Yew Warbows

[AH]

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.

[AH]

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!

[ionicmuffin]

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

[WillS]

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!

[Del the cat]

+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

[AH]

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.

[WillS]

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?

[adb]

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.

[AH]

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.

[ionicmuffin]

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.

[AH]

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...

[ionicmuffin]

if the wood is too stiff its not stressed like it could be.

[Josh B]

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

[AH]

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.

[Del the cat]

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