Introduction: Very Strong Shopping Bag Rope - No Tools Needed
I started thinking about rope recently after Mr. Balleng posted his rope making instructable. I also remembered this old instructable in which they made a rope from shopping bags using a giant twisting device made out of bicycle parts. Then I thought, why do you need to twist it? I think twisting makes sense if you are using a very fibrous material so the fibers can kind of grab together and get intermeshed. But plastic shopping bags aren't really fibrous, so maybe you don't need to bother with the twisting.
So I came up with this way to make a very strong rope. The cool thing about it is you don't need *any* tools to make it.
Step 1: Materials
plastic grocery bags - lots of them. You can get a lot by asking on freecycle.org. I posted a message asking for them and got enough plastic bags to make 150 feet of rope!
Figure on approximately 2 bags per foot of rope
Step 2: Flatten the Bags
Straighten out the bag and flatten it out as indicated in the photos.
Step 3: Tear Through the Middle
You can use your fingers and tear them vertically from bottom to top very easily as demonstrated in the video.
Step 4: Optional Tool: Scissors
okay, if you have some scissors around, you can just cut them en masse
Step 5: Make Strands
Tear a tiny hole in the side near the bottom seam.
Thread the handle of another section through the hole you just made.
Thread the body of the other section through it's own handle you just passed through.
Pull it tight.
Repeat until you have about 5 or 6 half bags connected together into a strand about 6 feet long.
Make at least 2 of these strands to get started. It helps if they are contrasting colors, but not especially necessary.
Step 6: Start Braiding
Take the two starter strands and wrap them around something solid. I'm using a c-clamp clamped to the edge of a table. You can use your feet though, to hold it still while you braid.
Offset their knots so that while you are braiding, the knots are not lining up together all at once (which would resulting in a much nappier rope).
Step 7: Braid
You have four strands.
The pattern is
Right two strands:
Right over left
Left two strands:
Right over left
Middle two strands
Left over right
Step 8: Splice in New Strands
Try to keep your strand length to a maximum of 6 half bags or so. Otherwise they start getting tangled and you spend a lot of time untangling the free ends.
Step 9: How Strong Is It?
It is very very strong. However I have yet to devise a test that will strain it to the point of breaking it.
Will a single strand of it support my weight? I *think* so, but I'm still working on a test for that that isn't too scary.
If I braided two or three strands of it together into a big fat rope would that hold my weight. I'm certain it would. You could probably tow a car with it.
Would I stake my life on its strength? Um... no.
Would I use to to go mountain climbing. No way.
Would I use it to save myself if I had nothing else to work with? Absolutely. Yes. it is really strong.
I'm thinking of making something out it... Still playing around with some ideas.
Step 10: Some Cautionary Statements
Many people have pointed out in the comments that grocery bags will degrade in sunlight over time.
I did think about that and pondered possible solutions - however all my ideas were expensive and laborious. E.g., what if you painted the rope with some kind of outdoor plastic paint. Or, what if I wrapped the rope in some other material that was not quickly degraded.
So, take that under advisement. This rope shouldn't be left out exposed to sunlight. It should be put away somewhere shady after use.
Maybe I will do some experiments and report back on just how long the rope lasts under various conditions. My todo list is already pretty booked though. but maybe I'll get to it.
Also, please use common sense. This was just sort of an experiment. There are no guarantees as to how strong this rope really is and whether it should be relied upon for any serious lifting or dangerous applications. Like a chain, a rope is only as strong as it's weakest section.