Osage limb length and 3 under

[The Ursus]

I’m working on a flat bow design using Osage and would like to know how those who shoot three under lay out their bow’s upper and lower limb lengths.  The bow is 64.5 nock to nock with the upper limb being 1-5/8 longer that the lower.  I draw 27.5” for what it’s worth. 

Luke

[Flem]

I don't shoot 3 under, so I might be missing something and always do the same layout. But do alter my tillering procedure to accommodate for 3 under if I know thats the way the bow will be shot.

[fujimo]

i used to lay them out asymmetrically, but recently seem to have gravitated to a more symmetrical layout, and for no particular reason.
What i do do is; utilize the "balanced limb timing" tillering method, as taught to me by Roy.
if that methodology is utilized, i dont think it really matters how you lay it out- to a point!
i think different layouts may induce less strain on a particular limb,  and ultimately contribute to its longevity.

[The Ursus]

Sounds good, I’ll just tiller accordingly.  I just wanted to see if leaving the top limb longer would help in the long run with performance of the bow.

[Pat B]

I don't shoot 3 under either but I believe you can just adjust the nock point to accommodate for 3 under.

[Eric Krewson]

I usually have a bow tillered with 1/8" positive tiller on the top limb for split finger shooters and very close to even for three under shooters.

[Bowjunkie]

Fujimo gets it... to a point. Hi Wayne 

It wouldn't matter to most folks, since most don't balance their limb's strengths relative to the shooter... BUT even within those that do... design/bow center location is quite relevant. Those that design their bows symmetrical because they think it makes it easier for them to gauge tiller aren't seeing the big picture. Exact center location can be what separates a really good bow from a great one.

In a bow of asymmetrical design, with the top limb about 1 1/2" longer than the bottom for instance, the bow's center can be precisely where the three under shooter's string hand fulcrum is located. This is the easiest design of bow, and string hold, to perfectly balance both statically and dynamically... that is, from carrying, to the very beginning of the draw through to the end, the best balanced and sweetest drawing and shooting bow there is. imo. If the bow hand grip is held neutral, not high or heeled, there is no fulcrum shift during the draw. Zero. Unfortunately I shoot split, so my bows aren't as perfectly balanced as these, but they're pretty dang close 

It's really, really hard... no, virtually impossible to make a symmetrical bow with all of these qualities.

[Bowjunkie]

Notice I didn't mention tiller measurements.

Tiller measurements are irrelevant. Two bows, designed the same, and balanced to ACT exactly the same, could end up with different tiller measurements due to subtle differences in limb shape, for one thing.

[fujimo]

hey Jeff
thanks for that very clear explanation.
i guess i will be meandering my way back to asymmetrical  bows then

this methodology of yours, of the balanced limb timing has truly been a revelation to me and my bow building, i use the principles with all my bows nowadays.
it just makes so much sense.
it always saddens me when i see new folk tillering the bow on the tree,and it looks good there, until  i see them doing a full draw pic, and then the tiller looks so off.
many thanks for sharing this with the archery world!!

thanks also for the re- education
cheers mate

[Eric Krewson]

I  tiller and tune to my rest, I only take measurements after the fact, what I stated above is what I find. I start with measured even tiller and adjust from there. About a dozen national championships and 40 or 50 state championships plus 2nd and 3rd in the IBO worlds with my bows tells me I get it just about right as far as tiller goes.

[Flem]

This is a good read for learning to tiller. Dean Torges was quite eloquent and concise in his descriptions.
http://www.bowyersedge.com/organic.html