12/20/2012

Tyvek Backpack

One night while reading Wired Magazine i saw a picture of this:
hyperlite mountain gear metro pack backpack cost make diy how to

It's called the Hyperlite Mountain Gear Metro Pack and cost $128.  It's appeal is in that it's light weight, has a large carrying capacity and is waterproof.  So i looked at all the pictures and decided that it wouldn't be too hard to make. 
tyvek backpack camping how to make diy waterproof bag

The best part is that i knew exactly what material they used, Tyvek.  About a year ago i bought a 36" x 150' roll of NovaWrap Tyvek material.  I used it to make a Parafoil Kite and as a waterproof barrier for my Backyard Pond.  It has tons of uses and it's great to have a roll sitting around.
tyvek, novawrap, how to make camping equipment, tarp, waterproof, breathable

Tyvek is great for several reasons:
  • cheap
  • light weight
  • waterproof yet breathable
I also learned from the previous kite project that there are two good ways to construct things out of Tyvek, tape or sewing.  While making the kite i tried 4 differently types of tape and found that clear packaging tape worked the best.  It seemed like the clear tape was able to adhere "into" the fibers of the Tyvek.  Click on the parafoil kite link above to see more information about the 4 different tapes i tested.

But i decided that the best way to make the backpack was to sew the pieces together.  I used a heavy cross stitch with nylon thread to make sure the seams didn't split apart.  Although i did use several small pieces of the clear packaging tape to hold the Tyvek together while i was sewing.

I started like i always do, with lots of drawings.  Here's one of the many sheets i drew up, with ideas and materials i thought about using.  I was trying to work out what buckles to use, if i wanted a waist strap or chest strap and how to attach the straps to the bag. 
backpack plans, instructions how to make, sew, build, camping bag

I decided that the goal of the backpack was to be small, lightweight and compact.  Therefore i opted not to add a waist strap or chest strap.

I forgot to take pictures at the start of the project.  But the main part of the bag itself was made with the full 36" wide tyvek material folded over on itself, sort of like a tube.  I'm not sure how tall i made it, i just kind of eyeballed where i wanted it to sit on my back and how high it would be at my shoulders.  (taking into account that the top 6" or so would be rolled up and buckled)  But here's what it looked like after i cut the main pieces out and sewed some of them together
 material to make camping equipment, backpack, bag, tent, tarp, tyvek

This is what the bottom of the bag looked like.  It's basically just like wrapping a Christmas present.  I sewed along the entire seam, then folded it over to the center on both sides.  Then i sewed again along each edge of the fold.  It all made for a very strong joint, which is good because the bottom of the bag is where all of the weight of the bag will be focused.  The other nice thing was that it made a flat bottom of the bag.
 tyvek, house wrap, backpack, sew bag, make camping hiking

For the shoulder straps i was originally just going to cut some off of an old backpack of mine.  But i decided to try and make shoulder straps of my own.  And i have to say that i'm glad i did, it wasn't really that hard.  Luckily i had some 1/2" foam in the basement, which i used as the core of the shoulder straps.

I used one of the shoulder straps from my old backpacks as a template.  I layed it on the Tyvek and traced out the shape.  I had to cut out 4 pieces from that pattern, front and back for each strap.  The hardest part was sewing the final edge and making sure the foam was pushed in tightly.
 diy camping how to backpack arm shoulder straps, padding, foam

Referring back to some of the pictures at the original Hyperlite Mountain Gear Metro Pack i knew that i needed an additional piece of Tyvek for support to attach the backpack straps.  If i just sewed the shoulder straps to the single layer of Tyvek it might rip under heavy weight.

 diy how to make a homemade camping backpack, tyvek, waterproof, house wrap, sew

Here it is just before sewing the straps on.  To make sure they were on securely, i sewed back and forth about 5 times, or until the needle jammed.
attach, sew shoulder straps to bag, backpack, construct

At this point it looked pretty good, but i still had some tricky bits left. 
diy hyperlite mountain gear bag, tyvek, sew, plans, make

I really liked how simple the top of the original bag was secured.  All it needed was a buckle sewn at either side near the top.
homemade backpack buckle, how to make

You can see from the first two pictures that the top is rolled up and then these buckles pull in and clip to each other. 
how to make a hyperlite backpack, save money, cheap, water proof camping equpment

No need for straps or ties, this simple and strong method works great. 
simple and strong backpack top, buckle, fold, seam

The last step i had to figure out was how i was going to make the straps and buckles, which attach the shoulder straps to the backpack.  Here are the buckles on two of the backpacks i have.  They are made of pretty strong plastic, they have three slots for the straps to loop through.
backpack buckle, buckles, plastic, strap, camping

I decided not to "reinvent the wheel" but i didn't like the original design.  I thought that i could make it work with just one cross bar instead of two.  It would be stronger but it meant that two straps would have to go through the same slot.

I couldn't decide what material to use so i made both.  The two buckles on the left are made out of thick Lexan.  (Plexiglass)  The two on the right are made out of aluminum.  I really liked the plexiglass, it was easy to work with and looked good.  But ultimately i decided to use aluminum.  It was only a tiny bit heavier then the plexiglass but a lot stronger. 
homemade backpack buckles, how to, lexan, plexi glass, aluminum

I did round off the four corners and smooth the edges, since my arms would be swaying as i walked and most likely brushing against the buckles.  I used a couple different metal files/rasps and finished with 220 grit sand paper.

how to make aluminum backpack bag buckle, file, metal, round, sand

Next i looped the straps through and sewed them by hand. 
sew straps to buckles for backpack bag

As you can see these are what transfer the weight from the shoulder straps to the aluminum buckles.  The reason why i made those two little humps with the straps is still a mystery to me.  It's like that on all of my backpacks.  I know that it's suppose to be a place where you can attach things like a compass or water bottle, but i've never actually used them.  Ultimately though i thought that it makes it more professional looking so i copied the design.
attach, sew straps to bag, through foam, padding, backpack

This is how the straps attach.  You can kind of see that the slot on the right has two straps going through it.  This is where i changed the design a bit.  Normally the buckle has three slots for the three straps.  But i think this is just as good, if not better. 
how to attach backpack strap to buckle, loop through clasp, strap

I sewed the other end of the straps to the bottom of the bag by hand.  Again i made sure that they were securely attached since they would be carying all of the weight.
sew bottom of backpack bag, strap, tyvek, waterproof, hyberlite,gear

And that's it, the backpack was done.  It ended up taking just a few days to make.  Mainly because i had to buy the white plastic buckles and i was designing the details as i went along.  If i had to make another one from start to finish it would take about 4 hours.  Cutting, drilling and filing the aluminum buckles did take some time though, so it might be a little longer. 
homemade hyperlite mountain gear backpack bag, tyvek, water proof material

Here i am wearing the backpack.  I put my sleeping bag in the backpack, nothing heavy.  It was fairly comfortable but i did notice the small bit of folding horizontally where the shoulder straps attach.  I didn't think it was a big deal though.  You can also see the seam i sewed running up the back.
waring the hyperlite mountain gear bag, diy, homemade, camping bag

Here it is from the side.
test, side view, wearing, hyperlite mountain gear bag, rate, rating

I had to keep reminding myself that whole point of this backpack is to be light weight and compact.  It's not going to replace my big camping backpack.  It doesn't need all the side pockets, waist straps, zippers and things.
full, carry, weight, hyperlite, mountain gear, bag, backpack

This is what it looks like all folded up.  It's super compact and would be a great thing to put in your trunk or to take with you as a spare bag on a trip.
fold up, diy, camping backpack, how to make, compact

I haven't tested it yet, but it should be somewhat waterproof, probably more like water resistant.  I mean if you fell in a river while wearing it i suspect that water will get in through the top and some of the seams.  But if you wear it while it's raining i don't see why anything will get wet.

I may end up making some other bags, probably not backpacks though.  Just simple, smaller bags with the same buckles at the top.

7 comments:

Anonymous said...

Have you tested out some decent weight for it yet by chance?

Sweet design man!

Dave Wirth said...

No not yet. It's still just folded up in the closet.

I don't think it would be ideal if you are carrying a lot of weight. It's drawbacks are that it doesn't have a waist strap and the back support isn't rigid.

I guess the real advantage of this bag is that it's strong, waterproof, light weight and can fold up to almost nothing. I could have added a waist strap and still kept it pretty light.

This is still just sort of an emergency/backup bag that i might carry with me or keep in the trunk of my car. If i intended it to be my primary backpack that i hike with for several miles i think that i would have added the waist strap and looked into how to add two curved aluminum or wood back supports.

Actually it might not have been too difficult, just sewing two channels in the back part. I probably would have also added a chest strap, pockets for water bottles on either side, maybe some more zipper pockets and straps too.

Also a week after making this bag i made a small 12"x18" square one using just the clear packaging tape. It worked great, so you might not have to sew it together at all.

-Dave

Anonymous said...

Nice design. If you have a foam sleeping pad you may be able to roll it into a cylinder to give structure to the back and walls.

Dave Wirth said...

Ya that's a good idea.

The one thing i noticed after i made the bag was that it didn't hold it's shape very well.

Unlike most big camping backpacks that have some sort of metal frame for your back, the tyvek bag was very flexible and had those stretch marks from the shoulder to the bottom.

Anonymous said...

Hyperlight uses a material called cuben fiber. It's produced in a similar way to tyvek but is far stronger. Definitely not the same thing.

here is a link to the tech section of their website: http://www.hyperlitemountaingear.com/technology

Sweet repro though!

Vonda B said...

Try Dupont Tyvek still light weight water and windproof ,try carpenter tape or some call it carpet tape (tape will out last tyvek)instead of sewing it keeps seams water proof. and velco closing. Dupont Tyvek (Lowes or home depot have it)can be used for bigger bags. Run thru washer (cold water only & no soap) cuts down on sound but still water and wind proof.

@coldasroman said...

oh wow! Recycle & DIY for life! Keep it up!