# Arrow Spine and Plunger Tension



## larry tom (Aug 16, 2012)

Hello Archers. Here's a quick question. I currently shoot with arrows with a 950 spine. If I went with a stiffer arrow, say in the 600 to 700 spine, would I increase or lessen the tension on the plunger to achieve the same arrow flight. Regards, Larry T.


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## midwayarcherywi (Sep 24, 2006)

The plunger is a fine tuning mechanism. You would first adjust your limb weight. 950 to 600 spine is a very big jump. I would say you will be making too large a move in weight at one time. 

BTW weaken your plunger for arrows tuning slightly stiff.


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## larry tom (Aug 16, 2012)

midwayarcherywi said:


> The plunger is a fine tuning mechanism. You would first adjust your limb weight. 950 to 600 spine is a very big jump. I would say you will be making too large a move in weight at one time.
> 
> BTW weaken your plunger for arrows tuning slightly stiff.


Understood Midway. Are you suggesting that I increase the limb weight if I go to the stiffer arrow. Larry


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## midwayarcherywi (Sep 24, 2006)

It depends on how weak your current arrow is with your present set up. Don't forget that you can adjust the weight of your ILF recurve by turning out the limb bolts. So, if your bare shafts are impacting a couple of rings to the right (assuming you're a righty) try backing out those limb bolts a couple of turns. Index the bolts by marking them with a magic marker. You'll want to make sure you are turning each bolt equally. Verify you have by measuring the distance between the string and where your limb enters the riser (tiller). 

If you have turned the bolts all the way out (leave 6 threads in the riser for security) and you're still shooting your bare shafts to the right of the fletched group, you'll need arrows with a slightly stiffer spine. 

If you have never done any of this before, try working with someone who has.


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## TheAncientOne (Feb 14, 2007)

larry tom said:


> Hello Archers. Here's a quick question. I currently shoot with arrows with a 950 spine. If I went with a stiffer arrow, say in the 600 to 700 spine, would I increase or lessen the tension on the plunger to achieve the same arrow flight. Regards, Larry T.


Seems like too big of a jump, what is your draw length and bow weight? What made you decide to change your arrows?

TAO


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## Houngan (Oct 19, 2007)

TheAncientOne said:


> Seems like too big of a jump, what is your draw length and bow weight? What made you decide to change your arrows?
> 
> TAO


There's the important question, why? What draw length, arrow length, and poundage are you shooting now? You can stiffen the shafts by cutting them, putting in a lighter point, dropping the bow weight, or a combination of any of these.


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## Viper1 (Aug 21, 2003)

larry - 

If the bow you're talking about is the one in your sig, you're shooting a 950 spine and they tune, I'd guess that your DL is around 27" and your release is less than crisp. 

Stiffening the plunger can go a long way to adjusting the dynamic spine of an arrow, and the stiffer the arrow, the softer the spring tension needs to be. 

As others have said, if a 950 is tuning, seriously doubt there's anything you'll be able to do the tune a 600 - 700 from the same bow.

Viper1 out.


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## larry tom (Aug 16, 2012)

Thanks guys for all the input. 

Here's what I was thinking, and feel free to tell me if I'm heading in the wrong direction. I shoot bare bow with the bow in my signature. I've been shooting with the Super Club 15/25, at a full 30" length, since I started last fall. They spine at .950. I think I have my bow and arrows tuned pretty well given my groupings. I adjusted the draw weight of the bow down from 32# to 30# and the arrows seem to fly pretty well. Viper, you are pretty close on your estimate of my draw length ... it is 27.75". I was thinking of getting some Easton ACC arrows to see if they make a difference. I was thinking of going to a 29" shaft length, maintaining the 30# weight. According to the charts, I should get the 3-04 arrows which spine at .680. I was also thinking of trying the Carbon Ones as an alternative. Again, referring to the charts, I should be shooting with the 660s.

So what are your thoughts? 

Thanks, 
Larry


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## Houngan (Oct 19, 2007)

Hmm, the confusion is that a .950 spine shouldn't tune at all for 30# at full length, they should be very weak. Easton's selector doesn't even go that weak for it's lowest weight option. 680 is much closer to what is expected. I think you've found a happy point where the arrows are grouping, but a bareshaft test should show very weak.

I would think moving to properly spined aluminums would give you a good result without having to invest all the way into carbons.


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## larry tom (Aug 16, 2012)

Houngan said:


> Hmm, the confusion is that a .950 spine shouldn't tune at all for 30# at full length, they should be very weak. Easton's selector doesn't even go that weak for it's lowest weight option. 680 is much closer to what is expected. I think you've found a happy point where the arrows are grouping, but a bareshaft test should show very weak.
> 
> I would think moving to properly spined aluminums would give you a good result without having to invest all the way into carbons.


Houngan. That's an interesting thought, and you're probably right that my current arrows are too weak. More confusing, having researched the Carbon Impact Arrow Selection chart, the Super Club 20/30 are what's recommended and their spine is .820, seemingly still on the weak side. So if I read you correctly, upper .600 spine is where I should be at for my next arrow purchase. Right? Thanks, Larry


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## Houngan (Oct 19, 2007)

larry tom said:


> Houngan. That's an interesting thought, and you're probably right that my current arrows are too weak. More confusing, having researched the Carbon Impact Arrow Selection chart, the Super Club 20/30 are what's recommended and their spine is .820, seemingly still on the weak side. So if I read you correctly, upper .600 spine is where I should be at for my next arrow purchase. Right? Thanks, Larry


For what it's worth, Easton's selector says low .500s would be right, but that seems too strong. I'm shooting a 2014 at 31" and 30" 1/4" draw and it seems to be tuned well, my bareshafts fly straight and even with the fletched, this is at 34#. The 2014 is listed as .579 but the extra length probably knocks it down a bit. I tried 1916s but they were always weak at my draw. They might be perfect at 30#.


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## larry tom (Aug 16, 2012)

Houngan said:


> For what it's worth, Easton's selector says low .500s would be right, but that seems too strong. I'm shooting a 2014 at 31" and 30" 1/4" draw and it seems to be tuned well, my bareshafts fly straight and even with the fletched, this is at 34#. The 2014 is listed as .579 but the extra length probably knocks it down a bit. I tried 1916s but they were always weak at my draw. They might be perfect at 30#.


Thanks Houngan. I'll give that some thought. Larry


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## Viper1 (Aug 21, 2003)

Larry - 

I can only give you my opinion on which arrows. 
For me, the next logical step would be the Carbon Ones due to benefit/cost ratio. 
The ACC's won't buy you much at a bit more money.
The next step after that would be ACEs, which I think would give you an overall better shaft, but at a higher price. 

Not sure why you want a 29" arrow with a sub 28" draw, but if that works for you, it's fine. 

Assuming a 29" arrow, with a 30/32# draw, you're in the 800 - 900 range, but should do well with something like the C1s in 810. 

Viper1 out.


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## larry tom (Aug 16, 2012)

Thanks Viper as always for the advice. Given my draw length, what would you recommend for the shaft length. I gather you think 29" is too long? Larry


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## Viper1 (Aug 21, 2003)

Larry -

Except for tuning purposes in the trad world, I don't like carrying excess baggage on the arrow. 

If your draw length is 27.75 to the back of the riser, general range would be 27.5 - 28". 

Have you bare shaft tuned with the 30" 950's and if so, how close are they?
Do you know the head weight?

Without seeing tuning data (in person) kinda hard to do the "pick an arrow" thing with this type of shooting. Best we can do is get close.
Still think the C1 in 810 / 28" might be pretty close. 

Viper1 out.


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## larry tom (Aug 16, 2012)

Thanks Viper.


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## HikerDave (Jan 1, 2011)

larry tom said:


> Thanks guys for all the input.
> 
> Here's what I was thinking, and feel free to tell me if I'm heading in the wrong direction. I shoot bare bow with the bow in my signature. I've been shooting with the Super Club 15/25, at a full 30" length, since I started last fall. They spine at .950. I think I have my bow and arrows tuned pretty well given my groupings. I adjusted the draw weight of the bow down from 32# to 30# and the arrows seem to fly pretty well. Viper, you are pretty close on your estimate of my draw length ... it is 27.75". I was thinking of getting some Easton ACC arrows to see if they make a difference. I was thinking of going to a 29" shaft length, maintaining the 30# weight. According to the charts, I should get the 3-04 arrows which spine at .680. I was also thinking of trying the Carbon Ones as an alternative. Again, referring to the charts, I should be shooting with the 660s.
> 
> ...


Go with Viper 1's recommendation for 810 arrows.

I'm shooting Carbon One 725 from a high performance bow with 38 pounds on the fingers and draw length of 30 inches, with the arrows cut as short as they possibly can be. They bare-shaft just fine with 100 grain points, plunger at medium tension, and center shot just in the right place. If anything, the Carbon One 810 at 28 inch draw length will be just a little bit stiff for you, so leave the arrows a bit long at first and cut them down to your desired length gradually, after you bare shaft -- assuming you want to stay at a nice low draw weight for now.


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## John Hall (Jan 10, 2013)

Larry, when I switched to carbon, I followed the Easton chart recommendation for my stats and bought a dozen Carbon One 660's... @ 28" they tuned way too stiff for my 30# Fantom w/ 28" draw length. I then tried 730's and even THEY were too stiff with my poundage cranked all the way in! I finally was able to get a great tune with the 810's and have shot some good tournament scores this spring with them. I was even able to tune the 810's when I jumped to 34# limbs by letting out the limb bolts to their safe limit. Well, recently my coach introduced some form changes that increased my draw length to 29" and my wonderfully tuned 810's started tuning too weak on my now 34# Fantom setup with no more room to let the bolts out. But luckily those 730's I bought are now tuning great on my new 34# 70" HPX/Carbon 720 rig which is giving me 201 fsp vs. my Fantom's 187 fps.

So, to make a long story short (not)... if you decide you want to jump into some Carbon One 810's... I have a bunch or sale here:

http://www.archerytalk.com/vb/showthread.php?t=2003499

John


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## HikerDave (Jan 1, 2011)

John Hall said:


> Larry, when I switched to carbon, I followed the Easton chart recommendation for my stats and bought a dozen Carbon One 660's... @ 28" they tuned way too stiff for my 30# Fantom w/ 28" draw length. I then tried 730's and even THEY were too stiff with my poundage cranked all the way in! I finally was able to get a great tune with the 810's and have shot some good tournament scores this spring with them. I was even able to tune the 810's when I jumped to 34# limbs by letting out the limb bolts to their safe limit. Well, recently my coach introduced some form changes that increased my draw length to 29" and my wonderfully tuned 810's started tuning too weak on my now 34# Fantom setup with no more room to let the bolts out. But luckily those 730's I bought are now tuning great on my new 34# 70" HPX/Carbon 720 rig which is giving me 201 fsp vs. my Fantom's 187 fps.
> 
> So, to make a long story short (not)... if you decide you want to jump into some Carbon One 810's... I have a bunch or sale here:
> 
> ...


I remeasured my draw weight and it is 36 pounds, not 38 for my Carbon One 730s to tune. 725 was my just wishing I was using McKinney II arrows which come in that spine.


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## ArtV (Jan 29, 2008)

Are you shooting the longer shaft to help with your point of aim?


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## John Hall (Jan 10, 2013)

HikerDave, I too am pulling 36# on my fingers with the 730's tuning nicely cut to 28" (carbon end to carbon end) w/ 100 grain points. Good suggestion to leave them long at first, that's exactly what I did... started full length, cut to 29", then finally to 28". Once you cut 'em you can never make 'em longer!

John


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## larry tom (Aug 16, 2012)

ArtV said:


> Are you shooting the longer shaft to help with your point of aim?


ArtV. That was exactly what I was doing, as I use string walking as an aiming method. The 30-inch lengths on the Carbon Impact Super Clubs that I currently use seemingly helps with that. Larry


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## Houngan (Oct 19, 2007)

John Hall said:


> HikerDave, I too am pulling 36# on my fingers with the 730's tuning nicely cut to 28" (carbon end to carbon end) w/ 100 grain points. Good suggestion to leave them long at first, that's exactly what I did... started full length, cut to 29", then finally to 28". Once you cut 'em you can never make 'em longer!
> 
> John


Do carbons spine differently than aluminum? I haven't tried carbon yet and I've found Easton's guide to be on the weak side, but you are all saying that the carbons are very much stronger than Easton's guide would suggest.


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## John Hall (Jan 10, 2013)

Not sure if they spine differently, but the Easton carbon recommendations run one or two spines stiff, at least for Carbon Ones. I experienced this and the same was confirmed by others on this forum.

John


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## HikerDave (Jan 1, 2011)

Houngan said:


> Do carbons spine differently than aluminum? I haven't tried carbon yet and I've found Easton's guide to be on the weak side, but you are all saying that the carbons are very much stronger than Easton's guide would suggest.


The carbon arrows vibrate faster for a given stiffness because they are lighter. Vibration frequency is proportional to the square root of the stiffness divided by mass. Therefore lighter mass means higher vibration frequency. Because the arrow has to be timed to the bow, the carbon arrow has to have a lighter spine to slow down its vibration frequency as compared with the aluminum arrow.

This effect is probably less for a denser, heavier arrow such as a Carbon Express Nano Pro as compared to a lighter arrow such as a McKinney II. If you look at the Carbon Tech charts you'll notice that the recommended spines for their arrows are fairly light compared to other charts.


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## rookcaca (Oct 10, 2002)

Have been playing with arrow spine also. I find I always have to shoot a weaker spine than normal. Usually two spines under what is recommended.

I am shooting 34lbs on my fingers. My draw length is 29 5/8" and my arrows are Easton Carbon 1's in 810 spine. They are 29 1/8" from nock to tip excluding the 80grain glue-in point. Arrows are fletched with spin wing vanes. I find they are a pretty good indication of tune because if you have any kind of arrow, rest/plunger contact they will let you know as they will get damaged. 

I eventually want to move to CX Nano SST's when they are available but it sure does get expensive when you make a mistake with regards to spine. I wish you could get one or two arrows to try before committing to a dozen.

Hopefully this helps.


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