what is stacking?

[sailordad]

        hello again everyone here on PA.
now as most of you know I'm pretty new to this. I'm on the site just about everynight,sometimes multiple times a day. I've been doing alot of reading here on PA.
 I've asked some questions,learned alot already. However I still need to learn quit abit more,and I figure if I ask questions,some of the knowledgeable people here on PA would be happy to answer and teach all at the same time. I've learned some of the terminology used, however I still am unsure what the term "stacking" means. I know it's a probably a real basic ( or maybe dumb ) question,but if you don't know and don't ask, you never learn anything at all. so thank in advance.



                                                                       PEACE,

                                                                             Tim

[1/2primitive]

Hey Tim,
Stacking is basically when the string angle at the nocks gets over about 90 degrees, the bow starts to gain weight rapidly, instead of having a nice smooth draw. And the reason that no one wants their bow to stack is that 1) it's uncomfortable, and 2) it makes it hard to shoot accurately, and 3) the efficiency is reduced, and the bow does not shoot as fast for it's draw weight.
    Sean

[sailordad]

     Sean,
thank you. Once again I new that I could learn something by asking the right people.
 I really appreciate the share of knowledge from everyone here at PA. Everyone here is so friendly and willing to help all of us newbies,which I for one and am sure others are very thankfull for.


                                                             PEACE,

                                                                 Tim

[mullet]

   Tim, Just keep asking. Somebody has an answer.

[sailordad]

  cool 

[markinengland]

An interesting and confusing question that has got me thinking in the past. Not sure if I got it right yet but this is my thinking.
I think of stacking as mainly about the difficulty in drawing the bow not the wieght itself.
I magine picking up a heavy object as being similar to drawing a bow. This object increases in weight the higher you lift. By the time you pick the weight up to shoulder height it is at 50lbs.
Some bows, due to string angle allow you to pick the weight up the easy way close to your body. Close to your body the weight increases progressively and smoothly and so does the effort needed. The weight is 50lbs at shoulder height.
Some bows, again due to string angle force you to progressibly move the weight further away until it is at arms length at shoulder height. The actual weight doesn't necessarily increase but the difficulty with which you can lift it does. There may come a point at which it feels as if you have hit a wall, as if the weight has suddenly increased in weight. If you did manage to lift the weight to shoulder height with arms fully extended it would still weigh 50lbs but it would be much harder to do.
As I understand it the issue is about leverage. Imagine a very very very long bow where the string lies at a very low angle almost parallel to the limb. You could pull the arrow five inches or more to get one inch of tip movement getting a mechanicl advantage helping you, almost like the effect of a set of pulleys or a lever.
On a very very short bow the string might be at an angle of 45 degrees to the limb so one inch of pulled arrow gives one inch of limb movement. Now you have no mechanical advantage, no lever or pulley advantage, no help.
So you have easy to pull 50lb bows and hard to pull 50lb bows almost totally due to string angle at full draw. You could almost say the bow string is stacking, I am not sure that the bow is really doing anything other than bending! If you added a stiff central rod to the string thus altering the string angle at the nock the bow would now be easier to pull and would not "stack".
I think that some stacking bows may be close to breaking or reaching the physical strength limits of the wood. Actual draw weight will increase at a steeper rate as the breaking point is neared. This means that you get an actual sudden increase in draw weight at the same time as stacking at worst string angle. This may appear to show that actual drawn weight increase IS stacking, as if stacking can be measured on a set of scales. I don't see how this could be the case. A way to test this would be to use the stiff rod idea and see if this changes anything.
Mark in England