Additional bracing patch b/n bridge and heelblock (Full Version)

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Andrew -> Additional bracing patch b/n bridge and heelblock (Dec. 31 2009 3:31:12)

Has anybody on the forum tried putting an additional bracing patch (similar to the contrapuente patch under the bridge) between the bridge and the heel block to help reduce potential soundboard wrinkling in this area?

Would this have an adverse affect on the sound?

Similar concept to the Reyes plan (with the individual block patchs b/n fan braces) by Tom, but continuous rather than broken. The individual patches look like an after thought.

I've tried the Reyes bracing with the individual patches but that seemed to accentuate the SB waveness b/n fan braces. Maybe I glued the fan bracing and the little patches too hard. In future I think I'll use a rub joint for the fan braces.

With a SB thickness around 2.1mm it seems that you have to be careful not to create waves/ripples in the top when glueing braces.

Andrew



TANúñez -> RE: Additional bracing patch b/n bridge and heelblock (Jan. 1 2010 8:59:15)

quote:

I've tried the Reyes bracing with the individual patches but that seemed to accentuate the SB waveness b/n fan braces. Maybe I glued the fan bracing and the little patches too hard.


Yes, these have to be glued on very lightly. You can also just use angle braces down there like Barbero did or like on the typical Torres design.



estebanana -> RE: Additional bracing patch b/n bridge and heelblock (Jan. 1 2010 11:17:33)

Wow, you're getting telegraphed braces and I bet those separate contrapuente sections telegraph more than a continuous piece. I leave that patch off these days, I talked to lots of older builders who came to the same conclusion.

The individual pieces will bend less than a long thin strap probably making situation worse. Telegraphing is pretty normal and if it's guitar you built just chalk it up to experience and go forward.

Eugene Clark once told me how he keeps his sound boards from telegraphing the fan braces. He shapes the tops of the braces first so he does not have to mess with a chisel after the braces are in, and then presses them in by hand with hot glue. Then he has to shape the taper from the top of the brace to the sound board. Preshaping the top of the braces before gluing removes some of the mass and tension in the brace so it's not going to spring out so powerfully and distort a thin top. The other thing is to brace the top thicker and sand out any telegraphing when you do the final thickness adjustment of the top.

He recommended thinning the top to about a 10th of an inch for bracing thickness. That gives you plenty of meat to sand to a final thickness and hopefully correct telegraphing. I have done that with good results, but I have also braced thinner tops and lived with telegraphing. I'm not sure if Eugene does the exact same thing all the time, but he dropped that hint to me and I found it useful.

From what I can see Reyes is a maker who likes building with rather thin tops and his older guitars seem to show some telegraphing. So I doubt at that time he was too worried about it. Some older Reyes guitars also have a reputation for being moody. I've always wondered if this is true, and if it's because he built thin in a shop where the relative humidity was not consistent. ( just my own supposition I've mused on from time to time. ) If you have a thin top with patches or grafts glued in that expand and contract across the grain at different rates due to humidity, it could effect the "moodiness " of the guitar. It would loosen and tighten the top in unpredicable ways, not that anything is really predictable.

As with anything in guitar building you have to make it your own somehow because we all have a different touch. Hope that is useful for you.



Andrew -> RE: Additional bracing patch b/n bridge and heelblock (Jan. 2 2010 2:45:26)

Telegraghing - have not heard that term before.

Interesting about the E.Clark methods, i read a GAL article by him and intented apply some of his methods that you've mention. In particular the rub joint for sb braces with the sb clamped in between the braces to hold the form.

I think one other possible cause of the telegraghing is my solera. It's based on the courtnall book which says to leave 1cm(?) flat around the perimeter so that you can make the tentallones square - that's great but the top is forced into an un-natural shape, flat then is pull up into a curve - I think it's very bad. I'm changing my solera to have a smooth curve right to the edges. Do you have any suggestions on how to get a good smooth shape into the solera - i presently just doing it by eye and feel.

So with the esteso you repaired, were the tentollones square, E.Clark told me once that D.Esteso shaped them to fit the solera shape.

Thanks for your help, appreciated.
Andrew



Andrew -> RE: Additional bracing patch b/n bridge and heelblock (Jan. 2 2010 2:49:18)

Tanks Tom,

with the Barbero bracing pattern, do you think it's a bad to have the centre fan brace not going the full length of the lower bout (making contact with the end block)?

Andrew



jshelton5040 -> RE: Additional bracing patch b/n bridge and heelblock (Jan. 2 2010 7:17:34)

quote:

ORIGINAL: Andrew
Do you have any suggestions on how to get a good smooth shape into the solera - i presently just doing it by eye and feel.


The way I make soleras is using the violin making method. Draw the outline of your guitar then lay out your design in a grid then make cardboard cutouts of the profiles on the grid lines in both directions. As you're carving and sanding the solera use the cardboard profiles to verify that you are following your design accurately.



Anders Eliasson -> RE: Additional bracing patch b/n bridge and heelblock (Jan. 2 2010 8:26:29)

The last couple of years I have worked with a flat solera for the soundboard. Result is a better curve in the top, no braces sticking out, better seperation in the notes and more volume.
When you glue the braces, dont use a lot of pressure. just enough to squeeze out excess glue. You can use a little more pressure if using titebond than if using hot hide glue.



nhills -> RE: Additional bracing patch b/n bridge and heelblock (Jan. 2 2010 8:33:27)

Anders:

?? How do you get the "curve in the top" if the solera is flat?

Cheers,
Norman



TANúñez -> RE: Additional bracing patch b/n bridge and heelblock (Jan. 2 2010 8:53:33)

quote:

Tanks Tom,

with the Barbero bracing pattern, do you think it's a bad to have the centre fan brace not going the full length of the lower bout (making contact with the end block)?

Andrew


It don't think it's bad at all. I'm sure Barbero new what he was doing and the guitar which the plans were taken from was a great guitar IMO.



estebanana -> RE: Additional bracing patch b/n bridge and heelblock (Jan. 2 2010 10:05:26)

Anders,
Are you using an arched caul under the bridge to suck the top up into the bridge to get a partial arch?



estebanana -> RE: Additional bracing patch b/n bridge and heelblock (Jan. 2 2010 10:07:55)

quote:

Has anybody on the forum tried putting an additional bracing patch (similar to the contrapuente patch under the bridge) between the bridge and the heel block to help reduce potential soundboard wrinkling in this area?


The center fan brace over the seam in the top is not doing a good enough job between the bridge and tail?



Andrew -> RE: Additional bracing patch b/n bridge and heelblock (Jan. 4 2010 3:57:25)

Dido Normans question, how do you get the top curve if you build with a flat solera?

Andrew



Mike_Kinny -> RE: Additional bracing patch b/n bridge and heelblock (Jan. 5 2010 5:38:03)

WARNING: DO NOT TRY THIS AT HOME.

I have also switched to flat solera and a perfectly flat bridge. The top gets domed of itself.

The reason for my warning is that there are other factors that play a role. The flat tops I have made have a big neck angle and the bridges are a good deal thinner than the usual.



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