adding 1.5 inches to arrow help weaken spine

vernon · July 14, 2014, 04:32:00 PM

I shoot a 54# pronghorn 3pc. I shoot easton axis arrows that are 29.5 long, 100 grain insert, and 150 BH. My draw is 28".

When paper tuning at my neighbors awhile back my arrows showed slightly stiff which we were able to correct by adding point weight. However, I own a lot of 150 BH that are paid for, plus I like the wide assortment available in that weight.

going to buy a dozen new arrows and wondering if full lenght (31") instead of 29.5 would help weaken my spine at all?

My personal issue is "creeping". When I creep my arrows clearly show stiff. However, when I continue pulling through it only slightly shows stiff. So just curious of the 1.5 inches of arrow length would help that so i continue shooting 150 BH with my 100 grain insert.

Thanks

Gooserbat · July 14, 2014, 04:41:00 PM

The last bow I tuned for myself it took 1 1/4" to change what was equal to 75 grains of point weight. That said I think you should be plenty able to find a length that will work.

R. W. Mackey · July 14, 2014, 05:18:00 PM

Just my thoughts but aren't you gonna spend some serious bucks for the longer shafts!! How many heavier BH's can you buy for that price. Then what happens if you cure your creeping problem, got a bunch of weak arrows. I'm a big believer in setting up your arrows to proper length add or subtract whatever weight is necessary up front and don't practice your form until you get it right, practice it until you can't do it wrong. Proper form cures lots of problems, your creeping being one of them.
Just my two cents worth!!!!
RW

July 14, 2014, 06:12:00 PM

Adding 1.5" will make a big difference, and could very well solve your stiff problem. All you can do is try it and see.

Bisch

kat · July 14, 2014, 06:37:00 PM

Another 1-1/2" will surely weaken your arrows up. If you beat your creep problem, you can always shorten the arrows. Much easier to cut some off than stretch them.

olddogrib · July 14, 2014, 06:56:00 PM

It will definitely weaken spine, but the only way to know how much with all the other variables involved is to try it. I just went from .500 spine to a full length .400 that gave me around an extra 2" plus a 50 gr. increase in point weight to get a heavier hunting arrow. May be worth the cost of an arrow test kit to try it first. I think Big Jim may even sell blems by the single shaft.

damascusdave · July 14, 2014, 08:32:00 PM

In general changing shaft length of carbon arrows changes dynamic spine more than changing point weight

DDave

old_goat2 · July 15, 2014, 12:14:00 AM

Have you thought about adding an aluminum footing to up your point weight a little on your existing arrows. Accomplishes weakening your dynamic spine and toughens up your arrow at the same time. I just footed arrows for the first time and I'm extremely pleased at some of the hits they have taken and laughed off! My experience with Axis arrows is I would do this anyways, they are tougher now than when I used them but still would prefer some metal for the head to rest up against!

nineworlds9 · July 15, 2014, 09:58:00 AM

QuoteOriginally posted by damascusdave:
In general changing shaft length of carbon arrows changes dynamic spine more than changing point weight

DDave

I agree with Dave, this has been my experience also.

FerretWYO · July 15, 2014, 03:14:00 PM

QuoteOriginally posted by Gooserbat:
The last bow I tuned for myself it took 1 1/4" to change what was equal to 75 grains of point weight. That said I think you should be plenty able to find a length that will work.

This is very interesting as I have found it to be very different. Something more like 1/4" to 50grs

beachbowhunter · July 15, 2014, 03:16:00 PM

QuoteOriginally posted by damascusdave:
In general changing shaft length of carbon arrows changes dynamic spine more than changing point weight

DDave

...way more

Friend · July 15, 2014, 03:40:00 PM

Best of luck!

Bowwild · July 15, 2014, 04:10:00 PM

I can't stand an arrow that is too long. This being for me an arrow shaft that is more than 1" beyond the back of the bow shelf.

I'm a point of arrow aimer which means I admit vaguely seeing the point of the arrow in relation to the target. Changing arrow length impacts my sight picture.

I would fix the creeping problem. Focus on active bow arm and drawing arm back muscles once you have the bow at anchor/aim. Your mind will aim without continuing to think about it. Follow-through should be the last thought in your mind which is achieved by "pushing" the bowhand (I don't like the term but it is simple) and pulling (with the back)into the anchor.

Then I prefer, as RW mentions to play with point weight to get the tune.

However, as others have pointed out, changing arrow length has a dramatic impact on spine, much more than incremental changes in point weight.I just did this with some new Easton FMJ Injexions because point weight choices are EXTREMELY limited with this new super narrow, Deep Six system. In fact, I'm having a few dozen 155 grain of the Deep Six field points created especially to match a 155 grain broadhead I want to use.

I still don't like to have an arrow more than a 1/2" longer than my preference.

BWD · July 15, 2014, 09:58:00 PM

QuoteOriginally posted by FerretWYO:

QuoteOriginally posted by Gooserbat:
The last bow I tuned for myself it took 1 1/4" to change what was equal to 75 grains of point weight. That said I think you should be plenty able to find a length that will work.
This is very interesting as I have found it to be very different. Something more like 1/4" to 50grs [/b]

That's what my backyard piddling tells me too.
All other things being equal, an extra 1 1/2" of shaft length should turn your slightly stiff to fairly weak, imo.