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Braced top
http://w-ww.luthiersforum.com/forum/viewtopic.php?f=10102&t=14892
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Author:  blindreality [ Mon Dec 10, 2007 4:17 am ]
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I figured after all your support that I would post a followup. I picked up Mayes' DVD set in the swap meet and decided that it was time that I pull them out for a viewing. John, thank you for the great DVDs! I learned some things that I had not thought of, for one, that is isn't exactly a right way to brace. I was concerned because one of my XBraces was a little off, but I think it will be fine. I started off tapping and I got a thud. My braces probably too thick, 6/16ths at the base of the joint and are 3/4 of an inch tall. This is as a result of building them too small last time and having to take them off.  I will probably put a taper on the Xbraces starting about 2/3 of the way from the end of the Xbrace to the joint and then see if I can remove a little off the sides as well. I probably should have gone for scalloped bracing, but here I am. I do think that I will put in the bridge plate first next time and see if that makes it easier. Dad has most of my powertools so I can't do that one until I get my bandsaw or at least scroll saw back.



Full Size image


Here is the other thing on my work bench.


Author:  Michael Dale Payne [ Mon Dec 10, 2007 4:37 am ]
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for future refferance:

The X, finger and tonebars do look too thick (appear to be at least 3/8" thick) 3/8 thick on a Dread X brace is fine and the height is not an issue in fact tall braces allow you to brace thinners, but the tonebars and finger braces can be a good bet less thick. Maybe 5/16" or 1/4". In fact tall braces allow you to brace thinners.

My big concern is the upper transverse brace. I appears to be 3/8" thick also. This brace need to be stout, 1/2" or even 5/8". This brace resists the downward force of the fretboard extension. This is one of the two areas where the major loading on the top accrue. 3/8" may work since you have a fairly beefy upper transverse graft as well but will be at the minimal end of desired thickness for this brace.

Author:  JohnAbercrombie [ Mon Dec 10, 2007 4:58 am ]
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Jared-
Glad to hear you are 'back at it' in the shop.

re:bracing- I'm no expert, (and you can find lots of pics of braced tops around the OLF to refer to) but I agree with you that your bracing looks a bit on the heavy side in the picture.
You would have to make the bracing really light to get serious structural problems in your guitar, I think, so you should not be afraid to lighten things up quite a bit. You can certainly remove wood from the sides of the braces without much problem (not knife-edged, but thin), and the height can taper a lot as well.
Just for interest, here's a pic of the bracing on a spruce-top OM I built a few months ago- it sounds fine and hasn't exploded! (medium strings, and I like a 'bit' of doming/belly in the top)



Keep us posted with more progress shots!

BTW, you should ask Santa for a small (Japanese-style) handsaw if you don't own one already- great for bridgeplates and such.

Cheers

John

Author:  JohnAbercrombie [ Mon Dec 10, 2007 5:01 am ]
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Jared-
Note-
I was using a different bracing arrangement above the soundhole, so you should follow Michael's advice about the upper transverse brace, not imitate the one in my pic.

Cheers

John

Author:  Michael Dale Payne [ Mon Dec 10, 2007 5:05 am ]
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John the sound hole stiffners on yours adds a lot of strength to the UT brace on yours

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