After some trial and a lot of frustration, I think I've arrived at an arrow that shoots reasonably well for me. Except that in the process I ended up with a lot more point weight than originally planned.
If I use Stu Miller's spine calculator to come up with a spine number for these arrows, and then calculate "backwards" by changing shaft type/deflection and point weight to arrive at the same spine number, will these "new" arrows be close to what I need?
I figure yes, but maybe someone has some experience with this. I realize of course it will only be approximate specs, and will have to be tested and tweaked on the range.
Details:
Morrison ILF recurve w/ glass foam limbs. 45 lbs at my 27" draw length. Shooting 3-under.
Arrows: Carbon Express Blue Streak 250 = 0.413 deflection, cut to 29 5/8" BOP. 50 grain brass insert, 3 x 4" feathers, 5.5" double-dog Onestringer wraps.
Originally 145 grain points, but now up to 200 grain points.
As my form improved - not great but improved ;) from what it was - my arrows started to fly worse. After a lot of frustration I finally increased point weight and at 200 grain the arrows fly much better.
I could of course stick with what works now, but would like to keep the arrow weight around 450 grains for ~10 GPP
I'm new to carbons myself but have been looking into it a lot over the last few days.
.413 sounds stiff to me if you want 450 grains total.
I'll bet you'd like these...
http://www.shop.bigjimsbowcompany.com/BLEMS-Gold-Tip-Carbon-Shafts-Dz-GTBLEMS.htm
in the .600 spine with 200 grain tip.
Thanks Zradix,
Yes, .413 is probably too stiff a spine for my draw weight and length (20/20 hindsight, right :D )
But then I think .600 may be too weak a spine. Especiallly with 200 grain+ up front. I'll run it through the spine calculator and see if the numbers add up.
henrikBP a 1535 with nock, 50 g brass insert at 28.5" should be about 277g. add a 145-175 tip or even 200g and you will be in about the right weight.
For 45lbs and 27" the .600 spine is great medicine. Now You probably have a riser that is cut past center. This would tend to lean twords a stiffer arrow, but then you have a long limb and 17" riser. If your bow is more than 56" long, you will lean back tword a weaker shaft and so on.
Too much importance is put on the affect of the heavier pt. 200 up front is not that heavy on a carbon arrow and pt weight adjustmen is only for fine tuning. You will get more dramatic resluts from adjusting shaft length.
bigjim
Thanks Jim,
Yes, my Morrison 17" riser is cut past center (3/16" I believe), and overall length of my bow is 62".
I got a shaft "test kit" back when I first tried out carbon shafts, and never could get the .500 spine to shoot right. Now I'm thinking it was due to my release at the time (20/20 :) )
I'll take a look at .600 as well.
Thanks,
Henrik
I ran a few numbers through the calculator.
My bow is listed as needing 69 pounds dynamic spine.
My original arrow calculated out to 62 pounds.
My original arrows with 200 grain point => 51 pounds
A GT 1535 @ 28.5", 50 gr insert plus 200 gr point => 36 pounds
I know the calculator is just a tool to give general ideas, but that seems like a huge range in spine.