Zipper alternative

[Colin Krusor]

I'm working on an MYOG packraft, and I need some kind of strong fastener to hold two long edges of fabric together. Coil zippers, snaps, and hook and loop are not strong enough. So I purchased some molded tooth (delrin) zippers and, when they arrived, I weighed them. Seven ounces in zippers alone. So, I need an alternative.

I have some tiny (bracelet-sized) 3/8" side release buckles. I'm considering using these, with grosgrain, at 6" intervals to bear the load, with a strip of 1/2" wide hook and loop to keep any gaps closed. I would guess that a series of hefty buttons would be heavier due to the necessary reinforcement.

Are there any other kinds of fairly strong, lightweight clasps that I could consider?

[Colin Krusor]

It also occurred to me that I could use a series of Mandarin-style "frog buttons", where each one is essentially a nacrabiner/soft shackle, like this:

Has anyone attempted to use unusual kinds of fasteners as an alternative to zippers, snaps, or hook and loop?

[Troy Ammons]

How about nacro biners

[Bradley Attaway]

I anticipate using small rare earth magnets to attach my underquilt to the hammock I'm making. Seemed to work well in my backyard.

Each magnet pair requires about 3kgs to separate, more than enough to hold. The 8 magnets, in total, weigh approximately 24g. Cost for 10 round magnets was roughly $8 on Amazon: http://www.amazon.com/gp/product/B001KV38ES/ref=wms_ohs_product?ie=UTF8&psc=1

Just gotta be careful to keep them away from my phone when I'm on the trail ;-)

[Colin Krusor]

Bradley, I thought of magnets, too. I like the idea for the sleek simplicity of the design, but for a structural fastener on a boat, I think I would need magnets about ten times stronger than yours, and I would need a lot of them. Even with grade N52 rare earth magnets, I think it would be quite heavy. I haven't done the calculations, but I think small side-release buckles would probably be much stronger per unit weight.

I have always liked magnetic closures, though. They are the most durable, the least fiddly, and the most cosmetically tidy of all fasteners.

[David Scheidt]

Stitching.

What's the actual application and what are the expected forces?

[Colin Krusor]

David, I'm happy to attempt to explain my somewhat half-baked idea for this packraft project, but I don't understand how stitching is an alternative to a zipper, in any application.

Maybe one of us has a basic misunderstanding of what zippers and stitching do.

[Ryan Smith]

Have you tried any of the various high strength hook & loop? I used some 1"x2" pieces to mount a nitrous controller on my T/A that was pretty difficult to separate by hand. It actually snapped together as opposed to whatever velcro normally does. Granted, I don't really know what your application is so this may not really help.

Ryan

[Daryl and Daryl]

Colin,

"I have some tiny (bracelet-sized) 3/8" side release buckles. I'm considering using these, with grosgrain, at 6" intervals to bear the load, with a strip of 1/2" wide hook and loop to keep any gaps closed"

I don't think I could improve upon this combo.

Daryl

[Jesse Anderson]

What about some kind of system where you either attach a series of small rings via grossgrain or else small eyelets in the material itself. Then you could run a small, strong length of cordage through the rings/eyelets and lace the whole thing together. Don't know if that would work for what you have in mind, but it's probably as strong as any other connection you'll find. Of course, deployment could take a bit longer.

[Colin Krusor]

Ryan, I think hook and loop is an attractive option. I've considered looking for stuff like you describe. I know there is very strong hook and loop, although I've read that durability is negatively correlated to holding strength. The strongest hook and loop materials, I've heard, last only a few hundred cycles before the holding strength drops off. I'll keep it in mind, but right now I'm leaning toward options like buckles that might withstand use better.

Jesse, I agree with you. Lacing would be the lightest and strongest option. I considered attempting to install bootlace hooks that loops of cordage could be looped over. The only general problem I see with lacing is the one you referred to: the fiddle factor. I might find it tedious to run laces through a bunch of hooks or eyelets every time I want to use the boat. But that option is pretty durable and it definitely wins for light weight and strength.

I'm inclined to agree with Daryl at this point. A combination of small buckles and a non-load-bearing hook and loop flap seems to be the best option overall so far. Although lacing, strong hook and loop, and magnets all have their advantages.

[David Scheidt]

No, I suspect we both know what zippers and stitching do. It's just I don't understand what part of the raft you're talking about, nor why it needs to come apart. Knowing that would help to figure out what would be a good alternative.

There are a surprising number of high-strength hook and loops around, which tend to optimized for particular uses. There are three ways H&L things comes apart: peel, shear, and tension. H&L optimized for one often does poorly in the others.

[Franco Darioli]

A bit slower but a lot more secure version of the frog buttons is the Dutch Lacing.
This is how it's done :

[David Olsen]

Someone posted making super light buttons punched from the top of caps of water or pop bottle lids. Then using a bit of gross grain with hot cut slits sewn to the other side. A hot cut slit in one side of the velcro with a button stitched to the other side might be a possibility at stress points. Maybe too fiddly.

[Tim Marshall]

snaps, dependiong on your application and the direction of pull (the biggest factor in snap connection strength) a tiny snap can handle a serious load. I use size 20 kam snaps on my quilts and you can tear the tabs out before the snaps release, not what i was originally going for but they sure hold well. But if you pull it at the right angle it takes a tiny amount of force to open it so it really depends on the angle of pull. You can get much larger snaps than the size 20 too im sure

-Tim

[Colin Krusor]

Franco, that Dutch lacing is clever and it looks very secure.

I think, so far, it sounds like mini buckles and a lightweight hook and loop flap might be the winner for strength, low weight, and simplicity of use (relatively low fiddle factor).

The application to my little packraft project is a bit difficult to explain, and I'm not sure it will work, anyway. So, rather than post a lot of illustrations and try at length to explain it, I'll just post photos when I have something to show.

Thanks to everyone for the input.

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