Official Luthiers Forum!

Hi. my name is Alan, and I'm a hobbyist luthier. I've built two acoustics, one of which is a Weissenborn style one. I had a feeling when I was building it, that the bracing was a little weak, so I went from .380" to.450" on the x-bracing. Three years later, I'm noticing a cave in, at the waist, near the x-brace joint. If I put a straight edge at the waist, from side to side, there is a strong 1/8" dish. I'm using tight grained spruce bracewood. My question is, should I beef the bracing up to 3/8" x 1/2"? I've got two more of these git-boxes under construction now, and would appreciate any advice. Thanks, Alan.

P.S.- I really don't know what I'm doing, I just put it together, and pray it works!

Cave in can occur as a result of moisture loss in instrument wood especially in low winter r.h., Im sure your prolly aware of this - but I mention it just in case your not, or perhaps if you built your own instrument >mabye you wouldnt have a hardshell case for it??
Keeping your instrument in the case with a humidifier would cure this.
Keeping instruments in open air conditions when they are not being played can cause an appreciable reduction in moisture in an instrument >> even when there is an humidifier in the soundhole I was made aware of this in a recent discussion about humidity and cave in on an instrument top.
{which is still in the discussion pages here somewhere}
Im not knowledgeable in Weissenborn construction techniques so I will let someone else chime in on that score.
Good luck
Cheers
Charliewood

Hi Alan,

Welcome to the OLF.

I'm not an expert having built only one Weiss a month or so back and using my own bracing pattern so I don't know what state it will be in in 3 years time.

When you say .38" to .48" are you referring to the height of the bracing you used for the X braces? How wide were they. What is the brace height at the X brace intersection? What is the scale length and what gauge strings do you have on?

Has the dip developed suddenly or have you noticed it forming through time?

More importantly how does the Weiss sound and play? On a normal necked guitar the bulge behind the bridge and dip in front is usually an issue as it effects playability as the action goes up and intonation goes out - these are not generally problems for a Weiss. If the instrument isn't going to curl up on itself then play on.

The bracing height is probably more critical than width - I used around 1/4" wide by just under 5/8" high on mine.

With a Weiss if the bracing supporting the end of the fingerboard was too light you could also see such a dip in the waist area.

As Charliewood says, humidity could also be an issue.

_________________
Dave White
De Faoite Stringed Instruments
". . . the one thing a machine just can't do is give you character and personalities and sometimes that comes with flaws, but it always comes with humanity" Monty Don talking about hand weaving, "Mastercrafts", Weaving, BBC March 2010

Hey thanks for the info so far. The plan called out 38 thousandths of an inch, by the same width. I went up to 45, roughly 3/8" and 7/16", respectively. Instead of square, I was thinking about narrowing down to  1/4", and make it taller, to 5/8", and if that's what you use, I could try making some, and seeing how much stiffer they are. Tricky stuff. For me it's a lot of guessing.  Also, my git-box gets played every day, and I leave it out. It sounds nicely balanced, but isn't very loud. Probably because it's made of some figured mahog, for the top and back, with straight grained sides. I didn't have enough material for the sides, and it was my first try at bending, which was a lot easier than I thought, no jig. Another thing I did wrong, was to seal the interior, which I found out later, is a "no-no". Oops. Alan.

Alan,
welcome to the OLF! Do be forwarned that as an initiation rule you must post pictures of your work in order to validate your membership!

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Peter M.
Cornerstone Guitars
http://www.cornerstoneukes.com

[QUOTE=peterm]Alan,
welcome to the OLF! Do be forwarned that as an initiation rule you must post pictures of your work in order to validate your membership! [/QUOTE]

Well alrighty then. I'll also send some shop photos from another thread here. Aaaalaaannn!

Cool

_________________
Dave White
De Faoite Stringed Instruments
". . . the one thing a machine just can't do is give you character and personalities and sometimes that comes with flaws, but it always comes with humanity" Monty Don talking about hand weaving, "Mastercrafts", Weaving, BBC March 2010

Thanks Dave. I checked out your site. Great git-boxes. Thanks for the Weissey building steps. I learned a few things there. Nice job. I like the way you decorate your instruments, not too much blink-blink,but nice and tasteful. Alan.

Very nice Alan! How does she sound?

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Dave Rector
Rector Guitars