Official Luthiers Forum!

A 1/4" hole in the middle of the brace won't hurt. In fact, you can drill holes all along any brace without weakening them too much; the same principle that works for I-beams and trusses is at work here.

V brace, A brace, whatever ya wanna call them. I first saw them in a 1990 Gibson....Mario38637.0441435185

[QUOTE=Scott Thompson] [QUOTE=CarltonM]    If everything in the upper bout area were only structural, we'd all be building round (banjos, anyone?), teardrop (dulcimers?) or square (Bo Diddley?) guitars. [/QUOTE]

Carlton, not necessarily agreeing with Mike, but I think you and Mike are talking about different issues. You are talking about the configuration of the sound chamber and Mike, as I interpret it, is talking about the contribution of the vibrating top.[/QUOTE]

Yeah, I guess I did veer off the subject a bit. The point is, though, that folks are saying that the addition or removal of one little cross brace at the tippy-top of the upper bout does change the sound of the instrument, not just its structural integrity. There's SOMETHING going on up there. It might be just a little something, but every little bit counts in lutherie!

On reflection, a thought has occured to me that although the TVCPVLVBS (Mario's) address's the potential cracking problem, it may not be such a strong support for the (wanting to tip back) headblock, as the A frame method.
As I wrote earlier, I found the A frame to be Tricky and don't look forward to doing it again. That is,unless Alan or someone can come up with an easy method.
Maybe a good compromise would be to employ the TVCPVLVBS , but with heavier dimensions and letting them in a little into the transverse brace .
Just thinking out loud here and putting in my $6.20 a gallon

KiwiCraig

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CRAIG LAWRENCE of AUSTRALIA
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I like the idea of the A frame bracing; really do. Just never got around to setting up for it, and I like to fix the back to the sides first, so that makes it even tougher.

My braces do run to the linings and are let into them and the sides. From there, they run up to, and butt against, the large transverse brace. Keep in mind that my linings are either solid or laminated; never kerfed, so they offer up much strength, also(again, always look at the whole, and not just bits and pieces). Not as strong as an A frame let into the neck block, for sure, but so far seems a nice compromise. It does lend a fair amount of triangulation to the entire area, and that counts for much.

But if you want to pursue the A frame, I would urge you on. I don't see anything wrong with that setup at all.

Mario38637.0460763889

[QUOTE=Mario] I like the idea of the A frame bracing; really do. Just never got around to setting up for it, and I like to fix the back to the sides first, so that makes it even tougher.
[/QUOTE]

I use the A frame let into the headblock, and also like to fix the back to the sides first. What I do though is brace and prepare the top and back ready to join to the kerfed sides/blocks assembly. This way it's as though you are joining the top on first and can get the A frame geometry/carpentry sorted through an open back. Make sure everything fits then glue on back first, then top.

Also I was the builder that 'fessed up to using double sided tape for the f/b extension. Now I don't glue them at all. I'm going down the route of free-floating f/b's with the extension supported as part of the neck construction rather than a neck block extension, and with adjustable necks similar to that done by Mike Doolin. I'll post on this later when things are more advanced.

The role of the neck in an acoustic guitar is wothy of a thread all of its own!!

_________________
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

I have my extension floating at the moment and it sure is tempting to leave it at that as all seems solid (bolt on neck). Violins, cellos, archtops etc. come to mind. I do feel however, that fixing the extension in some way or another ,restricts any side movement the player may introduce to the neck.
Ya know how some guys can really start leaning on and bending things around during their "carried away " moments......."yeh man ,,,,really got it happening!..."

I have also noted that there are some designs , people have put forward, for bolt on extensions .This is good as it solves not only the potential crack problem but also ,quick and easy adjustments for neck angle (hello Mr. Taylor).

With hardwood being glued to the soundboard on these setups ,albeit from underneath ,isn't that just shifting the same problem from top to bottom. Maybe I'm missing something here? after all , what do I know , I'm only a b....y Kiwi.!

As for installing an A frame , my method is to draw the whole bracing pattern on tracing paper . I then overlay the paper on the headblock and scalpel the lines through the paper onto the headblock to give me the headblock pocket outlines, the n do the same on the soundboard to give me the A frame brace positions (there's gotta be an easier way)!!! Hello Alan Carruth

It gets even trickier (excellent word) as the build goes along , fixing the plates etc. As you grind down the sided to conform to the dished soundboard, you also lesson the depth of the "pockets"

I ended up glueing the headblock to the soundboard first , (before attaching to the sides) ,but before doing so ,put a carefully calculated radius on the headblock glue area (We do everything backwards over here) Sure would like to know how others do it .

Probably quite easy for a man like Mr. Carruth. I read where he can make a "V joint" on a neck headpiece in a matter of minutes!!!!!   Phew!! .....makes me feel very inferior

Kindest regards to you all   , KiwiCraig

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CRAIG LAWRENCE of AUSTRALIA
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There's no easy way I know to inlet that A-brace into the block: you just have to tough it out. I got two guitars without them back for top replacements when the necks got whacked, and I _hate_ fixing guitars once I've built them, so I switched; probably fifteen years ago. The inlets don't have to be very deep, and it would probably work fine to just butt them, but I feel more secure with them inletted. The A braces are about 1/4" square, and go through the shoulder brace at full height. Make the notches in the shoulder brace nice and tight.

I fit the top and back to the sides, and trim the plates to shape, while the sides are in the 'horse collar' form. The sides might twist around a little once you take them out of the form, but if you get the top and back on with all the braces in their pockets and no overhangs anywhere all the twist has been taken out.

A think a bead of glue down the middle of the fingerboard extension would also allow it to shrink without pulling a crack, and I've seen them done that way. The only problem is that the 'board might curl away from the top on the edges, and buzz. I make my 'chin' wider than the fingerboard, and with the grain running along the top, and have had no problems. Knock wood.

My feeling is that the upper bout's main contribution to tone is from the air cavity. It's pretty easy to find the resonances of the air in the body, and some of them do put out sound more or less directly trough the hole. Many of the ones that don't make a direct contribution do influence the way the top and back (and sides!) vibrate, and get their spoke in that way. The relatively complicated shape of he guitar helps produce the complex and 'interesting' tone that we all like. Simpler shapes have been tried, repeatedly, and abandoned just as often. They don't sound like 'guitars'.

It's hard to look at the vibration patterns of the top on either side of the fingerboard, since they tend to be at high frequencies. This is, of course, just where your hearing is most sensitive, and where small amounts of input can make a difference in timbre. So, yeah, I'd bet that removing the popsicle stick brace changes the tone some. The next question is, is the 'change' an 'improvement'? Mario indicates that, on the average, it is. That's good enoung for me, as far as it goes. I will note, though, that it may not _always_ be an 'improvement'. Saying that the 'average person' is making more money doesn't do you much good if you just lost your job.

Popsicle brace...

I stopped using it after the first few. I got tired of cleaning all the sticky orange goo off the top from the melting posicle. Nasty to clean from cedar especially.

_________________
"I want to know what kind of pickups Vince Gill uses in his Tele, because if I had those, as good of a player as I am, I'm sure I could make it sound like that.
Only badly."

[QUOTE=Don Williams] Popsicle brace...

I stopped using it after the first few. I got tired of cleaning all the sticky orange goo off the top from the melting posicle. Nasty to clean from cedar especially.[/QUOTE]

It seems retirment is working!!! your clearity on issues is back to normal

The next question is, is the 'change' an 'improvement'?

Ah, good point that hasn't been addressed.

The change that is reported all the time is the the instrument sounds brighter, cleaner.

Now, for some ears, with some guitars, this would NOT be an improvement at all. There are many overly-bright guitars out there that don't need to go that way further.

But, when yuo make a guitar nrighter, that allows room to go in and loosent the top more, gaining back some bottom, and some volume. It's always about the whole....

Thanks for your input Alan. Please forgive my ignorance, when you say "chin", I assume you mean an under soundboard extension of the headblock ? .As per Taylor and others.Yet you say you have been installing "A frames " for 15 years. I can't see how you can employ both methods at the same time ?

   As I wrote earlier, I can't see a lot of difference between glueing hardwood on top of the soundboard (the fingerboard), or glueing hardwood underneath (for bolt on fingerboard system ). They both invite the common soundboard crack.
   In my piano world , I often see cracks on soundboards , which don't (in most cases) affect performance, providing the crack is wide enough to not cause a buzz. Problem is , upon a humidity change the crack closes a little and ,well, you guessed it.
   I do come across quick fix methods ,where someone has shimmed the crack with a sort of wedge to keep it from closing up.I have done this myself when absolutley necessary, (doesn't look very nice)
   In a workshop situation,upon a rebuild/restring etc.,
I carve out the crack wider with a special "V" shaped chisel and glue in a "V" shaped strip of spruce and refinish the soundboard. Almost invisable.
Interestingly enough, ,very early builders would (before installation) expose their soundboards to extremes, and I mean extremes,to get them to crack.The more cracks develop , the better. they would then repair these and install the plate on the instrument, assured that this baby ain't gonna let me down.
Sorry! I've digressed from the subject at hand (again). That of the popsicle stick, or the crack it is supposed to stop happening. Even with the pop. stick ,it still happens though doesn't it. It's not the answer me thinks.
Hardwood bridges are glued cross grain on spruce with no real common crack problem ! why?? . I think it's because the soundboard bracing keep it from happening.
I, (IMHO), therefor believe that the "A frame" format for the upper bout is the way to go. It curbs the crack as well as provides headblock support .
I first heard it from George Lowden. Maybe he can tell us the easy way to install A frames. ..............
.....Is George on this forum??????????

   HELLO GEORGE!!!!      ... ARE YA THERE GEORGE????

                GEEOORRGGE!!!!

    Regards KiwiCraig

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CRAIG LAWRENCE of AUSTRALIA
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[QUOTE=KiwiCraig] Please forgive my ignorance, when you say "chin", I assume you mean an under soundboard extension of the headblock ? .As per Taylor and others.Yet you say you have been installing "A frames " for 15 years. I can't see how you can employ both methods at the same time ?[/QUOTE]

I'll weigh in here as a newb who's used Al's approach. There are a few pictures of the combo (A-frame and chin) at the MIMF, I believe, from Al, but here's an inside shot of my first, which has the L-shaped headblock (chin under the top, thinking about adding a small 'foot' for the back as well), and the A-frame upper bout bracing let into it:



As per Al's comments, the 'chin' tapers slightly, so it's wider than the fingerboard and so the edge doesn't follow any single grain line.

Here is how I do it.

I make my head block. It is important to put the 1-1/2 degree slope in the top part of the block. I slope the back part too but don't recall the angle at the moment.

On my table saw, I cut two 1/4" X 1/4" slots to accomadate the A braces. I use a wooden extesion screwed to my miter gauge so that the block is fully supported when it passed through the dado blade. I use a stop block to hold the head block in position on the miter fence. Since the stop block is placed by measuring, it is a bit of a hassle to get right so I make up several blocks at a time.

I slice these all the way through. When I mentioned this to Al, he said that he thought that having the A brace snug up against a stopped dado was important for the structure. You don't want the brace to be able to slide. Since my dado was not a stopped dado, I decided to put a stop in it. I drilled a 1/4" hole in the bottom of the dado at point where I want it to stop and glued in a hardwood dowel which I trimmed flush with the top of he block.

I make my A braces 1/4" X 1/4" X slightly long. I clamp the head block in its proper position on the top of the guitar with the A braces inserted into the slots. I then trace around the A braces. My A braces pass under the upper transverse brace and the upper X braces. Removeing the head block, I glue the A braces down onto the top. These are the first braces I glue down. Next I notch and glue the upper transvers brace. I notch the upper part of the X braces when I glue them as well. Once X is glued down, I trim the A braces flush with the side of the X brace.

The A braces also serve as a way to align the top with the head block. This was an advantage that I hadn't considered and only noticed when glued the top the rims.

There is a slight change in the depth of the dados in the head block once you sand the rims. A bit of chisel work while fitting the top cleans it up nicely.

Here's a hand drawn sketch of my pattern.:

That's beautiful looking work Mattia. Wow!
   Looks incredibly strong. And very neat as well!
thanks for sharing it .A picture worth a thousand words.
I included a bottom foot on mine. I don't know if it will assist all that much,but it must help a bit.
I'd be interested in how you go with letting in the headblock.Everything has to lign up perfectly. the transverse brace join, the headblock pockets,and the headblock angle in relation to the body and neck.
Having now completed one ,I think next time may be a little easier...........I hope

KiwiCraig

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CRAIG LAWRENCE of AUSTRALIA
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If you look at Mattia's picture (thanks!) you'll see that the chin is wide at the sides and tapers down to about the same width at the end as that of the fingerboard. Thus the edge of the chin does not run along a sinlge grain line, and it's less likely to crack.

One other thing, Mattia: where's your patch across the junction of the X brace?

;)

Mike Mahar....
You better be careful bro! That pic borders on Pornography!!!

_________________
"I want to know what kind of pickups Vince Gill uses in his Tele, because if I had those, as good of a player as I am, I'm sure I could make it sound like that.
Only badly."

[QUOTE=Don Williams] Mike Mahar....
You better be careful bro! That pic borders on Pornography!!!

[/QUOTE]

The subconcious does tend to leak out sometimes.

I missed your post yesterday Mike. We posted at the same time
     Your A frame method is very helpful. I have recorded it for next time . Thanks for taking the time and trouble. I really appreciate it!
    So, thats your subconcious eh ! She ain't a bad looker! I might pin her up on my wall!

   Regards Craig

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CRAIG LAWRENCE of AUSTRALIA
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[QUOTE=KiwiCraig]
That's beautiful looking work Mattia. Wow!
   Looks incredibly strong. And very neat as well!
thanks for sharing it .A picture worth a thousand words.
I included a bottom foot on mine. I don't know if it will assist all that much,but it must help a bit.
I'd be interested in how you go with letting in the headblock.Everything has to lign up perfectly. the transverse brace join, the headblock pockets,and the headblock angle in relation to the body and neck.
Having now completed one ,I think next time may be a little easier...........I hope [/QUOTE]

Thanks for the kind words!

As for making it, I don't have an elegant way to do it worked out yet. I carefully line everything up, carefully clampe in place, mark the intersections, use a pencil cut /chiseled in half lengthwise to sorta mark the edges on to the chin, and route/chisel/test fit until it fits nice and snug. I'll probably make a small jig for the next few, to cut both the notches in the upper transverse and the headblock more precisely, but I'm not quite sure how yet.

[QUOTE=Alan Carruth]
One other thing, Mattia: where's your patch across the junction of the X brace?

;)
[/quote]

Added that later, just like the little diamond center seam reinforcement patches ;-)

That photograph's got the top test-fitted and held by clamps, not glued in place. Although to be honest, I keep forgetting to put the patch in before gluing the top to the sides. Lucky for me I do that first, I suppose :-)