Tiller - What does it do actually? What is its purpose?

[halfphaze]

Hey all.

Recently, a credible archer in my country explained to me how the tiller worked and this information that he shared with me really conflicted and changed the way how i traditionally thought how the tiller works. And now i'm utterly confused, not with the information but with the purpose and function of the tiller. And the information he shared with me really opened up my eyes bigger O.O. No offence to him, if he happens to read this thread. It may provide useful information for him as well.

And also, according to him, the different manufacturing brands have different tiller settings - partly due to the default setting that goes with the same brand limbs. This is rather new for me and it's taking some time for me to digest.

I shared the information with a knowledgeable senior of mine, and he too concluded with the aforementioned question - What is the purpose and function of the tiller?

I have read heavily debated opinions of the tiller some of which are :-
- geometry change
- change in duration of powerstroke of the individual top and bottom limb
- angle of grip in hand
- uneven force distribution on the different limbs
- angle of limb to the riser (geometry change?)
- pull up and pull down

Some of the opinions mentioned above may be repeated, please kindly explain why is it as such.

I really really need some insight on this. It's getting me all confused and mixed up. And at the same time i can get more information of the various perspectives. Please help me out on this.

What is the function and purpose of the tiller?
Do different manufacturing brands have different philosophies/concepts/ideas behind the tiller? If so, how?

Cheers all.

[Pete-60]

The Tiller measurement is the distance between where the limb connects to the riser and the string, when measuring from the first point mentioned across to the string at right angles. (Hope that makes sense)

This distance should be the same for both upper & lower limbs, if not then one limb is working harder then the other. This will possibly cause the arrow to either fly high or low depending on which limb is out.

No doubt there will be someone here who is far more knowledgable then me and will be able to explain easier.

[tel]

Originally Posted by Pete-60

....This distance should be the same for both upper & lower limbs...

Not so I'm afraid - a forum search will throw up enough on this to keep you going into the new year

[TWIW]

Originally Posted by Pete-60

The Tiller measurement is the distance between where the limb connects to the riser and the string, when measuring from the first point mentioned across to the string at right angles. (Hope that makes sense)

This distance should be the same for both upper & lower limbs, if not then one limb is working harder then the other. This will possibly cause the arrow to either fly high or low depending on which limb is out.

No doubt there will be someone here who is far more knowledgable then me and will be able to explain easier.

There was a request on this forum some time ago for posters who gave information as a statement, such as your post, to justify their statement and back it up with proof.

I sit with bated breath for your proof, mathematical, or otherwise, that the tiller on a bow should be the same for both limbs (popularly known as zero tiller). If you can't provide this proof then a retraction woiuld, i feel, be appropriate.

Don't state your opinions as fact unless you can back it up.

I have just attended an excellent seminar delivered by Keith Gascoigne of KG archery who categorically stated, and demonstrated with the limbs he builds that a recurve bow requires a tiller of approximately 5mm greater dfference on the top limb.

I will leave it to the likes of Border Archery to explain the mechanics behind it because they too build tiller into their limbs and are much better at explaining it than I.

[geoffretired]

- geometry change
- change in duration of powerstroke of the individual top and bottom limb
- angle of grip in hand
- uneven force distribution on the different limbs
- angle of limb to the riser (geometry change?)
- pull up and pull down
Hi Halfphaze,
The list above are mainly the results of having tiller on a bow.They are not the reasons/purpose for tiller.
Tiller is put into a bow because we can't have the bow hand/arrow and the string hand, all on the centre line.(unlike a crossbow, where the limbs are fixed at the center and the arrow(bolt) it half way along the string.
Drawing the bow the way we do, makes the bottom limb easier to bend than the other.By making the bottom one stiffer than the top one, it counter acts the apparent imbalance.

[chrism]

This is a purely personal post as I am not qualified to get involved in the maths of tilller ...but....I found that when "tuning" my bow I found that minor adjustments in tilller/poundage/nock point seemed to make no real difference in my shooting (either when "paper" tuning or on actual round scores). Obviously ,gross changes did have an effect (smashing into the riser/missing the boss)

My tiller is zero ( as recommended by Hoyt) and this is opinion, as it is based purely on my own experience, not fact.

[tel]

Originally Posted by chrism

...My tiller is zero ( as recommended by Hoyt)....

Where do Hoyt recommend this?

[tel]

Cancel that - I have found a recommendation on their site FAQ to "initially" set tiller to zero. However looking through the recurve manual .pdfs they have on the same site the recomendation ranges from anything from 1/8" to 3/8" positive tiller, depending on which year you pick. The common factor seems to be that there is not a 'right' setting for everyone.

[Zippo]

You can always give Sid an email, I'm sure he'll be more than happy to explain it to you

[emdrum]

I wanted to address the question of what tiller does in a way that, hopefully, can be understood without a maths degree.

In a perfect archery system, the limbs would be of identical strength and deflect identically with increasing draw. The grip would allow the bow to be drawn so that the arrow could pass directly through the central point of opposing force where it is held - i.e. the middle of your bow hand grip.

In most bow designs this is not possible, so the grip is positioned below the arrow rest resulting in an uneven distribution of force with respect to the arrow and the grip. This introduces an unwanted vertical force into the bow system. Please note that we are completely ignoring any horizotal force component at this point.

If you are still having trouble visualising this at this point then imagine a bow where the grip gets lower and lower, gradually approaching the bottom limb tip and I think you will see that as the offset gets greater, the effect increases.

In order to compensate for the uneven distribution of forces arising from not having the grip in the centre of the limb tips, we can increase the poundage on one limb (or decrease it on the other) and 'correct' the imbalance.

However, if your personal style results in gripping the bow in such a way that the centre of effort holding the bow is below normal (whatever normal may be for your bow) then the effect of the offset is increased. Similarly if you use a higher hand position that results in a centre of opposition closer to the centre of the bow then this will reduce the effect of the offset, though as your hand approaches the centre point you may risk contact with the arrow or fletchings on release.

Also, if you draw the string from below the nock by putting most pressure on the bottom fingers then you are moving the centre of the draw effort at the nock and again introducing a vertical force. Similarly putting the majority of force on the top finger will result in a change in vertical force.

You may see, therefore, that there is no 'standard' tiller setting because it relies on the archer's grip and style and must be adapted to each individual. Most manufacturers will provide you with an initial setting, but this is only as starting point.

Bear in mind that until you have a consistent and stable shooting style, there is little point in changing your tiller as changes in your style will alter the way your tiller settings affect the shot.

I hope that helps to clarify what tiller is for.

Cheers

Mike