Point weight?

Hudzi93

New member
Hi, I've bought a used set of 610 nav's and I want to know the point weight as it seem a little to heavy. The problem is I don't really want to remove a point as I have zero experience dealing with this stuff and I don't have a set of scales sensitive enough anyway.

I measured the FOC and its about 19% which seems pretty high. The total arrow length, including the point, is 30 3/8" and the FOC is 2 7/8".

The shaft is 29 3/16" long at 6.9gn per inch and has 3 x 1.75" FFP vanes weighing 9gn total. The nocks weigh 2gn but I don't know how much the pin adapters weigh. Can anyone hazard a guesstimate as to how much the points weigh? I reckon they would be around 100gn but I'm not sure.

PS. I have tried contacting the guy I bought them from but he hasn't replied and he doesn't seem to be the type of guy that'll know anyway..

Thanks
 

backinblack

Active member
Hi Hudzi,

Sorry if this is too obvious, but if you know the total weight of the arrow in grains, you can subtract the weights of the other components to get a point weight.

Easton's shaft selector software suggests that a 29.25 inch ACG shaft weighs 214 grains which should give you a clue as to the shaft weight alone as the Navi was the forerunner of the ACG. Also, Easton do two different points for this - a longer 120, 110, 100 grn break off point, a shorter 100, 90, 80 grn point. The Navi points were the same as the current ACE points so you might get a feel for their weight if you look at the two different point types on the Easton site.

| Easton Archery

Hope that helps you some,
Backinblack
 

Hudzi93

New member
Yes I thought of that but I can't weigh the arrows accurately enough. I weighed all 9 of my arrows and averaged the weight. It came out to 20.2g (about 312 grains) but this measurement could be out by upto 5 grains either way. Adding up the known weights of the remaining components of the arrow, this could also be out by a +/- a few grains, especially since I don't know the exact weight of the pins (I've assumed about 10 grains). All in all, that leaves at least 10 grains of uncertainty. I've identified it to be ace screw in points. I did a side by side comparison and it seems to be the same size and shape as the 36 grain point (four different weight points, each a different size). If that's correct, then it only leaves the inserts. So it's either the 49 or 59 grain insert. Summing up all the weights points to the 49gr insert, so 85gr in total. It just feels heavier than that though and the FOC is too high. Ah well, I'll give them a shoot and see what they're like. I guess there's no point (no pun intended) making a big deal deal out of it unless they're not shooting properly or giving me trouble with long distances.
 

Hudzi93

New member
I'm really sorry to have wasted your time with my stupid mistake (you can tell I'm a noob). I divided the distance from centre by half the arrow length instead of the full arrow length. So it's actually more like 9.5% FOC.

Although it was pretty stupid of me, it does seem to make more sense though. Say hypothetically that the balance point was at the tip of the arrow. That, IMO, should be 100% FOC but its actually 50%. I guess I can't go about changing standards though 😜
 

Mike47j

New member
Easton calculates the FOC using Nock groove to end of the shaft and not the full length, so perhaps your FOC is just under 12% ?
Which might be 90 gn points.
 

Hudzi93

New member
Easton calculates the FOC using Nock groove to end of the shaft and not the full length, so perhaps your FOC is just under 12% ?
Which might be 90 gn points.
I've not really measured it but i think measured this way the centre moves back about 1/8th of an inch and the arrow is about 29.6" long giving a new FOC of about 10.2%.
 

Hudzi93

New member
I just checked it. Measuring from nock groove to the end of the shaft I get an FOC of about 10.3% which is about right.
 

joetapley

New member
I'm really sorry to have wasted your time with my stupid mistake (you can tell I'm a noob). I divided the distance from centre by half the arrow length instead of the full arrow length. So it's actually more like 9.5% FOC.

Although it was pretty stupid of me, it does seem to make more sense though. Say hypothetically that the balance point was at the tip of the arrow. That, IMO, should be 100% FOC but its actually 50%. I guess I can't go about changing standards though 
There isn't really a "standard" for FOC so you can define it how you want :). Some heavier points are quite long and so have quite a large cross sectional area so including the point in the FOC calculation would make sense physically. As you say FOC can vary between +/- 50% and zero though in practice maximum value in the mid 20's.
 
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