Tillering bows

[Justin Snyder]

"The reason the knock point is not at 90 degrees??"

Taking into account the arrow's dia. and the distant that the string nock pushes the arrow nock down (because of string angle) your string nock will most likely be between 3/8 to 1/2" above square on average. ART

Art, I would appreciate it if you could expand/explain this a little more. I have always felt that adjusting the nocking point for the shooter was crucial. I think positive or negative tiller can be compensated for, at least partially by adjusting the nocking point.  I don't have a complete grasp on it, so your input is very interesting to me.

[zenmonkeyman]

I'm with Del on the tiller-setup-can-compensate question, but I think setting your pulley off center so it pulls through the off-90 nocking point is what makes it work.  Simply setting the handle in the right spot won't do it by itself if the bow isn't drawn the way it will be drawn by hand.

Nobody's mentioned the high nocking point in terms of fletching clearance...  If the point isn't high, the fletching and nock bounce off the shelf and cause poor arrow flight.  If the nocking point is tuned so the back end of the arrow just clears, the flight is self-correcting.  A vertical-plane archer's paradox to go with the regular around-the-handle paradox. 

If I'm wrong correct me!  I'm here to learn.

Garett

[radius]

i think the reason we do nock grooves at 45 degrees is this:

more or less, a bow is made where the overall length is twice the draw length plus the handle.   That is, each limb handles half the stress.   25" draw means approximately 54 to 56" overall length.   each limb, then, equals the draw length.  Pretend it is a triangle, with the 3 sides being the string, the arrow, and an imaginary straight line running from handle to tip.  Two of the "sides" are equal:  in this case, say, 25".   It's a right triangle, because the string is pulled perpendicular to the handle.    Any right triangle with the base and height being equal (1:1 ratio) gives a resulting 45 degree angle at both other points of the triangle.  I know this is a terrible explanation.  But draw yourself a picture. 

In practice, 45 degrees for the nock groove is NOT usually exact, but it is near enough.

[artcher1]

Justin, the one thing I've learned over the years is that a good release is way more important that having an exact string nock position. If the bow is in any way out of tiller then timing is compremised and so is the nocking position. That's why it's so critical to lay an arrow pass out and then grip the bow accordingly for best limb timing. In my opinion, you want the arrow to leave the string as close to 90 degrees as possible.

If you will take an arrow and nock it on a bow string and then cant (mimicking the arrow at full draw)  it about 45 degrees you will notice the arrow nock fits tight against the front of the string nock and  has a  gap of around  1/16" between the back of the string and arrow nock.  When the arrow is released, it does not stay directly under the string nock, but rather below the string nock that 1/16" I mentioned earlier. I read about this close to 40 yrs ago and ever since then I have included this in my calculations for nock setup. Plus the dia. of the shaft of course.

Zenmonkeyman, if I read you correct, you're referring to a similar effect of archer's paradox or the bending of the arrow upon release where the arrow first bends inwards against the arrows pass. Yes, I think you will get a similar but less effect of over the shelf paradox (porpoising) just from the arrow itself (with the string nock being in the correct position). This could bump the arrow up slightly upon release and create a need for a higher string nock then one would think.

But to reiterate, a good release cures many ills. ART
ART

[Steve Cover]

Thanks Art,

I've been archery since 1951.

Your explanation of why the nock point is raised above the arrow at 90 degree to the string, is the first one I've seen that is clear enough for me to visualize.

Thanks for you excellent answer.  I haddent considered the possibility of a vertical Archer's Paradox like action of the arrow. 

PS no slight is intended to the others who have courteously answered too.

Your responses have greatly helped my understanding, with perspectives I hadn't considered...... (I'm not all that bright..)

Steve

[robbsbass]

You guys have got me totally confused now. If one limb is shorter than the other when you tiller it, one will be heavier, but they should both bend equally to form a "D" is that right.

[artcher1]

Robbsbass, this is my take on things.

Even strain on your limbs should be felt at full draw. So the amount of hand/heel pressure used determines how much extra weight/stiffness will be needed for the lower limb to achieve equal limb balance at full draw. Only reason to have an off set handle/shorter lower limb is if you use a medium to straight wrist grip. Here less hand/heel pressure is used creating a lesser need for positive tiller/stiffer lower limb. The proper amount of positive tiller will "create itself" if limbs feel even strain at full draw, using the proper arrow pass layout for one's desired grip.

Knowing this, we can recommend, say for example, 1/4" positive tiller for same length limbs w/low wrist grip, 3/16" positive tiller for a 1" shorter lower limb w/medium grip,  around 1/8" positive tiller for a 1 1/2-2" shorter lower limb w/high/straight wrist grip. Or an even tiller for someone that shoots three-finger under where the hand placement on the handle and the finger placement on the string is pretty much center of the bow.

Again, just my opinion here folks.................ART

[Badger]

Makes good sense Art. Steve

[artcher1]

Thanks Badger................ART

[robbsbass]

Thanks for clearing this up for me.

                      Robb