easton chart suggests too stiff arrows?

Infinity

New member
So i just add some info to this thread about my personal journey with Easton cheap arrows and their spine chart.

Recurve medium 68" limbs , riser. Limbs range from 24lbs to 40lbs at 28" draw.

I just want to warn that i was forced to throw away about 4/12 arrows from every batch of x12 Inspire arrows because they was so "wobbly" and curved. Coach dont alow to use those during practice at the club. We talking about 0.5mm - 1.5mm after beeing cut.
I know this and Inspire are dirtcheap arrows so this was expected.

Hopefully this will help some to be able to tune there bows a bit more accurate with Eastons cheaper type of arrows and dont have to second guess the result.

A sample picture how a read the Easton spinechart.
https://imgur.com/a/6UcQ1w8


link to the pdf:
https://eastonarchery.com/wp-content/uploads/2018/10/2018-Easton-TargetShaft-Selector.pdf


Easton Inspire 750.
These are getting a nice papertune at 39.5lbs at 28" draw. 36lbs gives 3" tare barechaft. 35lbs 4" tare and keep getting worse.

Easton Apollo 670.
These are getting a near perfect papertune at 40lbs. Behave almost exactly the same as Inspire 750. Anything below 40lbs will create large tares.

Easton Inspire 630.
These i only can get within a 0.5 inch papertare. My guess is they tune straight at around 45-50lbs.

Easton Inspire 570.
These are so stiff they are not tunable with my setups. My rough estimate would be that they tune straight at around 50lbs or more. I wouldnt use these for recurve target bows its way to stiff.


Easton Apollo 1070.
To be continued... I ordered a batch of these to run with 24-28lbs limbs to focus more on form/technic.




The correct spine groups according to me personaly. 28" draw target recurve medium 68" bow.

Easton Inspire 750.
Belongs to group T3(27-32lbs). on the Easton spinechart 2018. Id say they belong in group T6(40-44lbs)because i cant tune em at below 39lbs.

Easton Apollo 670.
Belongs to group T5(36-40lbs) on the Easton spinechart 2018. Id say they belong in group T6(40-44lbs)because i cant tune em at 39lbs or below. The higher quality in Apollo is significant versus Inspire.

Easton Inspire 630.
Belongs to group T5(36-40lbs) on the Easton spinechart 2018. Id say they belong in group T8(48-52lbs) for sure and just maybe can be tuned for group T7(44-48lbs).

Easton Inspire 570.
Belongs to group T6(40-44lbs) on the Easton spinechart 2018. Id say they belong in group T9(53-57lbs) for sure and just maybe can be tuned for group T8(48-52lbs).

 

Timid Toad

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Interesting.

Have you bare shaft tuned any of these at 30m, or walk-back tuned them as a comparison? I'd be interested to see how your paper tuning corresponds to other methods.
Personally I have never achieved reliable results paper tuning a recurve.
 

Infinity

New member
Interesting.

Have you bare shaft tuned any of these at 30m, or walk-back tuned them as a comparison? I'd be interested to see how your paper tuning corresponds to other methods.
Personally I have never achieved reliable results paper tuning a recurve.
Good point. The range to the paper was ranging from 1meter to 18meter.

But one thing i got to mention is that the higher quality arrows you use from Easton the more accurate the spine chart is. I borrowed some high end stuff from clubmembers and those arrows was tuning perfect according to the chart with only minimal tries. But becuase its not my personal arrows i cant rely on it as proof, with so few tries.



A sample picture how a papertare from my tests look like.
https://imgur.com/a/kUdBymt

- The first top tare is almost horizontal but it starts from left to right. So bit more lbs and adjust the nock up just a smidge.

- Same with second tare. There was a bit of stiff plunger button on this one and low knockingpoint.

- The 3 and 4 tare in the bottom are just overspined arrow.
Im a lefty also*
 

Infinity

New member
So i built some new arrows to add. And my conlussion is in the bottom if this post. So the Easton Apollo 1070, cut em down to 28". They fit my 28lbs limbs perfect. The only tuning i needed was change the plunger spring 2turns. Very nice and well flying arrows.

The Easton Apollo is according to tolerances. No arrows was scrapped of Apollo 670 or 1070. And they are very affordable and i shoot good groups and they surpasses my archery skills by alot. So i will buy more of these arrows in the near future.

Here was my previos notes on tuning the diffrent arrows.

Easton Inspire 750.
These are getting a nice papertune at 39.5lbs at 28" draw. 36lbs gives 3" tare barechaft. 35lbs 4" tare and keep getting worse.

Easton Apollo 670.
These are getting a near perfect papertune at 40lbs. Behave almost exactly the same as Inspire 750. Anything below 40lbs will create large tares.

Easton Inspire 630.
These i only can get within a 0.5 inch papertare. My guess is they tune straight at around 45-50lbs.

Easton Inspire 570.
These are so stiff they are not tunable with my setups. My rough estimate would be that they tune straight at around 50lbs or more. I wouldnt use these for recurve target bows its way to stiff.

NEW!
Easton Apollo 1070.
These tune well at 28lbs without adjustment.


So after watch Sam hapers youtube clip i decided to play around with checking the deflection of the arrows i have.
https://www.youtube.com/watch?v=pkZ_6GYFb-A


I know the ATA(AMO) spine chart is for wooden arrows. And the newer ASTM spine chart is for carbon arrows. The article written by Arco Vienna and Konstantin Tomanov is a nice source of information on this subject.
https://targetcrazy.com/archery/resources/ata-astm-arrow-spine/



So lets see where the diffrent arrows end up with the ASTM spine chart vs Easton chart.


Easton Apollo 1070. ASTM chart says 29.5lbs wich is very close to what the arrow tune well to on my bow. Easton arrow selector says apollo 1070 is in grp T1, but it belongs in grp T3 when looking at the ASTM chart.


Easton inspire 750. ASTM chart says 753 at 42lbs. I tune the arrow fine at 39.5lbs. thats 2.5lbs off. Easton arrow selector say inspire 750 is in grp T3, but it belongs in grp T6 when looking at the ASTM chart.


Easton apollo 670. ASTM chart says 47lbs. I tune the arrows at 40 lbs, thats 7lbs off. Easton arrow selector says apollo 670 is in grp T5, but it belongs in grp T7 when looking at the ASTM chart.


Easton inspire 630. ASTM chart says 50lbs. i guessed 45-50 that i still feel is resonable. Easton arrow selector says inspire 630 is in grp T5, but it belongs in grp T8 when looking at the ASTM chart.


Easton inspire 570. ASTM chart says 55-56lbs. My previos guess was 50+lbs and still holds true. Easton arrow selector says inspire 570 is in grp T6, but it belongs in grp T9 when looking at the ASTM chart.



So when looking at my own previos quess im somewhere between the Easton chart and the ASTM chart. I would say my personal guess is closer to ASTM spine chart between the two.

The correct spine groups according to me personaly. 28" draw target recurve medium 68" bow.

Easton Inspire 750.
Belongs to group T3(27-32lbs). on the Easton spinechart 2018. Id say they belong in group T6(40-44lbs)because i cant tune em at below 39lbs.

Easton Apollo 670.
Belongs to group T5(36-40lbs) on the Easton spinechart 2018. Id say they belong in group T6(40-44lbs)because i cant tune em at 39lbs or below. The higher quality in Apollo is significant versus Inspire.

Easton Inspire 630.
Belongs to group T5(36-40lbs) on the Easton spinechart 2018. Id say they belong in group T8(48-52lbs) for sure and just maybe can be tuned for group T7(44-48lbs).

Easton Inspire 570.
Belongs to group T6(40-44lbs) on the Easton spinechart 2018. Id say they belong in group T9(53-57lbs) for sure and just maybe can be tuned for group T8(48-52lbs).

Conclussion:
So what i want to say with this is that ASTM spine chart is very close to the reality what i have been getting good tunes on my arrows and my bow, with the draw weight and spine deflection. Its also fits when messure the deflection on my Easton arrows according to the ASTM established forumla at home.

And i also would like to stick out my chin and advice people to actually messure deflection according to ASTM and select arrows accordingly, and NOT trying to guess your way by looking at the Easton chart wich is deviating more and more the stiffer the arrow(less deflection) has.

Like Easton Inspire 570 that is off by 3 grps on the Easton chart. From T6 according to easton and grp T9 according to ASTM. And my personal guess was off by 2 grps.


Picture of the fletching of Easton Apollo 1070.
https://imgur.com/mexzQ9B
 
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