Primitive Archer
Main Discussion Area => Bows => Topic started by: willie on January 08, 2017, 10:30:19 pm
-
Can anyone comment on using Yew for a belly in a laminated or composite bow? What has worked for you and what has not worked?
Thanks
Willie
-
I've made three bamboo backed yew bows, if that counts. It's a great combo.
-
Heartwood is great belly wood. I usually glue in 2"-4" of reflex depending on the type of bow and backing.
-
DC-
I am curious as to whether you realized any differences in performance over a yew self-bow? Other than the extra work making a laminate, are there any down sides or advantages?
Bryce-
what do you look for in your backing choices?
-
My #1 choice is Moso bamboo and if you need a slat let me know.
My second choice is maple; and a good maple backing is pretty easy to come by. Straight grain is a must with any backing. 1/8" or so is plenty thick enough. But I like to taper my backing from 1/4" @ the handle to 1/16" @ nock
Can also use hickory and white oak
-
Yew heartwood makes a great belly, I've done Yew/Boo and Yew/Hickory and Yew/Yew (that's Yew sapwood backing strip from a log that had V thick sapwood put onto a Yew heartwood belly. All worked really well.
I have a secret plan to try Yew /Hazel... but don't tell anyone, I want to be the first to try it ::)
Del
-
I've made bamboo backed yew d/r bows, and made a couple where I kerfed the outer limb and slid a 12" lam in there so I could bend it into a full recurve during glue up.
I have also made trilams with bamboo and yew, and made one with a bamboo back, yew core, and osage belly. It's a deflex/semi recurve, and likely the best bow I've made.
Bamboo and yew is an awesome combo. I tested 3 bows of identical profile and draw weight... a d/r bamboo backed yew, a bamboo backed osage, and a laminated glass bow with maple lams. The yew bow beat them handily.
I would be sure to trap the limbs as the bamboo can overpower the yew in some instances... say if its limits are pushed otherwise.
-
Thanks, Bryce, Del, and DWS
seems like even a softer and lighter wood prefers a stiff backing.
How exactly does one tell if the backing is overpowering the belly?
-
Thanks, Bryce, Del, and DWS
seems like even a softer and lighter wood prefers a stiff backing.
How exactly does one tell if the backing is overpowering the belly?
The belly will chrysal...
I've done a heat treated Yew heartwood belly in a D/R shape and then boo backed it... V quick :)
Del
-
DC-
I am curious as to whether you realized any differences in performance over a yew self-bow? Other than the extra work making a laminate, are there any down sides or advantages?
The jury is still out on that. My gut says boo/yew is better but so far the chrony says the difference is marginal. But I'm reasonably new at this and I've only made 3 boo/yews. It's a great way to use up yew heartwood offcuts. Splice together some scraps and end up with a primo bow.
-
DC-
I am curious as to whether you realized any differences in performance over a yew self-bow? Other than the extra work making a laminate, are there any down sides or advantages?
The jury is still out on that. My gut says boo/yew is better but so far the chrony says the difference is marginal. But I'm reasonably new at this and I've only made 3 boo/yews. It's a great way to use up yew heartwood offcuts. Splice together some scraps and end up with a primo bow.
I think the big advantage of boo/Yew is that the back is clean and homogenous so it won't break.
The breakages I've had with Yew have all been the back giving way (usually at a knot or row of pins).
I had some Yew heartwood and wanted to make a boo Yew for a mate of mine, he said he'd rather have yew backed Yew (as I had a slat of Yew sapwood), he wanted a fast ELB with just a hint of R/D. It was a great bow for 2 years when the back gave out >:(.
I made him a new one Boo/Yew this time ::)
Del
-
There seem to be a few different backings mentioned so far, along with a few recommendations for application, and even some suspicions that there might not be much in way of performance gains, to be had.
Since knowing yew is hard to beat for a belly, perhaps knowing just how much backing to apply is critical to getting good results. Both tapering and trapping proportion the back to belly ratio, and the choice of backing species raises even more possibilities about proportions, if some backings are stiffer than others.
It was a great bow for 2 years when the back gave out >:(.
Could it be that a backing that just barely keeps the back from letting go, is what separates the great from the overpowered or marginal?
How exactly does one tell if the backing is overpowering the belly?
"The belly will chrysal"...
yes, of course, a simple answer to a simple question. Allow me to rephrase that....
Is there any way to tell during tillering, whether one should reduce the belly or the back to prevent overstraining the belly?
Does an overpowered design "get to thin" during tillering, or are there other observable effects to guide the tiller along?
I hate to think that laminated bow design is all "try it and see", with so too many variables to work with on the next try.
And if laminated bow design is only a process of one by one design elimination, what observations can you guys make about the bows that came in with marginal results?
underweight?
low early string tension?
doggy limb action?
thanks again for any comments
-
seems like even a softer and lighter wood prefers a stiff backing.
Yes, BUT! Before acting on this conclusion outside this particular circumstance, remember that yew, for all its light physical weight, is uncommonly ELASTIC in compression. Take most other woods of the same physical weight, and use them in the same bow, .....you'd be sorry.
In my experience and reading on forums, ERC and juniper would act much the same, but not most hardwoods in that approximate weight range. I'm beginning to believe plum might, but....
I have never made
-
I would be sure to trap the limbs as the bamboo can overpower the yew in some instances... say if its limits are pushed otherwise.
I've never had that experience with yew...
-
The Boo/Yew bows I've built were roughly rectangular section limbs. The Boo backing was pertty thin at the edges due to the natural crown, but there was no deliberate trapping of the back.
Del
-
"I hate to think that laminated bow design is all "try it and see", with so too many variables to work with on the next try."
It isn't, but it is a series of educated guesses.
The main thing to understand with laminated bows is how to get close to what you want to begin with. For instance, yew is very soft. It is not very stiff. It is great bow wood because it will tolerate a LOT of bend, not because it "adds power". Thus, it lends itself to narrower deeper profiles (thick wood is stiffer but bends less before taking damage, but yew can be thicker than most woods and bend the same amount). Since it is already light, this is kind of a double savings AND it can be laminated or worked as a flatter, wider limb, too, and do very well as long as it's thick enough to get the draw weight(stiffness) you want.
Also, because it readily takes compression bending, you can back it with bamboo, hickory (super stiff backings), maple or elm (medium stiff backings), or even rawhide and sinew (stretchy backings) and the yew will work with it one way or the other, within reason.
We talk a lot about backings overpowering belly woods, but bellies can overpower backs, too. In fact, when any bow breaks, one of two things happened; the belly refused to compress and the back stretched more than it could take, OR, the belly failed, usually by fretting, and the hinged spot put a kink in the bow forcing the back to stretch more than it could take right at that tiny spot. I mean, if we don't count things like delaminations and tips blowing off....
The bow that Del mentioned failed at least in part because, while yew sapwood is incredibly tension strong, since he had a "slat" of it, he had certainly cut through growth rings while cutting the slat. Thus, as he says, the bow would have survived much longer with a bamboo backing.
And Bryce has not had backing overpower yew, because yew is so elastic.
Stiff hard woods just need to start off thinner back to front, and elastic woods can be a bit thicker.
-
What is trapping?
-
Sorry. Trapping refers to removing wood from the front corners, creating a narrow front and a wider back, thus a TRAPEZOIDAL cross section. Trapping is done to balance strong backs and medium or weaker bellies, or just to balance tension and compression. Tough woods like elm, some maples, hickory, that are not super dense or super strong (or super elastic) in compression do really well to have either a crowned back as from a sapling, or trapped limbs so there is less back and more belly surface. This helps avoid set and helps avoid more limb mass than needed.
With backings it serves the same function. Bamboo is very tension strong (won't break) and tension resistant (won't stretch), which makes the belly wood really squish a bit more in compression. So, while I may not trap a bulletwood or osage bow backed with bamboo, I would trap a bamboo-backed black locust, muilberry heartwood, or goncalo alves
-
I have a secret plan to try Yew /Hazel... but don't tell anyone, I want to be the first to try it ::)
Del
It's already been done ;)