Shaft spiner?

[mnewcomb59]

What I was trying to say above was no matter how far apart the posts are, if you set a shaft that is the same as the distance of your posts on there and it pulls down .565 then your spine will be 50#. That shaft will not show the same deflection if you move the posts in, but a completely different shaft of a smaller diameter might show the same deflection and still be the same spine.

In other words a 28" 11/32 POC shaft can theoretically have the same spine as a broomstick, given that the broomstick was long enough to be that flexible.  But, cut it shorter and the spine raises. Same as piking a bow. Sorry for the confusion everyone.

[UKarcher]

Guys, all this confusion comes from the AMO standards. Bows are usually measured by weight at 28" drawlength, but arrows are spined between 26" centres. As long as you use the same measurement every time for your own personal arrows then you could have it any length you want. The idea of hanging a wrench off the end of the shaft is just as accurate as long as the wrench is place the same distance from the fixed end everytime.
Graham

[D. Tiller]

Interresting designs and ideas guys! How about just hanging the arrow between two uprights and then suspending a 2# fishing weight from the center and eyeballing it against a white peice of paper behind it. If you have one shaft of a given weight then you can compare the two and you should have a good enogh idea of what the spine is.

D. Tiller

[Primitive1]

Unless I missed the explanation for tapered/barrelled shafts?  I barrell taper mine...how will that change my setup?  I made a maple spinner which I use for shaft straightening that I want to make into a 'spine tester'.  I shoot 31" barrelled tapered arrows with a 26" draw length (and yes, I luv'em that way)...so how do I proceed?  The other item of consideration is how much your bow/string is aligned to 'true' bow center...I usually make my bows lined up to the left (I'm a right handed shot) so spine hasn't been too much of a problem.  I would still like to know and measure...and want to do it right the first time.  Any suggestions?  Thanks...

[Justin Snyder]

Guys, all this confusion comes from the AMO standards. Bows are usually measured by weight at 28" drawlength, but arrows are spined between 26" centres. As long as you use the same measurement every time for your own personal arrows then you could have it any length you want. The idea of hanging a wrench off the end of the shaft is just as accurate as long as the wrench is place the same distance from the fixed end everytime.
Graham

After you posted this I looked up AMO standards. CONFUSING They can even pervert the draw length and bow length issues.  So basically what I understand is that they measure between 26" centers but it is calculated for a 28" arrow.

Primitive: just fallow the instructions on the site Pat posted. Set it up at 26".  I shoot arrows several inches longer than my draw length because I don't want the broadhead getting to close to the back of the bow and interfearing. Justin

[Skeaterbait]

I got these plans from another site. They seem to be pretty simple, what you see is the dial face but read through the word doc for how to build the rest of it.

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[Evil Dog]

Was looking at dial indicators over on eBay and realized that I had absolutely no idea what deflection range I needed.  Would the shaft flex 1/4" or maybe up to 1 1/2"?  I suppose I could take some shafts that were factory spined and get somewhat of an idea.  These plans look like what I may have been looking for though and are a lot easier to fit in my budget too !!!  Thanks skeaterbait, I sure do appreciate it.

[Justin Snyder]

Jim Hill recomends using 1".   I got mine at the local Ace Hardware for about $15. Justin

[uklongbow]

I think your going to need at least 1" of deflection , carbon redline 600's  that work on a 40+# longbow = .6"  deflection . some of the carbons that they make are numbered by their deflection in inches ,600,500,460, 350 and so on. but I think they may be measured at 28"you might want to check either the manufacturer or one of the other archery forums.
If you can borrow some various spine carbons or some known spine woodies that will give you a data point to verify yours.

I was looking for that spine tester scale print out, so thanks for that.
Roger

[Evil Dog]

Went ahead and built the spine tester that Skeaterbait linked the plans to.  Was real easy and did the whole thing for less than 5 bucks !!!  Had enough scrap wood laying around the shop so that I didn't have to buy any.  Making the 2 pound weight was pretty easy too as I had a bunch of #7 1/2 shot and a reloading scale.  Just a matter of weighing the empty container and then weighing out enough shot to bring it up to 2 pounds total.  The meat counter at my local grocery store confirmed that it was 2.00 pounds right on the button.  The most time consuming part of the whole thing was making up a chart showing the various inches of deflection converted to pounds of spine.... a couple hours quality time spent with a calculator.  Not a bad Saturday afternoon project.

[Evil Dog]

Spent the last hour or two verifying the spine weight of about a hundred cedar shafts.... they were from probably 3 different suppliers, some directly from Rose City itself.  They were all represented to be 45# (actually 43# to 48#).  It was absolutely amazing to me the variation I encountered.... some as low as 40# and some as high as 57#.  I went through the entire pile three times and all of the readings repeated themselves.  I've no particular reason to doubt the accuracy of this home-built spine tester as all of the readings made were consistent rather than the same shaft giving 3 different readings.  Had a dozen come out at exactly 52 pounds and all weighing within a 5 grain spread.  Think I will set those aside for my next set of personal arrows.... have a couple of color combinations that I have been wanting to try anyway.

[Justin Snyder]

I built the Jim Hill model and started testing shafts that I had ordered. They had the weight on them 42, 44, 43 not just a 45 group.  My tester measured 2 pounds under on all. Then I tested one that said 57 and it was 75. OOPS somebody is dyslexic. Justin

[Primitive1]

Like bows, wood arrows gain and lose weight through water absorption or loss.  I would think it a difficult task to sell arrow shafts at a particular spine grouping since their arrival in Arizona would read differently from the same spined group arriving in Louisiana after acclimating over a period of time.  I also wonder how wet they are (or dry for that matter) when they are measured for spine and are shipped.  Come to think of it, the variables to be considered alone with a spined group of wood shafts would scare me away from making any claim; too much to consider! .  Porosity/density, grain straightness, length...hats off to those who stabalize enough to even get close!  It would be interesting to take a cedar shaft at 45# and put in a 110 degree hot box for a week and measure spine and then put it outside (assuming high humidity) for a week and measure the difference between the two.  I would guess that difference would be quite remarkable.

[Primitive1]

I'm finishing up a bow from that 'recently felled Ash tree' to go with the arrows from same...it's amazing to me how completely different the spines are from the arrows made from the same log of Ash...it is remarkable...there are some that are bendy as wet noodles and others which are quite stiff (shafts split out, not sawn and dried similarly).  I was also wondering, on the ones that are really bendy, if 'heat treating' them would stiffen them up enough if they are close to a particular spine weight (like a bow belly is heat treated).  Not sure, but once I finish up the bow I'll get some pics out and start on my spine tester...the neat thing is this bow is squirrely in the alignment department (in a good way) so that it's center shot...you can notice a difference in shooting the 'bendy' arrows however, although they hit in the same spot, but you can watch them 'wiggle' as they go down range; its weird to observe.

[onemississipp]

anyone got a pic of the finished spine tester "skeaterbait" linked to?