arrow stiffness ??

[Tom]

Have a '65 Howatt Hunter I am getting ready for the fall. 48#@29",r/h feather rest with soft side plate. Good flight with two sets of arrows but: 500 spline  GT carbon full length with 100 gr. insert with 145 field point show stiff while same arrows with standard insert with 125 gr fp show weak. Heavier set of arrows has parabolic while the lighter set has shield-shouldn't matter too much there i wouldn't think.Think I should try standard insert with heavier fp or heavier insert with lighter point?

[creekwood]

That makes no sense at all.  Do you really mean what you said? The heavier "loaded up front" arrows should show weaker, not stiffer.

[deerhunter_w]

I have noticed the same thing while using brass incerts. I'm not sure but I wonder if it stiffens the spine because it's inside the shaft.  Not on the front of the arrow.

Jeff

What creekwood said^^^^^^^

Is it possible you are reading the results backwards?

That is over 100gr difference. There is no way the heavier one should not be weaker.

Bisch

[AZ_Longbow]

Heavier inserts and heavier fieldpoints. Or just much heavier fieldpoints.a good fieldpoint test kit with points from 100 up to 300-315 gr will make life alot easier.
Your spine is to stiff and your bouncing off the shelf. Did you bare shaft test it?
And as far as parabolic or shield cut, it makes no diffrence. You want a bare shaft to fly slightly weak. As adding weight to the nock end increases stiffness of the spine.

[Bldtrailer]

longer insert acts like footing the gt 11 grain insert is 1 inch the 100grain brass  is 2 inches. you might also be getting a false weak the arrow striking the riser before the arrows clears the riser

[olddogrib]

What Bldtrailer said.  IMHO long brass adapters the same internal diameter as the shaft reduce the flexing portion of the shaft just like a footing.  Think cutting 2" or so off.  They're handy if you're a EFOC fan but they're not going to act anything like standards.

[Orion]

Arrows primarily bend in the middle, not near either end. The longer insert has a negligible effect. Very possible he's getting a false reading from the shaft bouncing off the riser, or perhaps is just reading the arrow wrong.  We're just guessing.

[Tom]

Tomorrow will paper tune and then bare shaft with one arrow from each point/insert group. Creekwood-my previous shooting was with a slightly heavier bow and they flew well. Split finger and 29.5" draw. Changed from a Bear rug rest/side plate kit to feather rest,Martin side plate. Adjusted nocking point and heavier arrows shot left and lighter ones shot right-slight r/l but definite. BTW I am right handed and not new to the sport or carbons.

[Shadowhnter]

Originally posted by Orion:
Arrows primarily bend in the middle, not near either end. The longer insert has a negligible effect. Very possible he's getting a false reading from the shaft bouncing off the riser, or perhaps is just reading the arrow wrong.  We're just guessing.

X2

[Orion]

Tom:  Did the side plate thickness change?  That can certainly change things. Thicker plate requires a softer spine and vice versa.  Or, put another way, a thicker side plate will make an arrow shoot stiffer (i.e., left for a right handed shooter)  than a thinner side plate.

[Tom]

Jerry,
Because I was getting stiff results I changed the rest and side plate material. Went to a feather rest and soft thinner strike plate. Like i say I am looking for good penetration vs speed. The heavier FOC arrows I have been using for hunting the last few years and have good flight and two sided trails. My goal is good flight and quick clean kills.

[olddogrib]

Then everybody is wasting their time cutting too-weak arrows trying to impact dynamic spine, especially since they never get inside the "centers" unless they have an extremely short draw.

[AZ_Longbow]

There is a point when you can't cut more and have to move up a spine.

[Captain*Kirk]

Arrow stiffness?

I've heard this helps....

[Tom]

Paper tuned the bow yesterday and realized was reading the results wrong. R/H shooter and bare shaft showed nock high left.