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Lower Harmonic bar – missing radius
http://w-ww.luthiersforum.com/forum/viewtopic.php?f=10102&t=13505		 Page 1 of 1
Author:  Ricallo [ Mon Sep 03, 2007 10:47 pm ]
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Hello to you all
I am just starting classic build No.3 and I have glued the lower harmonic brace onto the sound board without any radius. The fan braces are holding the lower bout to the correct radius.
The question is, do cut off the lower harmonic brace and start the brace again or live with a missing radius that might not be too noticeable if at all?
I am not under any time constraints but it seems a lot of effort for a little gain
What do you people think?

I have included a picture of the brace in question and I also included a picture of my first homemade rosette



Author:  JJ Donohue [ Mon Sep 03, 2007 11:38 pm ]
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Welcome Ricallo!

I know nothing about your dilemma but until the experts chime in here's a thought:

If you have made 2 other classicals with the brace radiused, you could complete this as is and compare this to the other 2 as far as structural strength over time as well as any tonal differences.

Then again...the classical experts will probably have a better idea.

Nonetheless...welcome!
Author:  Michael Dale Payne [ Tue Sep 04, 2007 12:54 am ]
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I am by no means an expert but most classical plans I have seen only the fan braces were arched and everything forward of the fan braces were flat.
Author:  WaddyThomson [ Tue Sep 04, 2007 12:57 am ]
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I think Michael is right.  All Bars are flat.  No radius beyond the fan bracing.  Flat is what the Romanillos plans call for.
Author:  WaddyThomson [ Tue Sep 04, 2007 1:01 am ]
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Oh, Welcome to the OLF.  If you've been hanging out long, you know this is primarily a st**l st**ng forum, but much of the shared information is cross platform, and there are enough classical builders to make it very informative.  I am on my first, and I, also, am building to the Romanillos plan.
Author:  jfrench [ Tue Sep 04, 2007 1:10 am ]
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I make mine flat.
Author:  vachterm [ Tue Sep 04, 2007 2:15 am ]
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and i arch mine...
but think its a matter of self preference, and doubt there's much reasoning to it.
Author:  Michael Dale Payne [ Tue Sep 04, 2007 2:40 am ]
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The reasoning to the flat upper section would be neck and FB fit-up as Historically Spanish heel necks were in a flat plane relationship to the body as apposed to a Steel sting with a 1.5 deg back angle. If you dome the whole body then you have a bit of fit up issue to deal with on the FB.
Author:  Martin Turner [ Tue Sep 04, 2007 2:44 am ]
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My lower harmonic bars are radiused.
Author:  jfrench [ Tue Sep 04, 2007 3:02 am ]
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Michael, we're talking about the lower harmonic bar here, which is in the waist area as opposed to the upper bout. I agree with Udi that its just preference.

Also Classical guitars are not necessarily built on a flat plane, with no angle.
Author:  vachterm [ Tue Sep 04, 2007 3:21 am ]
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MichaelP,
it is my impression that it is actually very common for the neck/fingerbaord to not be coplanar with the top on a classical guitar.
the angle is the other way though, than you'd expect on a steel string(and a lot less noticeable too. i once did the math and came to the conclusion that i needed a 0.347 degree if i wanted the nut end of the FB to be 2m taller than the "plane" of the top).
and true, it does often means that the underside of the FB needs to be tapered from the 12 fret and up so that it conforms to that "angle".
on side note, and R.E Brune had verified it for me as well, some makers actually glued their UPPER transverse bar so that it is arched "the wrong way" and by that causing a deliberate "sink" in the top and allowing the FB to be glued straight on the top without the need for any tweaking and tapering of the FB.
but thats soooooo close to hijacking the thread so i'll leave it at that.

Udi.
Author:  vachterm [ Tue Sep 04, 2007 3:37 am ]
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HEY!
no that i think of it, somebody(think it was granada-based-swedish luthier,Andres Elliason) once reasoned the arching of the lower bar by stating that the string to top distance should be measured not only at the bridge but also at the bridge side of the soundhole.
why?
what i understood(and i may be wrong),he stated, that as a a player, he feels that too much a gap at this critical point, where the thumb often rest, might result in "slipping" of the thumb into the void.
gotta add though, that he was talking "flamenco"-ish.
i'm no accomplished player, so i cant agree/disagree.
take it for what its worth.

Udi.
Author:  DP LaPlante [ Tue Sep 04, 2007 4:53 am ]
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I've made the lower bar both ways, flat or slightly arched. There is no advantage to arching the ones above the soundhole, it would only exaggerate the difficulty of fitting the fretboard given the 2mm or so lift at the nut as it passes onto the top.


Hauser seemed to have built his flat, the Romanillos solera has a slight arch in this portion onto which a flat brace is fastened.....usually this results in an assembly that has around half of the arch of the solera.


I think the thing to pay attention to here is not the arch of the brace, but its overall stiffness and mass.


 
Author:  Ricallo [ Wed Sep 05, 2007 10:57 pm ]
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Thanks for all your input. I am going on holiday next week and I shall think long and hard as to what to do. Meanwhile please se my latest posting ‘Historic Instruments’.
Author:  Michael Dale Payne [ Thu Sep 06, 2007 12:36 am ]
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Oh I did not say all. I said the plans that I had dealt with, mainly Hasser Sr. 1946 and Jose Rameriz 1966. neither of them had a back angle on the neck.

My point was that Ricallo would be fine with the flat braces past the fans.

The fretboard fit-up issue I mentioned was not meant to state it is wrong to do so just that the construction must take the upper bout dome into consideration. geez I feel like I have been spanked.
Author:  Michael McBroom [ Thu Sep 06, 2007 1:10 am ]
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Just to add to this -- I leave my upper bar flat and radius the lower bar. But if the lower one is flat as well, I don't think it will matter that much.

Best,

Michael
Author:  vachterm [ Thu Sep 06, 2007 2:14 am ]
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Hey McBroom!
long time no see!
i PMd you months ago regarding indevidual tuners, did you get it?
Author:  jfrench [ Thu Sep 06, 2007 2:20 am ]
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MichaelP - sorry! No spanking intended!

Ricallo - don't do anything. Leave it as is. We all do these things our own way and as this thread seems to prove it doens't make much of a difference one way or the other. Certainly no reason to redo previous work.


Author:  Michael McBroom [ Thu Sep 06, 2007 3:41 am ]
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[QUOTE=vachterm] Hey McBroom!
long time no see!
i PMd you months ago regarding indevidual tuners, did you get it?[/QUOTE]

Yup, thanks for the heads up. Been busy with stuff -- not all lutherie related.

Best,

Michael
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