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

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

Help Support The Rocketry Forum by donating:

  1. Jun 21, 2018 #1

    BABAR

    BABAR

    BABAR

    Builds Rockets for NASA TRF Supporter TRF Lifetime Supporter

    Joined:
    Aug 27, 2011
    Messages:
    3,145
    Likes Received:
    87
    I fly pretty much all low power, and I make my own chutes, usually cut an octagon out of store shopping bags (the Hobby Lobby and Target ones work really well, Walmart bags are a bit thin.) Fold in half, fold in half again, fold in half again (1/2, then 1/4, then 1/8), then cut. Use a hole punch backed with piece of cardboard to punch the a hole in middle edge before I unfold-- so all your attachment points are equally distributed. Use paper reinforcement rings (kind you would use to reinforce paper on a 3 ring binder) around the holes. Always attach the cords to a snap swivel.

    My problem is finding a good string. I have tried Kevlar thread, at least what I have is too stiff. Kite string unravels too easy. Anybody got any good ideas? Doesn't have to be flame-proof (pretty much if it is hot enough to melt my string the plastic chute is already toast.) Needs to be moderately strong, very flexible/scrunch-able, and ties without unraveling.

    thanks,

    Tom
     
  2. Jun 21, 2018 #2

    GlenP

    GlenP

    GlenP

    Well-Known Member

    Joined:
    Oct 4, 2014
    Messages:
    1,127
    Likes Received:
    31
    Same here, I pretty much raid the recycle bin for some of the more colorful bags to make into LPR chutes (for 13, 18, 24 mm rockets up to D power)

    I use a heavy duty cotton thread for carpet or upholstery, or "button & craft," you can find this at typical craft stores with a fabric goods section. I think they have some specialty polyester threads for outdoor upholstery which would be suitable too.
     
    Last edited: Jun 22, 2018
  3. Jun 21, 2018 #3

    Gary Byrum

    Gary Byrum

    Gary Byrum

    Overstable By Design

    Joined:
    Aug 4, 2011
    Messages:
    6,189
    Likes Received:
    121
    Gender:
    Male
    Location:
    Lincolnton NC
    I use a 50 lb braided fishing line you can get at Wally World. Right now I have this weird brand, but they're pretty much all the same. It's dark green and comes off the spool a little stiff, but you can easily relax it with your fingers with a swipe or 2. This stuff doesn't fry as easily as upholstery thread or kite cord and I have yet to see it break.

    upload_2018-6-21_11-50-48.jpeg
     
  4. Jun 21, 2018 #4

    neil_w

    neil_w

    neil_w

    In search of a good winter project TRF Supporter

    Joined:
    Jul 14, 2015
    Messages:
    4,533
    Likes Received:
    186
    Location:
    Northern NJ
    Based on the one chute that Gary made for me, I would have to endorse that stuff. Looks weird but feels nice and seems quite strong.
     
  5. Jun 21, 2018 #5

    dr wogz

    dr wogz

    dr wogz

    Fly caster

    Joined:
    Feb 5, 2009
    Messages:
    4,155
    Likes Received:
    111
    Location:
    Land of Poutine!
    +1 for braided fishing line.. and you might want to use 20lb test.. 50lbs might be a bit much! but is thicker. I once had a spool of pretty thick thread. some heavy stuff for buttons & coat hems. some sewing threads will have their strength printed on them..

    My I also suggest Mylar for your chutes, not plastic. Shiny / metallic wrapping paper.. space blankets.. light, shiny (good visibility) "space age"..
     
  6. Jun 21, 2018 #6

    Gary Byrum

    Gary Byrum

    Gary Byrum

    Overstable By Design

    Joined:
    Aug 4, 2011
    Messages:
    6,189
    Likes Received:
    121
    Gender:
    Male
    Location:
    Lincolnton NC
    I am wondering how that chute is holding up. I now make them with small grommets in the corners for added strength. That sewing method wasn't quite where I wanted to go with making them. I like the new concept better. The grommets are no bigger than a standard pencil eraser.
     
  7. Jun 21, 2018 #7

    neil_w

    neil_w

    neil_w

    In search of a good winter project TRF Supporter

    Joined:
    Jul 14, 2015
    Messages:
    4,533
    Likes Received:
    186
    Location:
    Northern NJ
    It's holding up fine after 1 flight. :)

    I don't expect the APRO II to be a frequent flier, so this won't be the most stressed-out chute in the world. But I'll keep an eye on it.
     
  8. Jun 21, 2018 #8

    BABAR

    BABAR

    BABAR

    Builds Rockets for NASA TRF Supporter TRF Lifetime Supporter

    Joined:
    Aug 27, 2011
    Messages:
    3,145
    Likes Received:
    87
    I like the durability and shininess of Mylar. For my BT50 and smaller rockets though it seems a bit stiff, even when I crinkle the heck out of it.
     
  9. Jun 21, 2018 #9

    caveduck

    caveduck

    caveduck

    semi old rocketeer

    Joined:
    Jun 6, 2011
    Messages:
    995
    Likes Received:
    17
    Polyethylene of 1/3 to 1/2 mil thickness work great, if you can find the stuff that hasn't been modified for anti-suffocation. You can color it with black magic marker if it's clear. I still have a supply of red cleaner bags from way back when. For shroud lines I use nylon rod-winding thread (got last batch from Bass Pro), attached with U-Line mylar tape. No reinforcement/grommet needed at the attachment points; the mylar tape is a great reinforcement itself and is ultra thin. These days a lot of the poly has been modified; you have to test by trying to put a crease in it. If it takes a crease, it's no good and will not deploy. Modern dropcloth plastic is no good despite tempting specs and wide rolls.

    1/4 mil mylar is also great, but a little stiffer. For competition I can get an 18-20" mylar chute to deploy out of a BT-5, but not much more without using a longer tube. Same shroud lines and attachment. 1/4 mil mylar is now hard to find - at the moment Andy at ASP is the only vendor I can think of that carries it. 1/2 mil mylar is much easier to get and works great for heavier models up to several ounces, but needs a larger tube and heavier model. If packed tightly into a small tube on a light rocket it won't deploy, especially if it's chilly.
     
  10. Jun 22, 2018 #10

    GlenP

    GlenP

    GlenP

    Well-Known Member

    Joined:
    Oct 4, 2014
    Messages:
    1,127
    Likes Received:
    31
    I found the spool that I have been using recently, actually a blend of 75% polyester, 25% cotton, Coats and Clark, Button & Craft, Dual Duty Plus, several colors are available. If you are using a plastic bag chute, that would melt long before this thread would burn, still have to use appropriate wadding.
     
    shreadvector likes this.
  11. Jun 22, 2018 #11

    BABAR

    BABAR

    BABAR

    Builds Rockets for NASA TRF Supporter TRF Lifetime Supporter

    Joined:
    Aug 27, 2011
    Messages:
    3,145
    Likes Received:
    87
    I think I will try this, found it on Amazon for decent price.
    Will also try some braided fishing line.
    Thanks folks
    I will get back with results
    Tom
     
  12. Jun 22, 2018 #12

    vcp

    vcp

    vcp

    Well-Known Member

    Joined:
    Jan 28, 2009
    Messages:
    740
    Likes Received:
    25
    Location:
    Boise, ID
    So do I. Bought a roll of red cleaner bag material from a supplier 40 years ago. Must have been 1000 feet - gave most away. Was amazed that I found it the other day - about 30 feet left.
     
  13. Jun 23, 2018 #13

    sl98

    sl98

    sl98

    Well-Known Member

    Joined:
    Dec 27, 2012
    Messages:
    377
    Likes Received:
    5
  14. Jun 24, 2018 #14

    BABAR

    BABAR

    BABAR

    Builds Rockets for NASA TRF Supporter TRF Lifetime Supporter

    Joined:
    Aug 27, 2011
    Messages:
    3,145
    Likes Received:
    87
    Looks promising. Colors are a nice touch.

    Does it unravel easily? That’s the problem I am having with my kite string.
    Is it flexible? That’s the problem I am having with Kevlar thread.


    Saved the site on my IPad, will consider it after trying out above.
    Thanks!
     
  15. Jun 25, 2018 #15

    sl98

    sl98

    sl98

    Well-Known Member

    Joined:
    Dec 27, 2012
    Messages:
    377
    Likes Received:
    5
    Last edited: Jun 25, 2018
  16. Jun 26, 2018 #16

    GlenP

    GlenP

    GlenP

    Well-Known Member

    Joined:
    Oct 4, 2014
    Messages:
    1,127
    Likes Received:
    31
    I just finished a Mini Max, and thought that the body tube is plenty big enough to fit a 9.5" chute instead of the streamer. I found an image of the larger 18" chute and traced it to fit on a chute cut from the blank back side of a Target shopping bag with a Permanent Sharpie. Kind of rough sketching here, but enough to get the idea.

    DSC_7637.jpg
     
    lakeroadster likes this.
  17. Jun 26, 2018 #17

    lakeroadster

    lakeroadster

    lakeroadster

    Lone Wolf... No Club TRF Supporter

    Joined:
    Mar 3, 2018
    Messages:
    782
    Likes Received:
    76
    Gender:
    Male
    Location:
    Central Colorado
    Nicely done sir
     
  18. Jun 27, 2018 #18

    Micromeister

    Micromeister

    Micromeister

    Micro Craftman/ClusterNut TRF Supporter TRF Lifetime Supporter

    Joined:
    Jan 19, 2009
    Messages:
    15,074
    Likes Received:
    20
    Gender:
    Male
    Location:
    Washington DC
    Tom:
    I've been using 13lb 2-strand Kevlar thread for years on chutes from 3" to 48" competition 1/4mil Mylar chutes and most Custom Thin plastic sport chutes for about the last 15years. The thread I'm using comes from Micor-Mark on a 600yd spool and costs about 20.00 per spool.

    I've found the only trick to using this very thin and flexable thread is to tie an overhand knot about 1/2" from the ends of the shrouds and create a horseshoe loop under the tape disc. This knot and half loop prevent the line from dislodgging even under High Load openings. below is a pic of the spool and how I attach the shrouds to the canopies. Hope this helps.

    PS: by using kevlar it has eliminated all shroud line burn offs from my sport and compeitition chutes.
     

    Attached Files:

  19. Jun 29, 2018 #19

    BABAR

    BABAR

    BABAR

    Builds Rockets for NASA TRF Supporter TRF Lifetime Supporter

    Joined:
    Aug 27, 2011
    Messages:
    3,145
    Likes Received:
    87
    John
    I looked online under Micor-Mark, Micro-Mark, and MicroMark and I am not finding 13 lb Kevlar.

    Thread Exchange has this at 14 lbs
    http://www.thethreadexchange.com/mi...een=CTGY&Category_Code=Kevlar_Thread_Size_046

    I bought some stufff from them before (I can’t remember exactly what it was called) and it was a single fiber. Thin, dry strong, but very STIFF. It does burn through when used as a shock cord eventually if it is attached to motor mount.

    do you know of any other sources for stuff you use? It sounds perfect.

    Thanks,

    Tom
     
  20. Jun 29, 2018 #20

    BABAR

    BABAR

    BABAR

    Builds Rockets for NASA TRF Supporter TRF Lifetime Supporter

    Joined:
    Aug 27, 2011
    Messages:
    3,145
    Likes Received:
    87
    Okay, update. I found what I got in my email folder

    Kevlar - Size 92 - Bonded - Monocord - 6 Oz Spool

    Good stuff, but as I mentioned very stiff.
     
  21. Jul 6, 2018 #21

    Micromeister

    Micromeister

    Micromeister

    Micro Craftman/ClusterNut TRF Supporter TRF Lifetime Supporter

    Joined:
    Jan 19, 2009
    Messages:
    15,074
    Likes Received:
    20
    Gender:
    Male
    Location:
    Washington DC
    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.
     
  22. Jul 7, 2018 #22

    caveduck

    caveduck

    caveduck

    semi old rocketeer

    Joined:
    Jun 6, 2011
    Messages:
    995
    Likes Received:
    17
    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
     
  23. Jul 7, 2018 #23

    vcp

    vcp

    vcp

    Well-Known Member

    Joined:
    Jan 28, 2009
    Messages:
    740
    Likes Received:
    25
    Location:
    Boise, ID
  24. Jul 11, 2018 #24

    hcmbanjo

    hcmbanjo

    hcmbanjo

    Well-Known Member

    Joined:
    Jan 18, 2009
    Messages:
    2,157
    Likes Received:
    3
    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.
     
  25. Jul 12, 2018 #25

    K'Tesh

    K'Tesh

    K'Tesh

    OpenRocket Chuck Norris

    Joined:
    Mar 27, 2013
    Messages:
    11,015
    Likes Received:
    85
    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.
     
  26. Jul 12, 2018 #26

    kuririn

    kuririn

    kuririn

    BARGeezer TRF Supporter

    Joined:
    Oct 3, 2016
    Messages:
    925
    Likes Received:
    105
    Gender:
    Male
    Location:
    Hawaii
  27. Jul 12, 2018 #27

    K'Tesh

    K'Tesh

    K'Tesh

    OpenRocket Chuck Norris

    Joined:
    Mar 27, 2013
    Messages:
    11,015
    Likes Received:
    85
  28. Jul 12, 2018 #28

    lakeroadster

    lakeroadster

    lakeroadster

    Lone Wolf... No Club TRF Supporter

    Joined:
    Mar 3, 2018
    Messages:
    782
    Likes Received:
    76
    Gender:
    Male
    Location:
    Central Colorado
    Last edited: Jul 12, 2018
  29. Jul 12, 2018 #29

    GlenP

    GlenP

    GlenP

    Well-Known Member

    Joined:
    Oct 4, 2014
    Messages:
    1,127
    Likes Received:
    31
    This has been a really informative "thread" on this topic. :)
     
    lakeroadster likes this.
  30. Jul 12, 2018 #30

    lakeroadster

    lakeroadster

    lakeroadster

    Lone Wolf... No Club TRF Supporter

    Joined:
    Mar 3, 2018
    Messages:
    782
    Likes Received:
    76
    Gender:
    Male
    Location:
    Central Colorado
    :rolleyes:
     

Share This Page