http://paleoplanet69529.yuku.com/topic/6208#.URYuD6U03wg

jlasud

Pretty sure you already know that traditional crossbows use an endless string which means continuous loops are wound around two spaced pins until you get the required number of strands. The beginning and the end of the string having previously been tied off to the side are then over lapped and then overlaid by the nock serving on one end. This means the end loops contain only half the number of strands.

Because the payload of my 100# “single string” bullet crossbow is only 12 grams I have 52 strands of B50 or 26 on the nock loops. The nock serving is braided spectra overlaid with cotton coxcombing. All of this may sound like overkill but I have got at least 2500 shots off this string.

Tom      

For a bow, you want the string to have a minimum of EIGHT times the draw weight, that means if the bow draws 50 pounds, the string should have a breaking strength of 400 pounds, minimum.  This is at the weakest point, usually where the string touches the limbs.  So, a 50 strand string for a crossbow means it has 50 strands at the nock on the limb, 100 strands where the bolt rests.  I don't know if a "Flemish" string can be used on a crossbow, if it can, it should solve your problems.  And, FWIW, Flemish twisted strings are used on English longbows that pull the same as your crossbow.

They are "primitive," defined in webster's as closely approximating an early ancestral type or being little evolved. Nobody said anything about ancient, traditional, or historically accurate. That's why we talk about steel knives and rubber banded slingshots here, too.

If it will make you feel better, silk is very close to B50, it stretches until it stabilizes, you need more strands and it is waterproof.  If you want something like Spectra or Kevlar, use linen.  High quality linen does not stretch, even when wet.  It will rot, unlike the modern materials.  FWIW, good linen thread of the proper diameter and strength is hard to come by in England and almost impossible to find in North America, and that's more countries than the US.

The English Warbow Society allows Fastflite strings, mostly because a broken string on a warbow usually means large pieces of wood flying in all directions at a pretty good velocity.  Pretty much everything else has to match what was available to the archers of the time, with a few exceptions that are classed as modern warbows.  That means a selfbow made of certain woods, horn nocks on the bows, geese feathers on the arrows and forged points that match a historical point type.  Turkey feathers were rather grudgingly added not too long ago.

jlasud wrote on Feb 15^th, 2013 at 10:38am:


Jlasud

When I said 12 gram payload I was referring to 3.4 grams for a 9.5mm (.375”) steel ball bearing plus the 9 gram shuttle on the bowstring that holds the ball for firing. This crossbow has been dry fired several times thanks to the tiny ammo escaping just before the trigger pull.

Tom

jlasud wrote on Feb 16^th, 2013 at 2:45am:


jlasud

I started with .400” lead balls (6 grams), 100 for $12 U.S. but they deformed easy and made accuracy testing futile. The steel ball bearings were $7 U.S. for 250 and are easily recovered from my target stand which has some scrap carpet hung inside.

My son David and I had an impromptu shooting match today and we both managed to place some shots through previous holes, (well slightly enlarged) at just under 10m, it is good cheap fun.

Tom