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I was wrong

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bumppo:
Adb, I'm out of town for the next two weeks, but I'll upload a pic of the spine tester I came up with when I get home. I cut my own shafts using Veritas dowel cutters both 3/8 and 1/2". I worked my way through poplar, ash, white oak and finally hickory in both sizes, put them on the spine tester and marked their deflection, I then shot them to see which worked the best. (I measure the raw shaft on the 1/2" before i taper to 3/8", and I measure all at 33" overall length) Currently I shoot 3/8" poplar on my #90, 3/8" hickory on my #110, and 1/2 tapered to 3/8" on my #120. But like I said, this is just a scale I came up with, I don't know how it would actually relate to how others measure spine. I'm not really happy with the 1/2" arrows on the #120, I think they are still too heavy, but the 3/8" are definitely not heavy enough.

adb:
Thanks! I look forward to seeing what you've come up with!

mikekeswick:
A heavy bow is just a lighter bow scaled up :) so of course spine matters.
I've made a few spine testers over the years but the simplest way of all is simply 2 pegs say 27 inches apart, put your shaft on and then hang a weight from the center and mark the deflection. You can easily magnify the deflection by adding an arm on a pivot to the set-up. The normal standard for measuring spine is to use a 2 lb weight however for these heavier shafts I would simply up the weight to maybe 3 - 3 1/2lbs. Just keep the distance between the points the same and the weight the same and you will get meaningful results.
As for the best taper for distance then barrelled shafts are the way to go with a slight foc balance point in the finished arrow with a light head.

adb:

--- Quote from: mikekeswick on August 12, 2013, 02:04:57 pm ---A heavy bow is just a lighter bow scaled up :) so of course spine matters.
I've made a few spine testers over the years but the simplest way of all is simply 2 pegs say 27 inches apart, put your shaft on and then hang a weight from the center and mark the deflection. You can easily magnify the deflection by adding an arm on a pivot to the set-up. The normal standard for measuring spine is to use a 2 lb weight however for these heavier shafts I would simply up the weight to maybe 3 - 3 1/2lbs. Just keep the distance between the points the same and the weight the same and you will get meaningful results.
As for the best taper for distance then barrelled shafts are the way to go with a slight foc balance point in the finished arrow with a light head.

--- End quote ---

Are you speaking from practical experience, or are you just guessing?

bumppo:
This is the spine tester I use, a simple pivoting arm in the center that deflects when I put weight on the shaft. I use a #2 diving weight hung from the center with the arrow grain perpendicular to board (this is normally the weakest spine of the shaft, and it means the nock when cut would be perpendicular to the floor). I normally measure the raw shaft at 33", (just ignore the arrow that's on there). "H" is accurate for 28" arrows at around #60, G is what I've been aiming for with shafts meant for my#120 bow but they still seems too heavy. I generally try to keep arrows for my #100 in the K - L range.

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