Though you guys might find this interesting, and find a possible use for it in sleeping pad construction, this guy made an inflatable polyethylene and used the top of a soda bottle to make the valve. It's pretty clever, and definitely MYOG style.

http://www.geocities.com/reystos/inflatable/index.html

Edited by debiant on 07/17/2009 14:41:10 MDT.

link?

forgot something didn't I, original post is fixed with link now... He also has properties of different plastics for making inflatables, which is very interesting. Found a source for both polyethylene and polyurethane film which is supposed to have pretty good properties... I don't know how well it would hold up, but it's fairly cheap...

http://www.fiberglasssupply.com/Product_Catalog/Vacuum_Bagging/vacuum_bagging.html

Maybe if Bill reads this he'll have some words... I know his testing of polyethylene met with limited success, but it appears polyurethane film is stronger with less air penetration after repeated usage.

Thanks for the link Gary...a while back I was looking for air valves on the net but didn't come across any. This is a great alternative.

Putting two and two together (heat sealing cuben + MYOG valves) leads me to believe we'll see a SUL inflatable mat in the near future? :)

Well that is my intention, I really don't want to pay retail for the Cuben, so I'm trying to get it from the manufacturer, as I had read that Bill was able to accquire it at a minimum of 9 yards much cheaper than from other sources. I would like to experiment in several ways, possibly with the polyurethane film as an inner core and the cuben as a protecting outer layer, or if possible a double layer cuben air mat (for durability). It will be interesting to see.

Steve you mentioned bonding cuben, what is the best method you have come across and is this an airtight seal in case heatsealing it is out of the question (which appears as if it may be)

I contacted Big Agnes to find out the thickness of the polyurethane they use, the 2 mil Stretchlon 800 that I have found I calculated at 1.7 ounces per square yard, so it's much heavier than cuben and would probably weigh in at about 5 ounces, add a cuben cover and we're looking at 7 or 8 oz (including the valve) for a full size air mat... 20 x 70. Of course if I could make an air mat entirely out of cuben we could be looking at less than 4 or 5 ozs even with a protecting outer layer.

I think this will be a neat project, and it will mean I have lots of cuben for other projects as well.

hehe...

I have purchased direct from Cubic Tech. It works out to be about 5 bucks cheaper for me then buying from the retailers. Just send them an e-mail and they will sell you a 9 meter panel.

I posted a thread here about bonding cuben fiber a while back. I tried numerous different techniques. It worked VERY well for me and was fully watertight...but air may be a different story. You'd have to give it a try but I think it should be good. The link is really long so just search for "Cuben Stuffsack - Bonded" and it will be the first one. I still think that heat sealing is worth a try if you have the equipment...it would make life easier and I think you would probably be the first...at least that I know of.

Keep us posted as any mat in the 4-5 oz range would have a huge interest.

Edited by Steve_Evans on 07/10/2009 22:00:21 MDT.

I also just bought two 9 meter sections of Cuben from Cubic tech. Price has gone up since my last try. It is now running 19 and change per yard.

I have been contemplating the air mattress with cuben for a while also. I agree with Steven. Bonding cuben with a urethane bond works extremely well. The problem with bonding is peel strength. The bonds/heat seal you see on air mattresses put all the joints in peel. I don't believe the bonds will hold up. I have also been thinking about heat sealing. It seems like good news to me that the material will stick together with heat sealing. That may mean it is just a matter of proper settings. There are four layers that have to be melted together in a cuben/cuben heat seal joint plus ideally the spectra fibers, Otherwise it will fall apart.

I think I have a way to make individual bonded air tight tubes but then they all have to be filled separately and held together. Kind of a pain.

The problem with bonding is peel strength

Scott has got it right. If you mimic the seam style of a typical air matress (placing all seams in peel), you will most likely have failed seams. Check out my thread on the bonded stuffsack and look at how all the seams are placed in shear. This produces a much higher strength joint.

The cuben fabric and Hysol adhesive is very strong, but like anything else that is built, you have to work around the limitations of the materials.

That may mean it is just a matter of proper settings

I also agree. Actually, if you have industrial equipment, you might want to give them a call and see if they have any heat sealing procedures in place. They are the ones that gave me all the bonding information that I ended up testing and using.

Gary,

Nice find on this link. I think I have thought of a way to improve on this and get rid of the cap. This is exactly the piece missing for me. I was planning to use a similar approach using the flex air pillow valve. I now think the cuben air matress is completely doable for somewhere under 7 oz.

I will post more after I try it and see it it works.

That's great... glad to hear that there are some other people out there that think if we can have a 1 oz pack we ought to be able to have a lighter sleeping pad.

One interesting thing that the OP in my link did do when he heat sealed the PE was to use paper tape on top of his seal to keep from burning through, I wonder if a similar process could aid in the heat sealing of Cuben...

Gary,

I agree the tape idea was a good one. I may give it a try.

I made a sample of one end of the tube using a bonded end cap. I am going to have trouble getting it off my mandrel. I think this will work on one end but I am stuck on the other end. Possibly Steven's cuben stuff sack method is the the answer.

> when he heat sealed the PE was to use paper tape on top of his seal
Thin Teflon film actually works even better.

Cheers

Much appreiciated.

Steve, could I ask what product line of Cuben you tried to heat seal?

Edited by debiant on 07/09/2009 09:09:02 MDT.

Hey Gary, are you referring to the weight of the cuben? If so, I tried it with the 0.33 and the 0.6.

If I get some time later today, I'll dig up the pictures I took to give you a better idea of what was happening.

I got an email from CubicTech and it says:

"Our light materials are not heat sealable. You may want to try the 3M tape 9485PC... this is what most hobbyist use.

Depending on your application, CT1K.08 may suit your needs for inflatable but if the item is going to see a lot of abuse, you will likely need to go a step or two heavier."

So it looks like bonding is going to be the way, as they do not discount the use of Cuben for inflatable purposes.

As an addendum, this is a chart displaying different properties of various 3m adhesive tapes...
http://multimedia.mmm.com/mws/mediawebserver.dyn?6666660Zjcf6lVs6EVs66S8PCCOrrrrQ-

the 9485PC is displayed to have a very high peel resistance... That being said, beyond peel cleavage is also a primary concern with an air mattress no?

Edited by debiant on 07/10/2009 22:59:06 MDT.

The 3M9485 transfer tape holds together many of the worlds top racing spinnakers. I use it myself: it has unbelievable holding power.

Cheers

Gary,

Here is my prototype 3 in diameter tube. One end is made with Stevens cuben stuff sack method the other is end is made with a 6 inch diameter circle wrapped over the end of mandrel. I had several leaks from the small folds in the material this causes. I thought I could improve on the one way valve using an O-ring and neoprene fender washer and a flanged nylon bushing as the fill tube. This isn't working although I am hoping it is because I was in a hurry and the O-ring an nylon bushing are interfering with each other. I still have patches curing and I need a cap for the bushing. Once I get it to hold air I will test it for burst.

I have bonded the whole thing together with Aqua seal.

When you do the inflation test. Looks good though!

Scott:
I've got some cuben ordered, and we'll see what we can do. My first attempt should be a dual chamber ordeal but in a very small scale say 8" x 12" with the same valve system we've discussed.

Roger:
I've also ordered some 9485pc at Roger's referral, Roger do you have any recommendations for application? The more pressure I apply the better for adhesion? Also I read on a data sheet for this particular adhesive that the bond actually improved after submersion in water, which I find interesting, and it just so happens I have a spare bathtub that never sees any use except for washing gear.

Steve:
I was referring to weight yes, but as the likelihood of heat sealing has been severely diminished the discussion would be moot. I hope to have some pictures to share in a week or so.

Edited by debiant on 07/11/2009 19:25:51 MDT.

Got my Cuben today. I taped everything up and I have what looks to be a two chamber air pad. I left a small hole in one seam to fill it with a straw, and have used a potato chip clip to seal it shut once I inflated it. I'm allowing the seams to bond right now under pressure, but I will have pictures here shortly. It's looking good. I will explain the process once I have pictures up.

I bought one of these a while ago, with a possible view to use as a lightweight meths bottle. The valve seems very air-tight, and the pouch must be HDPE or PP.

I'd imagine that a heat-sealed joint might be achieved with a number of other materials to add a valve to an inflatable thing.