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8 String Fan Fret Guitar Top Bracing Plan - Comments Invited
http://www.luthiersforum.com/forum/viewtopic.php?f=10101&t=37943		 Page 1 of 1
Author:  Pat Hawley [ Mon Oct 08, 2012 11:58 am ]
Post subject:  8 String Fan Fret Guitar Top Bracing Plan - Comments Invited
Hi All,

I've started to build an 8 string fan fret guitar hopefully similar to what Jeff Traugott did for Jack West. You can see it here: http://www.aheadbehind.com/guitar_geeks.html. I've already had a chat with Jeff and he was very gracious and gave me some good ideas about scale length etc.

In terms of bracing the top, Jeff said he didn't stray too far from a standard X bracing arrangement. So I played around a bit and this is what I came up with (it's a small jumbo shape):

Image

In order to allow for a low B and a high A below and above the regular six strings on a guitar, the fanning has to be fairly extreme. The scale lengths will be 27.5" and 23.5" on the low and high strings respectively. This results in a bridge that in on quite an angle. I drew the bridge and saddle location lightly on the plan, I hope you can see it. It ends up being in between and parallel to one of the X braces and tone bars. I didn't draw a bridge plate but I envisage one that will span most of the distance between the X brace and tone bar.

Any comments on this proposed bracing scheme in terms of stability, size required for braces, impact on final sound are welcome. I'm just going on intuition here.

Thanks in advance,
Pat
Author:  Chris Ensor [ Mon Oct 08, 2012 1:00 pm ]
Post subject:  Re: 8 String Fan Fret Guitar Top Bracing Plan - Comments Invited
Is it also going to be a lefty? If not, it seems to me that the "fan" is backwards.

I would be a bit concerned with the angle of the bridge making it so that only one corner of the bridge is supported by the x-brace. Other than those 2 things, it seems fine to me.
Author:  Jim Watts [ Mon Oct 08, 2012 1:55 pm ]
Post subject:  Re: 8 String Fan Fret Guitar Top Bracing Plan - Comments Invited
Pat, what are going to have going on for a bridge patch?
I don't know what it should look like necessarily, but seems like it could be critical with the canted bridge.
seem likes a fun project.
Author:  Pat Hawley [ Mon Oct 08, 2012 4:06 pm ]
Post subject:  Re: 8 String Fan Fret Guitar Top Bracing Plan - Comments Invited
Thanks for the comments Chris and Jim.

The guitar is for a right handed player. I should have pointed out that the view of the frets is consistent with the view of the braces, i.e. you are looking at the underside of the frets if you will. Look at how the fan of the frets corresponds to the sketched in cutaway and you will see that they are correct.

I did think about the fact that the bridge wings will not both be crossing over the X brace but I couldn't come up with a way of doing that. I am thinking the bridge plate will just about be up to the X brace on two sides, a tone bar on the third side and out as far as the bridge wing on the fourth side. I'm hoping this should be enough support.

Pat
Author:  Trevor Gore [ Mon Oct 08, 2012 5:07 pm ]
Post subject:  Re: 8 String Fan Fret Guitar Top Bracing Plan - Comments Invited
Though I'd probably be inclined to use falcate bracing or a sparse lattice (funny, that) if doing this with X-bracing I'd mirror the brace layout.

A guy I know has a really nice 1950's D18. It's a right handed guitar which he plays upside down, left handed. For various reasons (don't ask!) he's had it converted between right and left hand a couple of times. Sounds a lot better as a lefty.
Author:  DennisK [ Mon Oct 08, 2012 5:15 pm ]
Post subject:  Re: 8 String Fan Fret Guitar Top Bracing Plan - Comments Invited
First of all... are you really sure you want that much slant? It looks really uncomfortable to play. I'd accept a little less tone quality on the high and low strings for improved playability.

But given the current bridge, I'd go with a double X, rather than that pattern. That way you could have the second X catch the bass wing (is this what you mean by "sparse lattice", Trevor?). Right now it looks like it's sort of floating in the middle of nowhere and might have a hard time getting the whole soundboard moving.
Author:  Trevor Gore [ Mon Oct 08, 2012 6:17 pm ]
Post subject:  Re: 8 String Fan Fret Guitar Top Bracing Plan - Comments Invited
DennisK wrote:
...But given the current bridge, I'd go with a double X, rather than that pattern. That way you could have the second X catch the bass wing (is this what you mean by "sparse lattice", Trevor?)...

A sparse lattice has the struts on ~80mm pitch, whereas, for example, a classical balsa/CF lattice is on a 30 or 40mm pitch. But it is still built as a lattice, with a common section for the members. A double X is similar, but not necessarily the same, because the finger braces don't necessarily align with the upper ends of the lower X and the sections are often different. There's pics in the book and one here for those who haven't got it (yet!).
Attachment:
Inside top and back.jpg
Author:  Pat Hawley [ Mon Oct 08, 2012 8:31 pm ]
Post subject:  Re: 8 String Fan Fret Guitar Top Bracing Plan - Comments Invited
Thanks for the additional comments.

The degree of fanning is based on discussions with Jeff Traugott on what are good scale lengths to allow for a low B and a high A string.

As you can see in the picture, the single X brace is skewed to work around the bridge location. A double X would also be skewed but to the other side of the center line. I don't know if this means anything but I like the little bit of symmetry. What I'm thinking now is to enlarge and extend the small finger brace on the bass side so that it goes under the bass side bridge wing and across the two tone bars to make it a triple X braced top. So both bridge wings would be over bracing. I just don't want to over brace the guitar.

Think this is a good idea?

Cheers,
Pat
Author:  DennisK [ Tue Oct 09, 2012 3:02 am ]
Post subject:  Re: 8 String Fan Fret Guitar Top Bracing Plan - Comments Invited
Pat Hawley wrote:
What I'm thinking now is to enlarge and extend the small finger brace on the bass side so that it goes under the bass side bridge wing and across the two tone bars to make it a triple X braced top.

I like it.
Author:  Steve Kinnaird [ Tue Oct 09, 2012 8:25 pm ]
Post subject:  Re: 8 String Fan Fret Guitar Top Bracing Plan - Comments Invited
Pat, your solution is what occurred to me as the best option with that crazy bridge angle.
I like that the treble leg of the X is so close to the top string. Trebles should really be fat.

Steve
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