Low Power parachute shroud lines--- best string/thread

Discussion in 'Beginners & Educational Programs' started by BABAR, Jun 21, 2018.

  1. Jul 6, 2018 #21

    Micromeister

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    Sorry: Just checked both of my sources. neither are showing the 13lb two strand Kevlar thread anymore...so Sad!
    the unbonded 2-strand is much more flexible then the bonded monocord. it actually gets softer the more it is flexed.
    the other source was Edmund Scientific (www.scientificsonline.com) but the old stock number V34-863 is no longer valid.
     
  2. Jul 7, 2018 #22

    caveduck

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    Hey John, Superior threads has tex 40, 60, 80 spun (not bonded) Kevlar thread here: https://www.superiorthreads.com/thread/kevlar
    Strength is quoted as 5-6 lb for the 40/60. Any chance this is more or less a match for the old Micro-Mark stuff? One spool would be a lifetime LPR supply for a whole club. :D
     
  3. Jul 7, 2018 #23

    vcp

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  4. Jul 11, 2018 #24

    hcmbanjo

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    Try some #10 100% cotton embroidery thread. It's strong, soft and won't melt like some polyester blend thread.
    You can pick up a big roll at Hobby Lobby or Michael's.
     
  5. Jul 12, 2018 #25

    K'Tesh

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    I have it on good authority that a vendor used to use Coats & Clark Dual Duty Plus® Button & Carpet Thread for their LPR shroud lines... After a few changes with the vendor in question, I suspect that they still do.
     
  6. Jul 12, 2018 #26

    kuririn

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  7. Jul 12, 2018 #27

    K'Tesh

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  8. Jul 12, 2018 #28

    lakeroadster

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    Last edited: Jul 12, 2018
  9. Jul 12, 2018 #29

    GlenP

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    This has been a really informative "thread" on this topic. :)
     
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  10. Jul 12, 2018 #30

    lakeroadster

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    :rolleyes:
     
  11. Jul 15, 2018 #31

    BABAR

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    C’mon, stop stringing us along.
     
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  12. Jul 15, 2018 #32

    K'Tesh

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    I hope ThirstyBarbarian sticks his head in here... He always keeps us in stitches...

    If not... I'm sew over this.
     
  13. Jul 15, 2018 #33

    Klatuso

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  14. Jul 16, 2018 at 4:01 AM #34

    BABAR

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  15. Jul 16, 2018 at 11:48 AM #35

    vcp

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    Surprised I didn't think of this sooner, since my wife has tons of it hidden somewhere. Beading line. It has to be small, tough, and flexible. It says it's braided, it looks and feels like Kevlar.

    The good news is that you should be able to find it at any craft/beading store. The bad is that calling anything 'beading' really jacks the price.

    Wow! Not Kevlar. Hold a match to it and it evaporates like smoke in the wind. Flame ran up it so fast it might be a reasonable alternative for fuse. I thought it might set off the whole spool.

    Leaving this here so no one else is tempted to try it.

    Edit: That's funny, I just noticed it's called 'Fireline' and the color is 'smoke'.
    20180716_040411.jpg
     
  16. Jul 16, 2018 at 8:54 PM #36

    Micromeister

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    VCP You are so right! Most of the newer Fishing lines are Spectra Microbraids which are all very heat sensitive. I've tried SpiderWire, ProBraid, and several Burkley brands with the same Instant Poof results.

    I did a little more digging looking for the 2-strand Kevlar thread. here's what I came up with. Scientifics Direct no longer carries the spools DEEEEEEERATS!
    however www.thethreadexchange.com has two products that should do the job. I'm not sure if the 6lb is one or two strands but the 14lb has been told to me to be 2-strand.
    1: Kevlar Size 23 (tex 21) .006" dia. 6lb test Natural yellow #Kev023natloob 1/2oz spool = 780yds @ 11.00
    2: Kevlar Size 46 (tex 40) .008" dia. 14lb test Natural yellow #Kev046natloob 1/2oz spool = 312yds @ 8.00

    Since I haven't seen these threads other then the websites photos I can't say for sure if these threads are or will be as soft as the 13lb stuff I have but both above are more than sufficient for LPR rocket chutes. I'd use the 6lb for chutes up to 30inches and the 14lb for larger. also the 6lb stuff looks like it should get softer as it is used.
    Hope this helps a little.
     
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  17. Jul 20, 2018 at 4:42 AM #37

    BABAR

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    Thanks John. I have followed some other suggestions and gotten the cotton embroidery thread (looks like what Odd’l Rockets sends with their kits) and it looks like good stuff.

    Also got some braided fishing line and it looks strong and flexible.

    Obviously neither is flameproof.

    So I I’ll try the Kevlar from thread exchange too. Maybe best of all worlds.

    Was thinkin’ a bit, though. For plastic parachutes (either from vendors or made of garbage bags or shopping bags) if you don’t have good wadding or baffle or piston, doesn’t matter how good the shroud line are, if the flame gets up there your chute is a wadded up ball of singed plastic. The SHOCK cord is another matter, especially if mounted on the engine mount. I have seen you have used wire fishing leaders as well as Kevlar on some of your posts.

    Has anyone ever done NAR report on “how far” the torch effect of the black powder motor ejection charge extends up the body tube? Put another way, How long would the wire fishing leader need to extend forward of the front of the motor casing so there was no significant effect on the attached non metal shock cord?

    Estes got away with the elastic partly by attaching it on the front end with the trifold mount. I have always hated those because I think the inside of the tube where the laundry goes should be as smooth as the proverbial baby’s behind. Plus even if you mounted it forward, you still need to make sure you had enough wadding to keep it from dropping down right in front of the motor casing.

    Anyway, I’ll order some of the braided Kevlar. Thanks!
    Tom
     

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