For better limb tiller:

[Josh B]

Good point Chris!  I stand corrected on the mass.  Josh

[IdahoMatt]

This is a fun topic.  Got my brain working in a good way.  Making valid points.  I too don't have enough bows under my belt to contribute but what Josh is saying makes sense.

[Dances with squirrels]

Ya know, I used to think I knew what the heck I was doing, but I disagree with other bowyers so often, I'm beginning to wonder 

[lostarrow]

The key is the length of the power stroke.  The limbs don't know if they're reflexed, flat or deflexed.  They only know how far you bend them.  With 4" of reflex and a 28" draw, your limbs are under the same strain as flat limbs  being drawn to 32".   What that means is your storing the energy of 32" draw bow.  Longer power stroke.   You do however lose a little bit of that energy by the actual shorter stroke on the reflexed bow.  Meaning a flat profiled 50#@32" bow is transferring more energy to the arrow than the 4" reflexed50#@28" bow.  Likewise, the 4" reflexed 50#@28" is storing and transferring more energy to the arrow than a 50#@28" flat profiled bow.  But there's even more to it than that.  To get the reflexed bow tillered to 50#@28", you will have to remove more wood than you would from a flat profiled 50#@28" bow.  Resulting in less mass.  Strength is only one factor in the energy storage equation.  Strength and energy storage are not synonymous.  Josh

 ..... But  any bow of  regardless of design /weight/ length will draw 0 # at 0 " of draw. If then draw to the same draw length and weight, do they not have the same powerstroke? ...

[lostarrow]

Because it stores more energy.  Josh

  Is it storing more energy or just transferring it more efficiently to the arrow  by not allowing the limbs to vibrate as much as the arrow leaves the string?

[Josh B]

Ya know, I used to think I knew what the heck I was doing, but I disagree with other bowyers so often, I'm beginning to wonder 

Offer your rebuttal, disagreement or whatever and lets see.   I explain things as i understand them.   If I'm wrong, I'm wrong.   I don't have a problem with being corrected or challenged as long as the challenge is more substantial than "you're wrong!" .  If you can explain where I'm wrong I'm all ears.  Josh

[Josh B]

Lost arrow,   even though the archer is not drawing the string, the energy from bracing the bow is still being stored in the limbs.   Its just being held by the string at brace.  The reflexed bow having had its limbs bent further to brace it, is storing more energy before the archer ever draws the bow.  This is what people refer to as string tension.  The higher  the string tension at brace, the more energy there is stored in the limbs at full draw that is available to be transferred to the arrow.   Just for instance, if a flat profiled bow draws 10# at the first inch of draw,  the reflexed bow might have 15# at one inch.  This means that your force draw curve starts at an advantage with the reflexed bow in the first instant the bow is drawn.   I hope that makes some sense.  Josh

[George Tsoukalas]

I'm not sure what evenly reflexed limbs have to do with putting a more reflexed limb on the bottom but ok.

I will offer this. When  tillering reflexed bows they show high early draw weight so it is easy to under shoot weight.

Jawge

[Josh B]

Yeah Jawge,  that did spin off course pretty bad.  My apologies for my part in that.  Josh

[George Tsoukalas]

That's ok, Gun Doc. Those spin offs can be enlightening. Jawge

[mikekeswick]

 
First before you ever bend the wood draw the profile of the back onto something. This is the reference. Any set the bow takes will be show as deviation from this outline.
If one limb is reflexed and one deflexed - simply aim to get to full draw with equal set and you have done your job. Then look at the finished bow and notice how the limbs still hold that difference in r/d, at brace, during the draw and at full draw.
The problems come when you forget that the goal ALWAYS is to have the forces in the bow balanced at full draw.

[Gaust]

Mike,  maybe it's the goal but it seems to me that with wood bows, perfect balance would be difficult to achieve.  Too many factors.  So we're left with questions like - which limb should be on the bottom and why?  For those of us who have a hard time achieving the perfect tiller, it's take what you can get and just go ahead shoot it.
George

[SLIMBOB]

Gaust, most of us on here made bows before we knew or even questioned these types of things, and I would bet that many of those early "primitive" attempts are still shooting today.  Still, knowledge can be a powerful thing.  I honestly don't know who is right here, but I'm digging the debate.  I will typically put the weaker limb on top, but I would not necessarily call the deflexed limb the weaker limb.  I have looked back at mine and any I have with uneven handles, the deflexed limb ended up on the bottom, without much thought put into it really...

[PEARL DRUMS]

First before you ever bend the wood draw the profile of the back onto something. This is the reference. Any set the bow takes will be show as deviation from this outline.
If one limb is reflexed and one deflexed - simply aim to get to full draw with equal set and you have done your job. Then look at the finished bow and notice how the limbs still hold that difference in r/d, at brace, during the draw and at full draw.
The problems come when you forget that the goal ALWAYS is to have the forces in the bow balanced at full draw.

Although I don't trace any shapes, that's the best description to low set/perfect tillering Ive heard. Basic and concise. Nice work Mike.

[PatM]

Keep in mind that the extra energy stored in the bow to achieve high string tension at brace is not actually available to the arrow....