3 under tiller negative or even?

[Michael Arnette]

Well since I can't stay out of controversy with my threads I figured I better post something a little bit less controversial.

I shoot 3 under style and have for about 7 years now. Through the years I have done several different things with my Bows to try to get them to shoot and tune well. I've been shooting TallTines and have been having Brian make me a bow that has an even tiller  and have been doing relatively OK with tuning. I've had to have a very high knock point though. Recently I bought a used bow on the classifieds here and swapped the bottom and top limbs which were tillered for a standard positive 3/16" tiller. By swapping them I've ended up with a -3/16 tiller and let me tell you it shoots excellent! Much much quieter and for the first time in several years I can bareshaft really well without nock high issues. I was shooting bare shafts perfect out to 20 and 30 yards tonight

So, should I have Brian build a 3/16 negative tiller on my next limbs? What would you guys recommend? That or just have him build a standard positive tiller like these and flip the limbs.

[Michael Arnette]

Here is a picture of me shooting an even tiller a few years ago, see how my bottom limb is overloaded? Would this be better if I had a negative tiller?

   

I shoot split finger, and I have all my bows tillered even. Even just seems to shoot best for me. You might have a hard time talking a bowyer into purposely making one "out of tiller" like that!

Bisch

[md126]

What did Brian say about it?  I'd imagine him or other qualified bowyers would have tried that by now but there must be a reason negative tiller is not a more common practice

It would be interesting to have some bowyers chime in

[McDave]

If you will indulge me, I really don't understand tiller as well as I would like to.  Even tiller means the measurement from the fades to the string is equal top and bottom.  Easy enough.  Negative tiller means the measurement from the top fade to the limb is less than the measurement from the bottom fade to the limb, right?  Doesn't that mean the bottom limb is bending more at brace height than the top limb?  If it is bending more, does that make it the weaker of the two limbs?  If it is the weaker of the two limbs, why would it work better than even or positive tiller when you put more stress on it by shooting 3 under?

I'm not saying that my statements are correct, necessarily.  I would just like to know where my thinking is out of kilter.

[Michael Arnette]

He actually mentioned flipping the limbs to see how it shot.

[batbow]

My new Black River bow from Will Cocke is tillered for 3 under.
I requested it tillered 3 under, and this is what it measures.
7 1/16  bottom limb  dimension from string to  limb, at riser end.
6 7/8 top limb dimension from string to limb. At riser end.
So it is 3/16 difference.
And personally will always go this way in the future if I am ordering a bow.
Easier to tune in my opinion and quieter in my limited experience with this one bow.

[kenneth butler]

I am with you McDave. It seems if the fingers are lower on the string they would pull more on the bottom limb and the bottom limb is already bent more.That is the way positive and negative tiller is,and the way it works. I don't understand why.
>>>-----> Ken

[katman]

Michael, in the pic it appears you are putting the majority of your finger pressure on the long and ring finger so more pressure well below the nock point like a fixed crawl requiring a high nock point to compensate. I shoot a negative tiller with a fixed crawl on my ILF rig since it is quieter and smoother and uses a lower nocking point.

Sending a link to another site for a good read on tiller to you and Mcdave.

[md126]

Michael, if 3U is even tiller what would flipping the limbs do? Wouldn't it be the same tiller unless he tillers differently for 3U than other bowyers? Did he discuss anything about what he does differently for 3U vs split?  

On my bows (& most bows) switching the top and bottom limbs is not an option. Obviously not with a 1pc either

Interesting thread

[Hermon]

It is common advice for people that shoot three under to raise their nocking point when shooting a bow that is tillered for split.  This would increase the leverage arm on the lower limb.  That would be the same as flipping the limbs as Michael described.

Or am I missing something here?

 (md126- I believe Michael is saying that he bought a used bow that was tillered for split and switched limbs.)

[ronp]

I shoot 3 under and adjust for negative tiller with my ILF recurves. At least 3/16 negative.  My nock points are lower and my arrows sit flat.  Before trying ILF, my nock was pretty high and the arrow looked like it was pointing down hill.

[BAK]

Well, first let's consider the point of "tiller".  It is an attempt to get both limb tips to hit the end of the string at the same time, period.

In a perfect world the fulcrum of your support hand would be the center of the bow, but that is seldom the case.

Then consider where the center of force is in relation to that fulcrum point.  Three under moves it down.

Your bowyer should be able to graph out exactly what tiller is needed based on how you shoot his bow.  Talk to him.

[forestdweller]

Originally posted by McDave:
If you will indulge me, I really don't understand tiller as well as I would like to.  Even tiller means the measurement from the fades to the string is equal top and bottom.  Easy enough.  Negative tiller means the measurement from the top fade to the limb is less than the measurement from the bottom fade to the limb, right?  Doesn't that mean the bottom limb is bending more at brace height than the top limb?  If it is bending more, does that make it the weaker of the two limbs?  If it is the weaker of the two limbs, why would it work better than even or positive tiller when you put more stress on it by shooting 3 under?

I'm not saying that my statements are correct, necessarily.  I would just like to know where my thinking is out of kilter.

McDave, I'm only a beginner bowyer but from what I understand and from my very small time spent making bows so far, you want the bottom limb to be longer and weaker at brace because when you draw it you are dynamically increasing the stiffness of the bottom limb (just the same way as if you shortened an arrow) because you are increasing the rate at which it bends when drawn.

The top limb needs to be made shorter than the bottom limb because it becomes dynamically weaker since you are drawing the string further away from the top limb.

If you left the bottom limb as long or stiff as the top limb when shot 3 under the top limb would not bend as much as the bottom limb which would throw the limb timing off which makes the bow draw harder and louder.

Someone please correct me if I'm wrong.

[BenBow]

What everyone seems to miss is when you hold the bow the fulcrum is an inch or more below center effectively shortening the lower limb. Also with a 2 or 3 under hold the fingers are in line with the lower fulcrum point. The lower limb gets pulled further back so it is in effect pulling at 29" while the top limb is pulling 28". So if the top limb is pulling 50# the bottom limb is pulling 2-3# more. This causes the nocking point to go downward on release and causes the arrow to bounce up off the rest. I've seen this with my high speed videos. Once the pressure on the lower limb is reduced with negative tiller the nock travel straightens out and the nock point can be lowered.

[McDave]

Thanks for the comments.  It makes more sense to me now.

[md126]

I've taken video of myself shooting and find that on some bows my bottom limb sometimes kicks forward at release. I'm sure it's due to my release to some degree but now I'm thinking a lot has to do with tiller. Interesting

Any thoughts fellas?

[TOEJAMMER]

One would think that this issue would be addressed by some of the many professional bowyers that are members of Tradgang.

[TexasTrad]

Michael:

I think you are on to something.   I shoot three under and most of my bows are even tiller.  On the even (and positive) tiller bows, my nocking point is pretty high and the bow is still a little loud.  

I have one bow that requires a much lower nocking point and is very quiet.  I didn't know why but just checked and it has a negative tiller.

[joebuck]

" Alex....I'll take BenBow for $1000"