24hourcampfire.com
24hourcampfire.com
Previous Thread
Next Thread
Print Thread
Hop To
Joined: Oct 2012
Posts: 2,954
Campfire Regular
Campfire Regular
Joined: Oct 2012
Posts: 2,954
With 47# recurve in for repairs, I decided to tune some carbons for my 57# recurve. For my draw length and that weight, all the charts and those I've asked indicate a 400 spine as the place to be.

Now, I reasoned that if I went up to a 340 spine (stiffer) shaft I'd still be able to get a tuned arrow by using a combo of longer shaft and heavier point, thus getting higher FOC and higher overall weight. Maybe making a fine adjustment using brace height.

I am wrong here?

Last edited by Gun_Geezer; 08/02/20.
GB1

Joined: Apr 2006
Posts: 4,590
Likes: 32
J
Campfire Tracker
Campfire Tracker
J Online: Content
Joined: Apr 2006
Posts: 4,590
Likes: 32
Correct - heavier brass inserts are an option as well. 3 Rivers Archery has a spine calculator on their site that will let you plug in your bow info and help you get a feel how shaft length, spine and point weight, etc. impact the dynamic spine. It's helpful in getting to a starting point on how much more point weight or shaft length you'll need going from 400's to 340's.

I'm shooting bows in the mid-50 lb range with 340 spine shafts at 29" with 50 gr brass inserts and 175 gr points. How your sight window is cut is a variable in the equation also. I cut my sight windows anywhere from right at center up to 3/16" past center. Past center allows you to shoot a heavier spine shaft.

Joined: Oct 2012
Posts: 2,954
Campfire Regular
Campfire Regular
Joined: Oct 2012
Posts: 2,954
I've been using / referencing the 3R calculator. Amazing tool. Tried to us the "Other" shaft selection and it kind of blows up. They have an error in it someplce.

Joined: Jun 2008
Posts: 13,480
Likes: 9
M
Campfire Outfitter
Campfire Outfitter
M Offline
Joined: Jun 2008
Posts: 13,480
Likes: 9
You are correct. But unless you have a really short draw I would keep my arrows as short as possible. Stiffer arrows are going to more times than not hit on your riser and or rest.


Eat Fish, Wear Grundens, Drink Alaskan.
Joined: Dec 2005
Posts: 6,065
Likes: 20
CRS Offline
Campfire Tracker
Campfire Tracker
Joined: Dec 2005
Posts: 6,065
Likes: 20
I have done exactly that when wanting to shoot a heavier arrow out of my traditional bows.

I prefer heavier arrows in the 600gr range when hunting elk, moose and using three bladed broadheads.

My shot distances are close, I cannot remember the last time I took a shot over 20 yards. So arrow weight is not factor in to arrow trajectory at short distances.

I have a few bows that are tuned for both 400 and 340 spine.

My favorites broadheads right now are Cutthroats for two blade and VAP's for three blade.


Arcus Venator
IC B2

Joined: Feb 2020
Posts: 1,826
Likes: 22
W
Campfire Regular
Campfire Regular
W Online: Content
Joined: Feb 2020
Posts: 1,826
Likes: 22
One of the biggest variables is bow efficiency. I you can, reduce the centershot by going to thinner strike pad.
The 3Rivers calculator is a OK tool but lacks a lot of other variables that Stu Miller has on his later, and much better, version. I you can find it, it is the one that has variables for centershot, string, type of bow, arrow, etc.

Joined: Oct 2012
Posts: 2,954
Campfire Regular
Campfire Regular
Joined: Oct 2012
Posts: 2,954
A quick search finds the Stu Miller calc here: http://www.taylortel.net/~rickbarb/dynamic_spine_calculator.html

Oddly enough, it has a few errors someplace:
- It does not recognize (gives error for) Beman Centershot 340 spine shafts.
- For Beman Centershot 400 and 500 shafts shows the ID to be 0.201 instead of 0.231". And recommeds, therefore, the wrong inserts.

Entering same data into both calculators yields excactly the same dynamic spine for my Bob Lee. For the arrow, the two calcuators differ by about 2.5. Hard to say which is more accurate. I note that both allow for "calibration" for my "form". In the end, I think they both give you a good starting point to set up your arrow and tune till it flies well.

Joined: Apr 2006
Posts: 4,590
Likes: 32
J
Campfire Tracker
Campfire Tracker
J Online: Content
Joined: Apr 2006
Posts: 4,590
Likes: 32
Interesting - I've used both the Stu Miller and 3 Rivers calculators and don't recall encountering any errors with the data I've used for both carbon and wood shafts.

Joined: Oct 2012
Posts: 2,954
Campfire Regular
Campfire Regular
Joined: Oct 2012
Posts: 2,954
Originally Posted by JGray
Interesting - I've used both the Stu Miller and 3 Rivers calculators and don't recall encountering any errors with the data I've used for both carbon and wood shafts.

I didn't check anthing else. I'm setting up a bow with the Centershot 340's, so that is one that I tried. "Error". Danger Will Robinson!!!! The calc. does'nt seem to recognize it. At the bottom of the page it even states that the tool has a few bugs in it, or words to that effect. Still, nice tool.

Joined: Nov 2006
Posts: 1,774
Likes: 7
H
Campfire Regular
Campfire Regular
H Offline
Joined: Nov 2006
Posts: 1,774
Likes: 7
A selection of test point weights can come in useful in finding a balanced spine to point weight.


love, joy, peace, patience, kindness, goodness, faithfulness, 23 gentleness, self-control

& Proverbs 21:19
IC B3

Joined: Dec 2005
Posts: 6,065
Likes: 20
CRS Offline
Campfire Tracker
Campfire Tracker
Joined: Dec 2005
Posts: 6,065
Likes: 20
Originally Posted by Hunterapp
A selection of test point weights can come in useful in finding a balanced spine to point weight.


I agree, and have 75gr-300gr for tuning purposes.

Last edited by CRS; 08/13/20.

Arcus Venator

Moderated by  RickBin 

Link Copied to Clipboard
AX24


661 members (1Longbow, 1234, 10gaugemag, 1936M71, 02bfishn, 1100mag, 78 invisible), 3,861 guests, and 792 robots.
Key: Admin, Global Mod, Mod
Forum Statistics
Forums82
Topics1,230,280
Posts19,257,980
Members75,102
Most Online28,956
Jan 26th, 2025

×

 


Fish & Game Departments | Solunar Tables | Mission Statement | Privacy Policy | Contact Us | DMCA
Hunting | Fishing | Camping | Backpacking | Reloading | Campfire Forums | Gear Shop
Copyright © 2000-2025 24hourcampfire.com, Inc. All Rights Reserved.



Playwire

Advertise on this site.

Powered by UBB.threads™ PHP Forum Software 8.0.0
(Release build 20240826)
Responsive Width:

PHP: 8.3.16 Page Time: 0.226s Queries: 36 (0.139s) Memory: 0.6690 MB (Peak: 0.7257 MB) Data Comp: Zlib Server Time: 2025-02-14 21:43:10 UTC
Valid HTML 5 and Valid CSS