Ultra EFOC - How?

[DanielB89]

Originally posted by Earl Jeff:
what brand arrow have the lightest mass weight but the stiffest spine?

Victory HV series are the lightest ones I have found.

[Sapcut]

For my son's 50# bow, I built arrows that were 34+% FOC and weighed around 650 grains.  I started with a Gold Tip Ultralight 500 and used external footings. The external footings do well to stiffen the spine enough to achieve the FOC goals, properly tune the arrow and make a bomb proof arrow.

[Sapcut]

[olddogrib]

Pardons if I missed these being mentioned, but does anyone use the GT internal insert weight system? I have not, but they make a wrench where nocks can be pulled and weights added without pulling the inserts. Has anyone used it? I believe EFOC was the market the whole concept was developed around.  I know the jury's seems to still be out on end weight vs. internal weight relating to its effect on spine.  But from my limited experience tinkering, they do not act the same. Internal weight, if it's the same ID, seems to stiffen the shaft similar to footing and I can get away with more weight without weakening spine than I could if it was all up front.

[Doc Nock]

Richard,

I have no scientific evidence or source to prove this, but I THINK the reason that internal weights "seem" to increase spine is that effectively, you're shortening the shaft in a fashion...ie, you're moving weight rearward...by increasing weight on the end of the shaft, you're having the same effect as lengthening the lever...adding weight out on the end...putting weight INSIDE, moves the lever weight BACK toward center, thus stiffening.

I avoid all that head work but using what insert I want, head I want, then start tuning at full length and cutting from the rear...

Don't know if that makes sense or not, but it's how it's worked out in my riddled brain!    :eek: