Internal Footings Cabon Arrows and Spine?

[ErikT]

I am using glue-on outsert (sleeves) on carbon arrows and plan on gluing a 1.5" section of #8 threaded rod inside the carbon shaft to act as a footing to help prevent break-offs at the front of the shaft during hard hits.

Would the footing tend to increase dynamic spine or decrease dynamic spine?

Victory Archery VAP 400 shaft
Firenock Aero outsert
200 grn point

[Stump73]

I guess depends on how long they are. If longer than your normal insert I believe it would stiffen it.

[ranger 3]

It would weaken it, the weight on or in the end will weaken it.

[JimB]

You will only find out by shooting them.A glued in footing technically does some slight stiffening and added weight up front does some weakening.Often with internal footings,these two things cancel each other out.Bare shaft tuning will tell the tale.I once installed 7" tapered,internal footings behind the inserts,the first 3" of which was epoxied tight in the shaft.They didn't change tune at all.Weight behind the insert has less influence on the spine than the same amount of weight in front of the insert and a #8 stud doesn't weigh that much.Shoot them to know.

I will tell you,I don't think they will add much strength.Usually the impact force just moves back and the shaft breaks behind the footing,instead of behind the insert.

[TxAg]

Like they said. The weight wants to weaken, but the added footing wants to stiffen. Just gota experiment.  I don't have much experience with internal footings, but using external aluminum footings over carbon my experience is that they tend to cancel one another out....of course, i'm only referring to 1-2" of footing, nothing too long.