Primitive Archer
Main Discussion Area => English Warbow => Topic started by: AH on March 26, 2013, 03:12:05 am
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I am currently working on a yew war bow, just thought I'd share a few pics with you guys and take some advice. Tiller check, anyone? I'm still at 21" on the tiller, I don't really want to take it any farther until I get my pulley tiller tree set up, that way I won't get as much set and if it explodes, It'll blow on the tree and not while I'm pulling the string down on a tillering stick. this one is 77", made of pacific yew, 40 rings per inch, it's a pretty dense stave. It has go one nasty knot, but it seems sound and I have left a mountain of material around the knot.
I also have another yew war bow stave that I got from Carson at echo archery, but it'll be a while 'till that one gets on the tiller tree.
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thought I'd include some pics of the other stave:
This one is denser than the stave I currently have on the tiller, I can't really count the rings but I think it is around 60 per inch. It's also got a nasty knot which I've left a mountain around, but I'm not done roughing out yet. Thanks, Carson for the awesome stave!
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well, id say your left limb the one with the knots needs to bend evenly with the other one, and maybe better not touch the outer part of the right limb. Of course, make sure not to work those knots very much, better to have them stiff and have to correct that than to have it hinging at all the knots, but in general the limbs are imbalanced
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The right limb looks alright, although it may end up being slightly whip-ended by the time you get to full draw (not necessarily a bad thing for a warbow, as mentioned in TBB3)
Is it possible to see a pic of the knot? Yew can take some crazy violations unlike other woods and you may be playing it a bit too safe!
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+1 for what Iconmuffin said.
Knots are tricky.
IMO they still have to do some work else you are are just overloading the rest of the limb, and they are ok in compression, they just have zero strength in tension as they aren't really connected to the rest of the wood, they are like an unglued plug.
Check check and check again that the back is sound over the knot, if you have a good clean unbroken layer of sapwood you can reduce the belly to match up with the rest of the bow (ok, maybe just a whisker thicker). Check the knots ar sound.. any big knots on the belly that don't appear through onto the back ahould make you ask.. where do they go? If they have grown over, is the wood sound or rotten whener it's grown over.
When I get that situation I pick away at the knot to find out what's going on inside, but DON'T go through and disrupt the sapwood back.
Del
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The right limb looks alright, although it may end up being slightly whip-ended by the time you get to full draw (not necessarily a bad thing for a warbow, as mentioned in TBB3)
Is it possible to see a pic of the knot? Yew can take some crazy violations unlike other woods and you may be playing it a bit too safe!
yes, I am aiming for a bit of an elliptical tiller.
If by playing a bit safe you're saying I left too much wood around the knot, I figured that I would rather be safe than sorry and gradually reduce the thickness. if this thing blows while I'm still at 22" on the tiller I'm going to be pretty miffed.
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Agreed, definitely better to be safe than sorry. However in some cases too much wood around a weak spot stops you seeing the true amount the wood is working.
What kind of knot is it? Does it appear on the edge, or is it contained within the center of the limb?
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Right limb is getting whip tillered. Leave it 'til you get the left limb sorted. At some point, you're going to have to remove wood on the belly side under that knot to get that portion of the limb working. Leave the knot proud on the back, bet get that portion of limb reduced on the belly side.
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Did a little more tillering today, I got the left limb bending more but now it seems like it's pretty whip-tillered. The bow also seems rather underweight, it's
1 1/2" by 1 1/4" in the handle, yet it seems like it's rather light. ???
I'm not really happy. wish I could of gotten more work done but I was losing light and had no time to work on the bow after dinner.
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i believe that because those inner limbs arnt bending very much that your weight is effected by this, if you get the limb with the knots bending close to the other one then you should be in good shape, i think maybe your finding that the weight is low because the tips are doing more bending.
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i believe that because those inner limbs arnt bending very much that your weight is effected by this, if you get the limb with the knots bending close to the other one then you should be in good shape, i think maybe your finding that the weight is low because the tips are doing more bending.
So remove from the inner limbs, yeah? It makes sense, just seems ironic to me that removing wood could bring up the weight... ;)
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if the wood is too stiff its not stressed like it could be.
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That's not exactly how it works. If it's hinging close to the handle, it can make the limb seem weaker than it really is because a little excess bend at the handle causes the tip to travel a lot further. In that case, if you get the rest of the limb working and eliminate the hinge, the limb will be stiffer than when it was hinged. In your case, where its the outer limbs bending too much, the only way to fix that is to get the inner limbs working more, causing more tip deflection as you get it working closer to center. In short, you're gonna lose draw weight when you correct a whip tiller. If it were me, I would pike it now if your sure its gonna be under your desired weight and then retiller. Josh
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I couldn't resist messing around with photo editing programs.
I really just stretched the picture down to get an idea what the tiller will look like in the end if I leave it like this, which I won't...that whip tiller becomes a pretty bad hinge.
Since this is my first real heavy war bow attempt (all my others were 80 or lower) what do you guys think I'll land around? I'm at about 50 pounds at 22".
I'm not really going to rely on this stretched picture, I have serious doubts about the accuracy of this method anyway. I just think it lets me see potential weak spots easier.
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If you continue in the same way, you'll obviously end up with 50# at 32"
As an example I'm making one now, the guy wants 70# at 28", but capable of drawing out to 32"
Now I've got it to 70# at 28", but as I come back further, two factors come into play.
1. It will take a little set.
2. The tiller may need slight adjustment.
This means that once it's back to 32" it will probably no longer be 70# at 28", prob more like 65#
IMO I've screwed up and I should have insisted on specifying the required full draw weight at 32" so I could have been tillering to this from day one. (OK maybe a bit uder in the early stages).
The basic principle remains tiller to full weight else you'll come in under weight.
Del
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remove most of the knot and DO NOT touch the tips :o
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Yeah, that's a bit more concise than my post ;)
+1
Del
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Agreed. DO NOT remove any more wood from the tips! You gotta bite the bullet and reduce the limb thickness on the belly side under the knot. If it holds, it holds.
Also, I believe it to be bad practice to pike most bows, especially if you made the mistake of whip tillering it. ALWAYS start out with a goal in mind. If you come in under weight because of inexperience, and you have extra limb length, then maybe pike it. However, intentionally starting out making a bow longer than optimal design (with intentions to pike it) is also poor practice. When it comes to warbows, and heavy warbows, you want as much limb length as is reasonable. The bow will likely take less set and will probably last much longer. Piking away mistakes doesn't solve the initial problem.
And Del... yes, you're right... if a customer wants to draw his bow to 32", you have to tiller it to 32", and start out with that end result in mind from the beginning. The important thing is how the tiller looks at full draw, not 4" less. If he wants a certain weight and tiller at 28", and another at 32", he needs two different bows IMHO. That is definitely what I would advise. I think your guy is looking to work up to a longer draw, and wants two bows in one. Not something I'd do.
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And Del... yes, you're right... if a customer wants to draw his bow to 32", you have to tiller it to 32", and start out with that end result in mind from the beginning. The important thing is how the tiller looks at full draw, not 3" less. If he wants a certain weight and tiller at 28", and another at 32", he needs two different bows IMHO. That is definitely what I would advise. I think your guy is looking to work up to a longer draw, and wants two bows in one. Not something I'd do.
Yeah, I wouldn't normally do it that way, but this is a slightly experimental bow, Oregon Yew belly English Yew back ;D.
I'll post if it it doesn't explode ;)
You are spot on, he's trying to build up to heavier and longer draw. It suits me to some extent as it will be about my limit for comfortable shooting these days.
Del
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did some more tillering today, it's at 25" now. I don't know what the draw weight is, but it feels underweight. >:(
that left tip is worrying. by the way, it might look like a slight hinge forming at the inner 1/3 of the right limb, that's because there's a spot of reflex to the right of it which then goes back down to a deflex. The right limb is not purposely whip-tillered, but appears so because of the deflex.
I also included some pics of the knot
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I'd have to say that lump around the knot can come down quite a bit. It looks huge and the knot itself doesn't look too bad.
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As hasalready been said you needc to reduce that knot to just a shade over the dimension the limb would be withoput a knot.
Trust me that knot isn't bad but you will ruin a good stave if you don't remove it.
That left tip is horribly hingy now. The right limb isn't bad.
If you are under-weight then thats your fault for taking too much wood off! Simple! Concentrate on getting good tiller now...without good tiller you can't see what weight it will make. This bow should not have been braced in this condition - never ever brace a bow until the tiller is as perfect as you can get it. Another thing to remember is that a long string will give the impression that the mid limb to tip area is stiffer than it actually is when it's braced.
I also agree that piking is a bad idea.
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If you are under-weight then thats your fault for taking too much wood off! Simple! Concentrate on getting good tiller now...without good tiller you can't see what weight it will make. This bow should not have been braced in this condition - never ever brace a bow until the tiller is as perfect as you can get it. Another thing to remember is that a long string will give the impression that the mid limb to tip area is stiffer than it actually is when it's braced.
I also agree that piking is a bad idea.
yeah, I figured that out after I had this bow braced.
That long string theory...perhaps that's why a lot of my bows end up elliptical-tillered. :o
The bow is 65 pounds at 25" right now. I thinned down the knot some and scraped the inner third of the bottom limb a bit today, the left tip doesn't look as bad but still bending pretty hard. I will post pics tommorow.
It doesn't really look like I'll make my target of 100lb at 32". Live and learn, I guess.
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22" is the length you can start to predict the final weight. If I had 50lb at 22" I would know within a few lb's what I would end up with, however like what has already been said you could end up with 50lb @ 22" easy given the amount of damage we have seen.
Then is a golden rule here, as soon as you see a probelm, 'stop pulling any more', bad tillers never get better with more bend.
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Livefortheoutdoors, I am glad you are happy with that other yew stave. That was beauty, and should be a bit easier to tiller. As for this one you have here, like others have said, you need to reduce those knot areas. They are way overcompensated for. Keep at it, and keep posting your progress.
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Thanks, Carson.
I did a bit more work today, reduced the knot a bit, and added jatoba tip overlays. I probably will replace the overlays with horn nocks some time in the future, but as of now I have no horn and the string was making dents in the back over the temporary grooves. Now the bottom limb is a bit too stiff. :( This bow is not going to make a real war bow weight, I'm guessing probably around 70-80 ish @ 32". Well, I guess just live and learn, and be more careful on my next stave. Speaking of which, I got roughed out and floor tillered today. At least I'm happy with the unstrung profile. The original stave had about 0.75" of set, and it has about a smudge over an inch right now, which is actually very good, for me. last pic is the roughed out stave.
I do not know why my computer is turning these pics sideways...bear with me
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Unless it's an optical illusion that knot is still way proud! Look to the handle side of it in the 2nd last photo - way thinner. Thickness taper (if the design calls for it) should always always be even. Instead of leaving knot thicker make them them wider....although obviously this is difficult not! The other way to deal with knots is the drill them out and plug the holes with clean wood.
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Agreed. Thin the belly under that knot. For a warbow, it's also way too stiff in the handle.
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Just a little heads up, I won't be working on this bow during the next week or so, I am currently out of town.
I have scraped the middle area and reduced the knot some more, but no pics right now. ::)
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Alright, so I evened out that knot, now the tiller looks like a nice elliptical one to me. I think I will leave the handle area stiffer, or maybe just scrape a tiny bit more off. The bow is not actually as stiff in the center as it looks in the photo, but the camera took the picture at the wrong moment, I was still at about 28" draw. I have it at 31" now, pulling about 80 pounds.