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Discussion Starter · #1 ·
I have a new set of limbs, ILF, put upon an established riser for me and set up like I normally do. Paper tuned to good flight, stopped there as I am confused by the limbs as I shoot them.

Key tune / shooting parameters:
  1. Three under
  2. Even tiller
  3. Paper tune.. while shooting no observed porpoising of arrow, visually good
  4. Arrow tunes at a 550 vs. what I usually end up with in this range of ~650. This is different...
  5. These are quite lightweight limbs, about 22# @28", and more like 26# at my 31.5" draw. But all my limbs are in this area as I have shoulder issue
Observed difference: The setup shoots lower than my other rigs by about a foot / 30cm at 20yds.

I have had minor variations from limb to limb in past on where arrows landed, nothing I recall being much outside of a few inches of difference. This is striking.

Limb timing?
Solution- change tiller a lot? Or other?
 

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Is the arrow weight a lot heavier? What poundage do you normally shoot? The first time I tried really lightweight limbs the arrows went way lower than I thought they should. Turned out I was dropping my bow arm. I didn’t have that problem with my regular setups, but my guess is the slower limbs/arrow were magnifying any form problems a lot. On release, the arrow stayed on the string and rest far longer on that setup so I had to keep my arm up longer.
 

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I have a new set of limbs, ILF, put upon an established riser for me and set up like I normally do. Paper tuned to good flight, stopped there as I am confused by the limbs as I shoot them.

Key tune / shooting parameters:
  1. Three under
  2. Even tiller
  3. Paper tune.. while shooting no observed porpoising of arrow, visually good
  4. Arrow tunes at a 550 vs. what I usually end up with in this range of ~650. This is different...
  5. These are quite lightweight limbs, about 22# @28", and more like 26# at my 31.5" draw. But all my limbs are in this area as I have shoulder issue
Observed difference: The setup shoots lower than my other rigs by about a foot / 30cm at 20yds.

I have had minor variations from limb to limb in past on where arrows landed, nothing I recall being much outside of a few inches of difference. This is striking.

Limb timing?
Solution- change tiller a lot? Or other?
What is your tiller now? Sounds way positive tiller?
Adjust them both even tiller.
 

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Greg, without seeming too harsh, you might have bought a set of slower limbs than you normally run....on this "established" riser.
 

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First I would weigh both sets of limbs at full draw.
Second I would shoot both set of limbs through a chrono.

I wouldnt spend much thought on the problem until you did both of those checks.
 

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Is the arrow weight a lot heavier
This is likely a culprit. The difference in shaft weight between a full length 550 and 650 arrow may be only 30 grains (which at that draw weight is more than 1 GPP), but the difference in tip weight could be quite dramatic. When I tune a 500 spine arrow for a bow and then tune a 400 spine arrow the 400 spine arrow is over 150 grains heavier.
 

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Discussion Starter · #13 ·
Input- added comments to address ideas and thoughts above.. bolded new stuff so we can see "input" clearly in one area of thread. Keep in mind I have a ton of bows.. certainly more than 50 now, I lost count. So I have set up a ton of bows, and made a ton of errors along the way, and have a lot to compare this against. This is new to me...

Key tune / shooting parameters:
  1. Three under
  2. Even tiller
  3. Paper tune.. while shooting no observed porpoising of arrow, visually good
  4. Arrow tunes at a 550 vs. what I usually end up with in this draw weight range of ~650. This is different...
    1. This is compared to another set of limbs at same draw weight measured at my draw, and of roughly similar design- curvier than most, high carbon content, etc. etc. This is not a measured draw weight issue. And compared one set of curvy or super curve limbs to similar.
  5. These are quite lightweight limbs, about 22# @28", and more like 26# at my 31.5" draw. But all my limbs are in this area as I have shoulder issue
    1. Again.. I have a lot of limbs in this range and tested vs. limbs of similar design and weight measured by scale at my draw length. I have maybe 5-7 sets of limbs in this weight +/- 3#.
  6. Arrow mass is only 30gr different between similar bows. 550 at 330gr, 650 at 300gr within a few grains.
  7. Arrow length, fletching, nocks, other equipment IDENTICAL- I have portfolio of same arrow make, simply increase tip weight by 10Gr for each 100 in spine from 800 to 400.
  8. I have not checked speed on a chrony.. but if anything they seem faster than my other limbs, and bury the arrows noticeably deeper.
    1. Keep in mind, to get a foot of difference my arrow speeds would need to be about 50FPS slower or so.. no way this is happening. At most we have 10FPS difference here for 2" or so.
Observed difference: The setup shoots lower than my other rigs by about a foot / 30cm at 20yds.

I have had minor variations from limb to limb in past on where arrows landed, nothing I recall being much outside of a few inches of difference. This is striking. And when I say across limbs I really mean across limbs.. standard curves, super curves, foam core, wood core, solid (Uukha,), old stuff from 70's, new stuff from this year and last decade, etc. etc. etc. I have never run into this wide a variation, usually is within 4-6", and is usually mostly "faster or slower." This is not "faster or slower" issue.

Limb timing?
Solution- change tiller a lot? Or other?
 

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Again
Until you actually verify and normalize it compared to an existing set of limbs with....

-Draw weight at your draw length checked on a scale
-arrow weight with a scale
-velocity on a chrono

You dont have any idea whats going on.
 

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Discussion Starter · #15 ·
@Carboniac .. I did first two of three and tried to make that clear in bold updates. I have two bows set up, draw weights at my length within 1#, similar limbs (one is Uukha, other is a super curve that is causing me trouble), measured the arrow masses as stated and the differ only by 30gr total.

I have not done the velocity, might do on weekend or tonight. But there is no way they vary more than 20FPS or 4-5" at 20 yds, and I believe unlikely much over 10FPS / ~2" at 20yds. And it seems to me the problematic limbs are faster based on feel. I really dont believe this is issue.
 

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tiller GREG when you say even tiller - at even tiller are bolts even turns out? or do you have odd bolt turns top & bottom to gain even tiller at limbs?
you're experienced enough I give credit for everything except ability to discern speeds....and reliably tell how much slower = how much LOWER.
Need to chrony it.
your limbs are slow.
UNTIL you prove my guess is bad. haha.
A GOOD PUZZLE.
 

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Discussion Starter · #17 ·
Hi steve.. you and carboniac are likely right.. will chrono.

Even tiller is, to me, same distance from limbs to string top and bottom.

What I am wondering and can go recheck- the spine is odd, maybe I had to step up due to odd limb timing. This would also, I think, tend to change where on string the nocking point gave a nice paper tune. Perhaps I find that the nocking point is 3/8" higher than normal to compensate for timing, but that would shoot arrow down on target about 8-10"...
 

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even tiller me too the distance. I just wondered if your bolts turn the same in order to get there....even tiller.
 

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Again
Until you actually verify and normalize it compared to an existing set of limbs with....

-Draw weight at your draw length checked on a scale
-arrow weight with a scale
-velocity on a chrono

You dont have any idea whats going on.
@Carboniac .. I did first two of three and tried to make that clear in bold updates. I have two bows set up, draw weights at my length within 1#, similar limbs (one is Uukha, other is a super curve that is causing me trouble), measured the arrow masses as stated and the differ only by 30gr total.

I have not done the velocity, might do on weekend or tonight. But there is no way they vary more than 20FPS or 4-5" at 20 yds, and I believe unlikely much over 10FPS / ~2" at 20yds. And it seems to me the problematic limbs are faster based on feel. I really dont believe this is issue.
You actually have to measure this stuff to know.

You need to actually check the draw weight at your draw.


Its possible that the draw weight is at 31 is actually 5 lb different.
The arrow apparently weights 30 grains more.
And then its possible that between stored energy and efficiency one is inherently 10% faster.
All together that could make a big difference.
 
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