Shaft Tolerances

[Gdpolk]

Thanks for the answer Jerome.

[Gdpolk]

Originally posted by Bladepeek:
What we need here is someone as anal as I, but with enough money and time to test 5 or 6 dozen of all the popular brands of .001, .003 and .006 tolerance and give us a complete report      :D    

I certainly do not have the funds to do a report like that, but I can offer my time!  If folks would be interested in helping me doing so, I could get a spine tester and keep a log for all to view.  What I would ask is that people send batches of new shafts to me for the test, preferably all different types and not 10 batches of the same type over and over again.  We could set up a thread to keep it all organized and all public.  Then, at the end of testing, the test shafts could all be listed for the St. Jude's auctions and be mailed off to those interested!  You have my word, that I won't be keeping them for myself, unless I win the St Judes auction for them.  That would be a very efficient way to get a wealth of objective comparisons for us to all use and all benefit from, support the kids at St. Judes, and spread out the cost of a fairly large research project into palatable bites for those interested.  I'd have to buy or build a spine tester, which would be OK by me and would be more than willing to donate my time to test, document results, and provide a full report for those interested.

I would likely create a table and list the deviation in each shaft individually, the mean (average) deviation/spine for the batch, the standard deviations within the spines (measure of consistency), the extreme spread, high values, and low values.  The two numbers that I would consider the most valid would be the mean (how accurate is the spine to advertised value) and standard deviation (how precise are they at maintaining the mean at the advertised value).  These two numbers could help us that don't have the tools or inclination to test for spine to select shafts built to tighter tolerances and just hope that in doing so we have fairly accurate arrows being built.

I've done quite a bit of similar ballistic analysis and reloading stuff for my firearms and was recently thinking about looking into more of the technical data on my arrows as I build more batches of arrows anyway with regards to consistencies in spine, straightness, and weights.

[Matabele]

Really interesting stuff here guys thanks for taking the time to put down your experiences!

GDPolk what you are offering sounds great, it'll be interesting to see if folks jump on board with your offer. That'll be a great source of info!

[forestdweller]

Again though how much of a difference is even .050 of a spine difference going to make shooting a trad bow with fingers? Feathers correct the arrow very quickly and I have shot arrows .100 weaker and .100 stiffer and with 4" feathers you would not be able to tell the difference in flight at any distance.

Even when bareshaft testing I have found the difference to be minimal.

I suppose it's useful if you are using 2" vanes or are really really anal about your set up but in my experience it would make no difference to me.

The biggest difference to me would be arrow weight which luckily does not vary much between a few grains (if that) per arrow.

[Gdpolk]

Originally posted by Matabele:
Really interesting stuff here guys thanks for taking the time to put down your experiences!

GDPolk what you are offering sounds great, it'll be interesting to see if folks jump on board with your offer. That'll be a great source of info!

Yea I think it would be a very helpful resource for us.  I guess I could also offer to just ship them back to whoever bought them too for the cost of postage so whoever interested could basically get spine testing done and marked on their individual shafts for the cost of postage.  Either way it would be a win-win.  It'll be a lot of work, but days are getting shorter anyway and I've always been interested in stuff like this.  It'll be nice to see some objective info over a broad range of products as to who really does, statistically speaking, build the better arrows rather than just having folks post "I shoot these and have never had any problems," types of anecdotes.

[Gdpolk]

I've got a table made to report on tested spine and weight values. For statistics I've included mean, standard deviation, extreme spreads, high and low values.  What other types of information would folks like to see in the comparison?  

I don't have $1000+ to get 15-20x batches to test just to see what's the most consistent but I can swing some equipment to test on and time. If we can get folks sending some shafts in that they are already buying to test it won't take long before we can have a HUGE wealth of information available to all of us to help us truly figure out who is making some of the best shafts available.

I've got a wanted add posted on the spine tester. I already have a scale to test weights. What other competitive information would you guys like to see tested for?

Originally posted by forestdweller:
Again though how much of a difference is even .050 of a spine difference going to make shooting a trad bow with fingers? Feathers correct the arrow very quickly and I have shot arrows .100 weaker and .100 stiffer and with 4" feathers you would not be able to tell the difference in flight at any distance.

Even when bareshaft testing I have found the difference to be minimal.

I suppose it's useful if you are using 2" vanes or are really really anal about your set up but in my experience it would make no difference to me.

The biggest difference to me would be arrow weight which luckily does not vary much between a few grains (if that) per arrow.

Well, you must be better than me! The GT shafts I was shooting were marked .400 on the shaft. Idk if my spine tester is calibrated perfectly, but after spining hundreds of the shafts, I NEVER got a single shaft that was .400. They were all stiffer, with most being between .350-.370. That did not really matter to me because I was tuned with these. All that mattered to me was if they were consistent. Like I said above, before I started spine testing, and weeding out the whacked ones, I had flyers that I had to just throw away. After, I NEVER had any flyers. There is also no way you can convince me that you could take a bow that was perfectly tuned with a .400 shaft, and then shoot a .300 shaft off of it and have it not be wonky! The groups of shaft that I had that were in the .350-.370 I really could tell no difference in. But most of the real bad ones were waaaaay too stiff, like down to .300-.310, and those were the ones that I had to trash, and there was definitely a BIG difference in how they performed. I guess my biggest gripe about this is that for how expensive some shafts are, I expect them to be very close to what they are advertised, and waaaay closer shaft to shaft than what those were.

Bisch

[Sam McMichael]

If anybody wants to test these tolerances, they will need to also get a bow shooting machine, because there is not an archer on Trad Gang who can hold steady enough to notice the differences in these tolerances.

[The Whittler]

Might be a good reason to go back to aluminum, or are they not consistent.

[AndreasLundin]

Originally posted by Sam McMichael:
If anybody wants to test these tolerances, they will need to also get a bow shooting machine, because there is not an archer on Trad Gang who can hold steady enough to notice the differences in these tolerances.

I agree that with field point you may not see any differance but I can tell you my experience. I could shoot a dozen shafts consistently with field points but when shooting the same shafts bareshaft or with a decent size broadhead you would get flyers noticeable. I number my arrows and would find the fliers consistently would shoot the same spot but not where I was aiming. I have done most of my testing with wheels but I would go as far as saying with a broadhead tipped arrow spine index your arrows makes a differance.

Originally posted by Sam McMichael:
If anybody wants to test these tolerances, they will need to also get a bow shooting machine, because there is not an archer on Trad Gang who can hold steady enough to notice the differences in these tolerances.

I agree with this statement as far as straightness goes. I don't believe that there is anyone who can tell which shaft is which when you are talking about a variance of .005".

I totally disagree with this statement as far as spine goes. I have seen for myself how bad a shaft that is .050" off in spine will perform, and for myself, I will stick to a shaft that has tight spine tolerance.

Bisch

[Sam McMichael]

Bisch, I agree with your disagreement. Wow! That response may qualify me to become a politician. I was referring only to accuracy in regards to the straightness of the shafts. Spine becomes another matter. Some bows handle a variance in spine better than some others, but it is best answered on a bow by bow basis. I shoot wood exclusively, so I wouldn't know perfect straightness if it bit me in the butt.

[forestdweller]

Originally posted by Bisch:
 

Originally posted by forestdweller:
Again though how much of a difference is even .050 of a spine difference going to make shooting a trad bow with fingers? Feathers correct the arrow very quickly and I have shot arrows .100 weaker and .100 stiffer and with 4" feathers you would not be able to tell the difference in flight at any distance.

Even when bareshaft testing I have found the difference to be minimal.

I suppose it's useful if you are using 2" vanes or are really really anal about your set up but in my experience it would make no difference to me.

The biggest difference to me would be arrow weight which luckily does not vary much between a few grains (if that) per arrow.

Well, you must be better than me! The GT shafts I was shooting were marked .400 on the shaft. Idk if my spine tester is calibrated perfectly, but after spining hundreds of the shafts, I NEVER got a single shaft that was .400. They were all stiffer, with most being between .350-.370. That did not really matter to me because I was tuned with these. All that mattered to me was if they were consistent. Like I said above, before I started spine testing, and weeding out the whacked ones, I had flyers that I had to just throw away. After, I NEVER had any flyers. There is also no way you can convince me that you could take a bow that was perfectly tuned with a .400 shaft, and then shoot a .300 shaft off of it and have it not be wonky! The groups of shaft that I had that were in the .350-.370 I really could tell no difference in. But most of the real bad ones were waaaaay too stiff, like down to .300-.310, and those were the ones that I had to trash, and there was definitely a BIG difference in how they performed. I guess my biggest gripe about this is that for how expensive some shafts are, I expect them to be very close to what they are advertised, and waaaay closer shaft to shaft than what those were.

Bisch [/b]

To be fair my bow is cut 3/16" past center so the changes in tune between a shaft from one spine to another will not be as dramatic as if it was not cut past center.

I suppose with longbows and/or using less fletching it might become appearant but I use 4" feathers in a helical and can shoot .600, .500., and .400 spine arrows and with 4" feathers in a helical they all group together.

Bareshaft .400 will show up slightly stiff by a small amount and .600 weak by a small amount this is all considering the same point weight and arrow length.

With a very fast bow it will be much more likely to show up as well since the fletching has less time to correct the arrow.

Some have argued this is why Howard Hill used 6" feathers is because you can shoot very stiff shafts and not be able to tell a difference with enough fletching.

[Floxter]

For a tutorial on arrows, spine, weight, and straightness written by Rick McKinney a former world champion archer go to:
 www.carbontecharrows.com/arrow-spine-weight-and-straightness/

Click on "Tutorials"

Originally posted by Floxter:
For a tutorial on arrows, spine, weight, and straightness written by Rick McKinney a former world champion archer go to:
 www.carbontecharrows.com/arrow-spine-weight-and-straightness/

Click on "Tutorials"

I copied this one paragraph from the tutorial mentioned. It confirms my exact findings thru all the spine testing I have done, and also confirms my solution which was to group them in .010 spine range groups.

"If the arrow is too stiff it will favor the left side while if the arrow is a bit weak, it favors the right side. Thus you will get lots of rights and lefts if you have lots of inconsistent spines in your arrows and that is exactly what you will get with many of the arrows on the market today. Since most of the archers do not know how to measure this spine, they are unaware of why they are not grouping so well. Also, you will note that most arrows that are sold in dozen groups, only 6 to 8 arrows will group and the rest will not. Again, this is due to the spine more than anything else. Sometimes they can get a few more arrows to group by moving the nock around the shaft a little in order to find a near correct spine.
Many companies do not keep very tight tolerances on spine consistency. This causes all types of problems for the archer and the dealer. Of course, since most archers are not very good or accurate, they do not realize that the arrow is making them look even worse than what they really are.   According to tests that I have been involved with, the tighter the spine tolerances the more accurate the arrows become. Keeping them .005" plus or minus is what was set years ago with aluminum arrows and their accuracy has been proven over the years. Some companies have spine deviations of over .040" plus or minus!  Thus, it would be like putting spines of a 2113, 2116 and 2119 all in one group of arrows and expect them to shoot well. It will not happen!"

Bisch

[forestdweller]

Interesting.

I watched a video of Jeff Kav. (don't know how to spell his last name).

He uses 5" feathers on his arrows and shot 6 different arrow shafts of different spines going from a high spine to a low spine and grouped them all together at what appeared to be about 15-20 yards.

He uses 5" feathers as well.

I understand Rick was a world champion archer but those guys use hardly any fletching (less than 2" I believe) and are shooting at 75 yards trying to hit a gold ring the size of a DVD.

A left or right miss to them is probably 2-3" to the right of left at 75 yards and this is with less than 2" fletching.

I can group my arrows together right now just fine (as long as I'm shooting decently) and they definitely have spine differences as some are cut as much as 1/8th" more then others.

That's the beauty of using more fletching such as 4" to 6" feathers is that I know if I miss left or right it's due me and not the arrow as feathers stabilize an arrow very quickly.