Flemish Versus Endless

[Jason R. Wesbrock]

Zilla,

Chad nailed it. I make 3-color endless strings, and I can't begin to remember how many people thought they were flemish strings until I pointed out the end servings.

[Falk]

We have a saying over here which goes something like this: "Nothing lasts longer then an improvised thing ...!"
My endless-string-jig is a sure proof of this saying, as I use it for 20 years now. It's functional and versatile and was subject to change and additions thru time. It took all this and was even (ab)used in bowmaking when applying backings with hide glue etc. etc.

What it never did was, to assist me in the making of a multicolored "endless" string! Never was I able to sacrifice the "endless" character for looks, even though, it might not make a differents with todays materials. This just came to my mind after reading Jason's post above (no pun intended here). I count six ends in his "endless" string ... we might need a new name for this style of strings?

What I prefer myself is mostly a matter of which bow I need a string for. It goes more by feeling then anything else. I like endless for most RC. From theory I'd say endless has to be more efficient then flemish. I have no way to measure it though. It might only effect the mentioned FITA archers. Lightweight arrows and poundage plus long distance shooting will show the difference?!

What I don't understand is what Rob sayed about "endless is just as strong as flemish". I calculate with 40% less strenght because of the thinner loops in endless strings. This is only of real concern with linnen strings though - especially crossbow strings, which can't be made flemish style anyway.

Can a physicist please do the math and explain once and for all if/how the separation of strands effects the tensile strenght in string loops?

[Rob DiStefano]

In The Bowyer's Bible Volume 2, Tim Baker explains the physics of why endless and Flemish loops are equal in strength - I'll look it up and post it here.

[JImmyDee]

Originally posted by Falk:
What I don't understand is what Rob sayed about "endless is just as strong as flemish". I calculate with 40% less strenght because of the thinner loops in endless strings. This is only of real concern with linnen strings though - especially crossbow strings, which can't be made flemish style anyway.

Can a physicist please do the math and explain once and for all if/how the separation of strands effects the tensile strenght in string loops?

Nothing but questions, here...

A FITA friend says twisted strings are stronger than untwisted.  How's that?

The FITA boys seem always to be adding more wax to their strings.  Why's that?

Regarding Flemish twist strings: how many twists per inch should be in a finished string?

[Falk]

That's right Rob and I just did look it up. He explains on p. 218 ff. - plus he tells all the pros for an endless string.

But then again - BAKER (1993: 225)
"A Superior Quality Flemish String
A plaited loop is twice as thick as an endless-string loop. The plaited loop is almost twice the strength of the main string."

If I reverse this, I would end up with "almost half as strong as the main string" in endless-strings ... correct?!

Tim Bakers chapter in TBB Vol.II is for sure one of the best ever written on the subject. And I too use it as reference. Payne-Gallwey, who is cited by Baker, is an other good one. I have to check but think he suggested to calculate with 40% less in loops.

I have doubts about this point and would just like to mention "uneven" stress at the tips with slightly out of alignment working limbs. And as Baker said: "Many a fight ... has been started down at The Bowmakers Bar over just this subject."

    Falk

[chucker]

Ron, I like that jig! Neet & simple. Thanks for the photo!

[Falk]

Okay - the tensile stress along the string will be divided into both strands at the loop - each getting an about equal share of the load. Up to here I can follow and aggree. But - follow the strands around the bowtip. There is a single point at the back of the bowtip, where both strands find themself reunited - both holding one half of the stress and - Haa! What is this?! - the full stress will hit this very spot - but only 50% of the main boddy material is present.

@JimmyDee
FITA wax more often?
Maybe a left over behavior from Kevlar strings? In any case, it will cause a loss in efficience. But they wear all white and screw strange things onto their bows too  

Twisted is stronger?
Why? I don't see it!

How many twists?
Only as many as are nescessary to hold the splice together. Maybe a full turn every 5 inches or so. If you plan for more you'll only add mass and "springyness" to the string - both you don't want.

[Rob DiStefano]

Originally posted by Falk:
Okay - the tensile stress along the string will be divided into both strands at the loop - each getting an about equal share of the load. Up to here I can follow and aggree. But - follow the strands around the bowtip. There is a single point at the back of the bowtip, where both strands find themself reunited - both holding one half of the stress and - Haa! What is this?! - the full stress will hit this very spot - but only 50% of the main boddy material is present. ...

You have the TBB Vol 2. - reread Tim Baker's article on strings.

[zilla]

Dang for something that seems so simple it sure is complicated.. One twist per 5 inches?  I am gonna hafta make a new string now..

FWIW I finally ordered my "Doin The Twist" DVD.. Mainly cause if I am doin anything I wanna do it right and obviously I have been doing it sorta wrong..

[Rob DiStefano]

Originally posted by zilla:
... FWIW I finally ordered my "Doin The Twist" DVD.. Mainly cause if I am doin anything I wanna do it right and obviously I have been doing it sorta wrong..

That video is SUPERB for learning to build Flemish AND endless strings - highly recommended!

[O.L. Adcock]

OK, I'll throw some stuff out and stir the pot. I haven't read all the refferences folks are talking about so these thougts aren't to dispute all that's been written, but it will!  

Strings are stronger with twists, you won't find cables or ropes that aren't twisted for that reason. An untwisted/unwaxed string will "flair/parachute" during the shot which is bad news.

Now the stiring part...Differences between strings performance wise is caused by mass and aerodynamics...Stretch/springiness has nothing to do with it. A string is as stretched/sprung as it's ever going to be at brace height. The tension on the string is about 30% less at full draw as it is at brace.........O.L.

[Falk]

Zilla,
don't worry! I was talking about a MINIMUM number of twists - nothing wrong with a few more. BTW I intended to say one turn on 2" not 5". I am used to think in Centimeters and 5cm equals 2" - my fault when I wrote it down.

O.L. & JimmyDee - twist
Ropes etc. are twisted - yes. I was thinking of "stronger" in terms of more efficient - which is obviously not the same thing. So, yes Sir - you are right! With some twist the strands can lean to each other - thus absorbing energy by friction. To tow (is this a word?) your truck this is sure a good thing but in a bowstring it is wasted energy.

Rob,
I suppose you thought of the following text passage from Baker (TBB II: 219)?
"Determin the strenght of a strand of string. Loop it over a smooth hook of a pull-scale, two strands handing down. Pull both strands, noting scale weight at breaking point. ... Breaking strenght will be double that of a single strand broken in a straight pull. Almost!

And the amount of "almost" is what I need to know - in terms of numbers or percentage.

------------------
Paney-Gallwey (1903: 111): The Book of the Crossbow
"It is evident, however, that if the bow-string ... could be made with its end loops of the same thickness as the rest of the bow-string, the string would be stronger then the one I am about to describe, in which the turned parts of the string that form the loops, are only half the substance of its center."

And an other one of my favorites to boil all this down to the most important aspect        

Hodgkin,A.E. (1951: 69): the Archer's Craft
"Making a bowstring is a jolly business."

    :D     Falk

[O.L. Adcock]

Falk, That might be so but what is the weight difference between 1 twist in 5" and 1 in 1 like my flight strings are?? I doubt it's 10 grains with 70% of that in areas that don't hurt much. I use about a 1 twist in 1" so the string is ROUND and won't parachute......O.L.

[Rob DiStefano]

Absolutely, OL.  Bowstrings need to be twisted to round off and be made aerodynamic.  After spinning an endless string, it must have some twists added to round off for aerodynamics - but not for strength, particularly with modern fibers which can easily exceed 100# tensile strength per strand.  Same goes for the number of strands - while some small diameter modern fibers can have as few as 6 strands for a "hot rod" speed performance bowstring, that string will lack lots in stability.  Which is something that the string wax provides - stability in that it holds the strands together, making for a more durable string (and if lots of wax is used, upping the string's physical weight, a slower performing bowstring).

IMHO, the "spring" factor in a bowstring (stretch and creep) is an instability factor that messes with a bow's brace height and nock point location, and that affects shot to shot consistency.  So, the more inherent stretch and creep in a bowstring, the less consistent it becomes, and a reason to consider modern HMPE fibers (Dyneema, Vectran, etc).  IMHO. YMMV.

[O.L. Adcock]

Yep Rob, I wax the heck out of all my strings cause the difference with and without from a mass standpoint is tiny. Tell me something....These FITA folks have got it in their heads that a fatter string is more "stable"....For the life of me I can't understand the logic behind that. I suspect like other things in our sport some coach made that statement back in ought 6 and now it's gospel whether it's correct or not. Now I can see switching from a 16 strnd string to an 8 screws up their tuning but that's fixable and not the strings fault...I can see the serving cutting into their tabs making releases more difficult but thicker serving fixes that. I just can't find any logical reason in physics for that to be true...O.L.

[Rob DiStefano]

There are lots of things about the FITA folks that I don't understand - much is probably just tradition or hearsay, like mandating to wear white clothing on the shooting line and using fat 20 strand Dyneema bowstrings.  There is no question in my mind that heavier bowstrings make for more stable and forgiving releases/shots, and more strands will improve (to some degree) the overall stretch/creep factor - remember, freestyle FITA recurve shooting is LOTS about technical gadgets and precise sight mark tuning as it is about form technique.  But like anything, it can be taken to a silly extreme.  So, for the most part, I believe a 14 strand Dyneema bowstring for target work is nearly overkill on a 45# FITA recurve, but that same 14 strand Dyneema endless string on my 55# hunting longbow is plenty extra durable and shoots just fine as long as I do my part.  Go figger.

[Falk]

Tim Baker did a test about added mass due to "candle like waxing", which can be read in the already mentioned chapter in TBB-II. He used linnen strings though. There might be less difference with modern material, at least when only a few strands are involved.
But anyway: An unwaxed 110gr linnen string was heavyly waxed, wax rubbed in and lightly rewaxed. He got it to 180gr this way.
I would rather add 70gr to my arrow then to my string. I can't provide own data here as I hardly wax my strings ever again - after making them.

As for round strings
There should be no problem, with very moderate twisting, to get a round string. And I think a string with an arrow on it will be under enough tension to prevent "parachuting" during the shot. One interesting article which you 'ol Flight Shooters all probably know is this:
HICKMAN, C.N. (1931): Effect of String Weight on Arrow Velocity and Efficiency of Bows. - Ye Sylvan Archer, Vol.4, No. 8, p. 6-9, 3 figs.

Dr. Hickman writes on p. 9: It is the weight of the string that is most important and not its diameter. (i.e., the air resitance of the string is negligible.) This conclusion is based not only on these tests but on previous investigations, the results of which, have not yet been published."

... but I still need to find out where I got this minus 40% from ...

[LBR]

I agree with O.L. on everything except smaller strings/stability.  I can't put it into terms on paper, or even explain it, I just know for whatever reason my tournament scores went down when I tried a small diameter string.  Not a huge amount, but enough that I noticed.  That was with my longbow though--I have a 10 strand Dynaflight '97 on my selfbow, and I do just fine with it--go figure.  Probably has more to do with the monkey holding the bow than with the string, but I'm sticking to 14 strands on my longbow.  I can't tell you why it works, but I can say that it does work, for me anyway.

Almost forgot--I did hear about a wheel-bow test (been several years ago) where bows in a shooting machine grouped tighter with a moderate sized string vs. a small one.  Dunno if it was fact, as I didn't see the report myself, just heard about it.

I love these string discussions!

Chad

[O.L. Adcock]

Wow Falk, that's a lot! Maybe I ought to weight them!    OK...Just did..My whole tube of wax only weighs 400 grains counting the plastic tube! So he could only build 6 or 7 strings from an entire tube.  Juli's "flight" string on a 35# bow weighs 60 grains and that's waxed. I'll put a new string on and get it out in the heat and will buff off the excess that squeezes out with a dry rag

Chad, I've wondered if it had something to do with the string tracking the string groves?? That could be the case with the compound too, moving side to side in the cams?? Longbows won't have that problem. I've gone as low as 4 strands of 97 on a 30ish# bow and as long as I adjust the serving so it's the same size as 8-10 strands, I can't tell any difference except for a further point on distance. Doesn't seem to stretch or creep either after the first 50 shots or so. I think Rod shoots like 8 strands on a 40#. Rob, I hear ya, I've wondered why they just don't use poly rope..O.L.

[LBR]

Could have something to do with the wheels/cams--I really have no idea.  That's just the only test I've even heard about comparing strings that way.

I forget how many strands Rod uses, but I know he does like a tiny string, and it definately works for him.  

Probably more to do with me than the string, but you know how it goes--the mental thing with archery can make more of a difference than the equipment.

The only reason I even gave 10 strands another try (after almost a full tournament season of shooting a small string on my longbow) was to pick up some speed--switching between the two bows was tough because of the speed difference.  Now I just don't know if it's a case of what my longbow "likes", or my mentality, maybe the small increase in speed threw me off, or what....I do know it works on my selfbow, but I probably won't try it again on my current longbow.  If it ain't broke.....

Chad