Cuban Mahogany and Lutz Spruce 00

[Darryl Young]

Tommy, the benefit may depend on if your Catholic or Baptist! <smile>

So with the caveat that there are different philosophies, here are a couple of points.

Solid linings are definitely stiffer.......which most folks like.

Solid linings are heavier.........which some like and others don't.

I've wanted to try them and after reading Trevor Gore's book, I decided to give it a try. The thought is that stiffer, more massive sides will reflect more of the tops vibrations back into the top so there is less dampening. Also, if the top has more mass to push against in the lining, the bridge area may move up and down further so can move more air therefore louder. In other words, a top at the same stiffness would have more movement.

So that's the theory but I'm guessing not everyone believes it.

[BEJ]

Nice build going here, a question on the solid bindings, why did you choose ash? My experience with ash is it has wide spaced growth rings, some of the nasty splinters you run into, stiffer and tougher than hell, seems like there are easier woods to work with for shaving and sanding. Maybe you got better ash then we get out here.

Anyway nice work on the solid bindings, I like than you give a reason for doing something different than the norm what ever that is. The more I read on steel strings it seems like there isn't a norm just a range to work within with loosely defined boundries. Maybe after I get a build or 2 under my belt I might be able to add something to the conversation.

Bruce,

[Darryl Young]

I chose Ash for two reasons. One, Ash was recommended in Trevor Gore's book for solid linings. Two, I have several old, flatsawn Ash boards out in the shop.........and I like using seasoned wood and working on the cheap. The flatsawn works perfect as when you cut strips off the side of the board, they are perfectly quartersawn. Also, there is northern Ash, and southern Ash. The southern variety is lighter and more porous. This is the northern variety which is a bit more dense and a bit less pores (though still porous). I think the southern variety is what is typically used for bodies on electric guitars and basses since it's lighter weight.

[Darryl Young]

Thursday night I glued the solid linings to the rims. I'm using it under the soundboard. A while back before I decided to go with solid lining, I purchased enough reverse kerf lining for a guitar. Since I have it on-hand, I might as well use it up so I'm using the reverse kerf lining for the back. I have enough left for the back on one more guitar and after that, I'll likely use solid lining for top and back.

Tonight I sanded the back of the rim level in my 16ft radius dish. The neck and tail block were a bit proud so I put my focus there initially till I had it level with the rim. I then marked the sides with a pencil and sanded till I removed all the pencil marks.

I then tried flexing the mahogany RK lining to fit the tight waist of the 00 and it wouldn't do it without breaking. We have a faucette in our kitchen sink that puts out 190F "steaming hot" water so I ran the RK lining under this water and then it easily bent to the 00 body shape even in the waist. I clamped the lining on the outside of the waist to let it dry and tomorrow night I'll glue it to the rim.

I'm curious, to follow the back radius contour exactly, the lining would need to flex up/down to rise into the waist area and then fall back down to the level at the apex of the bouts. The lining flexes sideways but doesn't flex up/down. Well, there is a slight amount of flex.......so last time I did the best I could and if the lining ended up slightly proud of the rim, I just sanded it down to the rim later in the dish. So how do you guys handle this?

Here is a shot of the lining clamped to the outside of the rim where it can dry out while held in the shape it needs to be. You can see the solid, Ash lining glued to the rim on the far side where the top will glue.

FormingReverseKerfLining.JPG

[JVan]

keep the photos coming , Looks like that will be a sweet git!

So with the caveat that there are different philosophies, here are a couple of points.

Solid linings are definitely stiffer.......which most folks like.

Solid linings are heavier.........which some like and others don't.

I've wanted to try them and after reading Trevor Gore's book, I decided to give it a try. The thought is that stiffer, more massive sides will reflect more of the tops vibrations back into the top so there is less dampening. Also, if the top has more mass to push against in the lining, the bridge area may move up and down further so can move more air therefore louder. In other words, a top at the same stiffness would have more movement.

So that's the theory but I'm guessing not everyone believes it.

Darryl,
Although well reviewed, that Gore set is pretttty pricey. What's your overall opinion of the books and how strongly would you recommend a purchase? Any other Gore theories you'd like to share would be appreciated; either here on the Forum or in PM. Thanks.

tommy

[Kevin Sjostrand]

You are getting right along there Darryl.
I always glue the kerfing proud about a 1/16" or a little less and then it sands dow flush to side and you get a little bit of that radius on them. They do flex a little bit, but not much. The solid linings would be a different story I bet, especially on the back with the front to back contour. I'm not sure how you would work with that.

Kevin

[Darryl Young]

Tommy, the whole book is full of theory. Gore approaches everything from a physics/engineering standpoint. He doesn't just give a formula, he derives the formula so in that sense, it's similar to a college textbook. After reading it I was much more aware how the top, back, and main air resonances are coupled together and not independent.......so play with one and you play with all. He gives strategies for tuning these resonances. If you are technically oriented, then the book is well worth the money.

[Darryl Young]

Glued the reverse kerf lining to the rim last night and today at lunch I removed the clamps and cleaned up the excess glue with De-Glue Goo (good stuff).

I'm about ready to tune the soundboard and back. I went ahead and did the basice trimming to the braces on the soundboard and back.......tapered the upper legs of the X-Brace arms, scalloped the lower bout braces to nothing next to where they meet the lining, trimmed the ends of the upper bout braces down to roughly 1/4" where they will inlet into the lining (will reduce more later), triangulated the shape of the braces (looks like I forgot to triangulate the finger braces), lightly scalloped the lower X-brace legs, capped the X-brace, etc.

So I wanted to document where I'm currently at to compare with where I end up. First, here is a pic of what the bracing currently looks like.

IMG_0760.JPG

I recorded myself tapping the sounboard using the Analyzer Lite software on my IPhone and here is frequency distribution chart (Fourier Analysis?) of the tap. Below, note in the upper half of the picture the yellow line has peaks where there is more volume. This corelates to vibration modes on the soundboard.

AnalyzerLite.JPG

Note the tallest peak (the loudest frequency) is at 270Hz and it is the main frequency of the soundboard. That is quite a bit higher than I want it which is down in the 220Hz - 240Hz range. So now I wanted to see what the Chladni pattern for this frequency looks like right now. It should be the ring and a half mode but at this stage the ring in the lower bout probably doesn't form a ring. So I set my frequency generator up for 270Hz, sprinkled sawdust, and this is what the node lines look like (node line is the area of the soundboard that is NOT moving at this frequency).

270HzBeforeTuning.JPG

Pretty ugly as the "ring" opens up at the bottom and in the corner of the bass side of the lower bout. Also, I don't like that "kink" in the node line on the treble side of the lower bout. Hopefully, I can improve these.

[Darryl Young]

Note on the frequency spectrum pic in the post above that there are several peaks across the spectrum. Each of these corresponds with a vibration mode on the soundboard. I set the frequency generator to the frequency of each of these peaks and here are the Chladni patterns it generated.

235 Hz:

235HzBeforeTuning.JPG

334 Hz:

334HzBeforeTuning.JPG

413 Hz:

413HzBeforeTuning.JPG