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top bracing OM (another one of those eh)
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Author:  Frank Aarre [ Tue May 12, 2009 4:50 pm ]
Post subject:  top bracing OM (another one of those eh)
ok so here is another one of those bracing threads. [uncle]

i'm fully aware that it is near pointless to give accurate critique from a photo. but i'm a first timer and really have no clue what the **** i'm doing, so based on the pictures and the numbers am i way off here?
if you see something that just doesn't look right, please speak up.
the top is glued to the rims so i couldn't get low enough with the camera to get a good photo.

it is based on Michaels OM plans, the placements are pretty accurate but i've misplaced the bracing part of the plans so i'm not sure about where i'm at with the heights.

Attachment:
bracing4.jpg

Attachment:
bracing1.jpg

Attachment:
bracing2.jpg

Attachment:
bracing3.jpg


capped x - 15,5mm
x valley - 8mm
tone valleys - 6mm
peaks (scallops?)- 12mm

thanks for looking
Author:  Randolph [ Tue May 12, 2009 5:01 pm ]
Post subject:  Re: top bracing OM (another one of those eh)
Frank, that's a nice top. I'm not an expert, but there might be a couple of things. The finger braces look pretty big. Also, my understanding is that you would want the tonebars and finger braces to plane all the way down to the soundboard before they come into contact with the kerfed lining.

Maybe let someone with more experience comment before you change anything.
Author:  Frank Aarre [ Tue May 12, 2009 5:13 pm ]
Post subject:  Re: top bracing OM (another one of those eh)
Randolph wrote:
Frank, that's a nice top. I'm not an expert, but there might be a couple of things. The finger braces look pretty big. Also, my understanding is that you would want the tonebars and finger braces to plane all the way down to the soundboard before they come into contact with the kerfed lining.

Maybe let someone with more experience comment before you change anything.


Hi Randolph,

my initial plan was to tuck everything, looking at the lower x legs you can see that i deviated from this plan. This started out as a measuring error but then i saw that a lot of folks didn't tuck the lower x legs so i figured that i'd go with it.
btw, where is this 'kerfed lining' you speak of :shock:
Author:  Randolph [ Wed May 13, 2009 10:41 am ]
Post subject:  Re: top bracing OM (another one of those eh)
Frank, Again, I have to say, I'm not an expert and only know what I've studied from the more experienced builders.
It would seem that tucking the X-braces would be advantageous because of the force exerted on these braces from the bridge. If these braces are tucked under the lining then some of this force can be transfered from the top to the lining.
The tonebars and finger braces, however, stiffen their relative areas of the top and are not under the same stress from the bridge. Therefore they can run to zero thickness at the edges, freeing the top up to vibrate more at the edges. This will open up the sound more (like a drum).
By the way, my mistake - you don't have kerfed lining on this guitar. You have solid linings. They are the curved pieces glued onto the sides at the top and back of the guitar. Many people used the kerfed type.
Author:  Frank Aarre [ Wed May 13, 2009 12:26 pm ]
Post subject:  Re: top bracing OM (another one of those eh)
Do you think it'd be ok to just feather the finger and tone braces?
this is my first but i still want it to be as responsive a guitar as possible without it breaking into pieces when i string it up.
This guitar will only wear light strings.


btw, i did understand your reference to the kerfed linings, i just couldn't help myself i had to be a wise-ass

thanks
Author:  Randolph [ Wed May 13, 2009 12:56 pm ]
Post subject:  Re: top bracing OM (another one of those eh)
Frank Aarre wrote:
btw, i did understand your reference to the kerfed linings, i just couldn't help myself i had to be a wise-ass


Being a veteran wise ass myself, I'm surprised I didn't pick up on that one!!

Yeah, I do think it would be ok to feather the tonebars and finger braces. John Mayes's and Kent Everett's voicing dvd's both recommend tapering to nothing 3/8" - 1/2" back from the sides (from memory). My guess is that your tap will improve doing this as well.

I don't know about those X-braces, though. I wish someone with more experience would chime in here. My guess is that with the light strings you'll be ok (the tucking just being added protection?)
Author:  Rick Davis [ Wed May 13, 2009 1:30 pm ]
Post subject:  Re: top bracing OM (another one of those eh)
Oh boy. Bracing is such a mystical thing that whatever one says is bound to ruffle someone's philosophical feathers. But, fastening my metaphorical seat belt in anticipation of the wreck this could become, here goes ...

I agree that the fingers are a bit chunky and that they could be shorter and smoothly feathered to nothing. Actually, the tone bars look chunky, too, but all of this is supposition without flexing and hearing the soundboard. Reducing the dimensions of the fingers probably won't change the tap tone, by the way, but it probably will make a difference to responsiveness when the guitar's together.

The only structural issue is whether the X-brace needs to be tucked. The short answer is no, it isn't necessary. The longer answer is yes, it should be. I always tuck all four legs of the X and both ends of the upper transverse brace and if I screwed up and cut something too short I'd chop it off and replace it. But lots of people (misguided fools, he said jokingly -- repeat: joking!) don't tuck all those brace ends and their guitars don't explode -- at least not until a poor glue joint fails or the guitar gets a sharp blow while under tension. So I'd say that it's your choice whether to proceed with the understanding that the braces are a tad less durable than they could be or to bite the bullet and replace them now. I'd say that it's your choice: if you're confident about your joinery and aren't planning on selling the guitar, then you could reasonably leave them as they are.
Author:  Daniel Minard [ Wed May 13, 2009 1:30 pm ]
Post subject:  Re: top bracing OM (another one of those eh)
Unless your top is a little floppy, I would consider removing more mass from all of the braces south of the soundhole. Especially at the high ends of your scallops. You could taper them to a sharpish peak without losing a great amount of strength.
The tone bars could easily be scooped back quite a bit to de-couple them from the X braces. same with the finger braces.
You definitely want to feather the brace ends out more. An abrupt termination of the brace can eventually cause the glue joint to fail.
Otherwise, you have done a lovely job.
This is just one guy's opinion, & should be taken as such.
Tap & listen as you change things. You will be surprised at how much more resonant your top will become as you remove material. Be brave! Sharpen your favourite chisel! Have fun! Dan
Author:  Corky Long [ Wed May 13, 2009 2:47 pm ]
Post subject:  Re: top bracing OM (another one of those eh)
Caveat - I'm also a novice -
Here's what I've learned from a bit of research and from building 4 guitars.

Voicing the tops depend on lots and lots of variables - thickness of the top, size of the guitar, the top itself (flexibility and stiffness of that particular piece of wood), etc. I've built too light on one at least, by overscalloping the braces (after a year the Dreadnought is already starting to fold up), and a bit heavy on others.(sounds like &(*))

That being said, Dana Bourgeois has some pretty interesting interviews (available on the web - if not here on the archives) and articles which describe the process he follows to voice a top. http://www.pantheonguitars.com/voicing.htm

To brutally oversimplify, he removes material from braces, in order to reduce mass and structure so that by tapping the top on various points (he taps on the outside of the top opposite the braces) in order to get a wide range of tones from tapping. He doesn't tap to try to acheive specific tones, just to end up with a wide range of different tones.

I've attempted to mimic his approach on my last couple of guitars and found it to work pretty well.
Author:  Frank Aarre [ Thu May 14, 2009 5:12 pm ]
Post subject:  Re: top bracing OM (another one of those eh)
Thanks for the replies everyone.

i've removed quite a bit of wood and listened to the tap as i went(without knowing what to listen for of course) after i removed the mass i'm hearing more bass in the tap, but the high ' ping' is still there and there is some sustain.(i have no idea what constitutes a long or short sustain, but there is some sustain)

so here are some updated pictures, i'm going to clean it up a little nicer. but i don't have the nerve to remove much more material unless you can tell from the pictures that it's still heavy.

Attachment:
bracing5.jpg

Attachment:
bracing6.jpg

Attachment:
bracing7.jpg

Attachment:
bracing8.jpg


thanks again for looking.
Author:  truckjohn [ Fri May 15, 2009 12:10 am ]
Post subject:  Re: top bracing OM (another one of those eh)
Your work looks very clean....

I actually recommend stopping where you are and putting it together.... You have picked a good plan with initial bracing recommendations that are sensible (Not grossly too heavy.)

If you feel like it is too stiff after a couple months of playing.... You can always go in and shave a little bit. It is much harder to go in and put it back on 3 months from now.

Good luck with your build.

Thanks

John
Author:  truckjohn [ Fri May 15, 2009 8:52 am ]
Post subject:  Re: top bracing OM (another one of those eh)
I thought about the earlier reply and wanted to clarify a little bit....

As beginners -- we have no frame of reference for how a properly voiced soundboard is supposed to sound before final assembly... This is our frustration.... We are flying blind. We have no mental model to correlate the right "Bonk" with a good sounding guitar after assembly. We can think about "loosening up a little" or "Not quite so tight" or "Picks up a little sustain" or whatever....

Personally, what I find is that other's words may be fine descriptions for what to listen for... but I still feel like I need to experience it myself... How loose is too loose? How stiff is too stiff -- to get the connection made in my brain.

Now.... It is essentially a statistical impossibility that a 1st guitar will come out sounding "Absolutely awesome" except by pure freak of nature. It will either be too stiff or too loose, because of this lack of a real mental model..... This being the case -- On your #1 guitar.... there is a lower risk with leaving bracing a little stiff then shaving it a little after a couple months of playing.

The reason I mention this is that I am getting things ready to pull the back off of an early creation.... turns out my mental model of bracing schemes didn't really match what actually seems to happen.... and I left some components *way* too light.... so now, I gotta go back in there and re-brace.

Good luck

John
Author:  Lars Stahl [ Fri May 15, 2009 12:27 pm ]
Post subject:  Re: top bracing OM (another one of those eh)
Hej Frank. Hoppas allt är bra med dig. Looks like it gonna be a beautiful guitar !! Cant wait to see it finished. As you know I have only finished 1 and the sicont is like 95% done. I do agree with what John said on not "really knowing" as we are beginners, But if it has a good ring to it as you tap on it your on the right track, if it goes boink boink then carve some more carefully , but it also depends on if the top was stiff to begin with, my first top was 0.090 thin but stiff on Michaels SJ plan. your doing a smaller size guitar so If the top was stiff then I would not worry to much on carving until you get what you feel is a nice tone to the top, if you have the bracing dvd´s by john Mayes then that is quite helpfull. also as your in Norway, why not give our friend Arnt Rian a call and he might put you in the right direction.
I do hope someone with good knowledge could chime in on this and give you their say.

I resently opened up the top on an old Sigma guitar, "their most expensive model" 9000kroner !! always hated the sound of it so the top went of ! and in there I found like LOGS nothing carved at all the X was almost like directly from the bandsaw haha. It still sounded ok ! , if this is the first ? I am sure it will be great.

Lars
Author:  Frank Aarre [ Fri May 15, 2009 4:31 pm ]
Post subject:  Re: top bracing OM (another one of those eh)
Thanks for the replies guys.

I guess i really should be getting the mayes dvd's, or at least the voicing ones.
but i don't have the patience to wait for them, the body is sitting in the go-bar deck right now, but i'll be getting them dvd's for my next build though.
Author:  Randolph [ Fri May 15, 2009 4:54 pm ]
Post subject:  Re: top bracing OM (another one of those eh)
Hey Frank, I agree with Lars about the Mayes dvd's. If there's any way you could do both the Mayes and the Everett voicing dvd's you would lay awake at night voicing your guitar. They will definately open up your thinking process a lot. Good luck from a fellow beginner. I understand your pain and excitement. laughing6-hehe
Author:  Frank Aarre [ Sat May 16, 2009 6:15 am ]
Post subject:  Re: top bracing OM (another one of those eh)
thanks for the input Todd.
i glued it up yesterday, so will see how it sounds as is.
at least now i have the possibility of more responsive 2nd guitar :)
put a brush coat of shellac on the maple back and now i'm getting excited, i just had to show it.

Attachment:
back.jpg
Author:  Lars Stahl [ Sat May 16, 2009 6:29 pm ]
Post subject:  Re: top bracing OM (another one of those eh)
Looks beautiful Frank. Soon comes the scary part --- cutting the binding channels :shock: . haha. On both of mine I´ve been nervous as soon as the darn machine starts screaming !! . man its loud. :D .
I guess you´ve allready seen them, but if not, the clips that O´brien has made are awesome. ) "tips du jour" I think they are called.

Lars.
Author:  Terence Kennedy [ Sun May 17, 2009 1:20 pm ]
Post subject:  Re: top bracing OM (another one of those eh)
How did you bend your cutaway Frank?
Terry
Author:  Frank Aarre [ Sun May 17, 2009 3:49 pm ]
Post subject:  Re: top bracing OM (another one of those eh)
Terence Kennedy wrote:
How did you bend your cutaway Frank?
Terry


used solid bending forms with heat blanket.
viewtopic.php?f=10101&t=21375&p=296821#p296821
scroll to the bottom of this thread for a couple of pictures
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