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#2 Bracing Critique
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Author:  justink [ Tue Mar 09, 2010 2:19 pm ]
Post subject:  #2 Bracing Critique
Hi all, maybe a few of you gents have time to comment/ critique my #2 bracing. It is very fine grained Sitka for an OM (Thank you Allied!!!!!! Beautiful top). I still need to cap the X
Specs:
Top Thick - .095" at rims, .105" center
X height - 5/8 (braces are 5/16 thick)
U. Face Brace - 1/2" wide x 5/8" high (3/16" TR adjuster whole)
U. Trans. Grft - 7/8" x 1/8"
L. Face braces - 1/4" wide x 5/8" at peak
Finger Braces - 1/4" wide x 1/4" at peak
SH Braces - 5/16" wide x 3/8" at peak
Bridge patch - .085" IRW

Don't hold back! Thank You.
Author:  justink [ Tue Mar 09, 2010 2:20 pm ]
Post subject:  Re: #2 Bracing Critique
Oh yeah - it is a pretty stiff top (as far as I can tell) and rings decently all over, no thud spots when tapped
Author:  Lars Stahl [ Tue Mar 09, 2010 2:41 pm ]
Post subject:  Re: #2 Bracing Critique
Just by looking at the photos. ( as I cant hear the tone :D ) I think "with my limited knowledge" that the main X could be workt some more. Perhaps some more scalloping between center and second fingerbrace. Atleast thats how I would go.

Lars
Author:  Michael Dale Payne [ Tue Mar 09, 2010 5:32 pm ]
Post subject:  Re: #2 Bracing Critique
Only critical remark I have is that you tapered the UTB far too much. As it is even though it is full thickness under the fretboard extention it is so thin shortly there after that the top will likely sink on you over time. you need to keep the full height of the bace untill you get within an 1-1/2" to 1" of the linings then taper out for best resistance aginst the inward force of the fretboard extention under string tension. Also i would cap the X-brace connection. Outside of those two things it all looks very good
Author:  Darryl Young [ Tue Mar 09, 2010 7:13 pm ]
Post subject:  Re: #2 Bracing Critique
Justin, I don't have the experience to give you good advise......but I'll ask a question that maybe someone else here can answer. I haven't noticed anyone profiling the upper arms of the X braces......Is this typically done? I haven't noticed folks doing this. The taper in height from intersection to the end of the upper X brace arm I've seen, but not adding the parabola or triangle shape. Probably won't matter is what's left is strong enough.

Take this with a grain of salt, but I lean toward Lar's analysis........that you could remove a little meat in the lower X brace arms from the back of the bridge plate to about 1" below the X brace intersection. But please wait to hear from someone more experienced.
Author:  JohnAbercrombie [ Tue Mar 09, 2010 7:37 pm ]
Post subject:  Re: #2 Bracing Critique
Michael Dale Payne wrote:
Only critical remark I have is that you tapered the UTB far too much. As it is even though it is full thickness under the fretboard extension it is so thin shortly there after that the top will likely sink on you over time. you need to keep the full height of the brace until you get within an 1-1/2" to 1" of the linings then taper out for best resistance against the inward force of the fretboard extension under string tension.


I agree. Good advice from Michael.
Though it seems like a 'big deal' the first time you have to do it, chiseling off a brace like that UTB and replacing it is not that major. 30 min of work (total- off with the old brace, scrape clean and make a new one and glue it in) and you won't be worrying for the next 20 yrs about the top caving in ! Use a sharp chisel and work in the direction that has the splits going away from the top plate. Finish cleaning up with a small sharp scraper (or a chisel held vertically like a scraper) and a bit of sandpaper on a small hard block to give a good (bare wood) gluing surface if you used white glue originally.

Been there, done that!! [uncle]
Cheers
John
Author:  Burton LeGeyt [ Wed Mar 10, 2010 1:35 am ]
Post subject:  Re: #2 Bracing Critique
It is always hard to know what the top feels like etc... but generally I think it looks pretty good based on what mine usually look like. I think making a new UTB is a good idea although the one you have may work that is a better safe than sorry brace I think. If I was to recommend anything it would be to not have the finger braces be so peaky. Also, what Lars said about the x brace would be my preference also although many great guitars are made without that scallop. Tony K made the remark once that sharp points on the bridge plate can be problematic and I think that was good advice too. I wouldn't worry about what you have there but in the future rounding over that point may be a thing to do. Also, the lower of the 2 tone bars can generally be smaller than it seems like it should be. That area is one I focus on. I will also thin the top in that area more either before the top is glued on or after. Overall I think it looks very good. It helps to make a drawing of the top and exact brace placements and the top's thickness and the brace heights to refer to later. I look back over my previous guitars quite a bit and find it very useful.

That is a beautiful looking top! It will really shimmer under finish.

About Darryl's question, I do usually make the upper arms of the x pointed (like a triangle) at least a little. I think most people do although I am not positive.
Author:  Hesh [ Wed Mar 10, 2010 10:42 am ]
Post subject:  Re: #2 Bracing Critique
Hi Justin - nice looking top and you are almost there.

Other than what the others have brought up about the UTB the only thing that I see worth pointing out for consideration next time is 5/16" inch is a little thicker for an OM X-brace than I go. IIRC the Antes plan which is well known for being over-braced also calls out 5/16" X bracing. I have been using 1/4" X-bracing on OMs with good results and I think that some others do too. Again it's something for next time.

I carve my upper X legs into triangular shapes just like I do with all of my braces with the UTB being more rounded only to keep some beef above the truss rod adjust hole. In fact I try very hard to remove as much brace material as possible that is outside of the triangular shape. I see it as extra mass that does nothing for strength so off it comes. Most of my brace carving is done with finger planes.

Great job Justin!!! [:Y:]
Author:  Jim Kirby [ Wed Mar 10, 2010 12:53 pm ]
Post subject:  Re: #2 Bracing Critique
Bringing it up here probably constitutes a thread hijack, so I'll try to formulate my question more fully and start a new thread soon, but ...

I don't get this UTB stuff. On most classical guitars, the UTB is kept pretty much at the same cross section across the whole width of the guitar, or, if tapered somewhere, is occasionally tapered in the center. This is followed up by another transverse brace that can be just as massive. All of this on a lightweight instrument with moderate string tension load.

On the steel strings, there is this tendency to think of the UTB as somehow being a player in the weight vs strength conflict, so we taper the ends (too much in this one). And we back it up with a little popsicle brace or some other sort of modest little arrangement under the fretboard extension. All of this on an instrument with over twice the tension load of the classical.

Why do we mess with the UTB on a steel string guitar at all? Why are we concerned with having too much mass in the UTB or the area above the UTB, which most of us probably think is dead real estate for sound production. Why don't we put a whole lot more reinforcement up there?

Oops, I guess I went ahead and asked my question.

Jim
Author:  Michael Dale Payne [ Wed Mar 10, 2010 2:02 pm ]
Post subject:  Re: #2 Bracing Critique
Jim Kirby wrote:
Bringing it up here probably constitutes a thread hijack, so I'll try to formulate my question more fully and start a new thread soon, but ...

I don't get this UTB stuff. On most classical guitars, the UTB is kept pretty much at the same cross section across the whole width of the guitar, or, if tapered somewhere, is occasionally tapered in the center. This is followed up by another transverse brace that can be just as massive. All of this on a lightweight instrument with moderate string tension load.

On the steel strings, there is this tendency to think of the UTB as somehow being a player in the weight vs strength conflict, so we taper the ends (too much in this one). And we back it up with a little popsicle brace or some other sort of modest little arrangement under the fretboard extension. All of this on an instrument with over twice the tension load of the classical.

Why do we mess with the UTB on a steel string guitar at all? Why are we concerned with having too much mass in the UTB or the area above the UTB, which most of us probably think is dead real estate for sound production. Why don't we put a whole lot more reinforcement up there?

Oops, I guess I went ahead and asked my question.

Jim


other than rounding the top top of the UTB and tapering to Zero at the lining from about an inch prior to the binding I do not do much at all the the UTB. I want that beam to keep its full section modules near full width of the upper bout.
Author:  Jim Kirby [ Wed Mar 10, 2010 2:33 pm ]
Post subject:  Re: #2 Bracing Critique
Michael Dale Payne wrote:

other than rounding the top top of the UTB and tapering to Zero at the lining from about an inch prior to the binding I do not do much at all the the UTB. I want that beam to keep its full section modules near full width of the upper bout.


Michael - Thanks. This really does need it's own thread.

Why taper at all?
Author:  Hesh [ Wed Mar 10, 2010 3:49 pm ]
Post subject:  Re: #2 Bracing Critique
The UTB is tapered so as to smoothly transition into the height that is inlet into the linings. You don't want to abruptly drop the height of the UTB or any brace for that matter. I leave my UTB .1 high and inlet.

I agree Jim that added mass in the UTB probably.... is not an issue but then I am not sure that it's not either. Some well known builders think that anything north of the UTB is not as important when it comes to the potential for producing tone. When tapping free plates I definitely hear ringing north of the UTB so I am not so sure. It's also on my mind that it may not just be a question of the potential for real estate north of the UTB to produce tone - instead it may be about the potential for unnecessary mass north of the UTB that could act as an energy sink....

The more I build the less sure I become.... idunno
Author:  justink [ Wed Mar 10, 2010 4:02 pm ]
Post subject:  Re: #2 Bracing Critique
Thank you guys SO much for noticing the UTB!! That is what happens when you go from memory on your #2 for brace profiles. oops_sign I will remove it and rebrace that part. As for profiles, I (as Hesh said) try to make each brace have a triangular cross section (even if you can't see it in the photos.)

Thanks everyone! You may have just saved me a HUGE amount of head ache in a couple years.

Speaking of which, what do you say the average number of years one could expect to save in build-acquired wisdom by simply being part of the OLF? Maybe not as much as I think, but I think this is all quite priceless and it would take me years to learn the same lessons.
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