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Spine? IBO ABO? etc...?
I think I saw it mentioned on here before how to calculate the ideal/best spine etc...for your setup?
I'm not new to archery, but new to all these figures and numbers and what is best etc... My draw length is 28" current draw weight 63lbs, would like to become comfortable at 70lbs. shooting 100gr broadheads. have a few different arrow setups don't know exact arrow weights... 1 set is 10gr/in estimated wt... 418grs 2 set is 7.9gr/in.................... 353 3 set is 6.4gr/in................... 307grs Mainly trying to figure out if I could tweak my setup to shoot even tigher groups by determing an ideal BH weight, and or ideal spine/arrow weight etc... Is spine just arrow shaft diamter? and what is spine used to determine...? Thanks. |
RE: Spine? IBO ABO? etc...?
Spine is theamount of flex or bendof an arrow shaft under certain conditions. When you shoot the arrow it flexes as it leaves the string. If it flexes the correct amount then you have a correctly spined arrow and it will shoot best. If it doesn't flex enough then it is too stiff, too much flexing and it is too weak and either one too stiff or too weak is not ideal. A hunting arrow is usually set up with a slightly stiffer spine than a target arrow.
Someone can look up your info if you list your bow model and its' current setup and your arrow model with its' length and tip weight along with fletches. |
RE: Spine? IBO ABO? etc...?
Just to add to bruce's good post.
Shaft diameter has a small part to do with the spine. There are very skinny arrows that have stiff spine and very fat arrows that have weak spines. It all depends on the thickness between the inside and outside diameter, the overall diameter, and shaft material and design. Even arrow weight between manufacturers may vary. If all 3 arrow you listed are the same exact arrow manufacturer/model the heaviest one will probably be the one with the stiffest spine. As bruce stated supply your bow manufacturer, the arrow manufacturer/model that you have, the arrow length you intend to use and we can help you out. |
RE: Spine? IBO ABO? etc...?
Carbon tech arrows, whitetails, rhinos, cheetahs,plan to use whitetails or rhinos for hunting
most likely whitetails Spine for all 3 is listed at .400? Arrow Shaft lenght: 28" NAP quickspin ST speed hunters Matthews drenalin 70#, 28" draw, current weight 63# 100gr broadheads, muzzy 3 blade, not mx3, also have rage 2 blade 100gr |
RE: Spine? IBO ABO? etc...?
It looks as if you are marginally weak spine with that setup. Not awful but marginally stiff would be better. If you are going to get up to 70#'s you may want to look at the whitetails, rhino's and cheetahs with a .300 spine. You may also want to look at some other arrows in the .360 spine range, easton, carbon express, gold tips, etc.
Edit: Forgot to chnage the DL to 28" but you are still slightly weak. |
RE: Spine? IBO ABO? etc...?
If you are shooting the Drenalin with 80% let off your spine should be ok with any of those arrows up to 70 lbs. You may want to use a wrap though to stiffen the spine a little. Try to remember when looking at this that the spine is probably a little stiffer than what is shown. The program uses IBO speed and every bow's IBO differs depending on DL and the actual performance of the bow. Your bow's IBO will not be 320 FPS as listed by manufacturer because that IBO is for a 30" draw length unless otherwise specified.
You need the speed of a known arrow shot from your bow to adjust theIBO speed for your bow and a program like Archer's Advantage to figure out the exact spine. OT2 does not compensate for slower IBO's. So, ifthe program showsthe spine on the low side it is probably actually in the middle or slightly high. I've used this method with this program and have no issues with my arrows.  |
RE: Spine? IBO ABO? etc...?
65% let off, drenalin
so lower spine # equals a stiffer arrow? higher spine # weaker/less stiff? I'm typically at 63lbs, but if I shot more I know 70# wouldn't be a problem, so looking to get there. Always planning to shoot 100gr too, dont think I'll ever shoot 125grs, maybe for something large, but doubtful. Thanks for the info |
RE: Spine? IBO ABO? etc...?
ORIGINAL: salukipv1 65% let off, drenalin so lower spine # equals a stiffer arrow? higher spine # weaker/less stiff? I'm typically at 63lbs, but if I shot more I know 70# wouldn't be a problem, so looking to get there. Always planning to shoot 100gr too, dont think I'll ever shoot 125grs, maybe for something large, but doubtful. Thanks for the info |
RE: Spine? IBO ABO? etc...?
ORIGINAL: davepjr71 If you are shooting the Drenalin with 80% let off your spine should be ok with any of those arrows up to 70 lbs. You may want to use a wrap though to stiffen the spine a little. Try to remember when looking at this that the spine is probably a little stiffer than what is shown. The program uses IBO speed and every bow's IBO differs depending on DL and the actual performance of the bow. Your bow's IBO will not be 320 FPS as listed by manufacturer because that IBO is for a 30" draw length unless otherwise specified. You need the speed of a known arrow shot from your bow to adjust theIBO speed for your bow and a program like Archer's Advantage to figure out the exact spine. OT2 does not compensate for slower IBO's. So, ifthe program showsthe spine on the low side it is probably actually in the middle or slightly high. I've used this method with this program and have no issues with my arrows.
Hope this makes sense. |
RE: Spine? IBO ABO? etc...?
What program are you guys using? Is it free?
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RE: Spine? IBO ABO? etc...?
Have you found that to be true all the time? When I first got the program I was doing something with the program that would change the spine slider but forgot what it was. I stopped using it for a while and then I sent an email tothe guy who made it and he told me thatthe performance slideronly if you want to change your set-up for a particular arrow. So, that confused me about if I was doing it right so I stopped using the slider. If that makes any sense at all? That's when I started having the issues with the program spining the same way it used to for me.
Your last sentence mayexplain an issue I was running in to. I would change it on the equipment set-up tab and noticed that I couldn't reach an IBO low enough for my bow.Some things just are not explained out well enough evenby the guy who wrote the program. Thanks for the info. I'll try it out. |
RE: Spine? IBO ABO? etc...?
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RE: Spine? IBO ABO? etc...?
Actually Dave,I have found how to correctly adjust the speed of the program so it can be calibrated on OT2.OT2 does not use IBO,it uses cam style so when you get your exact speed,slide the performance scale down on the setup page(I believe) and then click over to the spine page untill you get it to show the correct speed for your setup.IT IS A PAIN but this is the correct way to calibrate it.It doesn't show the speed change when you do it on the same page,you must click over before it sets it. Have you found that to be true all the time? |
RE: Spine? IBO ABO? etc...?
I ran into problems with the program being correct when a particular bow didn't reach the performance goals set by the manufactuer,for whatever reasons.I would try and change the ibo speeds to calibrate it and the spine would not change.I ran it all the way up to 400 fps and spine did not change so I contacted ot2 and I was told that they did not use ibo but they used cam style to set spine.
I had to figure out the performance slider on my own which really upsets me that they can't explain how to use their product.[:@] Archers Advantage uses IBO and if a bow doesn't reach the numbers it is supposed to,just type in what it shoots and you are done,no quess work.Not to mention it is much easier for the average guy to grasp.SO,if I am asked from now on which program I recommend for spine calculations,I am with AA all the way. OT2 has some nice features but is a pain in the you know what to use.;) |
RE: Spine? IBO ABO? etc...?
do you think .300 spines would be better for my set up, than .400?
I know it was suggested to use .360 spines. I'm thinking about getting a chrono, and maybe in a bit I'll check back with some updated info. but considering having new arrows built. I'd like to shoot 70# with my drenalin 28" draw 65% let off. 28" arrow shafts, 100gr broadheads. |
RE: Spine? IBO ABO? etc...?
.300 will be very overspined. I use a 120 gr tip and would have to go to a 34" arrow for a .300 arrow to work.
I've been playing around with OT2 and I still think you can use the .400 with your bow even at 70 lb. Your IBO will not be 320 fps with a 28" DL and therefore your performance will drop.As I move the slider down the spine goes up for your bow using the Carbon Tech Whitetails in .400 spine. If you wanted to make sure about this just add a wrap to increase spine. I'm guessing that your speed will not be over 280 fps with a 28" DL even with that arrow. Therefore, if your speed is slower than what I've used the spine will be stiffer than what is shown.  |
RE: Spine? IBO ABO? etc...?
sounds good, and the whitetails I currently use are the .0015 straightness, I think im going to pick up another 6, and do it up.
Thanks for the help/info. If / When I get a chrono, I'll report back with some speed details. Anyone have a chrono they like? |
RE: Spine? IBO ABO? etc...?
Chrony BrandF-1 Masterwith the remote display seems to work well. It's the green model and the good thing about not having the display right on the model is that if someone would accidently shoot the front of the chrony with an arrow it will not destroy the display.
I found 1 online for under $90 last year. It will work for guns too. |
RE: Spine? IBO ABO? etc...?
You could also add the McKinney nock bushing to stiffen it up a little. I can see in davepjr71's screenshot that he has it in there although you may not be using it so be aware that his numbers include it. Also, the nock bushing weighs in at about 14 grains instead of the 12.10 that it shows. I use Carbon Tech arrows and have weighed the bushing.
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