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Forming an arch on a harpguitar

Posted: Wed Aug 03, 2016 10:45 pm
by Greg Martin
What is the correct way to form a slight arch on a harp guitar top. Are their any good articles or pictures here? Thanks

Re: Forming an arch on a harpguitar

Posted: Thu Aug 04, 2016 12:38 pm
by Barry Daniels
Use the search function and you will find a trove of info.

Re: Forming an arch on a harpguitar

Posted: Thu Aug 04, 2016 4:00 pm
by Alan Carruth
Normally this is done by the use of curved bracing, in conjunction with some mechanism to profile the edges of the rim to fit. Often enough on Classical guitars the top arch is something other than the spherical dome we're used to in modern American practice, and the edges of the rim may well be flat even though the top and back are both arched.

Harp guitars are often built on a version of the Spanish 'solera'. Basically they're built upside down, starting with the top and neck. Those are clamped to a fixture that holds everything in the proper relationship, and the sides are attached, often using 'tentellones' (Spanish for 'little glue blocks' ;) ) . Then the back liners are put in and the box is closed up. The top arch is achieved by dishing the fixture, and the braces can be glued in with the top clamped to it. On a harp guitar making the upper surface of the arm flat could be a big help, as it would facilitate getting all the strings on the same plane.

It's a VERY good idea to sharpen up a 3H or 5H pencil (if you can find one) and make a really careful drawing of EXACTLY what you mean to build. Start with the string layout, and work out everything else relative to that, in both top and side views. This will greatly decrease the number of surprises you'll run into as you try to install the sharping levers, and other such things.

Last summer I made a harp guitar that folds up, and fits into a 9 x 14 x 22 box that fits in most airplane overhead racks. I used a 'solera' to assemble it, but the woodworking was almost a detail compared with making up really accurate drawings both of the instrument and the box. After that it was just a matter of being careful to make what I'd drawn. You can see it on Ken Bofield's web site, including a short video of how to put it into the box.

Re: Forming an arch on a harpguitar

Posted: Sun Aug 07, 2016 12:56 pm
by Greg Martin
Alan thanks for your expert input.i was wondering if the hollow arm was flat or slightly domed,and how the string plane would play out. I have a bluprint coming for the 21 string wsullivan elliott version.i have 2 questions just from looking at pics.with both sub bass and guitar tuners on one head stock instead of 2 like a dyer. Does the guitar neck truss rod still work as normal? Seems like it wouldnt?
Also the way the 6 or 7 super treble strings have the tuners,so close to the fret board it would seem very hard to fret in the higher 14-19 frets.what other options do you have on the super trebles?

Re: Forming an arch on a harpguitar

Posted: Sun Aug 07, 2016 1:16 pm
by Greg Martin
Im not a good searcher.i found a ken bonfield but no ken bofield, do you have the link that you mentioned in the prevous post,id like to check it out. Thanks

Re: Forming an arch on a harpguitar

Posted: Sun Aug 07, 2016 6:02 pm
by Alan Carruth
Spelling error on my part; it's kenbonfield.com, I could not find the video on folding the thing on the site, but the first one on the video page is 'Jock o' Hazeldean' on the folding harp guitar, and, yes, it really does sound like that.

I made one a year or so ago loosely based on the Sullivan/Elliot instrument: I'll try to get up a pic when I have some time. Obviously the truss rod won't pull the neck back when both ends of it are nailed down, but it does give you some control over the relief, which is the real purpose of the thing.

The one I made had a 14-fret neck at customer insistence. The supers do pretty much render the body frets moot. Between the 14 fret neck and a short scale I had to do some fancy dancing with the bridge to get the lower supers long enough to sound good. In the end it all worked. I sure would like to come up with some better tuners for the supers than the banjo fifth pegs that Sullivan used. I've got some ideas, but it will take a bit of work to implement.