Trad Gang

Main Boards => PowWow => Topic started by: TNtrapper on July 27, 2012, 12:13:00 AM

Title: A little spine help...
Post by: TNtrapper on July 27, 2012, 12:13:00 AM
Hey guys,
Im new to the site and have been bitten by the traditional bug! Ive shot compounds for over 20 years and kinda got  burnt out. But these traditional bows are a whole new ballgame! Ive got a Whisperstik Mojostik I bought from a member here and Im needing a good starting point on arrow selection. Its 46# at 28" and I am wanting to use some 125 gr. Zwickey Eskimos I have.I shoot a 30 inch arrow but could probably go a little shorter if need be. Ive been reading old posts on here about how these bows like a stiffer spined arrow. Do any of y'all have a setup like this? If so i sure would appreciate some pointers on what spine you are using in a wood arrow. I need a good starting point. Thanks a lot!   :help:
Title: Re: A little spine help...
Post by: Richie on July 27, 2012, 12:20:00 AM
I think that a 3555 gt. should work fine, what is your draw length?
Title: Re: A little spine help...
Post by: jlowrey75 on July 27, 2012, 12:22:00 AM
i shoot a 52lb dryad  an i found that a 55/6o spine with 125s works real well. so maybe go with a 50/55
Title: Re: A little spine help...
Post by: Richie on July 27, 2012, 12:24:00 AM
Sorry I didnt see that you were wanting to use wood.  :banghead:
Title: Re: A little spine help...
Post by: Looper on July 27, 2012, 01:03:00 AM
Here's how I would figure it.

Poundage at 28": 46
Add for recurve: 5
Add for centercut: 5
Add for extra inch of arrow: 5
Add for FF string: 5

Total: 66 spine

That's where I'd start. It wouldn't be a bad idea to go ahead and get a test kit of arrows. Get some spines that surround that 66 spine, so a 55-60, 60-65, 65-70, and 70-75. That way you'll know for sure.

If you add a skinny string on it, you might need to jump 10 pounds in spine.
Title: Re: A little spine help...
Post by: Orion on July 27, 2012, 09:50:00 AM
I generally agree with Looper, except for the extra 5# for the extra inch of arrow length.  I add an extra 5# for an extra inch of draw length, which increases the draw weight, but a little extra arrow length doesn't make much of a difference, and since you have an inch more than you need, just cut it off..
Title: Re: A little spine help...
Post by: Blue Tick on July 27, 2012, 10:26:00 AM
I'm curious as to where the 5 is coming in from for the recurve, centercut and so on. I've seen others use this method and I'm just curious as to what it is and where it came from.
Title: Re: A little spine help...
Post by: SCATTERSHOT on July 27, 2012, 11:19:00 AM
What's your draw length? Most guys, especially those coming over from the dark side, don't draw as long as they think they do. Come to full draw, and have a buddy mark your arrow at the front of the shelf. That will tell the tale. Until you do that, anyone's guess is just that.

Good luck!
Title: Re: A little spine help...
Post by: TNtrapper on July 27, 2012, 11:29:00 AM
Thanks a lot guys...keep em coming. My draw length is 28.5 inches. So...its looking like Im going to need more spine than I was expecting. Do y'all think these 125s are going to be ok...or do I need to move up in head weight?
Title: Re: A little spine help...
Post by: Overspined on July 27, 2012, 11:32:00 AM
If you go heavier in head weight, then you need a stiffer spine.
I think I would do what you are, and work backward.  Take the 66# spine, cut it a little long, and then start shortening by 1/4 to 1/2" at a time until its perfect.  Then just transition to field points.  I find field points aren't necessarily going to fly the same. They can kind of hide errors in spine.
Title: Re: A little spine help...
Post by: Zradix on July 27, 2012, 03:13:00 PM
Get an arrow spine test kit.
Don't roll the dice.
It is something that you'll really come to appreciate.
Title: Re: A little spine help...
Post by: Sticks2117 on July 27, 2012, 03:22:00 PM
I would look at Rose City archery and invest in a test kit if I were you.
Title: Re: A little spine help...
Post by: Shedrock on July 27, 2012, 03:24:00 PM
65# spine woods is what I say as well with 125 gr heads.
Title: Re: A little spine help...
Post by: TNtrapper on July 27, 2012, 06:24:00 PM
Thanks a lot y'all! I really appreciate it.
Title: Re: A little spine help...
Post by: Looper on July 27, 2012, 09:22:00 PM
QuoteOriginally posted by Blue Tick:
I'm curious as to where the 5 is coming in from for the recurve, centercut and so on. I've seen others use this method and I'm just curious as to what it is and where it came from.
Well, basically the spine weights of wood arrows are based off of a longbow, not cut to center, using a b50 string, using a 125 grain head, and drawn to 28".

So, theoretically, a 50#@28" Hill drawn to 28", for example, will take a 50# spine arrow with a 125 grain point. Any variation to the standard setup will require an adjustment in spine. There are several of these variations that will affect the spine.

The very first thing to consider is the actual draw length. Typically, adding or subtracting 5# for every inch over/under a 28" draw is necessary. A 26" draw will need -10# in spine, a 30 will need +10.

Second is the limb type. A recurve or d/r longbow is much more efficient than a straight-limbed longbow, and will require a stiffer shaft. The limb design itself might require a 5-10# increase in spine. The more efficient (faster) the bow, the more spine required. A selfbow might not be as efficient as the standard, and require a weaker spine.

Third, the centercut needs to be considered. If the standard is 1/4" from center is standard, anything over/under that needs to be accounted for. I can't recall exactly, but I think it might be 2# for every 1/8". So a bow cut to center will need 4# or so over a 1/4" from center.

Fourth, the string type. A skinny FF string will require as much as 10# more spine than a B50. A regular FF string might only need 5# more.

Fifth, the arrow length. The standard is for a 29" arrow. Longer length effectively reduces the spine. That's why trimming a shaft works so well for tuning. Usually, this is accounted for when the adjustment for the drawlength is made. However, I've found that if you want to shoot a shaft much longer than 1" over your draw, that extra length needs to be accounted for. If it didn't matter, trimming a shaft wouldn't work. I use 5# per inch.

Finally, the point weight. Added weight over 125 grains, weakens the shaft. I add 5# for each standard graduation over 125 grains. So, 145 needs +5, 160 needs +10, etc.

There you have it. This is typically how shafts were selected before arrow charts and calculators came about. Stu Miller's calculator is a much more refined version of this basic system. It'll get you in the ballpark. In fact, I've found it works exceptionally well for my Hills. I can pick any one of them off my rack and the shafts that shoot best out of it conform to the above very accurately. It's still pretty close with my r/d bows, but I usually use carbon out of those bows, and carbons are a different animal than wood.

The most sure way, however, is to get a set of test shafts in a wide variety of spines and actually shoot them to see which one works the best.
Title: Re: A little spine help...
Post by: JamesKerr on July 27, 2012, 10:41:00 PM
I would go with some shafts in the 55-60 pound range and try some in the 60-65 pound range.
Title: Re: A little spine help...
Post by: Overspined on July 28, 2012, 07:32:00 AM
Good post looper
Title: Re: A little spine help...
Post by: Shortlongbow on July 29, 2012, 01:12:00 PM
A test set is definately the way to go. I would guess 70-75