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All about spine.

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billmac:
Is there a good resource for learning all about arrow spine for do-it-yourselfers?  I've read a bunch of stuff in various places but it's all a little confusing.  Do you spine test your shafts before tipping and nocking?  How do you reduce spine?  I read one fellow's advice to sand a bit in the middle of the shaft to reduce spine and taper sand the ends to reduce weight.  What does arrow length have to do with spine?  Do you match the spine exactly to the draw weight of the bow?

Justin Snyder:
For recurves and high performance longbows add 5-10# bow weight. For selfbows, subtract 5-10# bow weight. For high performance recurves add 10-15# bow weight. For 160 grain points add 5# bow weight. For 190 grain points ad 10# bow weight.  You heard right about reducing or increasing spine. Length affects spine by leverage. For every inch of arrow length (string grove to back of point) over 28" you need 5# more spine, for every inch under 28" you need 5# less spine.

Pat B:
Spine weight reflects the deflection the arrow shaft makes when shot. With most selfbows, lighter spine weight is needed to get the arrow around the handle.  With self bows I like 10# to 15# less spine weight than bow weight but that depends on the bow and arrows. The standard spine weight is measured on a 28" arrow. I believe that it includes a 125 gr point. For every inch over 28" you can decrease spine weight by 5# and for every inch under 28' you can increase spine weight by 5#. You can also reduce spine weight by sanding the center of the shaft, thus making it bend easier. Or you can reduce the arrow's physical weight by tapering the front and back of the arrow but leave the center thick. The arrow bends in the center so by leaving the center thick the spine remains high but the physical weight of the arrow is reduced. An arrow with a single full length taper, like a hardwood shoot arrow or a tapered arrow, the spine weight is reduced by the simple fact of the taper. The arrow doesn't have to bend as much to get the back end(the thinnest) of the arrow around the bow.    Pat   

billmac:
28 inch arrow shafts are tested on 26 inch jigs are they not?  Are the measurements buillt into most jigs assuming a 28 inch shaft?

scattershot:
billmac, that's correct.

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