Dynamic Spine Cal...help!!!

[benny]

Been playing around withs Stu's calculator.
With axis 400 arrows. I am using the other option. Putting in 78.8 for dynamic spine,9 gpi .265 for shaft diameter with a 250 gr head.
30.250" long
Dynamic spine of=47.

Bow specs=Morrison mini 14,D limbs.
51 @ 28.5. I draw 28.5. 3/16th past center cut.
Entering 1/8 because of calf hair strike plate.
R/D long bow
Dynamic Spine=63.6

Big differance uh.

Shooting this arrow shows bare shaft stiff..like 8-10" at 20
yards.

Any Ideas?

Thanks
Benny

[Rob DiStefano]

arrow spine calculators might nail the right spine for ya or maybe get ya in the ballpark.

the rubber meets the road when the real world testing begins ....

with your setup, even 500 spine might be too stiff.

[raideranch]

After measuring everything repeatedly and precisely the calculator said my arrows were #10 too weak but I had to add an additional 150gr. point weight to get the bare shaft arrows to fly correctly.  The calculator is a neat idea but that’s about it.

[xtrema312]

Are you sure it is shooting too stiff?  Which way is the bare shaft hitting from the fletched shafts and what hand are you?  I can get a shaft to shoot a little to the stiff side, but before too long it goes false weak on me.

[benny]

Rob...You are close.

I tried some axis 500 29.250 long with a outside footing 1.5" long.

Showed weak. Put insert in nock end. Showed slight weak.

Put on VPA 250 1.250" and they fly great and fast.

Thanks
Benny

[Flying Dutchman]

Originally posted by raideranch:
After measuring everything repeatedly and precisely the calculator said my arrows were #10 too weak but I had to add an additional 150gr. point weight to get the bare shaft arrows to fly correctly.  The calculator is a neat idea but that’s about it.

Did you take the centercut option in account? There is also a negative centercut options, which means past centercut.

[metsastaja]

Benny what release # of Stu's calculator are you using? Curious because I can not replicate your results for the bow on the most recent one 11-22-09/   http://www.heilakka.com/stumiller/

I am asking because I pre test Stu's releases on Mac and PC and with excel and openoffice prior to release.

 

which program are you using excel or openoffice to run the program.

Does you weight of 250 include the insert weight also.

thanks
Les Heilakka

[xtrema312]

Are you sure you are not hitting the edge of your shelf?

[benny]

Les
Mac and openoffice...with your help. I downloaded the version at the top of the list.
I am at work now. I think I entered 17 in box #4 and #6. 4" feathers. How do you do a screen capture? I will try and post it tonight.

xtrema312

Right handed...bare shafts hitting to the left of fletched.

Thanks
Benny

[MSwickard]

Benny

You may be getting false positives.  In the Calculator shows the arrow is weak.  Try dropping the point weight to see it you get better flight with bare shaft.  The arrow could be boucing off the sideplate more than it should, making the arrows go left.  Try dropping the point weight to around 160 plus the insert.  See what happens then?

Mike

[metsastaja]

with a mac there is a program called GRAB..
use finder go to applications/utilities

once open click capture then selection.. it will create a .tiff file  by opening in preview you can then save as  .jpg for uploading to photobucket or what ever.

Where are you getting your weights from most aluminum inserts are about 12 and nocks about 11.

[benny]

Okay...This took some head scratchin.

 axis hit inserts wieght 15.4 grs
Xnocks=9 grs
Wrap=6 grs
This is the 11/22/09 version.
4x4 nanner cut fletch.

[MSwickard]

Yep

That's about what I came up with.  If you already cut a shaft try dropping the point weight to around 160 plus the insert.

[Oscar-eleven]

I've found the Dynamic Spine Calculator to be very accurate for me...with everything but the bow I'm tuning now. I have a A & H ACS takedown but I'm not even close to what the Calculator recommends. I had to build out the side plate and use a heavy spined arrow and shaft (carbon). I have arrows and bare shafts grouping very well but I still don't really understand why I had to go so heavy but it shoots great.

[MSwickard]

Stu's calc has worked well for me.  I'd say it's pretty darn close.  However, I believe when the sideplate goes past center shot, arrows act differently.  From the sound of it, it is easier to tune an arrow being shot from a bow that is short of center and up to center shot.

[metsastaja]

Benny you could try 29.5 length, point 100g insert 100g  should bring you up to 62.8

[Flying Dutchman]

@ Benny:

A Longbow which is cut to -3/16???? I've never seen that! Those are recurve values! If you are luckey it is cut to 1/16 past center but then you'll have to take the arrow plate into account. If it is an standard calf-hair plate, it can be as thich as 2/16". So you should be at least to + 1/16 in Stu's calculator.

[benny]

Ad

Yes sir it is. A Morrison ILF handle. I have longbow limbs and recurve limbs.

Well I tried 175gr heads...the fletched arrows flew great. The bare shafts hit with the flethed. Only thing is bare shafts flew nock right. Maybe its my release. The fletched arrows are very accurate.

Thanks for everybodys help. Now I have to buy more arrows.I have alot of 250 & 300 gr broadheads.

Stu & Les tip of my hat to ya...great program. If your are ever in my small neck of the woods, stop by.

Benny

[MSwickard]

Glad to see you got them tuned.

[Flying Dutchman]

Ok Benny, apperently I was wrong. My excuses.   Never to old to learn I guesss... I am glad you got your arrows tuned, that's the main thing.