not be much to do there.

    IMG_1103[2].jpgIMG_1102[1].jpg

    Mark

  15. #14
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    Feb 2007
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    blue mountains
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    Starting to look like a harp. Thats the bit I like most on any project. The first time you fit the bits together and get to see what it all looks like.
    Great thread by the way. First time I have seen the innards of a harp.
    Regards
    John

  16. #15
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    Jan 2021
    Location
    Canberra
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    Thanks John, I am thinking that I might try and help out at mens sheds or similar so to hear I am helping others in a way is pleasing.

    I needed to put the harp together so that I can get the neck pillar joint in the right place. The size of it once assembled surprised me somewhat. The soundbox only needs the lower trim and feet applied now so I have to get to the pillar next, it was about the first thing I laminated and shaped so to get back to it signifies the end is nigh. The last thing to cut out is two cheek pieces for the pillar joint so the plans are all but packed away now.

    There is a whole lot of nothing inside a harp as I now know but it is a well designed nothing much like a guitar. I can hear a distinct very basey thumping sound at the lower end of the soundboard and that is even with the braces still in place hard against the soundboard. It fills me with confidence that once removed it will be a vibrant soundbox.
    The construction in the neck of a harp seems to be where the main science is but only for the strength factor. So much on the internet indicates that the type of timber is far less important than the construction itself.

    I am running out of bucket list projects so I will have to find something else to have a go at when this is finished.

    Mark

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