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[Gavin Baird]

I have posted several times on the subject of using reverse kerfing. I am wondering why there has been no significant response to the concept of this method. Is it because the material is not available or is it because it is not traditional? In any case I have been using this technique for many years and certainly understand the advantages of its contribution to the stability of the instrument. If any of you dedicated builders out there have constructive comments to make, I would certainly be interested in hearing them and perhaps carrying on a dialogue....Gavin

[tope]

Gavin, I have seen your method before in prior threads and your recent input on the rim not fitting the back of the IV kit got me thinking again. I have always thought that the way you make kerfing is probably a good way to make a stable rim assembly. I just haven't had enouph instability in my rims to give me the impetus to persue the new kerfing strategy.
I'd like to hear others thoughts.

[Dave Cohen]

I've been using reverse kerfed linings for about two years now, and I like them. They result in a much more stable, rigid rib set, and seem to be easier to execute. I have been making my own linings from spanish cedar, with ganged blades on my table saw. I apply them to the ribs in a rectangular cross section, as they seem to be easier to glue up tightly that way. I then carve a bevel onto the linings with an Ibex plane. The resulting rib sets are sufficiently rigid that the plates could probably be glued to them sans mold. What else can I say? I wish that I had seen yours before I re-invented the wheel myself.

[Gavin Baird]

Thanks for reply Dave. It just seems to me that the structrual aspect of the body is a significant factor not to mention the maintaining of the body shape. If done correctly you can rest assured that when you go to bringing the body to correct width that the reverse kerfing allows the process to occur without the problem of irregular widths due to the lack of stability of the assembly. I use a thickness sander to bring the assembled sides and blocks to width and can easily achieve +/- .005. It is every bit as easy to apply and the gluing face is the same as the regular kerfing...gavin

[Hans]

Gavin, sounds interesting...believe I'll give it a shot on my next set of ribs. I can only see advantages. Should be able to cut it out of the same guitar kerfing stock I'm using now.

[David Houchens]

I would like to see a picture of this if you could. Thanks Bryce

[tope]

Here is a link to the thread that contains a pic of the kerfing being discussed.

http://www.mandolincafe.net/cgi-bin....t=30735 (http://www.mandolincafe.net/cgi-bin/ikonboard.cgi?act=ST;f=7;t=30735)

[Gavin Baird]

Hans,
If the kerfing you are using is rectangular you will be able to use it. If it is tapered you won't be able to. What I do is to cut the blanks from Bass Wood 5/16" x 1". I then thickness sand the blank to .250" thick. Next I saw the kerfing slots, using a no off set blade [.062"] using a fixed stop to index. It takes a while but when you are finished you have a double set of blanks for your effort. The finished part is then resawn to the required size of 3/8" wide. I then use a jig that presents the blank to the thickness sander that removes that portion of the blank that I want to become the taper.
I think you will find that the use of this type of Kerfing will present you with a noticable difference in the way you are able to do the assembly and fitting of the body cavity....If I can be of any additional help or source of concepts, feel free to contact me.....Gavin

[Stephen Perry]

Why not use bent lining?

[Dave Cohen]

Solid (bent) linings will work fine in mandolins and guitars. They are sometimes used at the juncture between the ribs and the back plate on classical guitars. I used a bent laminated lining on a mandolin which I built with a screw-on back for experimental purposes. I pre-bent three 1.5 mm (0.060") strips and glued them together in place on the ribs in the mold. That way, I didn't have to jump through hoops regarding placement of all of the #2 x 3/8" screws for holding on the back plate.

On the other hand, violin linings are rather small compared to mandolin, and especially guitar, linings. Pre-bending a strip which is approximately 5 mm thick to a mandolin body shape is a bit of a frustrating task, particularly in woods like spanish cedar, basswood, etc. It is accomplished much more easily by making kerfed lining. Additionally, with the reversed kerfed lining, there is no loss of rigidity, and you accomplish that rigidity with less mass. So with the exception of linings made for special tasks such as I described above, I much prefer reverse kerfed linings.

[Stephen Perry]

I see. Do mandolins really require such substantial linings? I have no trouble at all with 2 mm thick violin linings of spruce and suspect I could bend a 3 mm or maybe more without any particular trouble. Of course, one can bend rather thick wood with steaming and probably other ways. Chairs and many other things use thick bent wood. I just wonder whether the gap in the longitudinal fibers of the wood is good, bad, or doesn't matter. Tests I can think of all seem a good deal of trouble!

[Gavin Baird]

Steve,
I think Tores used individual triangles of wood spaced apart from one another, so I don't think that is a problem. Steinway Piano company feel that the structrual integrety of the sides of the instrument is critical to the overall performance of the instrument. I don't believe it is the strength but rather the rigidity of that section that seperates the top from the back that is the important concept...G

[Dave Cohen]

Those triangles Gavin is referring to are called tentellones. They are the classic Spanish way of making linings.

I think that the 5 mm or so lining width used in mandolins is necessary, since (unlike violins) the part of the spruce top over the ribs is often entirely routed away to make way for binding.