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Update on 120# yew warbow - I don't like to complain, but...
WillS:
Here's a quick pic of the unbraced shape (the top nock exploded on me AGAIN so I have to order more horn and have a third attempt - crazy!) so I can't brace it, but you can see where the string follow is starting to show on the left (upper) limb.
If I brace the bow, and then immediately unbrace it, the left limb takes about 2 full inches of set before settling back to this, which is just under 1 inch. It's pretty frustrating, I have to admit. I could live with a bow that takes around 2" of set after being fully shot in at 32" because that's about normal for a heavy bow but to take that much just literally from bracing? Horrible.
The right limb is now a full 5mm thinner than the left and is still so stiff that the brace shape is completely off. If I take any more off the right limb it's going to look really daft.
meanewood:
OK now this is a dilemma I have encounted with an Elm bow recently and I'm not sure what the answer is!
The Elm stave had 3 undulations over its length. I start off like most people by roughing out both limbs to the same thickness.
Now when the stave is bent it is constanly checked to see if it is bending evenly and small amounts are taken off where it is stiff in order to ensure the wood is stressed evenly. That's easy when it's a straight piece to begin with, but how can you determine what may be a stiff area when the arc is uneven because of the undulations!
If you find one limb is becoming a lot thinner in an area compared to the corresponding area of the other limb, then the stresses are becoming uneven, even though the tiller 'looks' better.
Would it be fair to say, if the stave has undulations, the undulations should still be present even at full draw and be very wary of trying to tiller them out?
toomanyknots:
Well if you assess the the situation, I haven't seen the tillered profile of this bow, but given that you say the right limb is making the braced profile off from being stiffer than the left, I would guess it is stronger still (despite whatever the stave looked like to begin with) and I would guess that the tiller is off as well when being drawn. You wanna go easy on the bow for the most part when you don't got everything doing what it is supposed to. It's not the stiff limbs fault it is making the profile (or tiller) off, you need to weaken it to even out the tiller if it's too strong, and don't go drawing the bow out real far until you got a tiller you are happy with. I'm sorry the nocks broke again, this bow is really making you work for it! I mean this is just my guess at what is going on, I don't know what the tiller looks like, but it sounds to me like you need to weaker a stronger limb. if you get too frustrated with it, sometimes it is better to just let it be for a while, I usually am more prone to making mistakes when I am frustrated or in a hurry.
toomanyknots:
--- Quote from: meanewood on January 12, 2014, 12:19:45 am ---OK now this is a dilemma I have encounted with an Elm bow recently and I'm not sure what the answer is!
The Elm stave had 3 undulations over its length. I start off like most people by roughing out both limbs to the same thickness.
Now when the stave is bent it is constanly checked to see if it is bending evenly and small amounts are taken off where it is stiff in order to ensure the wood is stressed evenly. That's easy when it's a straight piece to begin with, but how can you determine what may be a stiff area when the arc is uneven because of the undulations!
If you find one limb is becoming a lot thinner in an area compared to the corresponding area of the other limb, then the stresses are becoming uneven, even though the tiller 'looks' better.
Would it be fair to say, if the stave has undulations, the undulations should still be present even at full draw and be very wary of trying to tiller them out?
--- End quote ---
Now to me, none of this pans out. It is all fine to say / assume / theorize that the wood cells are stressing more than others if the tiller looks good, and character bows need to be tillered according to their every bend and hump, but in reality if you take a stave with a bunch of deflexes and reflexes in the stave, and get the stave working evenly to where all the reflexes and deflexes bend the same amount, the bow is gonna take lots of set in the deflexed areas no matter what you do. You have to leave the deflexed areas stiff. And if any of the deflexed areas are near the outer limb, you are gonna have a stacking unpleasant to shoot bow. The deflexed areas are like built in set, they are already bent persay, they don't need too much more bending usually in the tiller.
--- Quote from: meanewood on January 12, 2014, 12:19:45 am ---
I start off like most people by roughing out both limbs to the same thickness.
--- End quote ---
When you rough out a stave with reflexes and deflexes before floor tiller, it is smart to leave the deflexed areas thicker, as they will be the weakest link in the tiller, and most likely and damaging to hinge, darn near impossible to fix if hinged, if the deflex is real pronounced like on snakey staves.
WillS:
--- Quote from: toomanyknots on January 12, 2014, 12:28:10 am ---Well if you assess the the situation, I haven't seen the tillered profile of this bow, but given that you say the right limb is making the braced profile off from being stiffer than the left, I would guess it is stronger still (despite whatever the stave looked like to begin with) and I would guess that the tiller is off as well when being drawn. You wanna go easy on the bow for the most part when you don't got everything doing what it is supposed to. It's not the stiff limbs fault it is making the profile (or tiller) off, you need to weaken it to even out the tiller if it's too strong, and don't go drawing the bow out real far until you got a tiller you are happy with. I'm sorry the nocks broke again, this bow is really making you work for it! I mean this is just my guess at what is going on, I don't know what the tiller looks like, but it sounds to me like you need to weaker a stronger limb. if you get too frustrated with it, sometimes it is better to just let it be for a while, I usually am more prone to making mistakes when I am frustrated or in a hurry.
--- End quote ---
The trouble is, while common sense (and even the most basic bow making experience) says "stiff limb must become thinner to even out" how far do you let it go?
When I look at this bow now, unbraced, there is a real obvious difference in thickness from upper limb to lower limb. It's nasty to look at, and almost looks like two different bows butted together in the handle the difference is so obvious. It's really going against all logic and common sense now. I guess what must be happening is I'm missing something fundamental and assuming that all the problems are in the stiffer limb so I'm constantly thinning that limb, and the problem isn't being sorted. I'm ending up with one limb a nice even taper and a good thickness for the draw weight, and another limb that looks like it belongs on a 50lb target bow wedged up against it! When it's braced, it looks like one limb (the one that started with reflex) is still too stiff, but simple common sense tells me that it can't be that anymore.
Somebody with a whole lot more experience than I have in making warbows has kindly offered to help out, and I'm not gonna touch this horrible thing until I know what I'm doing. It's super annoying though, because this was the first stave I paid a lot of money for as a "premium" warbow stave (yeah, I know...!) and there is literally nothing wrong with it - no dips, no knots, no cracks nothing and would clearly have been able to make a really top quality warbow. And yet with my inexperience and rushing I've almost certainly wasted a really nice piece of yew which is a travesty! I'll be lucky to get something over 100# once the tiller has been sorted out and that's a real shame. Hopefully I'll learn from this...
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