AMO standard (mostly used for wood arrows) measures at 26" and 2 lbs weight. ASTM standard (mostly used for carbon arrows) measures at 28" and 1,94 lbs weight. For calculating the value in ASTM standard use following calculation: ASTM = 0,825 x AMO. In your case 1139 x 0,825 = 940 Spine (for the 1000 Spine carbon arrow). For the measurement it does not matter. Just the scaling must be adapted or calculated to the right standard. Sometimes you have to take care how the manufacturer measures the spinevalue. AMO or ASTM standard. AMO is a older standard but still in use. (ARCHERY MANUFACTURERS AND MERCHANTS ORGANIZATION now ATA)
Hi Armin. I did a deep dive into measuring spine a few years ago, after reading numerous posts well known traditional and respected sources, and also wrote those sources with questions not answered. All said traditional measurement was 28”. My interest was measuring shafts of any length for various draw lengths for their spine. Ultimately, we are trying to address Archers Paradox, and arrow tuning, after shaft selection. It shouldn’t really matter what the shaft material is, but it does. All wood shafts have wood grain, and the orientation of the wood grain to the angle of deflection makes a big difference. I built my testing setup to measure from 28” to 36”. As you know, when you increase the length you reduce the spine amount because the shaft bends easier. You can estimate spine for traditional bows based on charts based on the bows poundage, but it’s never completely correct, once using a longer shaft than 28”. I use carbon shafts bescayse they are consistent, whereas wood is not, and can easily vary from shaft to shaft, based on the individuals shafts Janka hardness, and grain orientation. From my experience, a 30# @ 28” bow, drawn to 33” can be pulling 40-45#, and 500 spine works well for me. I err on slight stiffer as I think I need for Archets Paradox, knowing I can soften the spine with tip weight. Arrow tuning can adjust the spine even more. I typically shoot my builds bare shaft to see where the shafts group related is o firm/soft of center, and elevation of target center. Then it’s easier to fine tune the arrow grouping w/ tip weight, FOC, and fletch.
It would make sense to have a standard way of measuring all arrow types. By having some measured at 26” and some measured at 28” it’s like a carpenter having one tape measure for oak, and another for pine. Great video as usual Armin 🙏🏹
When I searched it up, I only found the old standard and so that is what I used... No machine, just a weight and a tape measure and place for the arrow... Oh, and manufacturers of carbon arrows seem to be using the 26 inch standard, the only one I could find...
For the standard measurement (like easton does) it´s 28" and a 880g weight. BUT: it´s done with a 29" long arrow without points and nock. Your electronic thingy gives 940 spine at your 1000 arrow (you have to look at the ata number. deflection in inches.) most likely influenced by the point and arrow length.
So according to the big arrow book by Vorderegger, wood is measured at 26‘ with a weight (the standard weight that is attached) of 2 English pounds = 907 grams, but carbon is measured at 28’ according to the AMO standard with a standard weight of 1.94 English pounds = 880 grams, so there is a difference or both are correct. You can also divide the wood spine value by 0.825 to get the corresponding carbon value. That would be the explanation for me. Hope it helps.
Closely, not divide, multiply! AMO-Spine (mostly wood) measures at 26" and 2# weight. For calculating the value in ASTM standard use following calculation: ASTM = 0,825 x AMO. In the case here 1139 x 0,825 = 940 Spine (for the 1000 Spine carbon arrow).
@rubberduck777 Hm, not quite you have to bring the wood stock spine value e.g. 50 pounds to a comparative value, so 26 (inches) : 50 pounds gives 0.520 / 0.825 gives 0.630 so 630 spine value for carbon. That's what the book tells me.
@ Your base value is not the spine of the arrow. I was refering to the spine value of the arrow. If you calculate the right spine for your bow to get the needed arrow spine, depending on the drawweight you are right. But this is not the issue here in the video. Spinevalue AMO x 0,825 = Spinevalue ASTM. If we use the example from before and divide it would be 1139 / 0,825 = 1380 for a 1000 Spine shaft. Nearly 40 % away from the manufacturer value. instead of just 6% in the previous calculation.
hi Armin, when i started archery, after using my 150€ foam limbs (30#) i tried my trainer bow with 800€ limbs (30#) i understood the problem : high tehnology bows used as reference ! so, if Bearpaw or other Easton say they use 600 spine it's because they use competition bows, then all the spine chart is indicative, not absolute those references are registred on 26" testing machines ! so, now i'm a 3 year old archer, i can advise beginners with "cheap" bows : 22# with 1100 spine, 26# with 900 spine, 30# till 800 spine after that all depends on the slow or fast delivery that gives a "kick" to the arrow (when you shoot outside with face wind)
I haven't found that spine affects flight. But I also haven't had much variation in advertised spine. While I ordered and paid for 500 spine carbon arrows, one set came 500 spine, the next came 1200spine, and yet a third came 600 spine. The 500 and 600 spine arrows were basically the same out of a 30lb recurve Black Hunter. The 600 spine were slightly better out of the ambidextrous longbow from wish but not enough to matter. The 1200s weren't good out of anything til i cut them in half and built a Joerg Sprave inspired crossbow. My biggest thing with ratings on arrrows is noone seems to pay attention to any standardization. And most of the suppliers of cheap arrows will mark them as whatever they want to sell you and be damned if you never buy from them again. Whole the expensive ones are too expensive (3 arrows for the same as 36 from wish) and don't last more than 5 shots. So I continue to buy the ones recommended by the charts on Wish or Temu for my bows and hope that they'll come spined enough that I can use them.
If you buy a 500 Spine and 600 Spine, you can have in worst case two sets with a 550 spine. If you shoot a bow with center shot or thumbdraw with khatra the spine makes nearly no difference at such close values. The 1200 spine arrows could maybe fit, if they are cut down to 26" or shorter for your 30 lbs bow. But else they are to soft. But depends on your handle of the bow. At a bow without arrow rest (shooting over handback) I used a light 700 spine carbon arrow with 85 grain tip, 30,5 inch long. For 30 pounds would fit too. For 35 lbs I would reduce the tip to 65 grain. Or use a 600 spine arrow with a 100 - 110 grain tip. Maybe that helps a bit to find your right arrows.
@rubberduck777 thanks. The 5 and 600 spine arrows fly pretty good from my 30lb Black Hunter recurve, with about 250gr in front w 3in turkey feather vanes. The 45lb limbs I bought for it exploded tho, no damage done. Unfortunately I'm looking for longer arrows with stiffer spines as I'm going up in draw weight and to a traditional rather than the take down recurve, center shot bow I learned on. With a 32" draw I'm finding it difficult to find arrows that are longer and strong enough, at a reasonable cost. $30cad for an easton arrow is ridiculous, especially since then you gotta tip it and nock it too and it's too short.
@ But I think the 32" shaft should be long enough. You can calculate the length of the nock and tip to it. Specially when you use such heavy tips. Such tips have 2", so 1 1/2" are straight and 1/2" for the nock you should be fine. Else the asian market could provide longer shafts. But it will not be cheap, because of the transfer costs. Bamboo arrows are aviable longer and cheaper, if this is a option. Carbon shafts are rare to find or you ask the manufacturer. I heard of some, that they could order it anyway. But it is not stock and connected with extra costs.
@ Was looking again and found Shaft | SPHERE Pioneer 6.2 - Carbon in 33" 4,70€ per shaft or shaft | SKYLON Bentwood - Carbon 33" 6,60 €. Not sure you will find it on US maket as well.
From my point of view measuring the absolute value is not that important, I care more about consistency within a set of arrows, and of course the spline (I had shafts with a spine difference of more than 100 depending of the direction). For the absolute spine value you should have got a calibration shaft with the device.
First off: I dont know what the standard are, but I can Help you understand and relating the difference: Carbon arrow is 26" at 1139 spine (the one you measured. The manufacturer says it has a spine of 1000 measured at 28". The difference is the length. The longer the measuring point, the weaker the arrow gets. So thats why it drops in spine stiffnes the further you place the stands apart. Roughly speaking: 26 divided by 28 is roughly 0,92. If you take 1139 and multiply it by 0,92 you get 1047 spine. so in the ballpark of the manufacturer. 0,92 is always the smae number to calculate what it would be on a 28" measuring machine. Your device calculates it according the total amount of pressure difference needed to touch the pedestall in the middle. Thats all there is to it.
@@ArminHirmer Iff I had them I would. I'm using wooding spine arrows that I make myself. So I actually don't have a refference. Thats why I asked the question? I looked it up in the meantime: Only difference to my first calculation would be you need to divide it by 9,2. That being said: I still don't understand why they don't measure it in tensile strentgh and compression strength?
There are different standards for spine calculation. One of the difference is distance between the support points, the other is a difference of weight used to create the bend. Google search for spine-o-meter pdf. (Oakarchery). It contains the definitions, the math and a table giving the relation between the different standards.
no such thing as best, gotta shoot groups and get the spine that agrees with your bow and technique the most. and after that if you change point weight itlll change the dynamic spine, static spine is only for initial measurement. really gotta listen to your groups. and even if you spine is off if you are shooting a barebow your mind will adjust. just have fun shooting.
@@이름모를누구-m4v Spine round about 500 - 600 if you use arrow shafts wich are 30 - 32 inches long. And you draw your bow in that length. And your bow has no arrow rest.
AMO standard (mostly used for wood arrows) measures at 26" and 2 lbs weight.
ASTM standard (mostly used for carbon arrows) measures at 28" and 1,94 lbs weight.
For calculating the value in ASTM standard use following calculation: ASTM = 0,825 x AMO.
In your case 1139 x 0,825 = 940 Spine (for the 1000 Spine carbon arrow).
For the measurement it does not matter. Just the scaling must be adapted or calculated to the right standard.
Sometimes you have to take care how the manufacturer measures the spinevalue. AMO or ASTM standard.
AMO is a older standard but still in use. (ARCHERY MANUFACTURERS AND MERCHANTS ORGANIZATION now ATA)
Hi Armin.
I did a deep dive into measuring spine a few years ago, after reading numerous posts well known traditional and respected sources, and also wrote those sources with questions not answered. All said traditional measurement was 28”.
My interest was measuring shafts of any length for various draw lengths for their spine.
Ultimately, we are trying to address Archers Paradox, and arrow tuning, after shaft selection. It shouldn’t really matter what the shaft material is, but it does. All wood shafts have wood grain, and the orientation of the wood grain to the angle of deflection makes a big difference.
I built my testing setup to measure from 28” to 36”.
As you know, when you increase the length you reduce the spine amount because the shaft bends easier.
You can estimate spine for traditional bows based on charts based on the bows poundage, but it’s never completely correct, once using a longer shaft than 28”.
I use carbon shafts bescayse they are consistent, whereas wood is not, and can easily vary from shaft to shaft, based on the individuals shafts Janka hardness, and grain orientation.
From my experience, a 30# @ 28” bow, drawn to 33” can be pulling 40-45#, and 500 spine works well for me. I err on slight stiffer as I think I need for Archets Paradox, knowing I can soften the spine with tip weight. Arrow tuning can adjust the spine even more.
I typically shoot my builds bare shaft to see where the shafts group related is o firm/soft of center, and elevation of target center. Then it’s easier to fine tune the arrow grouping w/ tip weight, FOC, and fletch.
It would make sense to have a standard way of measuring all arrow types. By having some measured at 26” and some measured at 28” it’s like a carpenter having one tape measure for oak, and another for pine.
Great video as usual Armin 🙏🏹
When I searched it up, I only found the old standard and so that is what I used... No machine, just a weight and a tape measure and place for the arrow... Oh, and manufacturers of carbon arrows seem to be using the 26 inch standard, the only one I could find...
For the standard measurement (like easton does) it´s 28" and a 880g weight. BUT: it´s done with a 29" long arrow without points and nock.
Your electronic thingy gives 940 spine at your 1000 arrow (you have to look at the ata number. deflection in inches.) most likely influenced by the point and arrow length.
So according to the big arrow book by Vorderegger, wood is measured at 26‘ with a weight (the standard weight that is attached) of 2 English pounds = 907 grams, but carbon is measured at 28’ according to the AMO standard with a standard weight of 1.94 English pounds = 880 grams, so there is a difference or both are correct. You can also divide the wood spine value by 0.825 to get the corresponding carbon value. That would be the explanation for me. Hope it helps.
Closely, not divide, multiply!
AMO-Spine (mostly wood) measures at 26" and 2# weight.
For calculating the value in ASTM standard use following calculation: ASTM = 0,825 x AMO.
In the case here 1139 x 0,825 = 940 Spine (for the 1000 Spine carbon arrow).
@rubberduck777 Hm, not quite you have to bring the wood stock spine value e.g. 50 pounds to a comparative value, so 26 (inches) : 50 pounds gives 0.520 / 0.825 gives 0.630 so 630 spine value for carbon. That's what the book tells me.
@ Your base value is not the spine of the arrow. I was refering to the spine value of the arrow. If you calculate the right spine for your bow to get the needed arrow spine, depending on the drawweight you are right. But this is not the issue here in the video.
Spinevalue AMO x 0,825 = Spinevalue ASTM. If we use the example from before and divide it would be 1139 / 0,825 = 1380 for a 1000 Spine shaft. Nearly 40 % away from the manufacturer value. instead of just 6% in the previous calculation.
Sorry. You are right.
@@AndreasWechtl No reason to be sorry. I didn't felt offended. Just good we found the point of missunderstanding. Schönen Abend noch
Can you put put the model of spine analyzer you are using in this video? I'd like to take a look at it.
check in my videos a few years ago HARS Arrow Analyser, thanks
@@ArminHirmer Thank you
hi Armin,
when i started archery, after using my 150€ foam limbs (30#) i tried my trainer bow with 800€ limbs (30#) i understood the problem : high tehnology bows used as reference !
so, if Bearpaw or other Easton say they use 600 spine it's because they use competition bows, then all the spine chart is indicative, not absolute
those references are registred on 26" testing machines !
so, now i'm a 3 year old archer, i can advise beginners with "cheap" bows : 22# with 1100 spine, 26# with 900 spine, 30# till 800 spine
after that all depends on the slow or fast delivery that gives a "kick" to the arrow (when you shoot outside with face wind)
I haven't found that spine affects flight. But I also haven't had much variation in advertised spine. While I ordered and paid for 500 spine carbon arrows, one set came 500 spine, the next came 1200spine, and yet a third came 600 spine. The 500 and 600 spine arrows were basically the same out of a 30lb recurve Black Hunter. The 600 spine were slightly better out of the ambidextrous longbow from wish but not enough to matter. The 1200s weren't good out of anything til i cut them in half and built a Joerg Sprave inspired crossbow. My biggest thing with ratings on arrrows is noone seems to pay attention to any standardization. And most of the suppliers of cheap arrows will mark them as whatever they want to sell you and be damned if you never buy from them again. Whole the expensive ones are too expensive (3 arrows for the same as 36 from wish) and don't last more than 5 shots. So I continue to buy the ones recommended by the charts on Wish or Temu for my bows and hope that they'll come spined enough that I can use them.
If you buy a 500 Spine and 600 Spine, you can have in worst case two sets with a 550 spine.
If you shoot a bow with center shot or thumbdraw with khatra the spine makes nearly no difference at such close values.
The 1200 spine arrows could maybe fit, if they are cut down to 26" or shorter for your 30 lbs bow. But else they are to soft. But depends on your handle of the bow. At a bow without arrow rest (shooting over handback) I used a light 700 spine carbon arrow with 85 grain tip, 30,5 inch long. For 30 pounds would fit too. For 35 lbs I would reduce the tip to 65 grain. Or use a 600 spine arrow with a 100 - 110 grain tip. Maybe that helps a bit to find your right arrows.
@rubberduck777 thanks. The 5 and 600 spine arrows fly pretty good from my 30lb Black Hunter recurve, with about 250gr in front w 3in turkey feather vanes. The 45lb limbs I bought for it exploded tho, no damage done. Unfortunately I'm looking for longer arrows with stiffer spines as I'm going up in draw weight and to a traditional rather than the take down recurve, center shot bow I learned on. With a 32" draw I'm finding it difficult to find arrows that are longer and strong enough, at a reasonable cost. $30cad for an easton arrow is ridiculous, especially since then you gotta tip it and nock it too and it's too short.
@ But I think the 32" shaft should be long enough. You can calculate the length of the nock and tip to it. Specially when you use such heavy tips. Such tips have 2", so 1 1/2" are straight and 1/2" for the nock you should be fine. Else the asian market could provide longer shafts. But it will not be cheap, because of the transfer costs. Bamboo arrows are aviable longer and cheaper, if this is a option. Carbon shafts are rare to find or you ask the manufacturer. I heard of some, that they could order it anyway. But it is not stock and connected with extra costs.
@ Was looking again and found Shaft | SPHERE Pioneer 6.2 - Carbon in 33" 4,70€ per shaft or shaft | SKYLON Bentwood - Carbon 33" 6,60 €. Not sure you will find it on US maket as well.
From my point of view measuring the absolute value is not that important, I care more about consistency within a set of arrows, and of course the spline (I had shafts with a spine difference of more than 100 depending of the direction).
For the absolute spine value you should have got a calibration shaft with the device.
even more confuse than before
First off: I dont know what the standard are, but I can Help you understand and relating the difference:
Carbon arrow is 26" at 1139 spine (the one you measured. The manufacturer says it has a spine of 1000 measured at 28". The difference is the length. The longer the measuring point, the weaker the arrow gets. So thats why it drops in spine stiffnes the further you place the stands apart.
Roughly speaking: 26 divided by 28 is roughly 0,92. If you take 1139 and multiply it by 0,92 you get 1047 spine. so in the ballpark of the manufacturer. 0,92 is always the smae number to calculate what it would be on a 28" measuring machine.
Your device calculates it according the total amount of pressure difference needed to touch the pedestall in the middle. Thats all there is to it.
and the higher the spine value, the weaker the shaft. So at 28" the 1100 spine shaft would be 1200 or more
@@ArminHirmer Are you saying that when the spine value is higher, that the arrow is more flexible?
@@KevskiStyle grab a 1200 spine arrow bend it and then a 300 and you will know
@@ArminHirmer Iff I had them I would. I'm using wooding spine arrows that I make myself. So I actually don't have a refference. Thats why I asked the question?
I looked it up in the meantime: Only difference to my first calculation would be you need to divide it by 9,2.
That being said: I still don't understand why they don't measure it in tensile strentgh and compression strength?
There are different standards for spine calculation. One of the difference is distance between the support points, the other is a difference of weight used to create the bend.
Google search for spine-o-meter pdf. (Oakarchery). It contains the definitions, the math and a table giving the relation between the different standards.
What do you think is the best spine value?
for which bow and poundage and draw length?
@ArminHirmer for 45lb carbon bow
no such thing as best, gotta shoot groups and get the spine that agrees with your bow and technique the most. and after that if you change point weight itlll change the dynamic spine, static spine is only for initial measurement. really gotta listen to your groups. and even if you spine is off if you are shooting a barebow your mind will adjust. just have fun shooting.
@@이름모를누구-m4v Spine round about 500 - 600 if you use arrow shafts wich are 30 - 32 inches long. And you draw your bow in that length. And your bow has no arrow rest.