G'day, and my apologies for a vague topic and question...

In the dusty recesses of the back of my mind, I recall reading something interesting in the way of someone's findings or research into spine requirements for heavy bows. I may be quite wrong in my recollection, and I probably didn't understand it right anyway, but it might've been something to do with a broader range of spines being suitable in terms of wooden arrows the heavier bows get in draw weight.

Again, my apologies if I'm mixed-up, but I just thought I read something along those lines somewhere, and was wondering if anyone knew more of what I'm trying to remember.

Thanks,

Ben

TTT...

Anyone?

Don't remember hearing / reading that but do remember some saying wood is more forgiving around it's spine range (unless I was reading it wrong too)
Don't know about heavy bows??

Hello Ben , after reading Dr. Asby"s reports on broadhead penetration and arrows I thought that  carbon arrow  were stronger or at least that was what I understood it to mean . So I switched to carbons and weighted them down with insert weights and tubes and made a poor hit on a hunt and the arrow broke behind the insert . Returning from the hunt I find his latest report saying that he felt solid wood arrows had a better chance to withstand impact whereas a few of the carbon arrows failed behind the insert . At least that was what I got out of it , so now I'm back to wooden arrows even though it is tough finding consistentcy in weights and spine . I guess what I'm saying is I think wood is better for big game . Good luck , Fred

Greyfox,What kind of wood do you use?I too believe a good heavy wood shaft is top of the line but Cedars are not durable or heavy enough for me.I have thought about trying the lam shafts in three Rivers but have yet to do it.RC

I might add that the shafts I liked the most were "Chundoo" I think they were called from Wildcat Canyon Archery.Don`t know if they are still making arrows are not.RC

RC , I have bought a lot of shafts over the years , I tried ash but couldn't find one that didn't corkscrew . I had some Chundoo shafts that were heavy and almost indestructible . Can't remember where I got them , I have an assortment of shafts that I don't know what they are or where from but I made up a dozen of nice ones that may be chundoo or spruce and they weigh around 750 grains without the broadhead . I have high hopes for these , Fred

WOW... 750g for a pine shaft?, were they soaked in Watco oil like some folks are doing? Thats what my ash arrows weigh. Ted Fry at Raptor hooked me up with some great ash and hickory tapered shafts. Got'em good and straight then dipped them and they've been straight since.

For a Super Duty carbon I think they would need to be footed with aluminum.

I think Twigg Archery still sell some Chundoo.

Eric

Amen to the Goodness of Woodness!

I'm referring to something I read that suggested a really heavy bow could tolerate a wider range of spines... But, as I've said, I might well be remembering wrong.

Ben, if the bow is cut past center yes they will. I have heard of Black Widow bows of 70 to 75 pounds draw weight being able to shoot upwards of 110-120 lb spined arrows with no ill affects on flight. Not sure if that is what you meant. Flint

I've hunted some w/Forgewoods, both the old ones by Sweetland and the ones that were made here in AK.  They were great for penetration, but I gave up so much in range that I stopped using them.  Even so, I know they resulted in an elk and kudu that I probably wouldn't have gotten without them.

The trick for carbons is to use a brass or steel insert up front and a good steel broadhead.  Then you won't have that breaking problem.

LKH  I had the brass inserts and brass weights that are screwed onto the inside of shaft to the insert and 190 gr. Grizzlies , granted better shot placement and I would be telling a different story , Fred

Fred, I have a Forgewood that hit the front leg on an elk.  Blew half out of the broadhead, splintered it back about 18", and bent the Zwickey into a "U".  I don't think anything works when you hit those big tough bones.  Have used carbons for years now and never broke one, but I keep them about 560 max.  
You planning on killing elephants with those arrows?  They should end up around 900 grains.

Ben:
If what Flint said is what you mean, maybe I can clarify the situation. Bows cut past center like the Widow, etc. once the minimum usable spine is reached you can go way over spine with excellent results. I have one client shooting some really heavy arrows that spine 130#@28" from a bow that is 74#@26" his draw they fly like the proverbial dart.
Why? A bow that is 3/16" past center will put the center of 11/32" shaft in the center of the limb. That arrow needs to be stiff enough to go through as little paradox as possible.
Bob

N/Ben, that article/idea your talking about rings a bell....just can't put my finger/hands on it. Maybe an early Asbell article ? I'll dig around and have a look for you. Cheers Ben

I got this e-mail from Doug Knight at   http://www.surewoodshafts.com   :

"Understanding spine, especially at the upper end of the scale can be a bit of a challange. As you probably know, spine is determined by hanging a 2 lb weight from the center of the shaft while it is being supported 26" apart (for wood; carbon and aluminium use 28"). With this weight hanging from it and bending the shaft, a measurement (in .000"
inch) is taken to see just how much it is bending, otherwise known as deflection. Once the "deflection" value has been acquried the simple math formula of [spine=26"(support)/deflection] calculates it into spine as we know it. ie, a 100 lb spine shaft deflects .26" of an inch with the weight hanging on it. Take a 110 lb shaft and it deflects .24" of an inch, or a difference of .020" for a 10 lb spread. At the lighter end of the scale, ie 20 lb spine has 1.3" deflection while 30 lb spine has .87" deflection or a difference of .43". Both represent a 10 lb spread but the difference of .43" vs .020" is quite a difference.
This simply tells us that spine is not linear. Do the math for each 5 lb spine group and plot them on a graph, then draw a line connecting all the plotted points. You don't end up with a straight line but rather a nice arching curve or parabola with the deflection steadily DECREASING (at some exponetial rate) while the spine steadily INCREASES. Around the 90 lb rate the curve tightens up and heads towards infinity as we continue trying to add more and more poundages of spine into a finite space as the deflection nears zero.
Recall our 20 lb shaft has 1.3" of deflection and our 100 lb shaft is .26". Now think of the fact we only have that .26" left on our scale (till it reaches 0")to crowd all spine poundages clear to infinity. Thus it becomes clear the higher spine (or less deflection) we have in our arrow shaft the closer we approach infinity as to poundage of bow it can be used with. In theory an arrow of 0" deflection could be shot from a bow of infinate poundage, in fact it could be shot from a gun, a cannon or any other means approaching the speed of light(disregarding the fact of course that it would burst into flames and burn up once it reached kindeling temperature due to friction).

As humans we have limitations as to how heavy a bow can be drawn and have devised this method of calculating spine to suit our needs within that range. We have also developed the formulas of adding or subtracting 5 lbs here 5 lbs there for bow types, head weights, string materials etc. etc.
This method of adding and subtracting is linear. It is a great tool, but recall spine is not. Thus it is most applicable and benificial to those in the (average) 45-60 lb bow weight ranges it was developed by and created for. The more we move out of this average upwards towards infinity of bow weight the less rate of effect these issues come into play."

That's what I was trying to recall.

Thanks, Doug!    

Ben:
Your argument is sound and correct, but what is the point!! The spine standard works for the bow weights being used, (Yes some adjustments need to be made when things vary from Grandpa's calculations)  but why try to make it something that isn't worth worrying about.
One of the things I have problems with is, those that try to take a primitive activite and make rocket science of it. Life is too short enjoy it.
Bob

Amen, brother Bob.  Amen.

It's absolutely pointless information for most archers, agreed. I wholeheartedly agree with keeping it simple.

I was just thinking out loud when I asked the question, just trying to wrap my head around arrow choices and changes for my particular situation, the 80# @ 28" Silvertip drawn to nearly 29". It just gives me a little direction when thinking about finding a stiff-enough arrow to wear the new and heavier STOS broadheads due out later this year.

It was more for my own thinking and education, as I've only been involved with traditional bowhunting for just over 4.5 years, and still have much learning ahead of me.