Primitive Archer
Main Discussion Area => Arrows => Topic started by: FunyFarm on December 31, 2015, 03:16:37 pm
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Hello world, first post / question. I have just picked up the sport of archery, I have no interest in compound bows or the like. I want to make my own self bow from local historic material ( here it would be Juniper) With that said.
I can not understand. SPINE. It appears to me that if you are talking about carbon it is one number that means ? Then there is another set of numbers for wood/ cane etc. like 55. 45 ,? I do understand is that spine is the flexibility of the arrow shaft. I also know the spine needs to be matched to the bow it will be shot from. And it is extremely important to accuracy. So here is the query: what number am I looking for. I am using a Samic Sage 52" 35# at 28" my draw is slightly longer 29 1/2 inch. So any help in understanding this would be greatly appreciated
FunyFarm
:D Alluminati not all conspiracies are theory
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Spine is really important to non-center shot bows. If you have a center shot, you can get away with much stiffer arrows. The farther you get from center the weaker the spine you'll need. Matching the arrow spine to the draw weight of a selfbow is typically a good starting point when matching arrows.
Archer' paradox is why selfbows need perfectly matched arrows. Read the wiki article on archers paradox and it will make more sense. It's been explained by better instructors than myself many times.
Basically the arrow has to bend around the handle using it's own inertia and the initial force supplied by release. After which the arrow straightens out, with help from the fletchings. Adding weight to the point weakens spine, by adding inertia to the resting arrow. Sanding the center of the arrow shaft will weaken the spine if you're close but still stiff.
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Ok. they system of determining a bows draw weight is standardized at 28 inches of draw length, so is an arrows spine. If you increase the length of a shaft you will weaken the spine by about 5lb per inch. If you shorten the shaft you will increase the spine by about 5lb per inch.It can get confusing. Say you want to make an arrow, since you draw 29.5", you will want a shaft that spines at about 65lbs at 28 ". This will allow for the extra 2.5 to 3 inches your arrow needs to be.
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Spine is the deflection of the arrow shaft as energy from the bow pushes it. With too weak spine the arrow bends too much as it goes around the bow and the arrow will go left for a right handed archer. If the spine is too stiff the arrow will not get around the bow cleanly and will typically go right of where you are aiming. There are ways of determining spine of any shafting by placing the arrow on uprights that are 26" apart, hanging a 2# weight on the middle and noting the amount of deflection.
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There are indeed several different standards for measuring spine. One way is to quote the "Deflection", or the ammount of bend under a standard pressure. Under this system, an arrow is said to be .400, .500, etc (Also known as 400, 500). To further confuse this system, there are two different standard pressures used . One system, called amo, calls for a 2 lb weight to be hung from the arrow, which is supported at two points 28 inches apart, the other system, called astm, uses a slightly lighter weight and slightly closer spacing of the supports.
Another way to express the stiffness is with numbers that represent draw weight like 50 lbs, 40 lbs. Or with GT brand carbons there may be a weight range like 15-35, 55-75.
It gets even more complex when you take into account the fact that arrows act stiffer or weaker depending on point weight and other factors .
Finding the right spine for your bow involves making a educated guess followed by testing. For me, the easiest way to arrive at the educated guess is to use a program like "Stu millers spine calculator".
Luckily for you, you have a very forgiving bow that is almost centershot.
Do a google search for "carbon arrow state university" for a good article that also applies to wood arrows.
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Here are some possible starting places, all based on a 30 inch arrow:
.500 spine carbons with a 125 to 175 point
Gt 1535's with a 125 to 150 point
wood 40 or 50 lb arrows with a 125 point
aluminum "1916's" with a 125 point
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Shoot cane .....and don't worry about spine.....that's what I've heard some say...... :) ;)
DBar
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Aaron, the AMO standard is measured between 2 points spaced 26" apart not 28" and it is for a 28" finished arrow with a 125gr point.
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Ok, thanks, pat.
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I agree with all of what has been said. I bare shaft tune my arrows and try to hit the target 3 inches to the right before adding feathers. I adjust the spine by sanding shaft as it comes to the right and try to balance with tip wt. This wt will also affect spine. More wt the more it moves right. The heavier arrow falls. This is a long hard process. Making good arrows can be as hard as making good bows.
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John, not sure of your reason to be 3 "right with bare shafts , feathers do not weigh enough to affect impact point I believe bare shaft and fletched should impact same spot. Feathers are only needed to stabilize broadheads or bad releases or arrows that are not properly tuned. your other instructions are also for right handed shooters vs. left handers. Personally I like cane because of natural taper is much more forgiving of spine. Funny Farm sorry for getting away from your OP, Like some others have stated spine is all about deflection measured in thousands with a given weight and distances between 2 points, Some arrows are marked in thousands like carbons 500,400 and ect. others like wood are in spine groups of 5# such as 46-50 Aluminums come a little different with 2 numbers 1916 the first numbers is dia. in 64ths as in 19/64 ths. second number is thickness of wall or 16
thousanths. I know clear as mud. ;D Hoping everyone had a Happy New Year. Bob
;D
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My understanding was not about wt but drag.
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Bob this is kinda what I do ...maybe not right but works for me.
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Just try a bunch of different arrows until you find one that shoots great. Then make or buy arrows that match that one. Simple. You might have to try shooting 100 different arrows but that's all part of paying your dues.
Or you can take the hard route and get a PhD in Arrowcraftology. You'll need to be in school for 6 years, minimum. Then you'll need to do what I suggested above before it makes any sense.
>:D
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John, very interesting ;D Bottom line is if they hit where your lookin good enough. As many deer as I have missed who am I to be giving instructions :-[ :-[ :-[ Bob
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None of this spine info is going to help very much aside from keeping an arrow from breaking. Untill you can shoot enough times to build skill to group your arrows, bare shaft tuning will not produce usable information. First thing I would do is spine the best you can using number data from these really good post. This will produce a safe arrow that will not blowup when you shoot it. Keep shooting those three arrows till you have fired your bow hundreds of times. During this time you will perfect release and good body mechanics. Making arrows and learning to shoot go hand in hand imo. The better you group the better you can tune. Bob's bottom line is spot on. If it hits center nothing else matters.
I make dogwood arrows and the numbers don't make sense compared to the bare shaft tuning results.
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Great info here guy's!
Patrick
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John, not sure of your reason to be 3 "right with bare shafts , feathers do not weigh enough to affect impact point I believe bare shaft and fletched should impact same spot. Feathers are only needed to stabilize broadheads or bad releases or arrows that are not properly tuned. your other instructions are also for right handed shooters vs. left handers. Personally I like cane because of natural taper is much more forgiving of spine. Funny Farm sorry for getting away from your OP, Like some others have stated spine is all about deflection measured in thousands with a given weight and distances between 2 points, Some arrows are marked in thousands like carbons 500,400 and ect. others like wood are in spine groups of 5# such as 46-50 Aluminums come a little different with 2 numbers 1916 the first numbers is dia. in 64ths as in 19/64 ths. second number is thickness of wall or 16
thousanths. I know clear as mud. ;D Hoping everyone had a Happy New Year. Bob
;D
Thank you bob KISS. Is my motto. And thanks to all that are trying to help me understand something I really am not at a level to grasp as of yet,, happy arrow flinging. 😜
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If you are shooting 30" arrows with a 100 grain field tip I would start off with about a .500 deflection arrow for your bow. That should be pretty close for starter. If it shoots left it is too stiff and shoots right it is not stiff enough. If you are shooting target you probably want to keep the weight down on the arrow so instead of adding point weight if the arrow is too stiff I would advise going to a softer shaft, go down or up about .05 deflection at a time until you zero in.
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Most of my arrows don't fly that straight (aren't tuned). I guess cane should probably be a little stiff, otherwise it could break easily or even not fly straight. I'm dreaming of making arrows from shoots or hickory that are barrel tapered or just tapered thickest at the arrowhead, and maybe 36" for my 33" draw (I hear arrows longer than the draw are more spine forgiving, although a fletcher I talked to told me otherwise). That should make them more forgiving. If your arrows are stiff and you're a right handed archer shooting from the left side of the bow, the arrows will go to the left, and point to the right when on the target, I think?
The .300 etc numbers are deflection in a spine tester, and the 45# or 50# means that the shaft is good for a common western glass recurve that is 45# or 50# at 28"? You don't have to be perfectly matched for learning to shoot, I don't think.
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loon, don't under estimate the strength of cane, it is a grass like bamboo. We had a contest at our club one arrow and last man standing wins . Targets are designed to break arrows unless you hit in a small kiil zone. Yep Pappy won hands down with a cane arrow. Pretty impressive some of the materials that didn't survive. Some example a steel deer with a small kill area. Another one was a very small foam rabbit in front of a very big rock. Also Pappy is a very good shooter. ;D Bob
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Haha, if I was actually a good shooter maybe I wouldn't worry so much about material durability! That sort of cane seems great for making light, fast arrows..
I've broken plenty underspined and very overspined bamboo arrows by missing and hitting stone. Same with POC arrows, which I don't think I'll buy again, at least not any time soon.
Maybe hickory arrows would survive. I guess somewhat underspined cane wouldn't break just by shooting it? At close range my underspined bamboo doesn't seem to fly that straight. One bamboo arrow broke near the fletchings from the sheer inertia force of hitting the target not straight, from a 50-55#@33" korean bow (33" arrow) at about 3 yards. iirc I shot it right side of bow and it was pointing to the left and the fletching portion broke off completely. maybe it was a poor release...
I hope tonkin bamboo will be much more durable. Once I feel like shelling out a bunch of cash, might try tonkin bamboo. A dark tannin and iron acetate stain, tung oil, shellac, white and grey feathers... mouth waters.
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loon, Hickory will make a tuff shaft but so heavvvvy,ash is a little lighter but seems to need straighted often, personally I like Hill or River cane over Tonkin,just make sure and get 2nd yr. growth. I shot a deer with a cane arrow and stone point, almost straight down about 8" penetration, looked like Moby Dick going out of there lots of shaft sticking straight up. I was in a over grown pasture full of crab apple s and multiflora rose and red brush, arrow clicking off everything as deer ran, never broke until deer fell over on it, Love some good cane, ;D ;D Later Bob
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I always bare shaft all my arrows, I never have understood the left/right impact of the arrow, tail left or tail right in the target I understand. tail left for right hand shooter/weak arrow/tail right for a right handed shooter /shaft to heavy in spine. nock high /lower nocking point /nock low raise it. I shoot at 10 feet or so, when the arrow hits straight in the target I fletch and am good to go. I start out with rough numbers close enough to be safe but a little on the weak side, leave the arrow long, then go from there cutting length to stiffen. I almost always use 160 grain hunting points so I don't use point weight much for adjustments. JMO. And yes Bob Cain arrows are tough but also a little hard to get a consistent set for me so I build them 1 at a time same as I do my shoot shafts. :) One more thing I am with all of you on the arrow must hit where I look but also if I see anything but fletching as it flies to the target I ant happy, very picky about that ,hitting target or not it has to fly straight. ;) :)
Pappy
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Yes.Some of my arrows will hit right where I'm looking but not fly like a dart,and some hit right where I'm looking and fly like a dart.By flying like a dart I mean I don't see nothing but the nock end of arrow as it flys.Personally I use the arrows for hunting with broadheads that fly like a dart and hit right where I'm looking.Those will get the best penetration and be the most efficient.The main reason.There's lots of shooting to be done to get them right,and to me watching the arrow hit it's target is sort of mystical in a way or fun to watch.
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Shoot cane .....and don't worry about spine.....that's what I've heard some say...... :) ;)
DBar
This is my approach, lol.
Loon, go to ebay and search for bamboo yumi arrow, I use them and their great. Takes a while to get here on the slow boat but for the price they can't be beat.
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Shoot cane .....and don't worry about spine.....that's what I've heard some say...... :) ;)
DBar
I have yet to do this , but I have read up on building bamboo shafts sounds intriguing
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I always bare shaft all my arrows, I never have understood the left/right impact of the arrow, tail left or tail right in the target I understand. tail left for right hand shooter/weak arrow/tail right for a right handed shooter /shaft to heavy in spine. nock high /lower nocking point /nock low raise it. I shoot at 10 feet or so, when the arrow hits straight in the target I fletch and am good to go. I start out with rough numbers close enough to be safe but a little on the weak side, leave the arrow long, then go from there cutting length to stiffen. I almost always use 160 grain hunting points so I don't use point weight much for adjustments. JMO. And yes Bob Cain arrows are tough but also a little hard to get a consistent set for me so I build them 1 at a time same as I do my shoot shafts. :) One more thing I am with all of you on the arrow must hit where I look but also if I see anything but fletching as it flies to the target I ant happy, very picky about that ,hitting target or not it has to fly straight. ;) :)
Pappy
I am thinking I should try this with my little flight arrows, you can't always see them fly because of the speed, I have never really tried bareshafting because they usually break when they stick in something. It might be worth sacrificing a few arrows and just copying the specs of the good ones.
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I always bare shaft all my arrows, I never have understood the left/right impact of the arrow, tail left or tail right in the target I understand. tail left for right hand shooter/weak arrow/tail right for a right handed shooter /shaft to heavy in spine. nock high /lower nocking point /nock low raise it. I shoot at 10 feet or so, when the arrow hits straight in the target I fletch and am good to go. I start out with rough numbers close enough to be safe but a little on the weak side, leave the arrow long, then go from there cutting length to stiffen. I almost always use 160 grain hunting points so I don't use point weight much for adjustments. JMO. And yes Bob Cain arrows are tough but also a little hard to get a consistent set for me so I build them 1 at a time same as I do my shoot shafts. :) One more thing I am with all of you on the arrow must hit where I look but also if I see anything but fletching as it flies to the target I ant happy, very picky about that ,hitting target or not it has to fly straight. ;) :)
Pappy
This is awesome advice. Thank you. It was just what I was beginning to figure out after all this time. I was wondering whether the tail left/right would correspond to weak or stiff spine. Guess it would be the other way around if shooting off the right side of the bow? (even if right handed) the bamboo arrow I broke was tail right. Makes sense that it was weak. They do straighten out pretty quickly after a while though... but they damage the side of the bow a bit.
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Steve I always try and get the arrow somewhat close by numbers before I start, because yes it will break and arrow especially if your target is pretty hard. I guess I need to try different Cain because I have never been able to as was said above, shoot Cain and don't worry about the spline. ??? :-\ I love Cain but they are a bear for me to get a consistent set so I build them 1 at a time in the same manner as I mentioned above. ;) :)
Pappy
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Steve I always try and get the arrow somewhat close by numbers before I start, because yes it will break and arrow especially if your target is pretty hard. I guess I need to try different Cain because I have never been able to as was said above, shoot Cain and don't worry about the spline. ??? :-\ I love Cain but they are a bear for me to get a consistent set so I build them 1 at a time in the same manner as I mentioned above. ;) :)
Pappy
The little flight arrows have no point weight and only weigh about 150 to 225 grains tops. Really hard to judge spine.
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Go to Easton Arrow site and watch their video on paradox. It will explain a lot of what you want to know.