Arrow spine tester

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This topic contains 4 replies, has 5 contributors, and was last updated by  conquestador 1 year, 5 months ago.

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  • March 14, 2013 at 9:20 am #568711 Back to Top REPORT

    fbear2

    Joined: 12/22/2007
    has anyone made a arrow spine tester or have pictures of one? I would like to make one.
    Thanks for the help.
    Bear
    March 14, 2013 at 10:16 am #568724 Back to Top REPORT
    bow-drawn
    Bow Drawn

    Age: 63
    Joined: 11/14/2007
    Location: Ohio
    View My Bows
    gjarcher has made one and he has shared it on here before. I’m not sure if you do a search you’ll be able to find it. I know 3 Rivers Archery sells them.
    March 14, 2013 at 7:48 pm #568821 Back to Top REPORT
    southshorerat
    SouthShoreRat

    Joined: 7/3/2008

    has anyone made a arrow spine tester or have pictures of one? I would like to make one.
    Thanks for the help.
    Bear

    This is a Custom RAM that has been modified a tat!

    March 15, 2013 at 11:29 am #568925 Back to Top REPORT
    gjarcher
    gjarcher

    Age: 71
    Joined: 10/3/2006
    Location: Colorado
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    Search the Internet, there are some good examples and a number of designs to choose from. http://poorfolkbows.com/spine1.htm  (page 3, Stykzz/JimHill style)

    I prefer the dial indicator style with 28″ centers and 1.94lb weight because it compares directly with Easton/ASTM spine ratings that arrow manufacturers use. Cost is about $50 -$75 depending on materials used and quality of dial indicator. You’ll need a dial indicator with at least 1″ of travel … they can be had at Sears Auto for under $40. When taking readings with the dial indicator mounted under the shaft, ease the indicator tip to just touch the shaft in order to nullify the return spring’s pressure, or calculate the return spring’s constant and increase the weight accordingly (usually anywhere from 15g to 30g … 880g = 1.94 lbs). SpineTester 001

    Designs that are built on 26″ centers and which use 2.0 lbs weight are for Traditional arrows (wood) and correlate to the AMO Spine Chart … not the Easton/ASTM spine readings.

    The reason for building a spine tester to the Easton/ASTM standards  other than manufacturer’s spine ratings  are bsased on the ASTM standard is for entering the data into computer arrow simulation software, like OnTarget2!.

    The one I’ve made, shown above, has extra holes in the base to move the supports to 26″ centers and I have a 420-gr weight I add to the 1.94 lb weight to make 2 lbs, so I can build and check my Trad arrows.

    I’ve checked the spine tester I’ve made against my RAM spine Tester and the readings compare very closely … within the third decimal place. The dial indicator on the RAM is about $150, which gives a very small increase in precision over the Sears Auto $37 indicator.

    If all you want to do is sort and match arrow static spine and/or find the stiff side of the spine, then it doesn’t really matter what the distance between centers is  or what weight is used as long as you can get a good reading.

    March 16, 2013 at 4:45 pm #569147 Back to Top REPORT

    conquestador

    Age: 63
    Joined: 12/10/2009
    Location: Upstate NY
    Here’s one that I fashioned up a few weeks ago.  It’s very good for testing for the side of an arrow with the strongest or weakest spine.  I had to fashion a bracket that would hold the micrometer as well as allow me to remove it for other stuff.  For testing actual spine, it’s very good but requires a little tinkering to get the arrow shaft to just make contact with the dead stop.  Brian’s set up is fool proof due to how the mic functions with relationship to how and where it contacts the arrow shaft.  Google “spine tester” and click “images.”  There’s a lot to draw from there.  Good luck.

    spine tester 001spine tester 002

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