Acoustic Guitar Construction

Hi All
I just started another guitar and I will be using Traditional Kerfing for the first time, on the other guitars I used Reverse Kerfing. I was just wondering if anyone has an opinion on the traditional Kerfing, both pro and con. I like the looks of both the traditional Kerfing and the reverse Kerfing, but I think the reverse Kerfing would be stronger. Any thoughts?

Thanks
Charlie

RR makes the rim stiffer for sure and I like the look -- traditional is a little easier to install. RR is a little newer design but hey -- tens of millions of guitars have been made with triangular kerf lining so I am sure its works just fine.

If you do use traditional kerfing, use the type that is sometimes called triangular flat (compared to just flat). It has extra top thickness for sanding the rim.

Hi
Thanks for looking and the comments.
I just finished gluing up the traditional Kerfing on the current project, and I must say there is a difference between the reverse and the traditional Kerfing, in how it effects the stiffness of the rims. I guess my comfort zone is having the rims more stiff, so I plan on using the reverse kerfing in the future.

Thanks again

Charlie

Reading the Gore/Gilet books, I noted that they recommend kerfed lining to attach the back to the sides, but they go with solid lining to glue to top to the sides. They say that they're looking for the most solid possible connection there. In that spirit, but unwilling to attempt solid linings, I attached reversed kerfed linings to my sides (both top and back) and then filled the kerfed slots with wood filler before contouring on the dish. (On my second build, going on now, I've filled the slots from both the out-facing side and the in-facing side because the partially-filled slots, visible through the sound hole on my first build, looked shaggy.)

Hans Mattes wrote:Reading the Gore/Gilet books, I noted that they recommend kerfed lining to attach the back to the sides, but they go with solid lining to glue to top to the sides. They say that they're looking for the most solid possible connection there. In that spirit, but unwilling to attempt solid linings, I attached reversed kerfed linings to my sides (both top and back) and then filled the kerfed slots with wood filler before contouring on the dish. (On my second build, going on now, I've filled the slots from both the out-facing side and the in-facing side because the partially-filled slots, visible through the sound hole on my first build, looked shaggy.)

I not sure you need to fill, The stiffness of the reverse lining comes from the fact that the both sides of the kerfed linings end up strapped. Sort of the way an I-Beam works. Even Gore says that reverse linings are a good substitute. I am not sure that the filled kerfs will add any stiffness. Maybe a bit of mass.

While filling the slots in reverse kerfing is certain to add some stiffness (the filled kerf opening can't do a parallelogram twist) it may well be very insignificant. I do like the looks of the filled kerfing on the inside, however. It almost looks like solid linings. It is a bit of work, though, as the inside of the sides must be carefully masked with tape before filling the slots and then, after the tape is removed, the kerfings must be carefully sanded. It takes me so long to build a guitar, though, that the time spent here is not a big deal.

Regarding the extra weight -- Gore/Gilet (vol. 1; pp. 2-28 to 2-31) show Chladni patterns for the top of a traditionally-built guitar and for a similar guitar with about a pound of steel rigidly affixed to the sides. The fundamental node line of the top was moved from ~1½" from the edges of the lower bout to ~½" from the edges by adding the weight. Apparently, with weighted sides, the sides and back don't move as much in opposition the center of the top, including the bridge. So I weighted the sides of my build (using 4 weights) and am very pleased with the resulting sound. As an experiment, after building the guitar, I removed two of the weights (that's all I could reach through the sound hole), and the lightened guitar wasn't as loud or as resonant. On my current build, I've divided the weight into seven pieces which I've distributed around the sides of the lower bout. We'll see what the results are, but I'm optimistic, based on the earlier result. Of course the added weight makes for a heavier guitar, which some (most?) folks won't like.