A few comments were made on the first one and they have been taken into consideration, and an additional section has been added for making 'Flemish' style strings from my initial attempts at this.
As always, any comments or variances appreciated
Thanks
(
/ \
/ )
>>---|-> get my point ?
\ )
\ / Rob McNeur
( Rob@ccc.govt.nz
===============================================================================
The majority of the following is intended for the fabrication of an
'endless string' style of bowstring, however a 'flemish' type bowstring is
more appropriate and authentic for traditional bows (longbow and flatbows) and
details for this have been appended at the end.
The flemish style does *not* need a string jig at all.
---------------------------------------------------------------------------
| N N |
---------------------------------------------------------------------------
(N = nail, dowel, or heavy pin)
============================================================================ | ------------------- | | B M M M M N| | | | | | A N| | | ---------------------------------------------------------------------- | ============================================================================ (A,B,M,N are all nails, dowels or heavy pins)Here, the string starts at A, goes right up one side, around the top, loops around B and then back to A once more, with the complete bowstring length being the distance A->top->B. Having multiple pins (M) means that strings of different lengths can be made, just use the pin at the correct distance from A.
This is made in 3 pieces and allows strings of anywhere between about 2.1m (83") down to about 30"
============================================================================ | ----------------------------------------------- | | O |XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX| | | ----------------------------------------------- | ============================================================================Cut, drill or rout out a slot (as marked by XXX) for 1/2 of the length. This goes right through the wood and provides a slot for the adjustable part of the jig to slide up and down. Drill a hole in the other end (the O ) this will be the fixed end.
=================================== | | | N O N | | | ===================================N = Nails, pins or vertical dowels (these are for the string to loop around) O = hole in the middle (end pins are equidistant from the central hole)
These are then put together with a bolt long enough to slide through the main body, and the crosspieces, and with a butterfly nut on the top to allow easy loosening and tightening.
--- ---
|N| |N|
| | | |
--| |-----------------------------------------| |---------
| |O| XXXXXXXXXXXXXXXXXXXXX|O|XXXXXXX |
--| |-----------------------------------------| |---------
| | | |
|N| |N|
--- ---
fixed end adjustable end
(rotates only) (slides and rotates)
With this, the crosspieces are turned parallel to the main board to set the
required string length (measuring from the outermost pins), then, after the
required threads have been wound on, turned at right angles (as in above
diagram) for ease of work. The adjustable end slides backwards and forwards
in the slot to the required location, then the nuts are tightened to hold it
in the correct location (butterfly nuts are easiest and fastest).===============================================================================
The requirement here is to make a string that is strong enough to withstand the massive stresses developed by firing arrows, to make the string as light as possible, and also not too bulky. A bowstring that snaps during use is putting the whole bow at risk of blowing apart, as there is no longer anything to absorb the shocks of the bow straightening.
Any string made heavier than suggested here will be stronger than required, and hence less likely to break in normal use, however the extra mass will slow the release slightly, giving a slight *decrease* in arrow speed. A string made lighter will be proportionally weaker, increasing the risk of accidental breakage, however the reduced mass of the string will actually allow a slight *increase* in arrow speed. (Many of those trying for flight distance records bring their strings down as low as possible to try to gain all the speed possible, and a much higher risk of the whole thing blowing apart on them).
A string made too bulky may have difficulty in fitting your arrow nocks, requiring these to be replaced/altered.
Thread used can be almost any type as long as it has not got too much stretch. Linen thread, silk, etc, all make strong strings with limited stretch. Some of the modern artificial fibres are more preferred as they are even lighter with almost no stretch. One warning here - many people prefer to *not* use fastflight etc with traditional style self-bows. As these materials have almost no stretch at all, this means that they have no give when the string reaches the end of its movement after firing an arrow, hence all the jarring of the final release is passed directly to the wood of the bow itself. It is often preferred to use a natural fibre thread with a small amount of give so that the final jar is absorbed by the bowstring, rather than the bow. Mileage here may vary, and this may also be a problem with modern fibreglass laminated recurves etc which may or *may not* be designed for the use of fastflight. Many bowyers will void their guarantee if fastflight is used, so check first with the manufacturer/dealer.
If there is no old string to work from, a general rule of thumb is to measure the distance on the bow from nock to nock and reduce this by about 75 mm (3"). This will give a close string, but is likely to need shortening by twisting when stringing the bow to give a decent brace height. (The brace height is the distance between the inside of the grip and the bowstring when the bow is strung/braced) Once you have the bow braced to the correct height for your style (opinions differ on the best brace height, this can be anywhere between 100-200mm (4-8 inches) but is usually around 150mm (6")), measure the nock-to-nock distance, and this will be the correct string length for future reference.
Divide the breaking strain of your thread into this total, and this will
tell you the number of strands required.
eg
If the drawweight of the bow is 40lbs, the required string breaking
strain will be 4x40 = 160 lbs.
A linen thread will often have a breaking strain of something around 10 lbs.
Hence, the number of strands required for this bowstring using this linen
thread will be
= (drawweight of the bow) x 4)/(thread breaking strain)
= (40x4)/10
= 160/10
= 16 strands of thread.
(using an endless string, as in this guide, this will be 8 complete loops of
threads, where each loop goes from end-to-end and back again around the jig)
Where this calculation does not work out to a whole number or an even number,
round this up to the next highest even number of threads. A slightly higher
breaking strain is safer than a slightly reduced breaking strain.
Take your string jig, set it for the correct string length (as above), then tie one end of your thread to the nail/pin at one end and loop the thread around the pins the required number of times, maintaining a constant tension on the thread at all times so as to keep it uniformly stressed. When the last loop is completed, untie the initial end from around the starting pin and tie the two ends of thread together, maintaining the uniform tension and keeping the knot near the nail. This gives a single, endless string where the stresses of use will be spread uniformly across all threads.
If you have the adjustable string jig, at this point the arms can be loosened and turned at right angles. allowing the string to be worked on more easily during the serving.
The following diagram shows the strings where they loop around the end pins where X = pin, =# is the bowstring threads, ^<v are arrowheads indicating the area concerned
----------------------------------
vvvvvvv |
==============================#< |
X#< |
==============================#< |
^^^^^^^ |
----------------------------------
Initially, the end of the serving thread is laid along the bowstring for an
inch or two in the direction the thread is to be wound, then the main spool
is wrapped around the complete bowstring (over the laid down end), continuing
to wind the serving around the bowstring and over the laid down end to
anchor it in place. The serving thread is continually wrapped around and
around the bowstring thread, each new thread immediately beside the
previous one, building up a continuous layer of thread until the serving runs
for a length of 100-125 mm (4-5 inches) along each end of the bowstring.
(as marked by the arrowheads in the previous diagram).NB. It is usually easier to slide the complete string around the pegs for several inches/cm to allow you to work on the side rather than against the pegs at the end.
Ensure that the knot which joins the two ends of the bowstring thread is within this area of serving, as it helps to protect and reinforce the knot area (nearly always a slightly weaker portion of the bowstring).
loop of -> ___________ ______ <- end of serving thread
serving thread / \ /
/ X
unserved bowstring-> =====|/=/=/=/=/=/=/=############ <- served bowstring
reversed
windings
Once all the reversed windings have been used up, the end of the serving
thread is pulled tight, which draws the final loop back underneath the
servings and anchors it in place, then the loose end of thread is cut off.
This leaves both ends being self anchoring with no knots, slackness etc.
______ <- end of serving thread
final loop __ /
of thread \/ /
unserved bowstring-> ===========##################### <- served bowstring
---------------------------------- ------------------------------
vvvvvvv | |
========================####### | #### |
X# | becomes ========######### X# |
========================####### | #### |
^^^^^^^ | |
---------------------------------- ------------------------------
### ###
#X #####=======================================#### X#
### ^^^^^^^^^ ###
(X = Pins, ### is the served string, === is the unserved string,
^^^ = area needing to be served)
Another serving, the same as the others, needs to be placed in the middle
of the string to protect the region of the string where the arrow is nocked,
where the archer's hand draws the string back and extend down far enough to
protect the string from contact with the arm guard. Determine the nocking point (string position at right angles from the arrow rest on the bow if there is one, or the string position the arrow will be held at when drawing), go up about 75 mm (3 inches) from here, then mark the string and down about 200 mm (8 inches). This length of bowstring should now be served as before giving the following final result.
### ###
#X #####==============#########================#### X#
### ###
A flemish string can be twisted far more than an endless loop type, so brace adjustment for this style of string has a much greater range.
If the brace height is too high then the string is too short, and a longer one needs to be made.
Cut this number of strands to the length specified earlier (bow length + 18"). Holding this bundle of threads tightly , use a sharp, flat edged knife to scrape the top 75-125 mm (3-5") of the bundle of threads. This is intended to wear away part of the ends, giving them a slight taper so that the threads end at different places, rather than all at one place when braided into the line. Divide the strands into 2 bundles and wax the top (tapered) ends of both bundles thoroughly for about 250 mm (10") using a block of beeswax.
Turning this loop around, lay the one of the short bundles of thread along
the main string and wax it thoroughly into one of the long bundles there.
Repeat this with the second short bundle, giving a loop formed at the end
of the string and both bundles of ends well waxed back into the main string.
From here, continue the process of twisting to the right and lay over to
the left using the groups made of the short and long strands together.
Gradually the tapered ends of thread will be braided into the main
bowstring as the bundles of thread are braided together. Hopefully the
tapering and twisting have been done smoothly and consistantly. If so, the
ends should disappear into the main string without trace.
Once the ends are braided away, you should have a pair of bundles of thread
with a single loop at one end. Wax all the remaining threads together for
the rest of their length, stretch them to an even tension and twist the
complete length of them to the left (anti-clockwise) about 30-40 turns.
Once the main length is twisted to within about 300mm (12") of the end,
fold a piece of leather over the string and rub it rapidly up and down the
full length of the string, allowing the heat from the friction to melt the
wax, making it sink deeper into the full string.
The bottom section is treated in a similiar manner to the upper section,
except no loop is (usually) formed.
Divide the main string into 2 bundles as was done at the start and follow
the above section 'Optional reinforcing for the nock loop' to add additional
lengths of thread into each of the bundles of thread, laying the non-tapered
ends even with the end of the string so that the tapered ends are further up
the string. Now, as before, twist each bundle of threads to the right and
lay it over it's companion to the left. Continue this twisting to the end
of the string, which should completely hide the tapered ends of the added
reinforcing threads. When the base of the string is reached, use thread to
tie off the end of the completed bowstring (or place a small serving as
detailed in the 'endless' string description).
After the string has been used to fire several arrows, it is likely to have stretched slightly and may require re-bracing to adjust back to the correct brace height. Once this initial stretch has occurred, it will remain that length permanently. This can be pre-stretched if you wish by placing the loop over a solid hook and stretching the string to close to the maximum breaking strain, eg a string intended to be 200 lb should be able to have a weight of 180 lb hung from it without problems which should soon remove any remaining stretch from the string.
If you desire, the 'Flemish' string may have another loop braided into the other end by the same process as the main loop, however this is not recommended as the new string will usually stretch a small amount, and it is difficult to estimate the amount of stretch that will occur, hence requiring further adjustment by twisting of the string as the stretch occurs. Most of the original 'Flemish' strings were of the single loop style.
Thanks to the following for their thoughts, comments, fixes and additions :- ap941@yfn.ysu.edu (Mark W. Thurm)
Any queries, changes, additions or abuse for this section of the FAQ to
Rob McNeur
Rob@ccc.govt.nz
