Advantage with heavy points?

[sambow]

Originally Posted by Random_guy

Sambow, look at this video. Its particularly obvious when the arrow hits the target in what direction its bending.

It looks up down on impact but also consider something I had overlooked earlier, notice how much the arrow is rotating during flight. Not sure exactly what impact this is having, but I would guess the plane of bending is rotating. What I would say is when I am powder testing for interference, sideways contact with cable guides and inner edge of riser tend to be areas of concern, despite when measured staticly there is plenty of clearance with the vanes. I wish it wasn't that way because I could bring in my cable guides more and reduce the torque on the limbs.

Originally Posted by Random_guy

Also, as i said, heavier point weights will effect the AMPLITUDE of the oscillations, and if these are too large the arrow will be unstable, as you quite rightly said, but i couldn't speculate on how they would effect the FREQUENCY

Agreed

Originally Posted by Random_guy

Also, what constitutes a *heavy* point weight depends on the stiffness of the shaft (hence easton's different recommendations). So i guess it's safe to assume that the effect of point weight on AMPLITUDE is reduced the stiffer the arrow (as makes intuitive sense).

Agreed, at the end of the day shaft stiffness, length, point weight and acceleration are all interelated factors that will determine the amplitude of "bend". Which I guess is why they are taken into account for shaft selection programs.

Originally Posted by Random_guy

Hence there is no such thing as an arrow that is truly *too stiff* for compound, as in general its only the AMPLITUDE that compound archers need to worry about, rather than FREQUENCY, which is the major concern for recurves, and a stiffer arrow with the same point weight will probably oscillate with a smaller amplitude.

I have no idea as to whether point weight changes the frequency of oscillation, and is thus a valid method for recurve tuning. I wouldn't even like to speculate, as I don't know enough about the mechanics involved.

Agreed.

I'm not sure we're really dissagreeing on much.

[Random_guy]

No, not really

I think the main thing is that you can't "tune" a compound arrow with point weight, as altering point weight will not alter the spine of the arrow. Perhaps lowering point weight *might* let you get away with a slightly weaker arrow shaft, but why would you? It'll drift more, make the bow less efficient as it'll extract less energy from the bow, and you're still compromising the tune of the bow.

In reality i doubt that the amounts of weight we're talking about changing would make a significant difference to amplitude anyway, if you're close enough to too weak that changing the point weight up a few grains will give you clearance issues then maybe you're too close in the first place?

I couldn't speculate on recurve tuning with point weight, as i don't know what difference it makes to the frequency of oscillation....

[Jerry Tee]

OK so back to release aid compound. I have had a at Joe's site and I find it unclear as to whether not not he was talking about release aid or fingers. The main difference between the two is that as far as the paradox is concerned on a finger loose the nock and string are free to oscillate from side to side, with a release aid the paradox is in the verticle plane (or the far greater portion of it) so as the arrow is fixed at the nocking point then the nocking point must be where the back node of the arrow is, when the arrow is on the string. (It will have a very small degree of freedom of movement but only after it overcomes the mass of the bow). As soon as the arrow comes off the string then the node will shift forwards to the natural point as the arrow is free to oscillate normally It would seem to me that for the minimum amount of arrow disturbance that the spine of the arrow should be selected so that the arrow is flexing towards or at a straight and level point in its oscillation as the nock comes off the string.

On a separate not there may be some thing in the 'higher bracing height more forgiving' thing there. Is it that a higher bracing height allows more distance for the arrow to flex and clear the rest?

[Jerry Tee]

Originally Posted by Random_guy

No, not really

I think the main thing is that you can't "tune" a compound arrow with point weight, as altering point weight will not alter the spine of the arrow. Perhaps lowering point weight *might* let you get away with a slightly weaker arrow shaft, but why would you? It'll drift more, make the bow less efficient as it'll extract less energy from the bow, and you're still compromising the tune of the bow.

In reality i doubt that the amounts of weight we're talking about changing would make a significant difference to amplitude anyway, if you're close enough to too weak that changing the point weight up a few grains will give you clearance issues then maybe you're too close in the first place?

I couldn't speculate on recurve tuning with point weight, as i don't know what difference it makes to the frequency of oscillation....

Not according to Easton there is an effect but it is not large.

[Marcus26]

You can't tune any bow with point weight. Some people may try, but they are correcting an error with an error.
The only way to change the frequency of the arrow is:
• Change to a different spined arrow
• Change the energy being delivered to the arrow by adjusting it's poundage or string thickness

Now as for release aid shooting. It is highly ridiculous to claim you can adjust the spine of the arrows with point weight when you have no actual way of measuring whether the spine is correct or not.

Originally Posted by Random_guy

I think the main thing is that you can't "tune" a compound arrow with point weight, as altering point weight will not alter the spine of the arrow. Perhaps lowering point weight *might* let you get away with a slightly weaker arrow shaft, but why would you? It'll drift more, make the bow less efficient as it'll extract less energy from the bow, and you're still compromising the tune of the bow.

In reality i doubt that the amounts of weight we're talking about changing would make a significant difference to amplitude anyway, if you're close enough to too weak that changing the point weight up a few grains will give you clearance issues then maybe you're too close in the first place?

I couldn't speculate on recurve tuning with point weight, as i don't know what difference it makes to the frequency of oscillation....

[Random_guy]

its always good when experience backs up speculation

The real question is, will i be able to make 90m if i switch the 100grn points in my FMJ's for 125's..... sounds like an experiment for after exams!

[T101]

Originally Posted by Jerry Tee

If you want to you can see exactly how much difference the point weight makes by using the 2006 Easton shaft selector. Use the 'Hunting' selector, that allows you to put in different point weights, where as the 'target' one assumes an optimum point weight for the arrow and increasing the point weight won't affect the selection.

cheers but you can't differentiate between 90 or 110g on it, and nothing like my arrows r on there.

[Jerry Tee]

The vertical paradox on a release aid bow is a little more complicated than finger loose because the rear node of the arrow moves forwards when the arrow comes off the string. When the arrow is on the string then then rear node of the arrow is at the nocking point because a node is the point on the arrow that does not move as the arrow flexes. The string holds the nocking point fixed unless the arrow can over come the mass of the bow which it can't. When the arrow leaves the string the node will move forwards ot its natural point on the shaft. To get the minimum disturbance of the shaft then arrow should be at point of its oscillation where the shaft is straight as the nock comes off the string.

[Jerry Tee]

Since tuning basically involves aligning the nodes in paradox then it should not matter if the paradox is horizontal ( finger loose ) or verticle ( release aid ) The same basic rules of physics apply. So in theory it should be possible to bare shaft tune a release aid bow to align the nodes of the arrow in the vertical plane instead of the horizontal. I am going to give it a try and see what effect altering the Dynamic spine of an arrow will do and if I can alter the stiffness of a spring launcher in the same way that the button stiffness is altered on a finger loose bow.


If anyone else feels that they would like to try this experiment don't be shy I have not got exclusive rights to it.
I am going to use Axis FMJ 400 with a total point weight of 116 grains and a total shaft weight of 426 grains and 400 Carbonaeros with a point weight of 100 grains and a total shaft weight of 366 grains both cut to 28 inches. If mass has no effect on the how much the arrow flexes then the distance between the point of impact between the bare and fletched shafts for both arrows will be the same.

[T101]

Yeah Easily. With the Allegiance I struggled to make it with my high anchor but still managed with sight 6" out from the bow, but with my Constitution no problem. I have a small head so my peep gap is quite small.
When I shot 410 grain Axis FMJ's with 141grain points and inserts I still made 90m, I just moved my sight in.[/quote]

so what fps r u getting with your constitution, and how much more is it than allegince?

ok so i am trying 2 elimate possible probs here, hope u don't mind giving some more help

My sight is 4.25"(lens) from riser, on the closest divot already

could my idler wheel having to much lean cause loss of speed/kinetic energy. its double what the Mathews tech advises which is a 1/8th" light gap from shaft to string,(running arrow flat from wheel to nocking point method) and the serving wore through on roller wheel.(fixed)


another ai member has confirmed his switchback with v. similar set up got the same speeds i am getting and he had no trouble at 90m, but admitted his peep was naturally quite high.

arrows r grouping in gold at 60 yds and 50 most in outer 10 ring and i was getting an average of 4 out of 6 (just!) in the gold at 100yds. so its shooting what seems to me to be quite good. its just that i think the hold angle could be a problem on a york round 6 doz @100 yds.

doing some tuning next week as arrows r coming out of the bow fairly ragged,fishtailing a bit, and will sort wheel nocking point centre shot etc.

do u think any of this will help to get peep back down, as i don't really want to drop point weight, or increase draw weight.

would appreciate input from anyone, particularly switchback owners.