Crackle! Snap! and Pop! Testing Thread

[IndyDan]

No this is not Kellogg’s Rice Krispies!!!

Crackle is the first sound you will hear. It’s the stress of your hammock’s material (ripstop) from one or all of the following:

1. Improper sewing or stitching technique (example: incorrect thread and/or needle size, stitching length, bobbin tension, etc.,)
2. Excessive weight in the hammock or stressing ripstop by bouncing

If you hear the crackle, then Snap is seconds away. It could be a slow motion crash to the ground or depending on failure location a quick drop back to earth.

Pop is usually associated with failure from the support systems/ridge line. If you hear a pinging noise or feel a vibration, then get ready to drop back to earth!

I want to make sure I don’t hear that crackling sound with a snap. I have begun designing a cord hammock. The sides of a cord hammock carry or bear the weight of the individual. TeeDee, Schrochem, Grizzly Adams and others have used tubular polyester webbing for sides.

https://www.hammockforums.net/forum/showthread.php?t=1676
https://www.hammockforums.net/forum/showthread.php?t=2480

And just recently, Grizzly Adams has made new and improved cord hammock

https://www.hammockforums.net/forum/showthread.php?t=3557
https://www.hammockforums.net/forum/showthread.php?t=1297

The Experiment:

Since the sides of the cord hammock carries your weight, it’s that Crackle and Snap that I don’t want to hear. I just started sewing a few months, ago. I want to make sure the edge seams will hold at least 250 pounds.

Materials List:

1. Ripstop nylon, 1.9 oz/sq yd, 70 denier; 250 lbs weight limit purchased from Speer Hammocks.
2. Three different tensile strength polyester threads: 3.5, 7, 11 lbs. And C3 Seamstick ½” Spinnaker Tape (see Chart 2).

Chart 2.pdf



Ripstop Set-up:

Material was cut 8” x 12”, all four sides were sealed; two sides were single hemmed using 3.5 lbs thread. The two ends have 5/8” hems sewed for support testing bars.



Equipment:

I used similar equipment in a posting by unknown https://www.hammockforums.net/forum/showthread.php?p=49048. I built a fixture to hold the come-along, scale and test piece. The come-along is rated to 2,000 lbs and the dynamometer scale is rated to 4,000 lbs and in calibration. The load was always steadily applied, not shock loaded.







Testing:

Single stitch using 3.5, 7, 11 lbs polyester thread
Double stitch using 3.5, 7, 11 lbs polyester thread
Single stitch with C3 tape using 3.5, 7, 11 lbs polyester thread
Double stitch with C3 tape using 3.5, 7, 11 lbs polyester thread
C3 tape, no stitch, no thread.











Results:

As you can see from the Comparison Chart, the 11 lb tensile strength thread broke at a higher limit. I used a 100/16 needle. The larger needle size did not weaken the seams. The C3 tape adds strength to the seams. As the material begins to stretch around 200 lbs, the tape helps hold the needle hole and material from pulling apart. I did test on using C3 tape with no sewing and found the tape pulled apart between 100 and 125 lbs.






or

Chart 1.pdf


The only test that did not hold consisted was the Double Stitch with C3 using 7 lbs thread, which broke at 350 lbs. After examining, I found that I missed sewing on the tape on one row (beginner-sewing mistake).


In conclusion:

Using the 1.9 oz. ripstop nylon with the rating of 250 lbs and selecting thread size (3.5, 7, 11 lbs) with or without the C3 tape and double stitch will provide a breaking range between 350 and 480 lbs., which is in above the fabric manufacture rating.


Warning …please use the suggested weight from the fabric supplier, not this test as a guideline for fabric. As you can see, the manufactures have build in a safety range.
Future testing:

I am currently testing 1.1 oz/sq yd ripstop nylon and 1.1 oz/yd ripstop nylon w/silicone treatment using the double stitch with C3 and different size threads.

[Dutch]

Great test, I don't know what c3 tape is.

[IndyDan]

You can find information on C3 on page 2.

Chart 2.pdf

[headchange4u]

Are you sewing through the tape?

[IndyDan]

You remove the paper backing, which leaves a glue base.

Seamstick 1/2" Spinnaker Tape
C3 tape is the second generation of tape for spinnaker construction. It bonds ripstop nylon seams without the need for sewing. 55 Yard Roll.

Not only does C3 tape eliminate the need for conventional sewing, it is designed to stretch slightly without recoiling. C3 seams have similar elasticity to the surrounding panels—as the cloth stretches, the seam stretches with it, making a smoother sail shape.The seams are also stronger—under high loads conventional stitching pulls and cuts the weave of the cloth thus weakening the seam. And C3 seams are lighter and more air tight than sewn seams. If any needle gumming occurs while sewing, intermittently clean the needle with an alcohol swab or use Goo Gone.

http://www.sailrite.com/spinnaker-ba...=2&category=20

[Youngblood]

You remove the paper backing, which leaves a glue base.

Seamstick 1/2" Spinnaker Tape
C3 tape is the second generation of tape for spinnaker construction. It bonds ripstop nylon seams without the need for sewing. 55 Yard Roll.

Not only does C3 tape eliminate the need for conventional sewing, it is designed to stretch slightly without recoiling. C3 seams have similar elasticity to the surrounding panels—as the cloth stretches, the seam stretches with it, making a smoother sail shape.The seams are also stronger—under high loads conventional stitching pulls and cuts the weave of the cloth thus weakening the seam. And C3 seams are lighter and more air tight than sewn seams. If any needle gumming occurs while sewing, intermittently clean the needle with an alcohol swab or use Goo Gone.

http://www.sailrite.com/spinnaker-ba...=2&category=20

Great stuff.

A couple of questions I have, if you don't mind.

1- How long did you allow the C3 tape to cure? I noticed in the video they flashed something about letting it set up for 24 hours before they did the pulling on it for their demo.

2- Your testing was with 8 inch wide pieces of fabric, do you normally normalize that over an inch or foot of width when you talk about fabric strength?

[IndyDan]

I waited about 48 hours before testing the C3. By using the C3, you don't need pins! If you make a mistake in locating the tape, you can peel the fabric apart, realign and sew.

As for your second question ... you have many variables that can effect the results. I tried to control as many, as I could. First, I was looking for strength above the suggested fabric rating. And secondly, I wanted to prove that a double stitch seam with C3 tape and 11 lbs thread would be stronger than a double stitch seam and 3.5 or 7 lbs thread. Its was more about which sewing method, than breaking strength. That being said, I have no idea if you use 8", 12" or 36" width in determining fabric ratings. But, anyway ... good question.

[GrizzlyAdams]

For my cord-edged hammock I'm using the thread you get from Ed Speer, listed with a 3.5 lb breaking strength.

I've sewn through four layers of 1.1 oz sil, using three stitches.

I sure don't want to hear the snap! crackle! pop! either.

I just love it when folks measure stuff in the interests of hammock science...keep it up!

Grizz

[BillyBob58]

Wow! Incredible test!

[Youngblood]

I waited about 48 hours before testing the C3. By using the C3, you don't need pins! If you make a mistake in locating the tape, you can peel the fabric apart, realign and sew.

As for your second question ... you have many variables that can effect the results. I tried to control as many, as I could. First, I was looking for strength above the suggested fabric rating. And secondly, I wanted to prove that a double stitch seam with C3 tape and 11 lbs thread would be stronger than a double stitch seam and 3.5 or 7 lbs thread. Its was more about which sewing method, than breaking strength. That being said, I have no idea if you use 8", 12" or 36" width in determining fabric ratings. But, anyway ... good question.

I think your testing technique was great, I'm impressed.

I did think of another question-- did the sewing thread ever break or was it always a fabric tear?