jmidgley 0 #1 June 15, 2004 Hi Just curious - why nylon rather than polyester thread? Mechanical properties? UV resistance? Cost? There's bound to be a good reason... Regards John Quote Share this post Link to post Share on other sites
darkwing 4 #2 June 15, 2004 I suspect the reason is partly historical and partly engineering. Polyester has superior UV resistance, but the UV resistance of the thread is not the limiting factor on the overall UV degradation of the canopy. The fabric is the weak link there. Polyester also has different elongation parameters than nylon, and the relative stretchiness of the thread and fabric is an important part of the overall strength of a seam. I don't recall the relative breaking strength of same-sized nylon and polyester, but that may be another factor. Economics may also play a role--I don't know the cost of polyester compared to nylon. -- Jeff My Skydiving History Quote Share this post Link to post Share on other sites
nitrochute 2 #3 June 15, 2004 the stretchiness of the thread is more than likely the issue.if the canopy fabric stretches during inflation but the thread does not,then the thread will actually wear through(cut) the fabric . Quote Share this post Link to post Share on other sites
masterrig 1 #4 June 15, 2004 When I was first learning to sew, it was explained to me that cotton material was sewn with cotton thread, Nylon with Nyon, Polyester with Polyester thread. It was further explained to me that the thread has the same properties as the material being sewn. Perhaps, someone connected with the textile industry might read this thread and tell us exactly why. Chuck Quote Share this post Link to post Share on other sites
skydiver30960 0 #5 June 15, 2004 I was taught the same thing, that "like sews like" to keep a sewn piece's properties as uniform as possible. Elvisio "nylon rocks" Rodriguez Quote Share this post Link to post Share on other sites
FrogNog 1 #6 June 15, 2004 QuoteI was taught the same thing, that "like sews like" to keep a sewn piece's properties as uniform as possible. Elvisio "nylon rocks" Rodriguez I believe the failure mode of fabric sewn with thread that stretches differently is either: * thread isn't stretchy enough and takes too much load when the fabric stretches under load, and the thread snaps * thread is too stretchy and doesn't bond the fabrics together so they can act like one strong piece of fabric, and the fabric rips from excessive loading in places. -=-=-=-=- Pull. Quote Share this post Link to post Share on other sites
teason 0 #7 June 15, 2004 The answer is *DING * DING * DING*.... Joint efficiency. Using two threads with disimilar properties can adversly effect joint efficiency as the previous posts have suggested. FYI it's not just ant nylon thread, it's ticket#69 bonded "E" thread. Nylon thread is made up of many strands of nylon. By heating the nylon thread, the fibers stick together to form a single strand. Ripstop undergoes a something similar called calandering (spelling someone?). The fabric is put through 2 hot rollers and the nylon fibers are mushed together reducing the porosity, That's why it's bad to get F-111 wet. It reverses the calandering process and increases porosity. I think it also unbonds "E" thread. whenever I see thread fraying I suspect water damage. I could tell you more but I left my Poynter manuals at the DZ. Maybe that's a good thingI would rather be a superb meteor, every atom of me in magnificent glow, than a sleepy and permanent planet. Quote Share this post Link to post Share on other sites
masterrig 1 #8 June 15, 2004 Man! You get us going then... darn. Chuck Quote Share this post Link to post Share on other sites
Icon134 0 #9 June 15, 2004 Wow, I might be lead to believe you're a an engineer or something with an answer like that. I'm not a canopy manufacturer or a rigger but as a materials engineer I certainly understand the need for something as simple as "like to like" sewing. Because the different materials have disimilar mechanical Stress-Strain relationships and when applying stresses to them such as opening the Chute you would want a uniform stress-strain distribution so that no part will be more likely to fail (i.e. stress concentrations... etc...) of course I could be wrong... and wouldn't take offence if someone else says so... you know tell the inexperienced student skydiver to sit down and listen to the experts... of course there will still be stress concentrations at any joint the idea being to simply minimize them... ILivin' on the Edge... sleeping with my rigger's wife... Quote Share this post Link to post Share on other sites
teason 0 #10 June 16, 2004 Na, I'm just a rigging geek! At parties people generally start moving away from me when I start talking about the different types of string! I would rather be a superb meteor, every atom of me in magnificent glow, than a sleepy and permanent planet. Quote Share this post Link to post Share on other sites
jmidgley 0 #11 June 16, 2004 Aw. You guys, you guys. Thanks. Funny everyone should latch onto sewing canopies - I never mentioned that! But I suppose that the same consequence arises - having bought it for whatever original application, the temptation is, since you've got 1000's of metres of the damned stuff, you use it for everything. 'E' and '#69' as specifiers seem to be completely unknown in England, but M40 appears to buy the same stuff. Now, onto the differences between different kinds of string... Regards John Quote Share this post Link to post Share on other sites
mjosparky 3 #12 June 16, 2004 Quote'E' and '#69' as specifiers seem to be completely unknown in England, but M40 appears to buy the same stuff. "E" is the thread size and "#69" is the ticket number for commercial nylon thread. V-T-295, MIL-T-7807, "E" thread has a tensile strength of 8.5 pounds and "69" commercial thread has a tensile strength of 10 pounds. Type II (twisted bonded multiple cord), Class I (low elongation), Subclass A (general purpose) is best for parachute work. PPM, Vol. I Have never heard of M40. You might check with Irvin, a British parachute company that I know uses "E" thread. SparkyMy idea of a fair fight is clubbing baby seals Quote Share this post Link to post Share on other sites
Icon134 0 #13 June 16, 2004 "At parties people generally start moving away from me when I start talking about the different types of string!" I probably wouldn't do that... I'd more likely be like... "... tell me more... tell me more..." ah... the perils of being a scientist...Livin' on the Edge... sleeping with my rigger's wife... Quote Share this post Link to post Share on other sites
teason 0 #14 June 16, 2004 WOW You are my god! How about you Icon and I all go drinking! We could debate the merrits of type XIII vs. type VII and the geometric porosity considerations of overloaded reserve canopies! (ooh I love those big words!) Oh the people we could bore! I would rather be a superb meteor, every atom of me in magnificent glow, than a sleepy and permanent planet. Quote Share this post Link to post Share on other sites
