I have some Grizzlystik arrows and a bunch of 50 grain internal weights that screw into the back of outsert. I am wondering if I will stiffen or weaken spine as I add more weights. I know more weight up front weakens spine, but the weights act like an internal footing.

Weight applied to the nock end will stiffen the spine. Gold tip has a similar set up.

If the internal weights are contacting the shaft versus having clearance inside they will do both, stiffen and weaken.

WHAT?!?!?!

Let me explain. The weight as we know weakens. Making contact inside shortens the bending "beam" of the shaft thereby weakening it by effectively shortening the shaft.

That gives a mix of the two effects.

It also makes a difference if the internal weights extend past the contact point on the side plate closer to the shooter or out front. Again related to the bending end points.

WHAT! "Making contact inside shortens the bending "beam" of the shaft thereby weakening it by effectively shortening the shaft." Shorting a shaft doesn't weaken it. It stiffens it.

Bob

The length of the internal weights will "offset" the effect of weakening the shaft.

It directly depends on the internal weights length to weight ratio as to how much effect/weakening it will do.

Example:

An internal weight weighing 50gr X .5" long will weaken the shaft more than an internal weight weighing 50gr X 1" long.

Neither will weaken the shaft as much as simply adding point weight.

Stu's calculator takes all this into account, and figures it very accurately "if" the numbers are entered correctly.

Rick

Regardless the short answer is that it will weaken the dynamic spine somewhat, whether it touches the shaft or not, and hit most likely does.

If you have already registered, please

sign in now

For new registrations

Click Here