Official Luthiers Forum! :: View topic - Would like bracing suggestions.

you're off to a good start but IMO I think we can make some improvements. just my 2 cents:

-Engleman is not the greatest brace material. too soft and spongy, and won't drive the top as well as sitka or red spruce.
-Try scalloping the foward legs of the X. you need to increase monopole action here.
-The upper traverse graft is weakened by the scalloping of the ends. go straight across to the rim and butt into a rib brace.
-The soundhole strips are weak. too wide and flat. try tall and thin.
- I see gaps in the x brace at the intersection and elsewhere on other braces. these need to be fully coupled. tighten up the joint work and try imbedding the smaller braces into the X brace legs.
-That bridge pad is odd -slab sawn and at 45 deg to the top grain? what's it made from? try maple or rosewood, quatersawn and 90 deg to the top grain.

the top and it's bracing are only a part of what you are after. the rest of the guitar is important too.

good luck [:Y:]

Author:	Donald V [ Wed Jun 02, 2010 1:33 pm ]
Post subject:	Would like bracing suggestions.
This is guitar #4 for me. Still based on the Kinkead plans but getting farther from them each time based on previous experiences and some things I've read here. One comment I've seen a few times here is the Kinkead plan is over-braced. The first three have all sounded like guitars but I'm trying to get more from this one. Specifically louder with a little more low end and a little more treble. The top and braces are engelman. The layout in these photos matches the plans with the exception of the following. Plans call for 5/16" bracing at the X and tonebars - I did 1/4" Photos in book show scalloping the top legs of the x - I didn't Treble finger braces are slightly longer Plans show much longer "peaks" on the scalloping. The photos I've looked at of other guitars seem to be lighter than what I have here, but I stopped my hacking and wanted some input prior to proceeding further. I've heard it's easier to take more wood off than put it back on. Thanks in advance for any insight!

Author:	arie [ Wed Jun 02, 2010 2:24 pm ]
Post subject:	Re: Would like bracing suggestions.
you're off to a good start but IMO I think we can make some improvements. just my 2 cents: -Engleman is not the greatest brace material. too soft and spongy, and won't drive the top as well as sitka or red spruce. -Try scalloping the foward legs of the X. you need to increase monopole action here. -The upper traverse graft is weakened by the scalloping of the ends. go straight across to the rim and butt into a rib brace. -The soundhole strips are weak. too wide and flat. try tall and thin. - I see gaps in the x brace at the intersection and elsewhere on other braces. these need to be fully coupled. tighten up the joint work and try imbedding the smaller braces into the X brace legs. -That bridge pad is odd -slab sawn and at 45 deg to the top grain? what's it made from? try maple or rosewood, quatersawn and 90 deg to the top grain. the top and it's bracing are only a part of what you are after. the rest of the guitar is important too. good luck

Author:	Donald V [ Wed Jun 02, 2010 3:44 pm ]
Post subject:	Re: Would like bracing suggestions.
Thanks for the input Arie. I had read somewhere that scalloping the upper x was a bad idea and was holding off until I got some input such as yours here. Would you mind explaining what you mean by "monopole action"? The "gaps" you see at joints are actually pencil marks that I didn't get cleaned up. Guitar #2 had a bad joint at X and I had to chisel it off. I don't plan on making that mistake again. All finger brace and tone bars are inset into the X by about 1/16". The bridge plate is maple from Rockler. The idea was not to run the grain parallel to bridge pins in order to avoid potential splits. I probably should have researched that decision a little more before moving forward. Thanks for your input. It's given me some things to ponder.

Author:	arie [ Wed Jun 02, 2010 4:13 pm ]
Post subject:	Re: Would like bracing suggestions.
all right. thanks for the reply. "monopole" is the vibrational mode in which the guitars top acts like a piston or drum head moving up and down. it has a large impact on bass production. scalloping the front legs of the X is tricky, but will also free up the long dipole mode which is a vibrational mode associated with projection and percieved power. it's movement is a rocking motion fore and aft and parallel to the neck. freeing up the monopole can also be achieved by thining the top aroound the perimeter and by inserting the bracing into the kerfing just slightly, or not at all depending upon desired tap tone. sorry about what I thought were gaps -kinda hard to tell from the pics that they were pencil marks. planting the bridge pins location along an arc is one good way to run the grain of the bridge patch 90 degs to the top grain and avoid stress cracks. your guitar looks interesting, show more built pics as you progress

Author:	arie [ Wed Jun 02, 2010 4:42 pm ]
Post subject:	Re: Would like bracing suggestions.
Donald: if you were so inclined, I have found these books to be tremendously helpfull: http://www.amazon.com/Fundamentals-Musi ... 804&sr=8-1 http://www.esomogyi.com/books.html

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Author:	Donald V [ Wed Jun 02, 2010 5:03 pm ]
Post subject:	Re: Would like bracing suggestions.
Thanks again Arie. Hadn't heard of the first book, but the Somogyi set is on my wish list. I'll check it out. I appreciate the help.

Author:	Alain Moisan [ Wed Jun 02, 2010 5:03 pm ]
Post subject:	Re: Would like bracing suggestions.
arie wrote: you're off to a good start but IMO I think we can make some improvements. just my 2 cents: -Engleman is not the greatest brace material. too soft and spongy, and won't drive the top as well as sitka or red spruce. -Try scalloping the foward legs of the X. you need to increase monopole action here. -The upper traverse graft is weakened by the scalloping of the ends. go straight across to the rim and butt into a rib brace. -The soundhole strips are weak. too wide and flat. try tall and thin. - I see gaps in the x brace at the intersection and elsewhere on other braces. these need to be fully coupled. tighten up the joint work and try imbedding the smaller braces into the X brace legs. -That bridge pad is odd -slab sawn and at 45 deg to the top grain? what's it made from? try maple or rosewood, quatersawn and 90 deg to the top grain. the top and it's bracing are only a part of what you are after. the rest of the guitar is important too. good luck I have a different opinion on some of Arie's suggestion. Not that mind are better, but I just thought I'd share them. Specially since they are different (which is what the science of lutherie is made of: different opinions...) "-Try scalloping the foward legs of the X. you need to increase monopole action here." Upper arms are rarely scalloped. You need stiffness in that area around the soundhole. "- I see gaps in the x brace at the intersection and elsewhere on other braces. these need to be fully coupled. tighten up the joint work and try imbedding the smaller braces into the X brace legs." Many don't do this (imbedding the smaller braces into the X brace legs. For myself I don't and my guitars haven't suffered from it yet. "-That bridge pad is odd -slab sawn and at 45 deg to the top grain? what's it made from? try maple or rosewood, quatersawn and 90 deg to the top grain. The only thing I see wrong with the bridge plate is that it seems to be pretty thick. Other than that, slab cut and at a 45 degree angle is fine with me. You do not want it at a 90 degree angle with the top grain. That would put the bridge pins in line with the grain, thus favoring a split in the bridge plate.

Author:	David Malicky [ Wed Jun 02, 2010 5:13 pm ]
Post subject:	Re: Would like bracing suggestions.
The pics look reasonable to me, though there are better experts than I on this forum. How thick is your top? I wouldn't go any deeper on the X or LFB scallops, though the transitions to the peaks and X-joint are usually made more gracefully. Your lower X peak locations are similar to Taylor's. My limited experience scalloping/tapering the upper X legs is that it lowers the main top (monopole) frequency a little bit -- still, probably worth doing, if not overdone. Taylor uses a gentle taper starting ~1" from the X-joint. On soundhole braces, flat and ~wide is the norm for Martin and Taylor. Somogyi says different, but that may apply more to a light build. The scallops on your UTB are a conventional way to relieve stress concentrations at the ends. The bridge plate looks a little thick? (0.100" - 0.110" is pretty common.) A rift sawn plate, with grain slightly off 90 deg to the top, is often done to minimize cracks.

Author:	timoM [ Wed Jun 02, 2010 8:41 pm ]
Post subject:	Re: Would like bracing suggestions.
Hi, my first post. I am also building from Kinkead's book. This is #1 for me. My bracework compared to many I have seen seems heavy too. Thought it might be helpful to compare another's braces and top, this is an area of great concern for me also. Thanks T.

Author:	JohnAbercrombie [ Wed Jun 02, 2010 9:27 pm ]
Post subject:	Re: Would like bracing suggestions.
Tim- Are those 'reinforcement' patches on the centerline? If so, I'd shave them down quite a bit if it were my project, but the bit of extra mass probably doesn't make much difference in the 'big picture'. I like to feather the end of braces if they aren't tucked into the lining, but I've seen stub-ended braces in commercial guitars, sometimes with a dollop of glue on the end, so I guess this isn't too important. An interesting exercise for folks who are 'into' (dramatic) scalloping: The stiffness of a brace is proportional to the cube of its depth. Measure the brace depths at intervals along the brace (use mm-makes the arithmetic easier). Cube the depths and plot them on a piece of graph paper. The variations in stiffness are quite dramatic. Cheers John

Author:	Donald V [ Wed Jun 02, 2010 9:38 pm ]
Post subject:	Re: Would like bracing suggestions.
Alright two comments here and a little digging in the archives led me to agree with the bridge plate thickness being an issue. The plans called for 9/64 thick (.140). With some careful chiseling, scraping and sanding I got it down to about .110. Arie, David and Alain: Thank you all very much for your comments and suggestions. I'm going to study them a little more as well as any other comments that come in. T: Welcome to the forum! That top looks almost identical to my first with the exception of yours being much cleaner work. I wish I had lightened up the bracing before I closed up that box, but in the end it still sounds very much like a guitar. HOWEVER, I am here asking questions because I don't know that much yet and would recommend you do some digging around here before taking my opinion on the topic. The archives here are great. Also check out the UMGF bracing library. Lots of pictures there. Most are just lights inside the box but there are a good number of pictures of opened boxes. Here's the link. http://theunofficialmartinguitarforum.yuku.com/topic/847/t/MARTIN-BRACING-LIBRARY.html?page=1 Good luck!

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