I shoot all three, and always build 'em for the same dynamic spine. I do notice they each have their own flight characteristics, and have been noticing some folks actually choose a different spine depending on the wood species. Whaddya think?

“ have been noticing some folks actually choose a different spine depending on the wood species. Whaddya think?”

I think some folks choose a species in order to GET the spine that they need. Maybe even in order to get the spine that they need at (about) the weight/shaft diameter that they want.

But spine is what it is. Like the old joke of “what’s heavier, a ton of feathers or a ton of bricks?”

The only reason you’d change spine because of the type of wood is if the shaft - because of density - had such high (or low) mass weight that your bow’s dynamic spine requirement was affected... enough to really matter.

Arrows are measured in static spine. Dynamic spine is how an arrow behaves when you shoot it. Dynamic spine can be manipulated by many things including shaft length, point weight, amount of center shot, string material, and shooter idiosyncrasies, fletching size, etc.. Spune is not nearly as precise as most folks think, and bows will shoot a wider range of spines than most folks know.

Everyone has their own ideas about spine in all arrow materials that's not unique to wood.

My only thought to this is, like stated above, maybe some people are wanting a heaveir/lighter shaft and can only do that with certain woods at a given spine. In my quiver right now I have some maple shafts that weigh about 700 grains finished. Next to it is a cedar that is around 525 grains finished, and I have a few woods lighter then that.If I wanted a really heavy weight wood arrow in my spine the maple is the choice. If not looking for overall weight, then the cedars fly perfectly well. As FDP said, Spine is not nearly as precise as most folks think and a bow will shoot a wider range of spine than most folks know.. Unless your Byron Ferguson or Brady Ellison, you probably don't notice the minuscule amounts of change.

-Bones

Dynamic spine is not as precise as most folks think. Static spine is deflection and deflection is measured to the .001.

Bowmania

But Todd, arrows are spine grouped over a range of deflection not one number. And as the static spine measurement changes the spread of that measurement varies wildly between stiff and soft spines.

Does anyone sell woodies that are grouped any tighter than inside of #5?

I guess I can imagine some guys taking the time to hit a couple pounds either side of say #49, rather than just a dozen from the #45-#50 bucket, but picking a out dozen at exactly 49? That would take some serious inventory...

And just a little irony to start your day… Why is it that those tend to be marked in 5 pound increments AT the fives and tens, while arrows are sold so that most of them end up somewhere IN BETWEEN the fives and the tens?

I guess my money’s on “because it doesn’t really matter that much”!

GF, 45-50lbs. is a 6lb. spread. Wooden arrows were originally spined 40-44 and 45-49 as an example. I still spine mine that way.

Good input so far, I appreciate it. I do often choose my sets of shafts depending on the weight range I'm looking for. For instance, while I generally prefer doug fir, I sometimes go for cedar or spruce if the fir's available are too high in grains per inch; I really try to stay under 11 grains per pound for the finished arrow.

That said, a few folks have said, for example, that they'll shoot one spine range higher with doug fir than with cedar, to get the same tune. That's basically what I'm wondering; I shoot all three at the same spine range, curious if I'm missing something.

My only experience is with cedar and spruce. Other than the spruce being a few grains lighter, there is no perceived difference in flight or accuracy. I'm not Byron or Brady and few on here are close to that league. You can make it as simple (and I do) as you want or go over the top as some do.

I shot the same spine fir as I did cedar...as I did spruce..as I did pine...as I....well you get it. Spine is spine and is a deflection. Mass weight can likely alter the way a certain spine reacts, as does diameter...like a 45/50 pound 5/16 or 11/32...or 23/64. Diameter doesn't change static spine if it's already the same as the smaller diameter, but it will show different dynamics. That said...spine is spine when talking static measure.

Frank - right, as always!

I was getting sloppy there ;)

"Frank - right as always ! " not hardly GF. :)

You can take a single board and make a dozen arrows from it and have a wide variety of spines come from that one board. Trees don't grow evenly so where the grain its finer it may be weaker than where it is thicker broth rings...The species does not determine the spine in any way. spine is just how much a given piece of wood bends under the spine tester.

"Does anyone sell woodies that are grouped any tighter than inside of #5?"

Wapiti (cedars) and Surewood (fir) both list their spines in the 6 pond manner (45/50, etc), however in the several dozens I've gotten they are much closer in spine than that, within the group. Most are within 2-3 lbs spine.

"Does anyone sell woodies that are grouped any tighter than inside of #5?"

Depending on how they are spined (SP?) yes and no I hand spine all the shafts I produce, and I can group them so you get all 72# spine, it means a little more work and I have to have more shafts in stock to get the mass in a 10 grain grouping also.

But even with hand spined arrows, reading the scale is an estimate, a person is always guessing when they read the scale on a spine tester.

So I would say they can group them tighter but I would hesitate to promise that are withing a certain grouping.

I mill shafts at 36 inches due to imperfections caused by the machines in the first inch of each end. Then I spine them write the spine on them, choose which end is more damaged or has grain run out, then I cut them down to 32 inches and spine them again and weigh them for grains. Often on the second spinning they are different the the first (if I didn't cut marking off) by one or two lbs.

it is an estimate Just sayin

oz

If you don't have your own spine tester it may not be the right spine as marked when you get done gluing your nock and flecthing . Spine your shaft then rotate it 180 and spine it again it can be as much as 10#s different if you find the side of the shaft that's the right spine you need to put that side against you sight window .

Tim is right there.The other thing is to achieve correct spine on my hand made shafts I sometimes will barrel them or do a full taper.Now flight characteristics are different in flight recovery but the spine is right for the bow.No two wood arrows will be exactly the same even in the same spicie of wood.Trust me you want to have some awesome testing gear to see that.To get reasonable accuracy just make sure your arrows spine is orientated to suit the shelf of your bow.Some of my bows will shoot arrows with 10 lb variation and still deliver reasonable accuracy.One bow I have 2 1/2 lb is the limit.The more centre cut your sight windów / shelf is the more range of spine variation that bow will handle Osr144

So if that’s the case, then a guy had better decide cock feather in or out and stick to it, eh ??

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