Power Kite Forum

Best way to pre-stretch lines off spool?

skimtwashington - 28-6-2014 at 08:34 AM


I have some line (Blue line brand Dyneema?)I may want to cut and make some line sets. What is a good way to stretch it besides a method I've tried before... which is to wind the end around a dowel while I wrap a length(not other end piece-just a section at a time) of line around metal fence post and yank?

Is stretching whole length at once less effective than stretching in segments?


May have asked in distant past but forgot.:puzzled:

PHREERIDER - 28-6-2014 at 09:58 AM

longer segments will have less waste, beyond the knot won't be stretched. 2 knots, all at once and your done

skimtwashington - 28-6-2014 at 10:35 AM

What knot? I just wrap it around pole/dowel half dozen or so times around itself and pull. Held from slipping by friction .


Just wondering if say I can pull a 60-80 ft piece at one end with enough pressure to 'locS-P-A-M-L-I-N-K- whole line...vs wrapping off sections..a to b(15-20 ft?), b to c, c to d, d to other end.

Seems your saying I can pull and 'set/ lock...ie: prestrech whole length at once, regardless of how you anchor other end.

I was thinking stretching segments of length exerts more stretch than over longer or whole length.



ssayre - 28-6-2014 at 10:51 AM

I haven't tried it yet, but I always thought if I was making my own lines that I would pre stretch by hooking un-stretched line to an fb kite and fly off 2 lines only until they were stretched, than make final line length adjustments. It seems like that would be easy and you could do 2 at a time.

PHREERIDER - 28-6-2014 at 06:08 PM

a 25m lines set , pull the whole 100m at once

i use bowline +single to anchor on hook and shock load about 1/3 the rating for the line, and just cut at knot

skimtwashington - 28-6-2014 at 08:08 PM

How do you 'shock load'... and know your at a 1/3 of rating..?


PHREERIDER - 29-6-2014 at 09:55 AM

free drop slegde 16# looped on the handle neck. line breaking point divide by 1/3 or 1/2 seems suitable for stretch and bedding lines.

most lines i do this with are around 1200lbs. breaking limit. fixed above (knot over head, shop beam or hoist) loop onto neck of sledge, drop (free fall NO effort) about 1-2 foot, yields about 3-400 lbs. of shock load, based on potential energy of falling mass , PE = Mass x gravity x height. these are short segments depower line, leaders and stuff.

it is gravity dependent, so you need high bar, beam, hook or something above where the hammer can fall below.

for long fly lines i set up truck bumper (or post) at distance, then saw horse type rack (or the corner turn in a fence row top beam) at decent height to transition over and loop to hammer and drop , if its tight on the drop you can push the hammer A LITTLE, a meter of free drop on 16# sledge is around 1600lbs ! (a quick guess)

line abrasion should watched, has to be smooth, solid like SS , hard plastic in contact areas

and when the knots have "bedded" or "squeezed hard" your done , hence cut them off, unless its fixation is desired

B-Roc - 29-6-2014 at 04:39 PM

Bri, when I make my own lines I do it this way:

- if its a 25m set cut the lines about 27m. Sleeve both ends (one side red the other black - for instance). Hook the sleeved ends to a fence, and walk the middle out. Stick a dowel in the middle and slow stretch 10x holding the line tight as you stretch it out. Then bounce the lines (shock load) 10x. Then stretch them 3-5 times slow and hold to feel the lines lock in. Now cut the line in the middle. Sleeve both ends appropriately as you match the lengths to each other. The tricky thing is that the power and brake lines stretch differently so matching up the four can be a bit tricky so only securely tie off one side so you can adjust until you are happy that they are even.


skimtwashington - 29-6-2014 at 11:53 PM

B-roc....

If I am going to CUT the lines in the middle after stretching...then don't you mean start by cutting lines twice the length you want(52m) to get a 25m set (extra 2 meter is assumed for sleeving loop at ends) ?

B-Roc - 30-6-2014 at 06:18 AM

Quote: Originally posted by skimtwashington  
B-roc....

If I am going to CUT the lines in the middle after stretching...then don't you mean start by cutting lines twice the length you want(52m) to get a 25m set (extra 2 meter is assumed for sleeving loop at ends) ?


Yes, you are correct. Double the length. And you are correct again in that you leave an extra meter or so to account for the folding over and sleeving. I make 6-7" loops which means I need an extra 1 - 1.5' of line per line (so 2 lines = about a meter extra).