Laserweld Your Own Inflatables

For hiking, I wanted a small lightweight raft for crossing
rivers and creeks, that I can easily toss into my backpack and carry with me. The design should be very basic, just two layers of fabric welded together to from the tube and floor, with a valve added, like the Klymit design or the Halkett boat (https://en.wikipedia.org/wiki/Halkett_boat).

Step 1: Introduction

Nowadays you don`t have to sacrifice your rain cloak, as
there is TPU coated fabric available that can easily be welded together using a heat sealing iron.

But before building the actual raft based on my design, I
wanted to make some prototypes (inflatables sometimes behave strange I had to find out).

Step 2: LDPE

I didn`t want to use the expensive TPU material, so I
started using LDPE film (100 my thickness) I had lying around. But heat sealing iron didn`t work as expected, gluing doesn`t work with LDPE, so what could I do?

Step 3: The Problem..

Having access to a CO2 laser cutter, I thought that it might
be possible to reduce the cutting power to near zero and increase the speed to weld two sheets of LDPE together- but it either had no effect on the material at all or the laser beam cut right through it.

Step 4: Solution

Then it dawned on me: if I set the laser beam to be out of focus, it
automatically widens the beam, thus affecting a larger area and also reducing the amount of energy applied per mm². In my first try, the two sheets of LDPE film were welded nicely together.

All I had to do was move the lens holder to the top position and play around with the power and speed settings. And make sure the material lied really flat, as wrinkles affect the quality of the seam.

It is also possible to weld and cut with the same file, no
need to stop and refocus for cutting- just use more power to cut through the material, the cutting edge won`t be perfect as the beam is out of focus, but in my case it didn`t matter.

Step 5:

I didn`t stop with making prototypes for my
raft, but made all kind of oddly shaped inflatables, as you can see. You can also fill them with water, make lamp shades,wearables or ice”cubes”... there is no limits.

I use an old 60 watt CO2 laser, so the settings provided in the file attached might not work with your machine, but it is a good starting point.

Hope, you enjoyed my instructable. And packraft is next.

Comments

[Penolopy Bulnick]

Fun idea! I look forward to seeing the finished raft :)

[ralph124c]

Hi, sorry, took a while, but finally here`s a picture of the finished raft. Havent tested it yet in water, but interesting to see it wrinkles like its small scale test model.

[Penolopy Bulnick]

Really impressive! Thanks for sharing it :)

[ralph124c]

The raft is already finished, but I want to do a test ride first before I publish (in case it`s more like a submarine... ) I will let you know!

[NLBLUAL]

Hi there, this looks like just what I need! you mention that the TPU film can be easily welded together, with what sort of iron and where can you get the TPU film from??

[ralph124c]

Hi, depends on where you are living. I got my material here in Germany from https://www.extremtextil.de/. They got a wide range of TPU coated fabrics. For instructions about how to heat weld TPU have a look at https://www.diypackraft.com. They are selling packraft kits, and you can also get all kinds of fabric and stuff like valves and adhesives there. Located in Canada I think. Cheers, Ralph

[916110118xzy]

thank you! I was thinking about inflatable project for a long time but struggling about the Air leakage. I've inspired a lot from your instruction. And if you want the air bag strong enough for your weight as a boat, you may need more tests, I think. Good luck for you!

[ralph124c]

Yes, air leakage is always a problem. The intension behind the process I developed was to figure out how films or coated fabrics behave when inflated. And this can sometimes be quite surprising depending on the shape. Thanks!

[Michel93600]

Great for my project!
Do you know which width is your beam when unfocusing and welding?
Did you weld with different welding widths?
And which CO2 laser cutter do you use?
Thank you for your great article and photos.

[ralph124c]

Hi Michel,

The width of the unfocused laser beam at the surface of the material is about 1.5mm, I tried all kinds of different settings, but mainly played around with power and speed settings. I didnt change the weld widths much, but this can be easily done by increasing the distance between cutting head and material. My laser is an old chinese 60 watt CO2 laser, probably only 40 watt left...
As reference, use speed 30 % and power 25 % for welding, for cutting speed 30 % and power 60%. It also depends largely on the kind of material you use, just give it a go and you will see. Good luck and thanks for the kind words!

[jarkman]

Looks amazing!

I can't open your ECP file, can you tell me what power and speed you used ? And, what height did you set your laser to ?

[ralph124c]

Hi Jarkman,
as you can see in the first picture in Step 5, the settings for welding are speed 30 % and power 25 % (the red inner line), for cutting the settings are speed 30 % and power 60% (60 watt laser, black outline).You can do this in one go, so first the laser does the welding, then the cutting. The higher power setting for cutting makes the laser cut through the material. My laser is focused when the lower edge of the lens tube is 7,8 mm above the material, by moving the tube in the highest position its about 50 mm above the material. This works fine for me, but it depends on the machine you are using, the power settings, the material and so on. Sorry you couldn`t open the ECP file, I used Lasercut 5.3 for it.

[jarkman]

That's perfect, thanks!

[Robot Boy]

Where did you get the LDPE film? I guess I don't understand what 100 thickness is.

[ralph124c]

Hi, 100my thickness means 100 micron or 0,1 mm. For example, the material of a ziploc bag is about 40 my. But it doesn`t have to be 100 my, there is room for experimenting. I got the material from ebay, but it should also be available at home improvement stores, look for dust cover or constuction foil. Make sure it is Polyethylene, never use PVC- this would ruin your laser and your lungs...

[Makerneer]

Interesting idea, looks like it works well! I think this needs to go on my list of things to try, thanks for sharing!

[ralph124c]

You`re welcome. Once you get the settings right it works quite reliable. Just make sure the plastic lies flat. It`s a very easy and cheap process.. well, not the laser obvioulsy, but the rest :)

[Pave Workshop]

Very cool concept

[ralph124c]

Thank you very much!