Positive tiller..why is it required? How does it vary with shooting style?

[adb]

Red Dwarf...
Go back to the first page and read the initial replies. It's all there.

[Badger]

Several of my self bows started off with a little positive tiller but over time went slightly negative. If I didn't fix it I would normaly have to move my nocking point on the string a bit. I noticed this more on my shorter bows of around 60" or so, Steve

[Red Dwarf]

adb

I am fairly clear as to what positive tiller is at least!

I really am trying to get my head around this .

What do you mean by the term "A bow with symmetrical limbs"?
Is it a bow where the length of the working limbs is the same or, the centre of the handle is in the dimensional centre of the bow, or the centre of resistance on the grip when drawing the bow is in the dimensional centre of the bow, or.......??

Also, what is meant by the description "a bow tillered at it's geographical centre"?

Red Dwarf

[adb]

Red,

Give it time, and more experience, and it gets easier to understand. Not, perhaps, that you don't already...
 
A bow with symetrical limbs is one which has equal length limbs from the beginning. In other words, when you're laying out the bow's profile, both limbs are equal length from the start, and either limb could be top or bottom. As you tiller the bow, you can let the wood pick which limb will be which. When you tiller this type of bow, you place it on the tiller tree at the bow's geographic center. If you want positive tiller on the top limb, make it bend a bit more, and check tiller at brace as described earlier.

A bow with asymetric limbs begins with the bottom limb shorter than the top right from the start. Or, the top and bottom limbs are chosen from the start, and you have to tiller accordingly. The center of this type of bow is now at the arrow rest, and balances well in the hand.

I hope this helps!

[Red Dwarf]

adb

Thanks for trying to clear things up for me
So the way I am reading things a bow can only be described as "having symmetrical limbs" if the centre of resistance, where most of the pressure is on your bow hand, is in dimensional centre of the bow...correct?

When tillering on the tree, do you pull from the centre of the string or some other predetermined location?

Thanks for bearing with me on this one, I think I can see some light at the end of the tunnel!

Red Dwarf

[adb]

Red,
Yes, I supposse that would be correct. If I'm tillering a bow with symmetrical limbs, I pull the string from the middle. I'm careful to get the middle of the bow exactly on the center of the tree, and pull the string from the center, otherwise you might pull one limb off and fool your eye. I'm also careful to make sure the bow is sitting square and flat on top of the tiller tree, especially after it's tillered to brace height. I sometimes use a little shim under the riser to level it if I have to.
When tillering a bow with asymmetric limbs, I have the bow on the tree with the arrow pass in the middle of the tiller tree. Everything else the same.

[adb]

Here'a pic of a maple selfbow kids bow I made a few months ago. The right limb is the top, and notice how it bends just slightly more than the left, or bottom limb. That's positive tiller. This is a symmetrically limbed bow, tillered from dimensional center. Arrow rest is 1" above center, making the bottom limb 1" longer.

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[DCM]

[b][tt]http:// paleoplanet69529.yuku.com/topic/13568?page=2[/tt]

Is there a rule against posting a link to another primitive archery site?  I've included this link to one I frequent, and I'm sure many here will recognize.  They don't compete in terms of publishing a magazine and the topic includes pics I think are very informative. 

Admin if this is taboo please remove, and please forgive.  Or if regular members are offended let me know and I'll remove the post .

[Red Dwarf]

adb,  now you really have me confused!
In one sentence you say that the bow has symmetrical limbs, and in the next you say that the bottom limb is 1" longer???

Two steps forward, one step back!

Red Dwarf

[George Tsoukalas]

If the limbs are symmetrical and the handle doesn't bend then how can the bottom limb be longer? Just playing devil's advocate. I make bows the same way, adb. I've heard it put that way before. Jawge

[Justin Snyder]

If the limbs are symmetrical and the handle doesn't bend then how can the bottom limb be longer? Just playing devil's advocate Jawge

That is funny George. Ironically this is what Marc was saying about symmetrical "length" limbs and I agree. Regardless of where the arrow pass is, it doesn't change the limb length unless it has a bending handle.  It is called a riser and is not part of the limb.  Asymmetrical limbs are different in length from fade to limb tip.  As long as we are being the devils advocate Ill add a little more confusion. I have never seen a bow with symmetrical limbs.  They would have to be the same length and bend in the exact same arc to be truly symmetrical.   

Red, ignore the part about 1" longer.  What he meant to say but was lost in interpretation was farther from the arrow pass, limb length did not change. With that slight understanding of wording his information is perfectly correct in my oppinion.

Steve, an interesting thought since I have been wondering if adjusting nocking point and fine tuning positive tiller aren't accomplishing the same goal. 

All that said I'm with Rich.  Even length limbs and symmetrical at full draw. Justin

[George Tsoukalas]

Justin, that is true though we strive to get the limbs to bend the same way. Pretty hard to do with character staves.  Jawge