How much difference in spine is acceptable?
 

I was just wondering how much difference you as a consumer think is acceptable? Has anybody done any checking to see if a .340 shoots close to the same as an arrow that is advertised as .340 but actually checks out around .375 just for example. Say you bought a dz. arrows for .340 spine and had some that checked at .338 to say .375. Do you think this is acceptable. Thanks for any replys.

RE: How much difference in spine is acceptable?
 

I remember reading a post on Archery Talk about this. A guy checked a bunch of high end carbons and, if I remember right, they varied like .018 over the dozen.. Depends on what you pay for them. If I laid out $80 and up for raw shafts they had better be much better than that.

So far as I know Easton is the only companiy publishing tolerances. And that is in their Technical Guide for ACC's. Tolerance on them is .005 in a dozen. That sounds pretty darn good to me.

You know? I posted this question to someone at Carbon Express thru an email and they couldn't or wouldn't even tell me the spine tolerance of their arrows. They told me what the spine was for different sizes. Hell, I can read that almost anywhere. Way to go Koren Express.

Problem in the industry is that we have to take their word for it. Spine testers are very expensive.

RE: How much difference in spine is acceptable?
 

Try and get a hold of JeffB, he seems to be an expert on this sort of stuff. I don't see him post much anymore though.

I would say the tolerance you could live with would depend on what you were going to do with the bow, what kind of set up you have, and how well you shoot. I would say for an indoor target application with a fairly forgiving set up and an archer that shot from poor to fairly well spine wouldn't be as important. Now don't get me wrong, I feel it is important. Having good matched arrows is one of the most important things for accuracy in my opinion. I am just saying that in this case you most likely wouldn't notice as much. In order to notice spine variations you need to shoot well enough to be able to tell the difference. Many don't, that is just the plain truth whether they like it or not. And shooting target arrows with adequate fletching and target tips at close fixed distances is pretty forgiving any way. Most of it depends on the archer and how well he aims and releases.

Now if you are a much better shooter you may notice the difference. It could mean the difference between an X and cutting the line or something. And the faster you shoot or longer your shot the more you may notice as well. And for hunting with a fixed blade broad head it is very important. You suddenly have everything going against you. A short fast unforgiving bow, and a fixed blade on the tip. I believe this set up would be most critical of spine and an average shooter would notice the differences.

What is exceptable spine variation? I couldn't tell you to be honest, I have never tried to figure it out. However this is the reason you shoot every arrow you have to find the best matched ones in the bunch. Don't ever just shoot a few and assume the rest are good and your set up is ready to go. Shoot them all the way you intend to shoot them. This way you may find a few with spine or weight problems, or possibly a bent or warped arrow. Not to mention bad nocks and inserts.

I bet someone that is really into target archery might be able to answer your question better, like FITA or something. I would try asking on Archery Talk when it comes back online. Some of those guys are VERY anal about what they shoot.

Paul

RE: How much difference in spine is acceptable?
 

If you're talking about carbon arrows, I suggest checking each shaft at several locations around the shaft. Check, spin 1/4 turn and check, spin another 1/4 turn and check, etc. You'll likely find what I did, that each shaft will check differently at various points. Then, you can either pick a certain reading and orient all your arrows to that deflection OR, my choice, orient the cock feather over the stiffest axis of each shaft.

When I started doing that, it really helped my accuracy and consistency with carbon arrows. Still not as good as with aluminums or ACC's, but it was a definite improvement.

RE: How much difference in spine is acceptable?
 

Art, how do you check them? Do you have a spine checker?

RE: How much difference in spine is acceptable?
 

Yep. About a year ago I made a homemade spine tester that uses a 1" dial indicator reading to .001". It certainly helped explain many problems I've had with carbons over the past few years. I've found up to .045" difference in deflection around individual carbon shafts, and .065" from the lowest reading to highest within a dozen shafts.

RE: How much difference in spine is acceptable?
 

Arthur P, thats what I"M talking about. Yes they are carbons and I do check them at 12-3-6-9 o'clock. Did you shoot the arrows that were alot different? What were the results? Thanks

RE: How much difference in spine is acceptable?
 

Art, I'm gonna have to rig one up. This sounds very interesting. Man, what shafts did you check that were off that much? Ever check any ACC's? They say in their tech manual that the tolerance is .005 over a dozen. And do you ever get the feeling we, the consumer, are being taken advantage of just a bit? Advertisng and consumer ignorance can sell anything.

RE: How much difference in spine is acceptable?
 

BGFisher, are you sure that was the spine tolerance and not straightness? Where could I get a tech guide, I will check their websight. Thanks

RE: How much difference in spine is acceptable?
 

sjb3, after I started aligning my nocks and fletching with the stiffest axis of each shaft, the accuracy improved quite a bit, but still never got as good as I get with aluminum.

BG... What shafts were off that much? I really don't want to say (cough, coughgoldtipscough, cough) because somebody will get offended.;) The ACC's I've checked have been very close. No problems at all, as I'd expect for the price tag they come with.

Do I think we consumers are being taken advantage of? You're trying to get me into trouble again, aren't ya.[>:];)