Arrow weight tolerance

[nbuuifx]

I've been experimenting with some arrows to try and improve grouping.

The arrows are carbon aluminium and currently the balance point is about 2 or 3mm difference between arrows (deliberately picking the most extreme difference). Obviously this will change the FOC.

Weighing the arrows gives an 8gn difference between the lightest and the heaviest. If I remove them then all the arrows are within +/- 2gn from the average weight. This still gives a range of 4gn though.

Are these differences acceptable, will they make much difference? The weight differences seem to be in the shaft.

 

[Rik]

That sounds a lot, but probably doesn't make a huge difference at the target end, unless you're shooting quite well. Careful selection of which point goes with which shaft will most likely reduce the extremes of the range a bit, from what you said.

Minor differences in FOC... you're talking about variations in drag, mostly. I'm not clear on how big a difference you would have to see to be measurable on a target.

I'm a bit fussy about shaft weights, trying to get a set down to a grain or less in range, but I'm not convinced it's worth it in terms of grouping... I'm the major variable there

 

[Timid Toad]

Number your shafts, and go shoot them, and plot them. If they consistently land in specific places, it's time for you to get fussy over point weight. If it's still pretty random, just go shoot.

 

[geoffretired]

Every now and again, I hear or read a piece of advice that is so logical and easy to remember that it does not need to be written down. These are the "gems" that last.
TT's post is one of the gems.

 

[Senlac]

I’ve found that within a delivered set of ACE shafts the weight of the shafts will differ by around +/- 1% i.e. about 2grn in 200grn or so.
And a set of Easton 100grn points will vary in weight by around +/- 1% i.e between 99grn and 101grn.
So it’s worth matching heavier points to lighter shafts - though that will move the FOC a bit…
If you’re really into this, measure the spine of the shafts while rotating them. For ACEs, you can easily see the spine of, say, a 620 vary by +/- 10 as you rotate it. I.e. in one orientation it’ll be 610… in another orientation it’ll be 630. It’s caused by the method of manufacture: wrapping & gluing a trapezoid-shaped film of carbon around the aluminum shaft, then sanding down the edges. I found X10s are much more consistent, maybe +/- 3 on a 500 spine shaft. I.e. they’re better made. For ACEs and X10s you can chose the orientation that gives a lateral match of spines.

 

[Timid Toad]

But does it make you shoot any better? I always buy second hand arrows, dismantle and refettle. But it's never worth worrying about the odd grain here or there.

 

[Senlac]

But does it make you shoot any better? I always buy second hand arrows, dismantle and refettle. But it's never worth worrying about the odd grain here or there.

Ah ha, no it doesn’t. It’s interesting to do, but it’s probably one of those things that matter when your handicap is below 20. I.e. this is well over my pay grade, but it’s interesting.

 

[Timid Toad]

Something I do do, is to thoroughly clean inside shafts before assembly. You would not believe the swarf, dust etc that's stuck in there!

 

[bimble]

But does it make you shoot any better? I always buy second hand arrows, dismantle and refettle. But it's never worth worrying about the odd grain here or there.

I mean, it's probably worth more worry about than your FOC*, but unless you're good (and I mean properly good) you're right about not needing to worry about it!

* - seriously, if you're using a point weight in the recommended range for your spine your FOC is fine. And that is how much thought you need to give to it.

 

[geoffretired]

There are a good few archers who think that when they have done all the testing and sorting out, then any errors are down to their form. It can't be the kit because they have tested it.
A fair percentage of those archers then look for a test they have forgotten to do.... without working on their form.

 

[nbuuifx]

There are a good few archers who think that when they have done all the testing and sorting out, then any errors are down to their form. It can't be the kit because they have tested it.
A fair percentage of those archers then look for a test they have forgotten to do.... without working on their form.

A hooter shooter or similar would be great to rule out everything else, allowing archers to then work on form. It often is a mental thing but knowing the equipment is all correct only leaves you then. Gives a confidence that the changes you make on form really are valid.

Obviously with outdoors though you've got all the variables around weather too blame next though

 

[geoffretired]

Hi nbuuifx,
I follow that in theory. It would work in practice, too.... so long as the archer accepts that the problem is with their form.
That isn't always the case. I know some archers( including myself at times) who look for something else that they have overlooked. Perhaps the brace height is too high/low. Or centreshot is too far in/out. maybe the nocking point is too high/low.

 

[Timid Toad]

As a rule it's usually the nut behind the bow.

 

[geoffretired]

Hi TT agreed.
I think human nature tends to kick in and pushes us towards the easiest fixes. For most of us grassroots archers there is no one around to persuade and/or advise us on how to go against nature and adopt the very time consuming task of finding form weaknesses and working on them.

 

[ArcheryFox]

James Park has a paper on this: SAGE Journals: Your gateway to world-class research journals (If you want a PDF of it drop me a PM).

Tl;dr if a 'top-level' archer has arrows matched to within +/- 0.5grn then the score loss due to arrow mismatching is far lower than (i.e. lost within) the score loss due to variations in technique.

I never bothered matching a set of procomps and happily shot MB with them. I did match my protours (if you spend that much why wouldn't you) and got to +/-0.55 grn, but don't feel that it made any difference compared to if I hadn't. I think the main reason that a good-but-not-elite archer might bother to weight match is for the peace of mind and confidence in the equipment on a psychological level rather than any material benefit, as others have already suggested.

Upper end Easton arrows and components already come with good tolerances from the factory. You didn't say what you were using, nbuuifx, but to me +/-2 grn is enough to raise an eyebrow, but not horrendous (It's probably not the biggest shortcoming in your overall shooting). I'd say probably don't worry unless you are seeing any real anomalies as TT suggests. If it is bugging you you can remove the points and put the lightest point in the heaviest shaft (and repeat) to get a better matching across the entire set.

(I am halfway through writing a piece about different approaches to weight matching, but have been since summer 2020. If I ever finish it I'll try and return here to post it.)
(Also 'weight-matching' is often done on dry shafts and points only, but how much can variation do we get in hotmelt, vanes, nocks? 2" AAE vanes can vary by as much as 0.1grn, When we are talking variation of the order of +/-0.5grn in shaft and points, this could easily become +/-0.65grn (a 30% increase!!) by unfortunate choice of fletchings. Again, do differences of this scale actually matter to most mortals' shooting/scoring? Probably not.)

 

[Timid Toad]

Crimes committed with hotmelt and fletchtite, yes.

 

[Rik]

Crimes committed with hotmelt and fletchtite, yes.

Or the "that point is a touch light, let's really slather on the hotmelt" approach... I weighed some once, you would really have to be excessive to make a difference. Points can be a third of the weight of the entire arrow, so fractions of a grain of hotmelt added to that? Inconsistent fletching, on the other hand...

 

[nbuuifx]

Thanks for all the replies,

The arrows in question are my daughters and this time I'd avoided the usual Easton arrows as she keeps out growing them and I went for cartels instead. I have been moderately impressed with the quality of them and they are staying straight nicely, but the weight issue does put me off having another set.

The points are actually very closely matched with the differences between them being 0.1gn which is the tolerance of the scale anyway. They all either showed as 70gn or 69.9gn.

The fletchings themselves are fairly small 1.75" shield vanes, so are relatively light already so any tolerance on them is less of a difference in weight and seems to be negligible between the ones I have weighed. I guess the amount of superglue is a variable but is still nowhere near the difference in weight of the shafts themselves.

It probably does result in me needing to spend some more money on a more expensive set of shafts but it is so painful when they only last a short amount of time due to growing/poundage increase. Also made even worse by the dark magic of actually getting the correct spine of shafts

 

[Timid Toad]

If they are Cartels I'd definitely give them a good clean out inside. I found all of that brand I've ever shot have been gopping! I drop a big darning needle with a length of wool threaded through down the shaft and give it a good swizzle.

 

[nbuuifx]

If they are Cartels I'd definitely give them a good clean out inside. I found all of that brand I've ever shot have been gopping! I drop a big darning needle with a length of wool threaded through down the shaft and give it a good swizzle.

Thanks I'll give it a try, a nice easy fix if it works!