#16
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--- The fretboard tongue is more or less like a kerfed lining but once it's fretted and glued down it will become stronger. But I agree, that's not the issue here. |
#17
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No apologies necessary whatsoever, Rog ... I see no hi-jacking (and even if i did it would be welcomed!) All input so far has been pertinent to the discussion.
I don't have Frank's experience of holding necks by the end of the fretboard ( btw on my threads we have fretboards ... other threads may well have fingerboards, which IMO belong on bowed instruments of the violin family ... but I digress) but I would be surprised if pocket slotted fretboards, with closely fitting frets, and all the interstices filled with hide glue or superglue, are as floppy as he says. I can see that through-slotted boards with the frets hammered in dry might be like that. |
#18
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I would point folks to the works of Michael Doolin, who buttresses the neck block due to his unique cutaway design; Tim McKnoght and others who buttress their neck blocks with CF rod; Somogyi's L-shaped neck block, tied to the UTB; Rog, I think the reason that is not done is because of the shear stress of the spruce in that area. the UTB ties that whole upper bout together and "unitizes" that whole area, in conjunction with the bent sides of the upper bout, and back doming. There are those that do the so-called "A" brace, myself included, that do not form an "x" in front of the sound hole; rather they extend from the neck block/UTB to the sides of the sound hole. I believe Batson, who has only a side port and cantilevered neck, uses some form pf parallel bracing. McPherson, who also has a cantilevered neck, has an angled UTB that is laminated, and fits in a milled groove in the sound board. Also not to be neglected is the back. I do believe that dome retention especially in the upper part of the back is important for minimizing neck rotation. I've seen quite a few guitars whose neck had seemingly pulled up, and the backs have flattened or lost their dome. |
#19
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#20
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That's why I like cylindrical radius backs. Can't lose the dome if you don't have it to begin with |
#21
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Lots of interesting things here. FWIW I'm going to borrow ideas from everybody here and in other threads, with a C-shaped neck block with "horns" at the top that hug the shoulders (inspired by Glenn23 and his "geometry of tone" block), a foot like classical builders, a couple of CF rods holding the neck up, and probably an A-frame above the soundhole. I plan to use it to hold my house up in case of an earthquake.
__________________
Solo acoustic guitar videos: This Boy is Damaged - Little Watercolor Pictures of Locomotives - Ragamuffin |
#22
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Look here for examples of the A-brace. Basically - you use tall soundhole braces that go all the way from the X to the neck block:
https://www.martinguitar.com/feature...cing-patterns/ Note how the A brace runs close to the soundhole. I also don't do much voicing of the bracing up past the bridge. I know I am probably giving up some tone possibility.. But I have seen a lot guitar tops deform very heavily because of "shaved" upper X legs... This bracing does a lot of work keeping the top in shape between the bridge and UTB... Thanks |
#23
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I learned to make steel string guitars that way. My experience with them is that the extended foot on the back doesn't do much, if anything, to prevent or delay neck resets. I continue to use the extension against the top. I don't think that does much related to neck resets either, but it does offer a few other advantages when fretting and possible stability of the area (i.e. top cracks adjacent to the fingerboard).
In short, there is no harm in doing that, but I don't see any advantage to it either. If you use it like traditional classical construction, prepare to cut the neck off, or slip the back, when it comes time to do a neck reset. |
#24
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The follow-on question would be ...is it possible for neck block rotation to take place without the back being flattened/deformed to some degree ? |
#25
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But neck resets are not only about neck rotation. Even if the whole upper bout remains absolutely rigid, the rest of the box can bend upward, causing the bridge to rise relative to the fret plane. Double sides and solid linings help to resist that kind of deformation. And as I said in an earlier post, the farther you get from the neck joint, the more movement it takes to raise the action by a given amount. |
#26
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If the top bellies up, neck block rotation is likely. That is because as the top rises, the distance between the neck block and tail block gets shorter. You cannot stretch wood.
What usually happens is a combination of top rise below the bridge and sinking above the bridge, creating an 'S' curve. This is because of the torque on the top from string tension. With X style bracing, the sinking is less than the rise because that bracing design is stiffer above the bridge than below. The narrow waist also makes it stiffer in that area. I never understood the logic of the 'foot' on the bottom of the neck block. This is common on Spanish guitars, but can be found on certain steel string guitars as well. The back is flexible....even when overbraced. If you remove the top on a guitar with this style of block, the neck can easily be flexed up and down with moderate force. That is true with any conventional guitar that does not have triangular reinforcement (like flying braces, for instance). The sides, being perpendicular to the neck, simply twist when the neck is forced up or down. |
#27
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under the impression that the UTB needs to be fairly massive
What is UTB? What is USB? Thanks, Don. |
#28
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Upper transverse brace and universal serial bus.
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#29
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Thanks. Was reading on the subject and someone posted about UTB and USB. Did not know UTB and couldn't figure a connection between universal serial bus and guitar structure.
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#30
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Then there's UST, under saddle transducer, and also SBT, or sound board transducer. The USB is probably a typo....
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Rodger Knox, PE 1917 Martin 0-28 1956 Gibson J-50 et al |