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Author Topic: Understanding spine and wooden/bamboo arrows.  (Read 4533 times)

Offline klr650Teach

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Understanding spine and wooden/bamboo arrows.
« on: September 11, 2018, 03:00:12 PM »
On the 3Rivers site they have a program for calculating arrow spine to match the bow. According to that program and it's pre entered data for known bows, my Bear Minuteman should require a dynamic spine of 41.7. Firstly, how does dynamic spine differ from static spine?

With aluminum arrows you simply choose arrow diameter and wall thickness to match your bow poundage and ur pretty much set. With wood and bamboo do you simply match up the spine of the shaft with tips of your choosing to match the spine requirement of your bow? It seems the trad shafts open up a whole new barrel of variables to consider with different materials.  :knothead:

I'm a nube when it comes to wooden arrows and I made the decision to order 30-35 spined bamboo shafts for my 30# Minuteman. I'm thinking that according to that program that I should have ordered 40-45 spined shafts?  :banghead:

What types of target tips are preferred for wood and bamboo arrows? Glue on? Screw on or glue on adapters with screw in tips?  :dunno: I won't be using broadheads at all, just target tips.

How much difference should there be in the OD of the shaft vs the ID of the tip? Must the shaft's tip be made conical? Or slip into the point until it bottoms out and spins true?

I need some input here please fellas. tnx

Online McDave

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Re: Understanding spine and wooden/bamboo arrows.
« Reply #1 on: September 11, 2018, 04:55:19 PM »
Physics are physics, whether we’re dealing with wood, aluminum, or carbon arrows.  After deciding on what spine aluminum arrow to use, we start playing with tip weight and length to get the flight characteristics we want, just as we wouid with wood.

Some would disagree, but generally people who want to shoot targets want lightweight arrows, for flat trajectory, while people who want to hunt want heavyweight arrows, for penetration.

Since you state you want to shoot targets, your choice of 30-35# bamboo shafts for your 30# bow seems reasonable.  With 40-45# shafts, you would have to select a heavier point to get the same flight characteristics, which would give you a more curved trajectory and thus limit you to shorter ranges.  Just experiment with different points until you find one that flies best for you.

For regular wood shafts, like cedar, most people prefer glue on points, which come in different sizes, from 5/16-23/64, depending on the diameter of your shaft, and different weights, from 75 grains to 145 grains or more.  I would suggest that you start with 100 grain points.  Most people taper their shafts to fit the point, using any of a number of taper tools that are available, from cheap to expensive.  The taper tools usually have one end that has a long taper for the point, and the other end that has a short taper for the nock.  Probably the most common glue for mounting the point is Ferrel-tite, which is heated over a propane torch and dripped or smeared onto the taper.  Most people use the same glue for the nock they use for gluing on the fletches, like Duco.

This might not be the same for bamboo; somebody who regularly uses it should probably chime in.
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Offline WVFarrier

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Re: Understanding spine and wooden/bamboo arrows.
« Reply #2 on: September 11, 2018, 04:56:48 PM »
With bamboo you will want to order them for your spine BUT i also check spines at home to determine which ones are truly spined as claimed.  Often times they are not....however boo is incredibly forgiving and will shoot well out of several draw weights.  I use glue ons for all my wood and boo shafts.   For wood spines you may wanna order a set of differinf weights.  Forresters offers a variety pack so you can try several different spines.   Just because a bow draws 54# doesnt mean itll shoot a spine for that....it may require a 65 or 70 even.   Clay Hays on youtube has some good.videos on this subject
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Offline klr650Teach

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Re: Understanding spine and wooden/bamboo arrows.
« Reply #3 on: September 11, 2018, 05:24:09 PM »
Physics are physics, whether we’re dealing with wood, aluminum, or carbon arrows.  After deciding on what spine aluminum arrow to use, we start playing with tip weight and length to get the flight characteristics we want, just as we wouid with wood.

Some would disagree, but generally people who want to shoot targets want lightweight arrows, for flat trajectory, while people who want to hunt want heavyweight arrows, for penetration.

I would have to agree with this. What I was warned about was that because my Minuteman bow is of an older vintage now that I should be shooting a heavier arrow to make life easier on the limbs and lessen the chance of de-lamination.

Since you state you want to shoot targets, your choice of 30-35# bamboo shafts for your 30# bow seems reasonable.  With 40-45# shafts, you would have to select a heavier point to get the same flight characteristics, which would give you a more curved trajectory and thus limit you to shorter ranges.  Just experiment with different points until you find one that flies best for you.

For regular wood shafts, like cedar, most people prefer glue on points, which come in different sizes, from 5/16-23/64, depending on the diameter of your shaft, and different weights, from 75 grains to 145 grains or more.  I would suggest that you start with 100 grain points.  Most people taper their shafts to fit the point, using any of a number of taper tools that are available, from cheap to expensive.  The taper tools usually have one end that has a long taper for the point, and the other end that has a short taper for the nock.  Probably the most common glue for mounting the point is Ferrel-tite, which is heated over a propane torch and dripped or smeared onto the taper.  Most people use the same glue for the nock they use for gluing on the fletches, like Duco.

What I'm running up against is finding points under 11/32 and in 5/16 I've only found one so far 3Rivers and Lancaster and seems the smaller diameter the less choice you have in point weight. I suspect I'll also find the same scenario when I go looking for nocks.
http://www.lancasterarchery.com/pdp-5-tapered-field-points.html


Offline klr650Teach

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Re: Understanding spine and wooden/bamboo arrows.
« Reply #4 on: September 11, 2018, 05:30:06 PM »
With bamboo you will want to order them for your spine BUT i also check spines at home to determine which ones are truly spined as claimed.  Often times they are not....however boo is incredibly forgiving and will shoot well out of several draw weights.  I use glue ons for all my wood and boo shafts.   For wood spines you may wanna order a set of differinf weights.  Forresters offers a variety pack so you can try several different spines.   Just because a bow draws 54# doesnt mean itll shoot a spine for that....it may require a 65 or 70 even.   Clay Hays on youtube has some good.videos on this subject

Can you provide me with your source for glue ons? If not different than Forresters, got a link? tnx

Online Roy from Pa

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Re: Understanding spine and wooden/bamboo arrows.
« Reply #5 on: September 11, 2018, 05:42:07 PM »
Check the sponsors here on tg for points and other materials.

Do a search on YouTube for making bamboo or cane arrows, lots of them there.

Offline slowbowjoe

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Re: Understanding spine and wooden/bamboo arrows.
« Reply #6 on: September 11, 2018, 06:29:11 PM »
The length of your arrow has a definite effect on spine also. A 1" difference in arrow length, with wood shafts, will change the dynamic (functional) spine by 5#. Do you know your draw length? This will be important in getting those 30-35# dialed in for your bow.
I'd strongly recommend getting familiar with more common wood arrows (Doug Fir, Sitka Spruce, Cedar) before trying bamboo, for a number of reasons. What wood did you order for the 30-35's?
you're correct that there are fewer choices in 5/16", but you can certainly match up some good arrows once we know a little more. n 11/32 point will fit on a 5/16 shaft (the taper is the same), but it's not really desirable with field points as the ferrule end will stand a little proud of the shaft, which could be problematic when pulling arrows from your targets.
As McDave said, tapering the shaft for glue on points is by far the most common method of mounting points; screw on's exist but there again you'd be limiting choices even further.
And... you'll need to be sure your arrows are straight, mounting the nock and point only when the shafts are true. You'll also want to check the nocks and points when mounted to ensure they're spinning true also... I sometimes touch up my tapers with an emery board to tweak.

Do let us know your draw length befor you finalize what length you plan on cutting the shafts. And, there are a couple of VERY helpful threads in the "How To" forum here on building woodies.

Offline klr650Teach

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Re: Understanding spine and wooden/bamboo arrows.
« Reply #7 on: September 11, 2018, 06:31:47 PM »
Check the sponsors here on tg for points and other materials.

Do a search on YouTube for making bamboo or cane arrows, lots of them there.

Hi Roy, I think I've watched every Youtube video out there on bamboo arrows. The mechanics of building arrows as you know is not difficult once you have all your ducks in a row with all the parts and pieces. Assembly is the easy part.

For instance; I'm used to having my tips and inserts (aluminum arrows) being flush at the surface with one another. I have some 11/32 glue on tips here that fit over the tip beautifully on my bamboo shafts once tapered. My question is; with trad arrows is the glue on point also supposed to be flush with the shaft surface or slightly larger in diameter and not flush? I'd like to know all these things before proceeding.

Offline klr650Teach

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Re: Understanding spine and wooden/bamboo arrows.
« Reply #8 on: September 11, 2018, 06:38:33 PM »
The length of your arrow has a definite effect on spine also. A 1" difference in arrow length, with wood shafts, will change the dynamic (functional) spine by 5#. Do you know your draw length? This will be important in getting those 30-35# dialed in for your bow.
I'd strongly recommend getting familiar with more common wood arrows (Doug Fir, Sitka Spruce, Cedar) before trying bamboo, for a number of reasons. What wood did you order for the 30-35's?
you're correct that there are fewer choices in 5/16", but you can certainly match up some good arrows once we know a little more. n 11/32 point will fit on a 5/16 shaft (the taper is the same), but it's not really desirable with field points as the ferrule end will stand a little proud of the shaft, which could be problematic when pulling arrows from your targets.
As McDave said, tapering the shaft for glue on points is by far the most common method of mounting points; screw on's exist but there again you'd be limiting choices even further.
And... you'll need to be sure your arrows are straight, mounting the nock and point only when the shafts are true. You'll also want to check the nocks and points when mounted to ensure they're spinning true also... I sometimes touch up my tapers with an emery board to tweak.

Do let us know your draw length befor you finalize what length you plan on cutting the shafts. And, there are a couple of VERY helpful threads in the "How To" forum here on building woodies.

As posted above, I ordered the 30-35 shafts in Bamboo. My AMO draw length is 28 1/2 inches or 26 3/4 to the inside of the handle at it's deepest part. I had planned on using my shafts full length at first to test by either adding weight or shortening them to increase the spine if needed.

Sorry you must have hit the send button before I did as you answered my question that I posted afterwards regarding having the glue on point flush with the shaft. tnx

Offline slowbowjoe

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Re: Understanding spine and wooden/bamboo arrows.
« Reply #9 on: September 11, 2018, 06:51:34 PM »
If you leave 30/35's full length, you arrows will have a dynamic spine of around 25-30#'s; too soft. For a 28.5 draw, I'd cut 'em 30", giving you  29" to the back of the point. With 100 grain points, you'll at least be in the ball park. Don't get too hung up on the charts, they're a helpful guideline, not a strict rule for what will actually work for you.

Online Roy from Pa

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Re: Understanding spine and wooden/bamboo arrows.
« Reply #10 on: September 11, 2018, 08:56:36 PM »
Only start out with a couple arrows, working on the length.

Don't go cutting them all down at once.

Offline klr650Teach

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Re: Understanding spine and wooden/bamboo arrows.
« Reply #11 on: September 11, 2018, 09:07:41 PM »
Roy, that was the plan. I'm going to try them at full length also. I figured I'd take it slow and try a couple arrows at a time once I get all the pieces. Here in Mexico when it comes to finding anything you want to buy never happens quickly. I may even try those 11/32 tips and put 3 arrows together just so I can throw some bamboo at a stack of baled hay. Cheers

Online Roy from Pa

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Re: Understanding spine and wooden/bamboo arrows.
« Reply #12 on: September 11, 2018, 09:28:41 PM »
Just go slow and have fun, you're going to love it.

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Offline klr650Teach

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Re: Understanding spine and wooden/bamboo arrows.
« Reply #13 on: September 12, 2018, 09:33:28 AM »
When it comes to cutting arrows to length I supposed it matters if you want more or less spine as to which end of the arrow you cut or should a person always trim from one end only......which end? These bamboo shafts seem to have a nice natural taper to them.

Online Roy from Pa

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Re: Understanding spine and wooden/bamboo arrows.
« Reply #14 on: September 12, 2018, 10:13:46 AM »
Kinda depends on each shaft, but you could assess each shaft and cut the thick end to closely match the inside diameter of the points you are going to glue on for a start. Maybe some of them won't need trimmed on the thick end to get a good match.

Then if more length needs taken off, remove it from the nock end...

Quote
These bamboo shafts seem to have a nice natural taper to them.

That is what makes bamboo or cane arrows fly so well and they have a natural FOC weight:)

Yer gonna love em..

Offline two4hooking

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Re: Understanding spine and wooden/bamboo arrows.
« Reply #15 on: September 12, 2018, 10:15:19 AM »
With the boo I cut from the nock end as the fat end of the taper fits my broadheads and glue ons better this way by keeping the girth.   

Offline klr650Teach

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Re: Understanding spine and wooden/bamboo arrows.
« Reply #16 on: September 12, 2018, 10:17:41 AM »
Hey two4hooking, I got my Howard Hill quiver from Craig and could not be happier. Thanks for the recommendation.

Offline Caddo

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Re: Understanding spine and wooden/bamboo arrows.
« Reply #17 on: September 12, 2018, 12:24:23 PM »
Depending on where you ordered your Bamboo shafts from, I have found those on the big auction site from China, to be 5-7 #'s heavier than advertised. Just a heads up.

LD
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Online Roy from Pa

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Re: Understanding spine and wooden/bamboo arrows.
« Reply #18 on: September 12, 2018, 06:14:02 PM »
650teach, ya got a pm...

Offline NY Yankee

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Re: Understanding spine and wooden/bamboo arrows.
« Reply #19 on: September 13, 2018, 01:24:26 PM »
Static spine is what you read when you put a shaft on a spine tester. It simply tells you the deflection of that shaft. Dynamic spine is what you see in the arrow when it is shot after everything is added to the shaft to make it an arrow. Dynamic spine has many variables, like static spine, weight at the front of the shaft, Actual shaft weight, bow center shot, size of fletching etc. Static spine is merely a starting estimate of what you need. No two setups are alike. Many times you have to play with your set up to get perfect arrow flight. Don't forget to make sure your points spin true when you mount them too.
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