Limb problems

[buzz lite beer]

Originally Posted by Dougal

So anybody who has had a string break at full draw COULD expect their limbs to break? How many people in that instance would put those limbs to one side, and buy another set?

As already said, my technical knowledge is sparse so forgive me....when you release the string , the arrow tip moves directly forward, not sideways , not rattling about.The string prevents the limb tip from moving upwards out of the limb pocket as its attached to the bottom limb, doing the same job there.
Without the string to restrict its forward movement, the limb tip will continue to travel at speed away from the riser.Whether the limbs leave the pockets is don to the depth of the pockets.As the limb leaves the pocket, its under very little stress sideways, most of it is backwards and forwards.

I say it again, my limb has broken across the thickest part, where the bolt is.I assume its the thickest part in order to deal with the stresses it suffers, and equally, I would have assumed that the weakest bit, and therefore the bit most likely to break, would be somewhere else.

No one would expect there limbs to break after a string snap, and Border on many occasion have pulled there limbs so far back that the string has come off the limb tips as part of there R&D and repeated it with the same pair of limbs to ensure failures are minimised with production models, what I was saying is that the point at which the damage had occurred to your limbs (I saw the photos that Murray posted for you) is directly at the point the limbs are retained with no string on to keep them seated securely so all forces would be concentrated at this one place with no arrow or string to absorb the energy imparted on them, it would be naive of you to think that these limbs would just come out of the dovetail area in a perfect straight line without making contact with the sides of dovetail slot in there journey down the hall hence my rattled out reference, the area of breakage may well be the thickest part of the limb in cross section but there is a 8mm hole drilled through this point that should be considered.

[Dougal]

I'm confused now.

You state that Border have tested their limbs by pulling the string so far that it has come off. And then done it again. Have they repeated it until the limb breaks? How many times did they do that test? I was told yesterday that in days gone by, a bow was set up in the Border workshop and everyone who walked by was encouraged if not required to "dry fire" it, which they did thousands of times.

In my six years of ownership, I can only recollect that one occasion when my string has come off, and then 9 months later the limb breaks. I must have unlucky written through me like a stick of rock

[buzz lite beer]

I was told by Robbie the previous owner of Border that it was done several times (string pulled off) , and I would assume that Sid having met him would be even more stringent in his R&D. The difference between dry firing and totally isolating one limb from another which would be the case in a string failure would again increase the energy concentration not having each limb to absorb each others energy and that is not an ideal to subject any limb to in any case. it can take just one occurrence to start a area of stress then over the course of time it progresses ML limbs are high performance they are subjected to massive internal forces each time they are shot add a flaw that may or may not have been inherent in the material structure even before your one incident to compound it. Have you been unlucky I would say you are.

[WhitehartFB]

Limbs break for all manner of reasons, I know somebody who has had 4 sets of G3's fail on them somebody else has shot the same type of limb for many 10,000's of shots without a problem.

Even wrongly stringing a bow can add strains and tensions to the limbs that they were not designed for and cause failure. Likewise changing limb settings like tiller, weight and centre or even having them wound in too far. Then there is incorrect bracing height, leaving them in a hot or very cold car, arrows too light for the poundage or even the way they can be drawn up with torque in the handle. Other problems could be dropping them, dry firing and in some cases a string that does not have enough strands and is too light.

Limbs absorb loads of vibrations and stresses so it's not surprising that some from a production run do give up.

[BorderBows]

ok.. ive got a issue here...

ive had a glass of wine over dinner, but ive got an image of our workshop with a trap door, leading to a dungon, and some leather bound bow torturer. Thashing bows who are begging for mercy. Chained and flogged daily...

on a more serious note though

We have tested bows by dry firing them, They started with 4 dry fired shots before breaking, which is unacceptable in our books, after some re-enforcements and some design changes to prototypes, we managed over 4000 dry fires without failure. We stopped due to the slackenning of the riser pocket due to excess vibration during the process, the bolt holes were oval behind the limb pocket. This doesnt mean that the limbs would last forever after being abused. As for anyone walking by, That be a saftey issue, when some bows break they explode, Violently. We have tried our best to design a limb that if it breaks, it does so in big chunks, (like in two peices) or folds in a predictable and safe manner, but our bow torturer cant overcome all eventualities.

We have video of a 64" Black douglas (21" riser) with our CXC laminate being pulled to 42" before partial failure. The recurves on this hex5 were like ballarina's heals by the time the it passed 40". We do not support abused bows, there are maximum draw lengths for our bows and Maximum braceheights to prevent over drawing them. This is because there is a safety margin built into every product.


What happens to a limb thats been shot thousands of times? then has an accident? Dont know... The vaireables are huge. Drawlenght, string type, number of shots, weight of arrow, level of care taken, amount of preload on limb bolts, knocking point type. All these relate to each other making a total sum of stress the bow is under. Then we can get into the accident, how far into the draw length were you, what riser was it in.... list goes on.
Im sure you have answers to all these variable Dougal but we have tried to deal with this with a fair conclusion. So we dont feel the need to persist.

We test our limbs to distruction, and we have a dialema, How far do you over draw a bow, to test it. lets take a max designed draw length of 28" Lets pull it to 30", It survives, but will it do another 10,000 shots, but will it survive 31" & 10,000 shots, and can it survive 30 dri-fires.before and after the 10,000 shots... But was it unique, lets test another 30 limbs, and lets, test it for different bow weights, string types, riser types... up to 10% past the recomended on all variables. This kind of testing is beyond most companies, which is why a garentee is there.
We test new materials, but Limb failuers would not happen if all eventualities were covered, plaines would not fall out the sky, and cars would not suffer mechanical failures. You would be surprised how many twisted limbs with radial failures from twists are explained as "woops it wasnt me, It just happened". Why are we to be viewed as responsable for them, and why are we to be publicly paraded around for these twist failures too. Even when they possibly were due to a badly set up riser. There are alot of them about aswell. Are our broken limbs to be shown as potential product issues for a bad riser setup, is that fair?
The kind of failure in your case is not clear cut, As this is a first in our books, is this a bad setup, bad accident, or bad luck, bad design, bad material. Im not sure, i can guess, as it is the only one in our history and that it is probably one or a mix of the first three, but we are offering help.
We hope that when your current situation settles you can take us up on our offer.
There is no trail of evidence for us to analyse, we cant say, yes its 40lbs bows that suffer, so we cant learn much from this, nor can anyone else out there as there are no trends, as this is such a rare break. so we have never been sure what you would gain from asking so many people so publicly.
The only thing to learn is that we now have some paranoid ML2 customers that were happy with their product, due to one failure in a 7 year history of the ML2.
Always check your Gear, wither it be 1day old, to 99years old. Simple, that was the case before your misshap. The rest is speculation from this point on, and that would be the case for any make/model of limb in this situation. Not sure why this is a border thread...

[Dougal]

Its a Border thread cos they're Border limbs, if I wanted to cause trouble I'd have posted on the most public pages, not in a corner of the site where only someone with an interest in Border would look.
I know personally of two archers who shoot ML2s that have now checked and rechecked bow setup since my incident, and all 3 of us shoot Talisman risers.My setup had been checked by Olympic archers and national coaches,
and with little arms , I never drew it past 28".
You are correct when you say that we will never know the cause, there are many variables, and now that the limb has broken there is probably no evidence left to assist.But the top limb (cracked) is still in one piece.

Quote " Im sure you have answers to all these variable Dougal but we have tried to deal with this with a fair conclusion. So we dont feel the need to persist."

I don't have answers, and I not sure what makes you think that I do.You have been extremely fair and reasonable in how you have dealt with the issue, and for that I'm grateful.

But you do persist.

[Bird_2112]

Limbs flying down the hall.... that takes me back. Used to be quite common in the days of kevlar especially with Yamaha's. Happened to me a few times when the old kevlar string broke. Also bounced the whole bow down the hall a couple of times when my finger sling broke (made out of old kevlar strings) with the bounce knocking the string off. No visible damage and an old EX is still out there.

G.

winnex now border next

[JohnK]

I can't believe this thread persists.

I think there's a bit of talking at cross-purposes here. Hope I can
butt (pun intended) in.

Dougal: I know you've said that you think Border have provided
excellent customer service for you and that you aren't publicly
criticising them, but whether it's because of the limitations of the
written medium or some other factor, many of your posts do come across
as critical. Hence, I would guess, Sid's reaction (sorry Sid - don't mean to presume).

Don't take this personally, but it seems as if you're obsessing about
this breakage, trying to work out a more complicated explanation than
the one that is staring you in the face: the fact that your limbs went
for a short flight down the range nine months previously.

Are you familiar with the principle of Occam's razor?
Paraphrased/loosely translated, it is: "All other things being equal,
the simplest solution is the best." So, consider which is more likely:

A) The limbs on your bow were damaged when they flew down the hall.
The damage was very slight but over several months the stress put on
the damaged part of the limb took its toll and what was a tiny
internal fracture grew until the limb failed.

B) This particular pair of ML2 limbs had a previously unknown
manufacturing flaw that has never been reported to Border in the past.
Either this flaw takes four years of continuous shooting to manifest,
or it is only triggered when the limbs in question are shot off the
bow and down the range.

I know which I'd put money on.

If you threw one hundred sets of limbs from different manufacturers
down a hall the odds are that a lot of them would be okay. However,
there's always a chance that the tiniest chip or dent in a limb can
turn into something else over a period of time. There is no reason to
suspect that Border limbs are more susceptible to damage after being
shot out of a bow than other makes of limb... unless another
manufacturer has come up with a way of installing airbags in their
limbs.

What we can take from this thread is:

1. Everyone should check their bow regularly.
2. Everyone should be especially careful to check and recheck your bow
if they drop it, throw it, dance a jig on it etc.
3. This particular breakage isn't a known problem in the ML2, and
therefore it is highly unlikely the design of the limb contributed in
any way, shape or form to the breakage.
4. You have a brand-new set of limbs waiting for you at a knock-down price.

So I agree with Sid - if you're still wondering how common this sort
of breakage is and whether it's linked to limb chucking, then a thread
about limbs in general rather than Border limbs is probably more
appropriate. There you could ask how commonly limbs break at the limb
butt and whether this sort of thing generally only happens if you're
unlucky enough to drop your limbs.

Just a suggestion. Hope no offence is taken, because it isn't offered

[Andyakashrek]

If the forum is searched you will find lots of broken, cracked or delaminated limbs from other manufacturers, most only months old. The owners do not harp on or look for non existent problems, stuff happens, kit breaks accept it. It's a shame the limb throwing incident was forgotten until after the original post was made, it would have undoubtedly placed a different perspective on things.
Obsessed over the breakage, maybe but I think that Border have gone way beyond most manufacturers in offering help and should be rightfully seen as a quality company. Considering their products are cutting edge I bet they suffer less failures than most limb makers.

[Jay.g]

...sigh... I'm really surprised this thread is still going... Very surprised. down to the cream of it, its just a broken pair of old limbs. Not a big deal. you got 7 years out of it too and had it propalling down the hall too!! I've seen limbs break after merely months purely through shooting, so its not exactly a catastrophe that's worth 3 pages of writting.

Sid didn't persist, you did.

Just get over it.