Improving spine

[oldfarmsblueman]

OK now I am getting confused .I am beginning to think
shooting about 50-54# with a 26 " arrow puts me in a
in between place.I have bene shooting Beman ics Hunters
that are 500 spine.The 100 gr. point makes them bend more.
a 27" will bend more than a 25".49-50# will be stiffer than
52-54#.And now I wounder if a 500 with 7.3 gpi will act
like a 500 with a greater gpi.
How do you know when you are at the best place you can
be with out making your self nuts .With a computer I had
a guy tell me it is like a road map.There are many different
ways to get to the same place.

[royden]

welcome to archery

seriously ...

There are a lot of options out there and it boils down to comprimising...

What are your goals? Speed, weight, forgiveness, etc...

Personally I would go shoot - it is the easiest way to find out if an arrow combo works well. Shoot the field pts and the broad heads and check group size and location. then if something is different rule out the other options that could be affecting the arrow (rest, cam timing, fletch contact) and then spine. Spine is fairly easy to diagnose I think - increase or decrease bow poundage and or +/- broadhead weight and see if the arrow drifts right or left. A 500 will act like a 500 of the same brand, however different GPI will result in slightly high/low impacts.

does that make sense and help?

[BT]

Feb 8, 2009 20:00:05 GMT -5 oldfarmsblueman said:

How do you know when you are at the best place you can
be with out making your self nuts .
With a computer I had
a guy tell me it is like a road map.There are many different
ways to get to the same place.

I haven't found a program yet that will do anything beyond putting you in the area of spine that will allow you to achieve an acceptable tune.
I would take one (program) and use it if it were handed to me free of charge
(And yes...I have had plenty of offers)

As Royden said, first you have to know what you want and then use what you have available to perfect what it is that you want.
Nothing beats knowledge that is gained through trial and error
Unfortunitly....that is an expensive education

Keep in mind that the better the arrow spec for tolerances, the better the ability to tune.
The fastest way to drive yourself nuts is to try and work with a dozen arrows that have fliers caused by poor specs.
Many shops and individuals choose very stiff shafts to improve their ability to tune but this is a handicapping process at best and does not allow you to fine tune as best you could with a proper spined arrow

I would say (off hand) that you have the proper spine @ 26" and the variable would be the head weight.
Also keep in mind that when you change head weight you may need to also adjust your nock height or rest pressure....depends on how you are set up to start with.

Anyway....it's a long trial and error thing eventually so you might just as well jump right into it and get the learning curve behind you a.s.a.p.

[oldfarmsblueman]

Thanks
Next queston.If your spine is incorrect will it be seen at
one distance more than others.Lets say I shoot 10-20-
30-40 and 50 yards.Is it posible I will shoot better at
40 yds. than at 10

[BT]

Feb 9, 2009 6:57:16 GMT -5 oldfarmsblueman said:

Thanks
Next question.If your spine is incorrect will it be seen at
one distance more than others.Lets say I shoot 10-20-
30-40 and 50 yards.Is it possible I will shoot better at
40 yds. than at 10

No...unless you are consistently off the mark (to the side) and gaining as you go away from the target.
Whether weak or stiff, an arrow will track toward it's error.
If the spine is too stiff it will track (right handed shooter) progressively further to the left as distance increases to the target and right for a too weak spine.
While you may be spot on at 10 yards, you may be 4" left/right (for example) of the bulls eye at 30 yards.
Even if you were 1" left at 30 yards, this still shows that there is an error.

Error may be the arrow spine or it may be the tune.
Tune is more often the culprit.
For those who set center shot and then demand that the arrow capitulate to their demand for proper flight are generally the ones who are forever fighting with their arrows.
While it can be done, the faster and cheaper way to achieve proper arrow flight is to tune the bow to the arrow.

[oldfarmsblueman]

So is it fair to say two arrows same spine will act
the same if one is 25" with say 100 gr point.And the
other is 27" long with a 75 gr head. ???In Theory.

[SPIKER]

Feb 9, 2009 17:10:02 GMT -5 oldfarmsblueman said:

So is it fair to say two arrows same spine will act
the same if one is 25" with say 100 gr point.And the
other is 27" long with a 75 gr head. ???In Theory.

That's not too far off to see a noticable difference, except that the 75gr tipped arrow will hit higher.

[BT]

In theory your headed in the right direction but 25gr. isn't going to effect spine to that degree over 2" of shaft.
I find that 25gr. effects tune (left/right) to a sufficient degree on the same shaft if you are damn close to begin with.Head weight will change point of impact as Spiker pointed out due to the FOC change and not necessarily the weight change alone...although both are true.

[SPIKER]

Feb 9, 2009 17:24:59 GMT -5 BT said:

Head weight will change point of impact as Spiker pointed out due to the FOC change and not necessarily the weight change alone...although both are true.

Interesting, I've always assumed it was the head weight alone.

[omegabuck]

Okay I've got a bit of a question here. I just weighed 6 arrows that I recently had cut to 27" ... before they were 29" and weighed 355 GR + 100 GR tip. Now at 27" they obviously weigh differently than at 29". Four of the arrows weigh 294 GR and two weigh 295 GR. Now, the four weighing 294 GR, I put in tips that actually came out to 98 GR each to a total of 392 GR. The other two arrows weighing 295 GR, I put in tips that actually came out to 97 GR each to a total of 391 GR. Now, for my first try at matching arrow weights I don't think I did to bad ... but here's my question ...

According to the numbers presented all of the arrows SHOULD have come out to a matching weight ... why did they not?


That being said ... I think switching from an Easton Super Nock to a Bohning Double Lock Nock would save me ... 4 GR , that is of course a guestimation. Secondly switching from 4" Quick Spin Vanes to 2" Blazer Vanes would save me ... 16.5 GR ... again only guestimation, will have to do a little combination matching.

I think though that I have most likely improved FPS quite a bit by losing 61 GR overall before making any other modifications.