Need assistance with arrow spine.

[JamesG]

#5220

Pretty bummed out after shooting and attempting to find an arrow shaft/tip weight combination that works well with my longbow this past weekend. My go to bow WAS a DAS Dalaa. I shot off the shelf and simply picked a shaft that was close in spine, tinkered with tip weight and then used the adjustable sideplate to fine tune the arrow flight. It was easier to do then type it! I recently sold it and my other recurves and am concentrating on shooting my longbow. I knew going into this that it would be harder to get good arrow flight and that longbows were more critical of spine but this has me baffled.

Bow weight at my DL is 40.5 #. My DL is 26″ using the AMO standard. String is a 12 strand DF97 flemish. Centershot is 1/4″ before center including the thickness of the calf hair strike plate. I’ve tried using 28″ BOP 1816’s with a 7″ wrap and three 5″ sheild fletched RH helical with 100, 125, 145, 175, 200 gr screw in points. I’ve tried 28″ BOP 1916’s with a 7″ wrap and three 4″ parabolics fletched RH helical with 125 and 145 glue on points (inserts are the glue in taper type).

ALL shaft and tip weight combo’s are flying like crap. Every shaft is kicking the nock hard to the right and then straightens out to some degree or another. I’ve tried paper tuning, shooting bare shafts, and tried the bare shaft plaining method. I’ve gotten a wide variety of confusing results with the only consistant reaction is that the nock kicks to the right on 90% of the shots. When it does not, it flies basically straight. I’ve tried holding the bow vertical and canted. Same results. Aluminums are easy and I want to try to get close on spine and tip weight with ‘cheap’ and easy XX75’s first then buy some decent cedars based on the tuning results with the aluminums if that makes any sense. Every reference chart (I’m excluding the newer Easton charts) I can find says 1816’s should tune from the bow. The only good thing I’ve seen is an absence of porposing or a very nock high/low indication at the target. I should add that this nock kicking business is not fishtailing. It is ONE hard kick to the right and then it will straighten up to some degree. Should add that I am a right handed shooter as well.

[JamesG]

#38848

I tinkered around a bit with Stu Millers Dynamic Spine Calculator today. According to it I need to use 200 gr points with the 28″ 1816’s and 250 gr points with the 1916’s. Looking for some real world expertise here and not info off of some chart though. Anyone??

[Arne Moe]

#39246

James,

I for one am not ignoring you, but your “un-paragraphed” post is REALLY hard to read for these OLD!! eyes. I will re-attack this tomorrow and see if I can get you a recommendation for aluminum shafts. Stand by.

Arne

[Cameron Unruh]

#39417

I am anxious to see what Arne has to say…I believe that nock right indicates a shaft that is to stiff.

A little interesting side note…I twisted up a new string tonight for my longbow using 12 strands d-97. After i serve the string and tie on a nock I shoot it in a few times. My arrows always shoot just slightly weak until I put my wool silencers on and then they shoot dead on.

Little adjustments like that seem to make a difference.

[Stephen Graf]

#39754

It sounds to me like you are getting consistent results, which is a good thing…

I assume you are right handed. For right handed people, when the back of the arrow hooks to the right it means the arrow is over spined. The solution to this is to use a longer arrow, or increase the point weight. Obviously you can’t cut your current arrows longer, so I would try a heavier point.

Recurves are usually more forgiving of spine, and people usually shoot stiffer arrows out of them. You will need to go with a weaker spined arrow now that you have taken up the longbow.

Don’t fret over it too much. You will get there!

[JamesG]

#39767

I broke up my original post a bit.

I shot again last night and think I have the answer. I’ll know more after I shoot again tonight. Right now I’m leaning towards too much tip weight and shaft length was causing the 1816’s and 1916’s to act very, very weak. I stiffened up one of the 1916 shafts by a little trimming and less tip weight and the bare shaft flies like a dart out to 20 yards. However I would like to shoot more to verify that this is really the case and not an anomaly. I’ve heard that an overly stiff shaft will act weak due to deflection. I don’t know what happens with grossly underspined shafts in regards to flight characteristics, but I’m guessing that unpredictable flight with confusing bare shaft testing results are likely. I think that was what was happening with me.

edit- I should add that I realize that nock right indicates stiff arrow reaction. Is it possible that a very weak bare shaft could be deflecting off the shelf in some manner and end up showing stiff in flight??? Just asking.

[Arne Moe]

#39877

Thanks for breaking that post up a little — makes it easier to read.

Here are some ideas for you. First, when you shoot fletched arrows, are you getting satisfactory (satisfactory for you) groups? FORGET arrow flight for the moment, just shoot as consistently as you can and evaluate your groups. Here is the thinking behind this.

Any arrow of a given spine from too weak to too stiff (within reason and your current arrows are within reason) WILL produce good groups REGARDLESS of spine or arrow flight. That is IF you shoot them the same way each time and don’t try to “correct” with an execution change. IF you are not getting good groups (not talking about bull’s eyes JUST groups anywhere on the target!) then you need to correct your form and/or execution before continuing. Form/execution is BY FAR the MOST common reason for bad flying arrows — NOT tuning!!!!!!

You don’t mention how your bow is configured, extreme R/D, mild R/D, or “Hill” style. You do mention a Fast Flight string and the “short of center” cut. In any case, let’s start with your on the fingers weight (OTF) of about 40#. Hill style bows start best at their draw weight for spine. So 40# and let’s add 5# for FF string. IF an R/D add 5# for mild OR 10# for extreme.

What I find that works for me is to use the “old” wood spine standard for aluminum. In that “system” 1816 shafts spine at .500 which is about 52# spine rating. 1916s are .425 or about 61# spine rating. I don’t currently have a 1716 so don’t know offhand what the “wood standard” spine is for those. BUT… see below. Current spine listings are VERY different from this. An example is that 2016 shafts are listed as .500 but in the “wood standard” spine system 2016s are .360 or about 72# spine rating. No wonder most current charts recommend shafts that are too stiff???

NOTE: that these old wood standard spines are assuming a 125 grain point. Adding or subtracting 15 to 20 grains of point weight will change effective spine by about 5#.

Now, (here is my “disclaimer”) we DO all shoot differently (!) and have to find our own solutions but I think that IF you are shooting a Hill style bow 40# OTF and a 28″ arrow you will find “closeness” with a 1716. If more of an R/D 1816 should work.

For others that have a longer draw length, add 5# for each inch longer than 28″ (subtract for shaft lengths shorter).

Obviously this is not an exact science since personal form has HUGE effects on “theory.”

Hope this helps some and doesn’t just confuse.

Arne

PS. DO NOT RUSH to cut or change for tuning purposes!!!! Shoot for a few days before making permanent changes to your shafts. ONE session is not enough to base costly decisions on. A

[JamesG]

#39930

Bow is as follows-

right hand Great Northern Fieldbow

46# at 28″ (verified)

weight on fingers at 26″ is 40.5# (verified)

limb/bow design is a mild R/D flatbow with a straight grip (no locator)

window is cut to 1/4″ BEFORE center (includes thickness of calf hair plate

string is a 12 strand DF97 flemish with loops padded to 16 strands with one brass nocking point and two beaver balls

nock fit with the Easton X nocks is nearly perfect

brace height is within bowyers specs

I cannot get 1816’s to fly correctly with any weight tip. Don’t have 1716’s. To put it mildly I’m rather frustrated with all of this and am starting to regret selling my DAS recurve as I could easily tune arrows to that bow.

edit-

I’ll add that I even went to 250gr screw in points with the 1816’s and the flight only got worse than with the same shafts and 100gr points. What I’m finding with my shooting is that I’ll end up with a shaft and tip weight combination that is considerably stiffer than what EVERYBODY is recommending. So something is wrong. I found that Stu’s calculator was not even close with my DAS either.

[JamesG]

#40052

Anyone else have any ideas??

[JamesG]

#40985

Figured it out last night. It was the idiot pulling the string not the equipment. 1916 bare shafts and fletched shafts with field points and two different broadheads fly perfectly out to 20 yards. Problem solved once I got my head out of my……well you know!:D

[Author]

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