What exactly does it mean Tillered 3under?

[bigcountry]

I buy bows all the time.  Most are tillered split and shoot them 3under.  My nocking point is usually .5" over center with 3 under.  

But I finally get a zipper that was tillered 3 under.  And my nocking point is now like .25" over center.  

Now, this is messing me up shooting my different bows.  As my POI with the zipper is very high.  I am thinking about adding more wieght to get it shoot more like my other bows.

But what does it mean when bow makers say its tillered 3 under.

[aromakr]

bigcountry:
A bow tillered for 3 under will have more positive tiller on the upper limb. This will allow you to use a lower nock point. Its all about finger placement on the string. When you lower your fingers on the string the lower limb bends more, so you need to compinsate by tillering more the upper limb or raising the nock point which will raise your finger placement on the string. In order to achieve proper arrow flight both limbs must bend equally, otherwise one limb will give more thrust that the other causing porposeing of the arrow.
Bob

[bigcountry]

Thanks for the quick reply.  So if I understand right, if I measured the tiller on my bow that is tillered for 3under, I would see the top limb bend more, or the distance between limb and string would be less on top limb?  

I have never tillered a bow, so I am not sure where a bow maker would start pulling back (on the string), but I suppose if I requested a 3 under bow, they would start drawing on a drawing board, little below center for 3under and right at center for split?

[Chris Wilson]

A bow tillered for 3 under will have more positive tiller on the upper limb.

Are you sure of that?  That's not what I've always understood it.  When a bowyer tillers a bow for 3 under, typically they'll tiller the limbs even to no more than 1/8" positive on the top.  Split finger tiller is usually around 3/16" to 1/4" postiive.  A very slight difference, but enough to vary the nock point location.  I've had a few tillered specifically for three under, but most of mine are standard tiller.  I do have my hoyt set at even though.

[Bird Dog]

So, You can shoot a bow three under that's tillered split by raising the nock point slightly. It would seem that it would be difficult to shoot a bow tillered three under with split fingers as the nock would need be moved to at least even..??

[bowdude]

It also matters as to where you put the handle / pivot point when building the bow.  Some will lower the handle putting the rest and fingers closer to dead center on the string.  If I remember right the PSE Coyote is like that.  The pivot point below dead center.  Measure a bunch of bows, they are not all the same of course.

[Chris Wilson]

bird dog....You'd be surprised how well a bow with even tiller shoots with a split finger release.

[vermonster13]

When ever I order a bow I ask for even tiller. Easy to set-up for shooting either way and stays quiet.

[bigcountry]

So what exactly does a "more positive tiller on top" mean?  Does that mean when tillering the top limb will have more or less the distance to the string than the bottom?

and when tillering a bow, does a bowmaker usually tiller with the arrow cutout in the center or center of the handle?  

Thanks for the replies.

[aromakr]

More positive tiller means the distance from the fadeout to the string (measuring device is 90 degrees with the string) is more than the bottom limb measurement. Bow design will dictate where the shelf is located. Tillering is measured from the fadeouts, or where the most bend occurs at brace height.
Chris: Yes I'm sure of that, there is a lot of misinformation on the net!!
Bowdude: Is also correct the way you grip the bow can and does effect tiller. more heal pressure will cause the bottom limb to bend more, than if your use a high wrist grip.

Keep in mind positive tiller is measured in 1/8's" of an inch. most bows will be positive by 1/8" because of the way I shoot I prefer 3/16" positive tiller. Zero tiller will work, the only difference will be a slightly higher nock point, I prefer my nock point lower.
Bob

[Chris Wilson]

Chris: Yes I'm sure of that, there is a lot of misinformation on the net!!

Didn't find it on the net.  Was informed by a reputable bowyer and a shooting coach on seperate occasions.  Hmmmmm, looks like we need another opinion from someone who makes bows for a living.  Anyone bowyers care to chime in on the subject?

[James Wrenn]

Most bowyers make the tiller even for someone shooting 3 under and an 1/8" or more positive for split finger.Truth is except for the nocking point either works fine any way you want to shoot them because when you move the nocing point you change the tiller just like when you change your grip..The only time I worry about it is on a real short bow.Then I like more positive tiller just for the way I shoot to keep my arrow level on the shelf or rest.

[bigcountry]

On a takedown, where you measure this positive tiller?

[bowdude]

Bigcountry - Tiller is measured from the point where the fades stop.  
 On the bows tillered for split,(3/16 to 1/4) but shot 3 under, the high nock point is the result of the finger pull point being lower.  The nock has to ride higher to make up for the lower limb being pulled farther and thus reacts harder. Actually it doesn't now that you have moved the nock up because the high nock point has moved your fingers higher. The nock has forced you to migrate toward the opposite limb with your hand to get equal force on the limbs.  Just as if you were shooting split finger.
  The best scenario for a zero tiller bow would be to shoot 2 split fingers draw shooting thru your bow hand at the center of the bow.  Can't be done. But close is good enough as we can adjust it with nock point as was described above and Vermonster has proven it.
  The best way to keep tiller to a minimum would be to put the pivot point slightly below center with a low arrow shelf. Whether you shoot split or 3 under does not matter as it will force you to move your hand to the required location to get good arrow flight as described above.
 Some bowyers will put the pivot point dead center of the bow, yet this is not a requirement for a good shooting bow.  Some Japanese zen bows and  Mongol?  horse bows have much shorter lower limbs, but the rest of the bow is designed to make this work.  It all boils down to one thing. Push/pull must be equal on both sides of that arrow nock or it will get propelled incorrectly.  Wow thats a lot isn't it?

[bigcountry]

Thanks for taking the time to answer my questions.  When people refer to fade, are they talkin about there the limb is basically same thickness all the way up to the nocking point?

[bowdude]

The fades are the wedge in the middle of the limb where they mount to the riser.  As it goes off into the limbs they... fade... away...

[bowdude]

[SERGIO VENNERI]

Bob; I'm afraid i'm with Chris on this one. Positive Tiller generally means the distance from the limb fadeout to the string at 90 degrees is more than the distance measured at the same spot on the lower limb,  approx. 1/8 to 1/4' max. it can be measured in8th or 16 teenths' it doesn't matter. bows shot 3 fingers under are tillered even on both limbs or 1/8th more on the lower limb depending on the amount of pressure one puts
on the lower limb, for example by heeling the bow. Actually the correct term for "tiller" is "static balance" , because the string is at rest when this is measured. The greatest benefit of tillering for 3 fingers under is a quieter shooting bow, other than that  i don't find much if any difference.

[bigcountry]

Thanks bowdude for the pict.  Thats what I thought.  And I see that on my longbows, but on other takedowns, I do not see that.  

Does anyone ever measure tiller anywhere else or only here.

[James Wrenn]

On tds you can just measure at the limb butt next to the riser.As long as it is the same place that you measure from it will work.