Just finished a dial indicator spine tester last week, 26” span, 2# weight. FWIW, here’s some measurements I’ve taken on some non-wood shafts I have.

Gold Tip Entrada 600 .470” = 55#

Black Hawk Vapor 2000 .395” = 66# (labeled 35/45)

Beman ICS Venture 500 .402” = 65#

Swift 1816 .570” = 45#

Easton 1816 .525” = 49/50#

Easton 1916 .495” = 52/53#

Easton 2013 .480” = 54#

Easton 2114 .408” = 64#

Easton 2016 .428” = 61#

Easton 2117 .298” = 87#

Lone -

Nice work, but you're showing a little stiff for the aluminums (can't say for the carbons). Your numbers might be a little closer to Easton's if you used 28" centers and a #2 weight.

Viper out.

Thanks for the chart. The weights correspond to woodies, and it's very helpful.

Viper: I seem to understand wood measurements best, especially since I do still shoot wood arrows from time to time. I deliberately made the spine tester to reflect wood measurements so I could relate any shaft to wood shaft readings.

All the aluminums are within a pound of my homemade pointer style spine tester except the 2117 which you are showing a bit stiff (about 7#'s). Are you sure that's not a 2216?....Van

Lone -

Your initial chart is pretty close, but your matching them up to aluminum arrow sizes aree in the "pushing it" territory, meaning that you might be able to make them work, but you'd have to go to extreems.

If you use your first chart and marry it to Eastons aluminum spine deflections (not arrow sizes), you're good to go.

For example, I've shot 1816 from FITA bows approaching #45, but that with NIBBs (very light tips) and tune very far from center. Ain't pretty, but works.

An 1816 deflects .756" according to Easton, and that's close to #35, as on your chart, which btw, has been the standard arrow for #35 bows as long as I can remember.

Viper out.

Van/Tx: No, they are 2117’s (measured 4 of them) but they are the cheap models, ‘Gold Stalkers’. Maybe that’s the reason, failed specs for standard 2117’s?

Ok, nothing else to do this afternoon so I moved the uprights to 28” o/c and got these readings with the same 2# weight.

26”-2# 28”-2#

Gold Tip Entrada 600 .470”=55# .621”=42#

Black Hawk Vapor 2000 .395”=66# .493”=44#

Beman ICS Venture 500 .402”=65# .490”=53#

Swift 1816 .570” = 45# .715”=36/37#

Easton 1816 .525” = 49/50# .662”=39#

Easton 1916 .495” = 52/53# .598”=44#

Easton 2013 .480” = 54# .575”=45#

Easton 2114 .408” = 64# .487”=44/45#

Easton 2016 .428” = 61# .513”=50/51#

Easton 2117 .298” = 87# .343”=76#

These are more in line with what Viper is saying however; my intent was to be able to match an arrow to a particular bow without having to make corrections for different charts/materials.

Help me out here Viper. If I’m shooting an aluminum arrow that flies great from a bow and I want to shoot cedar arrows, then I’ll need to make a correction, using Easton’s charts, to use wood arrows from the same bow, maybe +10#? Or vice versa, subtract 10# if I was shooting wood and want to use aluminum arrows? It certainly seems to correspond to what I was shooting before my shoulder injury. I was shooting a 50# recurve and either 2016 Gamegetters or 60-65 Cedars for the same bow.

On the other hand, according to my 26” measurements, the 2016 Gamegetters fell right in there with the 60-65 cedars on the same spine tester.

I think all I’ve done is confuse myself now. I think for my own use I’ll stay with the 26” centers and create my own non-wood vs wood charts.

Darn, formatting didn't hold up. Read old/26" - new/28" in the columns.

Ya know....I just measured two of those 60-65 cedars at 28" and got .510 & .508" deflection. Would be perfect for a 50# recurve :-)

Lone -

You're right the first time. If you want your alum. to compare to your cedars for a certain bow you need to use the 26" spine. However the accuracy of your results greatly depends on how accurate your 2 lb. weight is. I took mine to the Maine Bureau of Standards. They weighed it up for me free! Mine's less than 1/10th grain off. My deflections are a bit more limber than yours, but not by much:

2020 - .312 83# 2114 - .390 67.5# 2117 - .324 80# 2216 - .303 86#

All these are XX75

Hope I didn't confuse. Just passing on what I learned doing the same exercise. :-)

Lonewolf See if this helps you sort out the spines.

The 28" method uses a 1.94lb. weight instead of 2.0 lbs. so just moving your supports to 28 inches doesn't work. Also, is the spring force of the dial indicator affecting your deflection? I considered a dial guage design but ruled it out due to this uncertainty.

When I designed my spine tester I used beam deflection theory to calculate a scaling factor between the 28" and 26" methods - and it works. If you know the deflection in the 28", 1.94lb., method just multiply that number by .825 to get the deflection in the 26 inch, 2 lb. method.

For the Easton aluminums that you tested here are the results you should get using 2 lb. at 26 inches:

1816 .624" 41.7lb. 1916 .514" 50.6lb. 2013 .504" 51.6lb. 2114 .421" 61.8lb. 2016 .438" 59.3lb. 2117 .336" 77.4lb.

I have verified these calculated spines with measurements so I stand behind them. I have tested many more aluminums than these and verified my calculations.

I designed the scale on my tester so that it displays wood spine, aluminum and carbon deflection at the same time so at a glance one can cross-reference them.

I have a write-up on the math behind this if anyone is interested send me an email address.

Kevin

Lone -

Sorry buddy, just haven't used woods since my early teens, so I don't know enough about woods to help. In addition to the raw deflection figures however, most woods recover from paradox faster than aluminum, but not as quickly as carbon. That can add to the fudge factors.

Have to go back to the original theory - charts, ANY charts are jump-off points. Features of the bow (limb acceleration, centershot, etc) and the archer (finger pressure, cleanness of release, etc) alos factor in.

Gotta tell ya, this is something I wrote for another site a while back and it makes it a lot easier than spine testers and looking for a perfect arrow:

Here's the deal: There are only seven arrow spines you need to work from #25 to about #100. (Note this is an approximation and you see way in a second).

IN GENERAL for 28" ARROWS +/- 1" ( 27 - 29") and 100 - 125gr heads:

#25 - #33 1716 #34 - #42 1816 #43 - #52 1916 #53 - #60 2016 #61 - #70 2117 #71 - #80 2216 #81 - #100 2219+ (Might want to play with 23xx and 24xx, gets a little dicey at those weights)

If you go to a 30" arrow, jump up one spine, 32". then two spine numbers. Ditto for going shorter, 26" one spine down, 24" two spines down.

This WILL NOT give you the perfect aluminum arrow for a given bow. It will give you a tuneable arrow, and that's all you need for starters. Once the arrow is tuned, you'll know if you're compensating for a stiff or solf arrow by the tuning requirements. Then you can go in to finer arrow choices.

For example, if you have a #41 @ 28" bow and are using a 29" arrow, you'd pick an 1816, right? And that would work. If you find that you have to move the rest/strike plate out a little more than you like, then you NEXT set of arrow might be 1914s. Same weight as the 1816s, but a little stiffer.

In addition, if I know a particular bow, I might suggest an arrow that's not one of the primary spine numbers. A certain #57 bow might work very well with a 2114, for example.

Viper out.

Lonewolf, you are probably right about the gold Eastons. Different alloys do measure differently. Try an XX75 2117 and you will see a big difference in deflection. I've noticed a few #'s of difference between old gamegetters, XX75 and X7 quality.

Here's one of mine.

I have one of Van's spine testers and it is very accurate. Kelly (of Arrows by Kelly) had a good spine chart on his website and my spine readings were very much in line with those. Van knows of what he speaks.........

TL

I'm going ‘shaft shopping’ tomorrow at the club and see what I can come up with. We always have a bucket full of lost or otherwise unclaimed arrows. I’ll borrow some of the ones I don’t have to expand my charts and then return them after I’ve taken the measurements. I'm curious as to what I come up with.

Don’t know if this info is going to be of value to anyone but here are the latest shaft samples I have. Picked up a few different ones at the club today. Again, these are measured at 26” centers with a 2# weight, same as wood arrow standards so the #spine shown is as compared to wood shafts.

Some of these have changed slightly from the original post because my 2# weight was off by .006 pounds. I ground off part of the weight to get it 2.000 pounds as measured on a self-zeroing digital scale. Also, where I had them I have averaged 4 samples per group.

Shaft 26"-2# #Spine Matrl Swift 1816 0.556 46.5 al Easton 1816 Fall Stalker 0.515 50.5 al Golf Tip Entrada 600 0.485 53.5 car Swift 1916 0.485 53.5 al Easton 1916 Legacy 0.481 54.0 al Easton 2013 Camo Hunter xx75 0.460 56.5 al Easton 2016 Green Gamegetter xx75 0.420 62.0 al Easton 2114 Mosey Oak xx75 0.398 65.5 al Black Hawk Vapor 2000 0.391 66.5 car Beman ICS Venture 500 0.390 66.5 car Easton 2213 0.365 71.0 al Easton 2018 Gamegetter II 0.370 70.0 al Easton 2312 x7 0.335 77.5 al Easton 2117 Green Gamegetter 0.325 80.0 al Easton 2216 0.293 89.0 al Carbon Express Heritage 350 0.272 95.0 car Beman Black Max 340 0.268 97.0 car

Wow, what a mess. Let me try again...

Don’t know if this info is going to be of value to anyone but here are the latest shaft samples I have. Picked up a few different ones at the club today. Again, these are measured at 26” centers with a 2# weight, same as wood arrow standards so the #spine shown is as compared to wood shafts.

Some of these have changed slightly from the original post because my 2# weight was off by .006 pounds. I ground off part of the weight to get it 2.000 pounds as measured on a self-zeroing digital scale. Also, where I had them I have averaged 4 samples per group.

Shaft 26"-2# #Spine Matrl

Swift 1816 0.556 46.5 al

Easton 1816 Fall Stalker 0.515 50.5 al

Golf Tip Entrada 600 0.485 53.5 car

Swift 1916 0.485 53.5 al

Easton 1916 Legacy 0.481 54.0 al

Easton 2013 Camo Hunter xx75 0.460 56.5 al

Easton 2016 Green Gamegetter xx75 0.420 62.0 al

Easton 2114 Mosey Oak xx75 0.398 65.5 al

Black Hawk Vapor 2000 0.391 66.5 car

Beman ICS Venture 500 0.390 66.5 car

Easton 2213 0.365 71.0 al

Easton 2018 Gamegetter II 0.370 70.0 al

Easton 2312 x7 0.335 77.5 al

Easton 2117 Green Gamegetter 0.325 80.0 al

Easton 2216 0.293 89.0 al

Carbon Express Heritage 350 0.272 95.0 car

Beman Black Max 340 0.268 97.0 car

Lonewolf,

You seem to be 3-4 pounds high on all of these shafts. The calculations that I sent I have verified by several methods.

I still have to wonder if the spring force of your dial gauge is affecting the result. Is the gauge below the shaft, or above? If it is below I would expect the spring to push back against the arrow and read stiff as a result. Kevin

The stalkers and jazz shafts run about one spine size bigger.A 1916 jazz shafts spines close to a 2016 ect.I used to buy 1916 to shoot from bows that would take a 2016 in other easton shafts.

arras r fun: Don't know what to say. It's the same type design I've seen many places and the dial plunger sure seems soft enough.

Kevin, I received the Spine-O-Meter yesterday! Beautiful! I had a little time before work this a.m. Got out some GT5575 Trads. I was surprised they came out at 80#! No wonder I was having to leave them long or add a bunch of weight upfront. I am looking forward to checking some POC and some Carbon Express Heritage 250s tonight. Thanks again!

Lonewolf - I just did a quick calculation using your 2016 measurement and mine and the difference indicates that your weight could be off by 1.3 ounces. If you have a digital arrow scale use that to measure the force of your dial guage as you press it against the scale. I seem to recall measuring 3-4 ounces on one of my gauges at .500 deflection.

Also, use your hand to pull the gauge down and just touch the shaft and see if that makes a difference. We are talking about .020" error here.

Snag, so glad you like your tester. I just finished a dozen GT5575 Trads and the were all around 74 pounds spine. Just goes to show you how some carbon brands vary quite a bit. Kevin

arras r fun: Wow! It's hard to hold it steady but I'm reading +/- 1300 grains (~3 oz.) at .500 deflection with this dial indicator. Never thought of that to be the problem.

So.... How to I account for that? Make my down force weight lighter? The washers I used are ~1.47oz. Guess I could remove 2 of them and be pretty near there, ya think?

Thanks a lot for your help. It is greatly appreciated.

Never mind, I see now what I need to do. StringDrivenThing sent me a PM explaining that I need to allow the shaft to fully deflect by depressing the dial indicator plunger a bit once the 2# weight has bottomed out and then release the dial indicator plunger so it once again touches the shaft to get the true reading. By depressing the dial plunger, it removes the spring tension of the indicator and allows the shaft to settle further. It does seem to make about a 0.020 difference on the 2016's I just checked.

I love learning new stuff. Now I guess I need to go back and re-read all those shafts :-)

I had a “Thanks to all” in that previous message but it got deleted while I was offline editing.

Also, Viper, you opened my eyes as to how small a sample of arrows I really need to tune bows. Thanks a lot for that bit of information. It has been printed and is now in my tackle box for future reference.

I removed the four screws on the back of my dial indicator and saw there was a light wound main spring on the gear and another heavier coil extension spring. I removed the coil extension spring.

I just checked a doz. old ACME POC shafts. The original box is marked 65#-70#. The first doz. were 68# or 70#...every one of them fell on one of these spine weights. How's that for consistancy in wood?

Snag, that is very cool that your POC is so consistent. I really need to get to making woodies instead of spine testers.

Lonewolf, glad I could help get you more accurate. I am an engineer so I can't control myself sometimes, but it sure is nice to know that your instruments are accurate.

Kevin

It's really cool that guys on here share the gifts that God has installed in them and they have cared for and made something of it. Don't ever be sorry for that Kevin! This is what makes this place so much fun and rewarding. Thanks!

The weight contact point with the shaft (point of bend) on Lonewolf's spine tester appears to be a fair amount wider that that for arras r fun which would theoretically make his readings higher (wider point of contact, shorter distance from 'center' to supports, promoting stiffer reading). That could well be the cause of the reading discrepancies.

This discussion has shown that not all spine testers yield the same results, but generally they're pretty close/consistent WITHIN, not across, either set of measurement parameters, i.e. 2#@26 inches OR 1/94#@28 inches.

Regardless, if your intent is to determine what aluminum shaft matches a given wooden shaft for your use, or vice versa, it's only important that you weigh them on the same tester.

Orion: You are exactly correct, and they all work because, spine is not that exact. It seems that the new crowd believes that a difference of a couple of pounds makes a big difference, when it doesn't.

Unfortunately Easton stirred up a huge hornets nest when they changed the spine standard from 26" centers & 2# weight to 28" centers and 1.94# weight. There was no need to "fix" something that was not broken.

Bob

Wow that is a change of tune coming from the arrow man .last time i posted about the spine tester you would of thought he was figuring the theory of relativity .i guess you guys are good now

"Unfortunately Easton stirred up a huge hornets nest when they changed the spine standard from 26" centers & 2# weight to 28" centers and 1.94# weight. There was no need to "fix" something that was not broken."

Ain't THAT the truth.

FWIW here's a "working approximation" correction factor that allows the between ASTM deflection (aluminum and carbon shafts 28" supports 1.94# weight) and AMO deflection (wood shafts 26" supports 2# weight.)

ASTM Deflection X .825 = AMO Deflection

AMO Deflection / .825 = ASTM Deflection

No, it is NOT precise, but it will assist in initial shaft selection if one wishes to switch from one shaft material to another. Running an actual tuning process must still be done.

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