Draw weight Quandary

[Archeress]

thanks Wills...yes the early stack is damned hard and i agree that my progress was slow because i coouldnt get the elbow back sufficiently to give the rest of it a yank.  Was like trying to push over a brick wall.  Though i did have the stratton bow back to eye level..that was ll i coould muster.  a couple weeks and the bow will come out to play...lets see what video tells us then.

[toomanyknots]

I am totally confused here, what is "early stack"?  The stacking I know refers to the dramatic increase in draw weight near the full draw, making a bow that is not pleasant to draw. A bow with no stack usually has higher early draw weight, but a smoother force draw curve out toward the end, making an easier bow to draw. Haven't read to much, I will go back and re-read the thread though...

[Del the cat]

I am totally confused here, what is "early stack"?  The stacking I know refers to the dramatic increase in draw weight near the full draw, making a bow that is not pleasant to draw. A bow with no stack usually has higher early draw weight, but a smoother force draw curve out toward the end, making an easier bow to draw. Haven't read to much, I will go back and re-read the thread though...

I'm glad it's not just me...
Often with a warbow it's the archer who is 'stacking' not the bow!
I plotted a force draw curve for the 130# Self Yew warbow I just made and it was remarkably linear, which is how it should be on a long bow with long working limbs.
Del

[WillS]

Basically, you get two types (bear with me, because I don't know the physics/mechanics behind this, just the feel!)

Type A ) Feels incredibly hard to pull to begin with, and really makes it difficult to get a full warbow draw, as it relies heavily on wrist tendons and arm strength to get the string back far enough for the back and shoulder muscles to start working as the elbow comes down.  At this point, the weight softens and the roll-back to full 32" comes relatively easily

Type B ) Basically the opposite, more well-known as "stacking" - nice and soft and linear to begin with, easy to get to around 20" or so of draw, but starts to stiffen up and feel heavier and heavier as you get towards the end, where the elbow comes down.

I think B ) is actually "stacking" whereas A ) is just... high performance warbow, I guess.  With bow A ) you get a HUGE surge and kick of power as the string gets to brace height, but with bow B ) you feel it all at the beginning, and it softens as it comes back to brace height.  Bow A ) is better for flight and distance stuff, and is the "holy grail" of a big bow. 

[toomanyknots]

Basically, you get two types (bear with me, because I don't know the physics/mechanics behind this, just the feel!)

Type A ) Feels incredibly hard to pull to begin with, and really makes it difficult to get a full warbow draw, as it relies heavily on wrist tendons and arm strength to get the string back far enough for the back and shoulder muscles to start working as the elbow comes down.  At this point, the weight softens and the roll-back to full 32" comes relatively easily

Type B ) Basically the opposite, more well-known as "stacking" - nice and soft and linear to begin with, easy to get to around 20" or so of draw, but starts to stiffen up and feel heavier and heavier as you get towards the end, where the elbow comes down.

I think B ) is actually "stacking" whereas A ) is just... high performance warbow, I guess.  With bow A ) you get a HUGE surge and kick of power as the string gets to brace height, but with bow B ) you feel it all at the beginning, and it softens as it comes back to brace height.  Bow A ) is better for flight and distance stuff, and is the "holy grail" of a big bow.

Okee dokey, I gotcha now. In my opinion, I think the holy grail of bows shoots like a compound bow, with hella early draw weight, and then randomly drops weight or so at fulldraw so it is easy to hold drawn. I have made some manchu style bows that feel like that when you draw them when the string comes off the string bridges at full draw, although I know it can't possibly be lowering in draw weight, I mean it just feels like that. And then rockets an arrow upon release, .

[JW_Halverson]

That yew is some rule breaking wood.  Stratton's bow has knots right on the edge of the limb, for crying out loud.  Isn't that supposed to be one of the most NO-NO of NO-NO's? But it's yew and yew is like honey badger, it just don't give a da..well, you know.

Thanks for taking it off for the pics, Kel.  Much appreciated over here in chilly South Dakota.  It's so cold here in South Dakota lately that our longbows are shrivelled up into horsebows.

Is it my imagination, or does the Stratton have whiter sapwood than the other? 

[WillS]

Steve himself posted a thread in this section a while ago showing a stunning Mary Rose replica with knots all over it, many of them right on the edges.  As long as the wood is good quality enough the knots won't be an issue at all, and you can more or less pretend they're not even there.

The very first bow I ever made was a yew longbow, came out around 50# I think (I posted it on here somewhere!) and I had never read/heard about how to treat knots so I ignored them all and there's a huge manky one right on the edge of one limb, and it's still shooting today!  Now that either shows that yew is magical, or that ignorance is bliss and I got lucky... I think it's probably the latter...!

[toomanyknots]

Thanks for taking it off for the pics, Kel.  Much appreciated over here in chilly South Dakota.  It's so cold here in South Dakota lately that our longbows are shrivelled up into horsebows.

 

[Archeress]

Your welcome...btw..my stratton yew has 8 knots in it.

[JW_Halverson]

Your welcome...btw..my stratton yew has 8 knots in it.

We all appreciate those lovely knotty bow photos. 

With the ranges typically shot by yew war bow shooters, I am thinking it would be an interesting video to have you come out here to South Dakota for an antelope hunt.  If you can get over here, I can arrange the rest! (antelope season is early in the fall, much more clement weather, if you are worried about that)

[adb]

How's this for a knot on the edge? No problem for yew... 

[Archeress]

vERY nOICE....Yew bewdy.

[mikekeswick]

How's this for a knot on the edge? No problem for yew... 

Yes but it's right at the tip where the stress is much lower than further towards the grip. The tips on most bows are actually overbuilt when you look at the amount of stress there...and I don't just mean 3/4 wide tips!
Yew isn't magical...i've had yew bows fail at knots just like any other wood. It very much depends on the particular stave and the particular knot. Not all knots are created equal 
Early stack is not stack....it's high early weight because the wood hasn't been overstrained and is therefore still springy. Bows with set are easy to draw intially. Straight or reflexed bows give you the early weight.
My advice if you are struggling is to drop your weight to a point that is comfortable for at least a handfull of shots or else injury is around the corner....sure as eggs is eggs. Better to build up very slowly - I wouldn't jump bow weight by more than 5 - 8 lbs at a time.

[WillS]

Early stack is not stack....it's high early weight because the wood hasn't been overstrained and is therefore still springy. Bows with set are easy to draw intially. Straight or reflexed bows give you the early weight.

Cheers for that Mike! Knew "Stack" was the wrong term really, but didn't know how else to describe it.  So it really is down to very good tillering and minimising set that gives you the high performance bows - sounds pretty darn obvious now! 

[adb]

How's this for a knot on the edge? No problem for yew... 

Yes but it's right at the tip where the stress is much lower than further towards the grip. The tips on most bows are actually overbuilt when you look at the amount of stress there...and I don't just mean 3/4 wide tips!
Yew isn't magical...i've had yew bows fail at knots just like any other wood. It very much depends on the particular stave and the particular knot. Not all knots are created equal 
Early stack is not stack....it's high early weight because the wood hasn't been overstrained and is therefore still springy. Bows with set are easy to draw intially. Straight or reflexed bows give you the early weight.
My advice if you are struggling is to drop your weight to a point that is comfortable for at least a handfull of shots or else injury is around the corner....sure as eggs is eggs. Better to build up very slowly - I wouldn't jump bow weight by more than 5 - 8 lbs at a time.

And that's exactly why I laid out the bow with the edge knot as close to the tip as possible. Being a warbow, however, I'm surprised it held up. I certainly worry less about knots in yew than any other wood.

I agree with the 'stack' term. Strong early draw weight is a good sign of any well made bow, with low set and minimal stress due to proper tiller. 'Stack' is the inability of wood to bend any further, and can be caused by several factors.