Tillering Question

[Wolftrail]

I read on here somewhere that some bowyers are ok with a tiller of 3/8" .. Having said that how can the limb timing be spot on and how can the tiller be spot on..?   I question this becasue most go by perfect tiller.  And is negative tiller OK..?
  :rolleyes:

[4est trekker]

How one holds the bow (high heel, low heel) and grips the string (split finger, three under) will affect the balance of the limbs as they are drawn.  Generally, the bottom limb should be a tad stronger for most shooters, in which case you'll get a positive tiller.  This is because the bottom limb, when drawn in hand, is often (not always) made effctively shorter by the position of the bow hand's heel and the bottom limb tip therfore has a longer distance to travel to reach full drawn than the top limb.  This is compounded by the fact that the string hand is drawing above the center point of the string.  

Thus, positive tiller.  Although this inequity is visible at brace and when drawn on the tree, it rectifies itself when the bow is drawn in the hand.  Many bowyers, myself included, work the bow out to about 22-24" on the tillering tree and then finish it out by drawing the bow in the hand.  That's because the tillering tree and string don't replicate the same forces at play when in hand.  A "perfect" tiller on the tree will most often quickly deform in the hand.  Hope that helps a bit.  

[Wolftrail]

Exactly what I do "work the bow out to about 22-24"  Then I shoot it in.. Yabutt,  what about negative tiller.?

Thanks.

[4est trekker]

I'm no bow doctor, but I can't think of any practical instances when negative tiller is desirable, UNLESS you were to stray from the accepted "norms" of bow design, bow hand grip, string release, arrow shelf placement, etc.

[Wolftrail]

"drawing the bow in the hand"  and doing the mirror shot works ok if you take a photo then draw a straight line from tip to tip on the Computer.  True enough you can see innacurate tiller in the mirror but that is just looking.

[Roy from Pa]

4est, I tiller bows for equal limb timing and quite often they end up with a negative tiller. But since doing this limb timing process more and more, I have began slightly over building the top limb and that equates into an almost even tiller.

[Wolftrail]

You build mostly Wood bows Roy.?  Realistically a wood bow will change in tiller over time will it not.  It will sure take some set after a few years. I guess what I'm trying to say perfect/even tiller will stay for a while but not forever.

[Roy from Pa]

Yes on wood bows. There is a far better chance of a bow with equal limb timing staying tillered than a bow that is not tillered correctly. But hey, that gives us an excuse to build another..  

[Bowjunkie]

"I read on here somewhere that some bowyers are ok with a tiller of 3/8""

I part ways with the majority of bowyers when it comes to 'tiller measurements' and what they mean. I usually don't even measure it. I don't care what it is. I adjust limb strength so that the arrow nock leaves along a line perpendicular to the shelf/handle, relative to the archer's shooting idioms, and then the braced profile simply is what it is... I may not know the measurement, but I know it's RIGHT.

I guaranTEE those predetermined tiller measurements so many use as their bowbuilding and tuning beacons don't always mean what folks think they do.

That said, if I made a bow the way I do, and 3/8" positive tiller was the result, I would be "ok with it". BUT, it hasn't happened yet. The way I design the bows and harmonize the limbs relative to the archer, the tiller is usually even... give or take... sometimes a little negative, sometimes barely positive. Sometimes it depends on the naturally odd shapes or inherent differences within the staves.

I mimic my holds on the tree, tiller/time the limbs all the way to full draw on the tree, exercise it well there, and it's done. Go shoot it. No measurements, no mirrors, no windows, no pictures to study then head back to the shop to readjust. No guessing. Tiller virtually never shifts either because the limbs have been realizing even strain(relative to how it will be shot) since very early in the process.

[fujimo]

look i am really sorry about all the things i have said about you guys in Pa    
looks like i need to come down there and learn a thing or two 'bout tillering.
it all makes absolute sense- and those criteria would be exactly the same applied to all bows, irrespective of their construction medium.

[4est trekker]

Each bowyer has his own secret sauce, I imagine.  For what it's worth (and that ain't much), I'll share mine.  I work my bows on the tree with the cradle and string centered on the bow.  Using a tillering gizmo, I get the limbs bending evening and symmetrically, exercising the snot out of the limbs with each change and never pulling past a good tiller/final draw weight/final draw length.  When I get to about 22"-24" (depending on final drawn length) I begin to slightly weaken the top limb (GASP!) by gently scraping the entire limb evenly.  I mark the entire belly of the limb with pencil scribbles to gauge this.  I thereby achieve a slightly positive tiller that manifests itself as even tiller/timing as I work the final inches in the hand. I also find that shooting the bow several dozen times with a heavy arrow, beginning 4"-6" shy of the intended draw length, really helps cement things.  That's because shooting imparts forces on the bow that a tillering tree alone can't reproduce.  

I've not experienced any changes in tiller since adopting this method, so long as the bow has been stored/strung/shot properly and as intended.

[Bowjunkie]

Whether tillered positive, even, or negative... when my bow is done, I know before the first arrow is released that I can set the nock point EXACTLY where I tillered it for, 3/8" to the bottom of the nock point, and fully expect the first arrow to fly perfectly. No porpoising. Inherently tuned(aside from arrow spine). No adjustment needed. These defining benefits are why we strive, or should, for perfect balance at full draw. Why not design/build it in from the get-go? Honestly, in the long run, it's easier.

Statically balanced to carry... Dynamically balanced with minimal shift to shoot... Such bows offer what all bowyers and archers seek. Roy has it and doesn't even fully know how he got it :^) But he's got it, so I'm content. It took me YEARS      

The only reason I would have to alter timing after I've taken a bow to the bales is if I did not place the handle/shelf exactly as I had planned/layed out... and that just doesn't happen  

4est trekker, I agree with bits and pieces of what you said... the rest, I'm going to respectfully have to disagree with.

[Bowjunkie]

A simple stick and string... who knew?

 

[Wolftrail]

Thanks guys, some really good insight and tips. I think that pretty well wraps it up.  I know this subject has come up a 1000 times or more. I guess its ok to shed light on the issue the odd time.    :rolleyes:

[takefive]

All I have to add is that like Jeff, Roy, and 4est, I haven't seen the tiller change much if at all on a wooden bow that was tillered well to begin with.  Good stuff here; lots to reflect on before I tiller my next one.

[mikkekeswick]

Originally posted by Wolftrail:
You build mostly Wood bows Roy.?  Realistically a wood bow will change in tiller over time will it not.  It will sure take some set after a few years. I guess what I'm trying to say perfect/even tiller will stay for a while but not forever.

This is only true if the bow wasn't correctly designed for how it is being shot or the environment it's being used in. Or of course if it isn't looked after correctly.
I'd be devastated if all my wooden bows acted like that! In fact I don't think i'd even bother to make anymore!
The real problem is that to own and shoot wooden bows (without killing them) you need to really understand wood and bow design.  To get to that point takes quite a bit of learning or a very good teacher and even better ears  

[mikkekeswick]

Originally posted by fujimo:
look i am really sorry about all the things i have said about you guys in Pa        
looks like i need to come down there and learn a thing or two 'bout tillering.
it all makes absolute sense- and those criteria would be exactly the same applied to all bows, irrespective of their construction medium.

the materials they are made from does make quite a big difference. Treating all bows ,irrespective of materials used, the same will lead to 'issues'!

[Bowjunkie]

Not all wooden bows change tiller over time. Some do though, and there are reasons why.

You know how some bows are trained to bend by pulling the string from the center of the handle, and then shot by pulling the string 2" higher? That'll do it.

Tillering them to a predetermined tiller measurement which isnt exactly what it needs to be balanced with the archer's holds... can cause it to eventually shift as it's used.

Flipping bows end for end? Yep. That too.

Then of course stuff like unseen flaws or weakness inside the wood, poor tillering, abuse... leaving them strung, overdrawing them, letting someone else shoot them who grips or draws the bows differently, etc.

I'm with Mike though, design and build them well, take care of them, and they'll hold tiller and resilience for a long time and a lot of arrows.

[Roy from Pa]

You know how some bows are trained to bend by pulling the string from the center of the handle, and then shot by pulling the string 2" higher? That'll do it.  

It sure will do it..

   

Flipping bows end for end? Yep. That too.

I never could understand the logic to that maneuver. Lay the bow out properly first and go with it as you intended it to be built.

I know guys all have their own secret recipe for building bows, and I'm sure they make a decent bow. But nothing makes a better shooting wooden bow than timing the limbs to bend in harmony. And it all starts with the layout preparations. Most important part is knowing where the arrow rest is going to be and placing the pull rope on the bow string where the center of your middle finger will be, below our predetermined arrow nock point. Jeff and I use a predetermined 3/8th" from arrow shelf to bottom of nock point. Then that 3/8th" measurement above the arrow shelf is where our nocking point is placed on the string when we setup the bow for shooting.

[Bowjunkie]

Maybe you just worded that wrong old timer, but I don't measure 3/8" from the shelf to the bottom of the arrow nock.... I measure 3/8" to the bottom of the nock point.

To the bottom of the arrow nock would be 1/8".