I bought 100 Rose City cedar shafts some time ago. They were grouped 70-75, with most at 72 1/2. Excellent shafts and served me well. I'm down to my last 12 shafts and while checking the spine again 4 of the 12 spine at 72 1/2 ,but when I rotate them 90 degrees they spine at 92 1/2. I kept rotating and get the following spine every 90 degrees. 72 1/2, 92 1/2, 92 1/2, and 92 1/2. The one 72 1/2 reading I get is with the rift horizontal to the spine tester. Any thoughts on how to orient these shafts for a spine of 72 1/2? Should I not use them? Thanks TLM

Test the spine bending it the way it would bend around a riser, best way I know to state it. You should watch a video on someone using spine tester.

https://youtu.be/T1-65kqCqnY

There you go

You generally test at the stiffest orientation, and make up the arrows that way. Shafts can get stiffer sitting around in dry conditions, but a 20lb gain is a lot. I would recommend you test your spine tester on some known carbon or aluminum shafts to make sure it's telling the truth.

Thanks. Its a Don Adams spine tester and is dead on. TLM

So how is the reading in comparison to how the nock would be placed? The arrow bending is directly related to nock orientation to grain orientation.

Seems very odd to me have a 20lb. spine difference in 90 degrees.

That is a bit wierd. There's usually some difference between the stiffest orientation of the shaft and it's spine 90 degrees from that, usually 2-5#. I've never experienced a 20# difference.

Regardless, usually, the arrow is oriented so the stiffest spine is against the side plate of the bow, and that orientation is usually the straight grain perpendicular to the side of the bow and the rift (if there is any run out) on the top and bottom.

Given that you want the 72# spione, you orient the shaft with the side of the arrow that yielded that spine perpendicular to the bow sight window. In this case, I suspect the rift would be on the side of the arrow as it sits on the bow arrow shelf.

the heaviest spine should be facing the side of the bow as the arrow sits on the shelf.

BTW, I don't recommend placing the rift perpendicular to the side plate. It's the weakest orientation of the arrow, and more susceptible to breakiing. However, some folks do it and seem to get away with it.

I always find it most interesting to hear how orienting the grain with the edge to the bow is the strongest, yet when we shape out a nice new self-bow we do so so as to bend wood across the grain. ???

JP, I have thought about that also. Keep in mind though that a bow is far more flexed than an arrow. it is also less frequently broken and driven through the hand of the person shooting it. When grading products for use, it is normal to test them for "spine" at given degrees of flex. And those degrees are normall in rations like 1-240, 1-360. In otherwords barely deflected. COnsider, musical instruments, spars on wings of planes, boats, it is really rate to have the deflection that is induced into a bow, in a structural component.

With a bow, the deep flex means you want wood that is equally stiff across the width, and taking the back from one growth ring is one way to get that. It is also economical in materials and labor, but it first off needs to work. Of course one can use any grain orientation.

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The fact arrows break and get driven through the hand makes it practical to use the rings perp to the riser and to have the grain rising from nock to head. To me that is the way to go, not where the arrow is stiffest.

I find it a little disconcerting that the weight variation is so great. But given if it flexes evenly, and the grain is tight, I guess it should be fine.

After years of making wooden arrows, I've never seen that much of a difference in spine, TLM. Have you double checked your measurements? Jawge

Bruce the reason we make self bows with the eye facing us, so it will bend. years back a fellow here bought some old Bears off of EBay. he had a 48 pound bow and the shafts were suppose to be 55-60s. He had three break while shooting. One blew up in the bow. On closer inspection we found that arrow had the eye facing the bow and it also had a serious flare. Curious, i sanded the paint off of some that I had. They paid no attention to grain orientation when making the arrows. Flared grain can greatly increase the spin of an arrow, that does not mean that the same will not break, following the flared grain direction. They can break right where the flare starts if orientated that way.

Is it possible that some of the shafts aren’t straight? If so, they may spine the same, but won’t give you the same reading if the pointer is against the shaft right on a bend.

MP

Can someone find any documentation on why we preach edge grain to the bow other than the fact it was to keep the arrow from splitting out at the self nock? Other than that it appears to be mostly anecdotal.

Here we go. LOL. Someone will disagree. That's ok. I'm not engaging since it is before nap time. It is to keep the arrow from impaling you on release should it break. It is to differentiate top from bottom. Arrows have this on one side >>>>>>>>>>>> and this on the other <<<<<<<<<<<. Point these <<<<<

I've heard all that George, just wondering if it is a recent truism, or if there is any historical support for it, perhaps in the annals of English archery.

IMPO as taught to me is wood arrows are designed to be shot in only one edge grain direction. For finger shooters the grain must be on top and bottom. If it is left and right sides facing up and down, the weaker direction, the arrow could break due to flexing left to right. Release shooters who dare to shoot wood must rotate the opposite as they left since their arrow flight porpoises. Nock install is parallel with the grain. Juts my .02 but what is your draw weight and arrow length as I'll bet when they spined the arrows they possibly made a mistake giving you what they had to fulfill your order.

Really strange spine readings. I normally get less than two pounds difference when rotating the grain ninety degrees. Are the arrows crooked and you're not zeroing the spine tester?

Good to know I can just throw my info away and just go by the stiff side - haha!

Sounds more like a crooked arrow.

I agree it sounds like crooked shafts. You have to straighten the shafts before testing, and zero the unflexed reading by whatever adjustment your tester has. Did you do that?

If the above doesn't work, make them into fluflus or tomato stakes. It's never worth trying to force a weird shaft to be a good arrow.

The problem with grain flare that goes from one side of the shaft to the other is that is a completely different spine on that end of the shaft versus the other. Shorten the stops on your spinometer and double the weight, check the spine on each end. The shaft will vary quite a bit on the flared end. Now if you declare that entire length span to be the correct spine, remember that the wood arrow snakes around the riser of a bow that is not a pure center shot giving that arrow a variety of spine stresses. I have this video, if you watch it in slow motion with the tight of the arrow scenes, you will see the arrow flexing into the bow at release. You can get a glimpse of it at 1:12 if you go to full screen and .25 speed on the Youtube setting. https://www.youtube.com/watch?v=Hbf8PyfVfkc Shooting a wood arrow that is seriously flared will react accordingly at that time during the shot. My wife had a painted arrow with the grain in wrong position blow with her 42 pound Hill. The spined 48 pound when cut to 27" bop, it had a 125 grain point. The arrow spit right through the deer hide side plate. If that would have hit her bow hand it would have gone straight to the bone or through. You want the eyes up and the side grain to the bow.

Sorry I missed a couple of words again. Said above wife is rattling on about something non-stop tonight, she is a bit excited about the spring Canadian canoe trip.

I will check the shafts for straightness. Then start over on the spine tester and taking some pictures. Shafts have not been cut to length. TLM

Well I have 2 different Adams and they vary. Some times I get fits so I just say oh well dead animal waiting to pile drive him through don't worry the animal wont mind.

The only way that a crooked shaft would affect spine to that degree would be if the "crook: was at a very severe angle. One easily identifiable with the naked eye.

The shafts appear straight. Its going to be a nice day today for some pictures. TLM

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