What's this called?

[makenzie71]

I hate using a paragraph to explain what I'm doing when there's a "proper" term out there.  I split the last 12" of my stave so that I could glue them back in a recurve instead of using heat.  It's an experiment but was a suggestion...just can't remember what it's called.

Also, I'm working on another bow that I wanted an "interesting look" when done...basically going to be backed in bamboo, then the belly is going to be 1/8" strips of hickory, masquite, elm, and red oak...does a laminate bow become something entirely different (in terms) after so many laminations?

edit:  also curious about this...I've been wanting to take so white oak and bend it into a horseshoe shape, then split it and splice onto the ends of a red oak stave.  What would be the best way to splice?  I would think a V-splice shouldn't be trusted so far out on the limbs but I don't know...I've only really seen it done with horn bows.

[radius]

i know that the cut itself is called a "kerf"  that's the proper term

[makenzie71]

i know that the cut itself is called a "kerf"  that's the proper term

Exactly what I was looking for.  Thanks Radius!

[CraigMBeckett]

Not sure you are correct Radius, a kerf is, I believe, a shallow thin cut, generally used for a lateral cut and when used to aid bending of wood you would perform a number of shallow cuts across a board and then bend it away from the cuts. If I read makenzie71 correctly he has cut his stave longitudinally for 12 inches. Not sure what you would call such a cut.

Craig.

[jthompson1995]

Any cut that does not go all the way through the wood can be called a kerf. A kerf also refers to the thickness of the slot a particular blade will cut. It doesn't matter if you bend parallel or perpendicular to the cuts, the term is the same.

[Dano]

Aside from all the name calling,  I'd worry about splitting a stave the last 12", even if you get a wedge to glue up nice, what's to keep the split from continuing? Also 1/8" is kinda thin for a belly lam, you'll end up going through that during tiller no matter how well you might taper it. Just my thoughts.

[Tom Leemans]

Yup a kerf is a kerf.

Dano, I believe if the kerf extends past the recurve into the limb far enough, it won't split if the thin strip that is glued in fits well and you used some Urac or some other good gap filling glue. It should be cut in though, and not split in. I see why you would be concerned, because he said he split it. I believe you need to plan for wood removal though,(like you eluded to) and still have the kerf near center of the limb, as viewed from the side.
-Tom

[makenzie71]

Also 1/8" is kinda thin for a belly lam, you'll end up going through that during tiller no matter how well you might taper it. Just my thoughts.

It's just something to play with...I have a bunch of strips from other projects and I wanted to try and make a bow from them (I like "scrap" bows).  I'll go through several of them, actually, during the tiller...it might not work at all, though.

I'm still curious about spliced on recurves if anyone has any opinions about that.

Thanks guys!

[ken75]

Mak if your gonna glue up a bunch of thin strips might be fun to make a pyramid bow , let the tiller be in the limb taper to the nocks , just a thought

[0209]

I have absolutely no idea how well it would work with the belly lam idea, but if you could taper it so that the the different lams could be seen as the belly tapers toward the tip that would be cool as hell.  Again I don't know if it would cause any problems if done like this, and I could see how the different woods might act differently in the belly, but if it worked I'd give it two thumbs up.
And for the split down the last 12 inches of the limb could he try and stabilize it by wrapping the entire limb with sinew at that said point?  Again just a thought and seems like a decent idea.  Anyways, have a good one fellas and keep crankin'em out.  Love to see the work.
-Ian

[jthompson1995]

I'm still curious about spliced on recurves if anyone has any opinions about that.

I've never made an asiatic bow or tried to splice recurves, but here's my $0.02 anyway, worth every penny you paid for it .

I would think to splice on recurves you would have to have a good bit of overlap between the recurve you were splicing and the limb you are splicing onto, probably in the form of a straight section of wood left on the recurve piece to attach to the limb. I would also think you'd need to have the recurve trapped between two laminates or set into a kerf similar to what you described above. You'll need to splice them together with a strong, flexible glue and probably wrap them in sinew or other strong fiber, sinew probably being the best as it will shrink and hold the pieces together better. Depending in the design, you'd probably want at least 4-6" of overlap between the pieces.

The big variable would be how the splice will hold together. You could make the splice area non-bending but that would decrease your bending limb significantly and many woods won't be able to handle the extra stress.  Making the splice area bend would be tricky as you'd have to make three pieces of wood bend as one and you'd have to worry about the sinew; it's hard to tiller after applying the sinew and if you tiller before the sinew, you'd be stressing the joint without it being reinforced. It seems kind of risky to do that.

In thinking this through, I can see why the asiatic composite bows used the materials they did. From what I understand, horn would be the best suited material for taking the compression on a short bending limband you'd want to sinew the back to deal with the high tension.

Now the longer you made the splice area, the less likely you would have to wrap the splice since you would have a larger glue are. If you made the splice longer, you could probably get the splie area working and tiller easier but at some point you have to wonder why not just glue up a laminate bow and glue in the recurves from the beginning.

I don't want to discourage you from trying, just pose some thoughts on how I would approach it to try to make it work.

[Kirkll]

this is an interestring concept "ripping"  the last 12" of a stave before bending and gluing the reflex. the term "Kerf" would be incorrect if you are splitting the wood clear though the tip of the stave. The term "Kerf cut" is typically used for shallow cross cuts in a piece of wood to relieve compression in tight radius work for stationary objects like furniture. any time you are cutting wood with the grain it is considered a "Rip".

Now what i would call this procedure you are proposing is a form of "Perry Reflex". what this is going to do IMO, is stiffen the tips dramatically, and allow much smaller tips in the mass department, and shorten your working limb, giving you less string angle.

while shortening your working limb, and getting rid of unwanted mass is a desirable aspect in the form of performance, it does transfer the energy storage to mid limb. i'm uncertain if an unbacked wood stave could deal with localising that type of stress mid limb. but it's a perfect recipe for a laminated bow.  the use of "Tip wedges" have become very popular in composite building.   

Kirk

[zenmonkeyman]

If I might weigh in here, a common woodworking technique to prevent splitting at the bottom of a crack or kerf is to drill a hole where the kerf ends.  The radiused end of the kerf then transfers forces around the weak spot.  And if it's become a poll, I'm for calling it a kerf too.

[Dano]

I think rip is a better term, Kerf in Websters, is a channel cut by a saw, that's pretty easy to understand.

[CraigMBeckett]

Seems I sparked a bit of disagreement here over the use of the term kerf.     To me a kerf is a shallow trench, a deeper cut would be a trench or if laterally across thinnish wood a notch, if deeper then a deep trench/notch, finally if deep and thin I would just call it a cut or if it cuts in longitudinally a rip. English is a language rich in words that have similar meaning but are used to indicate slight differences.

makenzie71, to prevent splitting from the bottom of the cut I would do as zenmonkeyman suggests, but would glue a dowel of the diameter of the drill in place.

Craig.