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ready to set up second falcate classical
http://www-.luthiersforum.com/forum/viewtopic.php?f=10101&t=46640		 Page 1 of 1
Author:  johnparchem [ Tue Nov 10, 2015 12:11 pm ]
Post subject:  ready to set up second falcate classical
This guitar is Lutz\Panama Rosewood falcate braced classical that I am building for my classical guitar teacher. He commissioned the guitar after hearing the first falcate classical and the falcate Steel string guitars that I built.
I used Royal-lac on top of a zpoxy pore fill for the back sides and the neck and a shellac French polish for the top.

I just finished applying shellac last week. I still have yet to level sand or polish the royal-lac back and sides or the French Polished top. It looks good in the pictures, but it definitely has a hand applied finish look.

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The bracing follows the pattern in the Gore Medium Steel String mapped on to a cutaway Hauser 37 body shape. I actually made 2 tops. I pulled the first one after closing the box and realizing that the final top resonance would be below 180 Hz. I went from 8 mm braces to 9 mm laminated European spruce braces. I did clean it up before closing the box.

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The back was designed with the active back design.

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The bridge is a laminated Brazilian Rosewood bridge. It ended up at 18 grams

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Here is the tap with the bridge but no strings. At 195 Hz it is a bit low but I will end up with around 188 Hz or so. Ten Hz higher than my last falcate classical and 10 Hz lower than my falcate classical retop so I should be able to hear the range.

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Author:  mike-p [ Tue Nov 10, 2015 12:39 pm ]
Post subject:  Re: ready to set up second falcate classical
Looks lovely. Panama as in tucurensis? Can I All where you got it? I'm trying to track some down.
Author:  johnparchem [ Tue Nov 10, 2015 2:22 pm ]
Post subject:  Re: ready to set up second falcate classical
mike-p wrote:
Looks lovely. Panama as in tucurensis? Can I All where you got it? I'm trying to track some down.


Yes it is. I bought this set a few years ago from LMI. They still have some http://www.lmii.com/products/panama-rosewood. It has gotten pretty pricey. The piece I have had really good tonal property and is gorgeous.
Author:  Colin North [ Tue Nov 10, 2015 3:00 pm ]
Post subject:  Re: ready to set up second falcate classical
Looking great, don't forget the soundclip when you get there!!
Author:  mike-p [ Tue Nov 10, 2015 3:19 pm ]
Post subject:  Re: ready to set up second falcate classical
Ouch! Yes. I won't be buying any from that source at least!
Author:  SteveSmith [ Fri Nov 13, 2015 2:19 am ]
Post subject:  Re: ready to set up second falcate classical
Looks real good John, I'll be interested to see how it sounds and also how the Royal Lac polishes up for you. I have two guitars in the drying cabinet with RL sprayed that are waiting for me.
Author:  Robert Lak [ Fri Nov 13, 2015 8:42 am ]
Post subject:  Re: ready to set up second falcate classical
Curious about the Fiber... is that just a CF string laid on top of the bracing or is it laminated within the bracing?

Some type of epoxy or CA?
Do you reduce the size of the bracing due to the addition?
How much weight savings and do you have figures for any difference in strength?

If you have any links to discussions on the use/benefits of CF I'd be interested in taking a look at those.

thnx
Author:  johnparchem [ Fri Nov 13, 2015 11:56 am ]
Post subject:  Re: ready to set up second falcate classical
Thanks for the comments

Robert Lak wrote:
Curious about the Fiber... is that just a CF string laid on top of the bracing or is it laminated within the bracing?

Some type of epoxy or CA?
Do you reduce the size of the bracing due to the addition?
How much weight savings and do you have figures for any difference in strength?

If you have any links to discussions on the use/benefits of CF I'd be interested in taking a look at those.

thnx


All of my knowledge is originally coming from the the Gore\Gilet Comtempory Acoustic Guitar books. If you search for falcate or Gore on this and other luthier forums you will find a lot of discussions. This is my fifth falcate braced guitar. Two SS, two new classical and one classical re-top.

The braces have carbon fiber threads, I pull rows from a sheet of 5.7 oz 3K fabric for my threads. I use epoxy to glue the CF between the sound board and the brace and on top of the shaped brace. The fiber is not laminated in the brace. Having the fiber on the top and bottom puts the carbon fiber as far from the neutral axis as possible. This is important as spruce is so stiff that inefficient use of CF will make a heavier brace for a given stiffness.

I am building to a bracing pattern that incorporated CF as part of the original design so I do not have experience about reducing the height of bracing but information about increased stiffness to mass could provide a start to figure out what to do.

The benefits of CF for weight and stiffness is dependent on the stiffness of the wood brace. For spruce the book showed a table with quartered spruce with CF as having 5 to 9 percent added mass and getting 28 to 54 percent more stiffness. Less stiff wood could see high increases of stiffness to mass ratios.

Another benefit is CF does not cold creep so the guitar top should be less likely to deform under string tension over time.

One downside other than the mess of dealing with epoxy is that you can not tune the top braces once the carbon fiber is added. Having a process where the various components can be normalized for stiffness is important for consistency. For example knowing the stiffness of a top to determine the thickness. I am also finding that it is important to know the stiffness of the brace wood to fine tune the height of the braces.

I strung this guitar up yesterday. My resonance target for the top was 190 Hz, almost got it at 188.4 Hz. The air, top and back resonances ended up at 94.2 Hz, 188.4 and 236.5 Hz respectivly. Graph below. I still need to clean up the nut and saddle buff out the finish but she sound really good right now I am excited to hear how it opens up in the next few days.

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Author:  Imbler [ Fri Nov 13, 2015 12:08 pm ]
Post subject:  Re: ready to set up second falcate classical
Congrats John, glad all your efforts paid off in the sound!
Mike
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