Wood Arrow Tuning Question

[mrpenguin]

Recently Terry (fillmorehd) made a set of arrows for me from chundoo an I love them... they're just gorgeous.  They have been a bit tricky to tune though.  We based the arrows off a previous set of similarly spined and made up arrows.  After playing around a bit, I am getting good arrow flight with tips, but the broadheads are less predicable.  I have one arrow with a broadhead that is very accurate to where I look, but the others, well, I would not feel comfortable using them... also, I have noticed that there is a black mark running down the shaft between the feathers on the nock end of the arrow.  It must be from the Bear leather strike pad. Is that just a cheap strike pad or a spine indication?

Here's the full set of the bow and arrow:
Bow:
Savannah reflex/deflex longbow, 55#
Center Cut (as far as I can tell from my online research)
12 Strand Astro Flight 3 bundle flemish string, double served
Brace 7 1/8
Nockset high (I just kept moving it till the porposing went away)
Beaver ball silencers
Eagles Flight Minimax bow quiver with 3 arrows in it weighing 685 grains (roughly)

Arrows:
Chundoo 65/70 spine
29 1/2"
190 grain tips
5" left wing helical feathers
Arrow weight approx 685 grs.

All the arrows are straight, matched within 5 grs.

Using Stu's Calc with the form factor, these arrows should be shooting like darts... and they do most of the time, but that marking on the beautifully dipped end of the shaft and poor bh flight are troublesome.  Thoughts??

[cbCrow]

Lets look at the simple thing first. Did you check your broadheads for straight alignment on the shafts?

[mrpenguin]

cbcrow,

Yes.  They all looked good and spin well.

[**DONOTDELETE**]

try this one.. loosen up the BH and turn it just a little bit.. let glue cure enuff to hold on and shoot again.. ( I use 3-blades with 4 fletch ) keep doing this till you go all the way around the shaft, so it would be good to mark both BH and shaft of Your starting spot.

I do this on arrow that do hit right where they need to be and it helps. The batch of arrows I just finished for this season had 3 arrows that hit way off. I started turning the point just a little at a time and they started to move to center (left to right / right to left).

[Don Stokes]

Eric, I think you're a bit underspined. That's a lot of point weight for your setup. You might try some lighter broadheads just to see if that helps the performance.

[Bowmania]

I worked with a guy on the same problem.  He told me he had spun all BH's and they were on straight.  After an hour, I put one on my spinner and it wasn't even close to straight.  Spinning to him was blowing on the feathers.

Bowmania

[Kelly]

Check broadhead alignment but most likely too weak of spine. 190 grain points is like weakens the spine by 10# so those 65/70's are now 55/60's plus you are 1.5" longer than 28 which also weakens the spine by another 6-7#.

What is your actual draw length while shooting when you are not thinking about the draw length?

Finally,are these shafts hand spined or factory spine? If the latter, then they may be nowhere close. Could be anywhere from 55-70# spine.

[mrpenguin]

Kelly,

The arrows are hand spined and I draw 28".  I also use a skinnier fast flight material so that adds another 5-10#s... maybe I underestimated the necessary spine for this bow??  I am going to pick up some 125 gr tips today and glue them on to see how they fly.  The other thing I was thinking was to cut them down a bit working my way to 28.5" at the shortest.

[**DONOTDELETE**]

Originally posted by mrpenguin:
Kelly,

The arrows are hand spined and I draw 28".  I also use a skinnier fast flight material so that adds another 5-10#s... maybe I underestimated the necessary spine for this bow??  I am going to pick up some 125 gr tips today and glue them on to see how they fly.  The other thing I was thinking was to cut them down a bit working my way to 28.5" at the shortest.

do that to only arrow first. You can try that before you go out and get lighter weight points.

[Art B]

I agree with some of the others that you're underspined. Another thing, wood's a funny animal, those shafts may or may not like (match) your bow even if correctly spined. That one that shoots where you're looking is a good example. ART

[luvnlongbow]

Just a thought but the recomended brace for the Savannah is 6.25"-7". If all else fails you might try ajusting the brace height to within these parameters and see what you get.

[Bjorn]

Cutting the arrow down 1/2" with the 190 up front will not help. If the arrows are indicating 'soft' with feathers they would show way 'soft' if you bare shafted. Also a BH makes things worse because it lengthens the arrow.

[mrpenguin]

Well, after cutting for spine down to 28.5", I am still getting inconsistent flight.  That said the groups have tightened at 30 yds!  I'm thinking I am still underspined here.  I reset the bh for 7" (seems to like it with carbons and alums) and will pick up some 125 gr tips later today.  I'll try those and see what I get.  Frankly, I am too frustrated to work on it anymore right now... I am very upset that the beautiful cresting job is marked and smeared in some places... ugh... hopefully changing the point weight will clear things up and not effect FOC too much.

[ChuckC]

Bjorn.  I don't understand how a broadhead makes it worse " lengthening the arrow ?  Can you explain ?

I use 190 heads (glue on) on essentially the same arrow (albeit cedar, not chundoo), same pound bow and get perfect flight.  Much better than anything else I shoot.
ChuckC

[danseitz]

I agree with the underspined group here.  Also if you decrease the brace height, you are increasing the power stroke which will add to the underspined problem.

[mrpenguin]

Hoping to make it out to Cabela's this evening... if not, I'll get there tomorrow.  They have 125 tips for a reasonable price in stock.  In the meantime, I have the the bow set up for my carbons.  I can practically stack arrows at 20 yds with the carbons!

[Fletcher]

I think you are right about the Savannah being cut to center.  When I run the numbers, I come up with you being underspined, too.  I get more like 80-85.  The 125 gr points should tell you if you are really underspined, but won't really fix things if you want to shoot 190 gr heads.  I'm hoping the black mark is from the shelf instead of the side plate.  Hitting the side is normally an indicator of being too stiff.

Bjorn's comment on the arrow length I agree with.  BOP and AMO spine are a static measurements.  Dynamic spine is affected by the whole arrow.  Broadheads, esp the heavy ones, are generally longer than field points and lengthen the full working dynamic length of the arrow.  It generally isn't much or significant, but when you are on the edge, little things can make a difference.

[Mike Vines]

I would have to agree with Rick.