Introduction: Tough, Lightweight and Waterproof Gear Bags From Dyneema and Tyvek
In this tutorial, I'll show you how to make a variety of useful zippered gear bags that are incredibly tough, lightweight and waterproof.
This tutorial is intended for someone like me: familiar with rapid prototyping tools like 3d printers and laser cutters, reasonably competent with hand tools, but pretty clueless about sewing and sewing machines beyond emergency repairs and hemming the odd pair of pants.
I promise that after less than an hour of trial and error on a sewing machine, you'll be able to create out an endless variety of useful stuff. Making clothes on a sewing machine is HARD. Banging out awesome gear on a sewing machine is EASY.
If like me you come from working with additive or subtractive rapid prototyping processes, you will discover that fabric has all kinds of mind-bending topological properties, meaning you can fold, scrunch and invert it in ways that allow you to conceal your sewing ineptitude.
We use some fancy gear--including an electric hotknife and a heavy-duty industrial sewing machine--but mostly to save time and labor. With a little persistence and creativity, you will be able to reproduce almost all of our steps with even the most basic sewing machines. If you want to have a bag right this instant, we are also offering some as rewards for supporting our Kickstarter campaign.
NOTE this Instructable is a draft! Help us make it better by putting your suggestions in the comments!
Step 1: Three Basic Gear Bag Designs
There's little novelty in basic bag design--once you understand the archetypes, you'll see them everywhere (and after you make a couple yourself, you'll be shocked by the prices). After some experimentation, we've identified our three favorite bags.
- The flat top-zipper case is useful as a pencil case, for wrangling snarls of USB charge cables and for protecting a passport and plane ticket from sweaty pockets and tropical downpours.
- The flat front-zipper case works as a document holder, a case for chunky gear and as a waterproof/bugproof sleeve for travel-size laptops.
- The duffel bag is perfect for keeping work clothes dry on your bike commute, as an overnight bag on short trips and as a bug-out bag for doomsday fantasies.
In general, I avoid projects that require lots of sewing skill because I have none. I've found that size and detail are the key variables: a small wallet with lots of little pockets is a nightmare. A giant set of drapes can be a hassle to feed through the machine unless you have an equally gigantic work surface. Our three favorite bags offer high utility and low fabrication complexity. I find the flat front-zipper case to be the easiest to build, and the duffel bag the most complex.
Step 2: Materials
We make all of our field research gear bags out of Dyneema (brand name of ultra-high-molecular-weight polyethylene, aka UHMWPE or UHMW, also sold as Spectra and cuben fiber). Dyneema is a composite material that is roughly twice as strong as Kevlar at half the weight. William Gibson described Dyneema as "sort of like if NASA made waxed paper." Popular with both high-performance sailmakers, ultralight hikers and the military, Dyneema is UV-resistant, tear-resistant and 100% waterproof. I bought a cuben fiber wallet in Hong Kong five years ago and after loads of abuse it still shows hardly any wear.
For the exterior of all the bags, we use a single layer of composite fabric, with a shiny inner lining of 48 g/m^2 Dyneema bonded to a matte outer layer of 50 dernier polyester. We've only found this material in grey and black. As far as fabric goes, Dyneema isn't cheap but a home-made bag will cost a fraction of a similar factory-made bag from Your Favorite Outdoor Company.
For the middle layer of the duffel bag, we use 62 g/m^2 Tyvek, the same material used in your home's vapor barrier, in tear-proof envelopes and in a million DIY wallet and kite projects. Tyvek is stiff and folds like paper, so helps the duffel bag keep its shape. Tyvek is hard to rip and relatively puncture-resistant, but it will pill up and get tatty over time if it gets a lot of wear.
For the duffel, we sandwich the Tyvek between the outer layer of Dyneema composite, and an inner layer of thin and nearly transparent 34 g/m^2 Dyneema. The thin Dyneema lets you see the Tyvek logo, which is useful for hipster cred, and in general makes for a bright bag interior that makes it easier to find stuff. We've recently started experimenting with replacing the inner Dyneema layer with mustard-yellow Robic XL ripstop nylon.
- We assemble the bags on our industrial sewing machine using bonded polyester outdoor thread that is resistant to UV, heat, abrasion, salt water and mildew.
- We use YKK Aquaguard water-repellent zippers, #3 zippers on the small bags and #5 zippers on the duffel.
- We give the bags additional waterproofing by sealing all of the internal seams with single-sided Dyneema seam tape.
- For handles on the duffel bag, we use 2" nylon webbing. Many vendors sell really coarse webbing that's tough to fold and sew. The softest webbing we've found is Sailrite's 1800# nylon.
- For the duffel bag strap, we use bright red 3/4" tubular nylon.
- For the zipper pulls, we use fluorescent yellow 1.2mm Dyneema line.
- We use 3/4" and 1" binding tape (grosgrain ribbon) to create zipper stops and loops
- The key to speedy assembly is "basting tape", a kind of heavy-duty double-sided tape that's used in making sails and awnings. We use the basting tape to attach things together before we sew them, for example the zippers and the Dyneema, and the fabric layers of the duffel bag. Everyone who actually knows how to sew seems to think that basting tape is tool of profligate degenerates. I like not stabbing myself with pins.
Step 3: Tools
MEASURING, MARKING AND CUTTING THE MATERIAL
- grease marking pencil (for marking cut lines)
- tailor-style fabric tape measure
- two- to three-foot straight-edge for tracing lines
- OPTIONAL: a 24" quilting ruler (much easier to make measurements off the edge of fabric, as the transparent ruler smushes the fabric flat)
- electric hotknife and a glass or metal plate (heat resistant cutting surface)
- OR rotary cutter, a self-healing cutting mat and cut-safe gloves
- OPTIONAL: an electric rope cutter (useful but not necessary for cutting and automatically fusing zipper tape and nylon ribbon)
Having blunted a whole collection of rotary cutters on Dyneema panels, we looked for alternatives. We did some experiments cutting Dyneema sheets on our laser-cutter, but given the simple designs of these bags and the hassle of fabric flapping around in breeze generated by the laser ventilation, it seemed like overkill.
We now prefer to cut the material with an electric hotknife. If you are going to cut Dyneema with a rotary cutter or something like a box-cutter or an Xacto blade, I strongly recommend you get a pair of cut-safe gloves.
We invested in an electric rope-cutter a few years ago for cutting and instantly fusing the ends of paracord, nylon webbing and dyneema line. For such a weird specialized gadget, it gets a surprising amount of use in the studio.
- a needle threader (who knew you didn't have to fish around trying to thread the needle for ages)
- a chopstick (for pulling thread from the lower bobbin, and gently poking out corners when you invert your bag)
- thread snips (worth having; more convenient than scissors and you'll be cutting lots of dangling threads)
- a seam ripper (for unwinding mistakes)
- basting tape (we prefer Seamstick 1/4" Basting Tape For Sailmaking & Vinyl)
We use a Sailrite LSZ-1 sewing machine. We really only need the walking foot, the powerful needle and the zigzag stitch when we're sewing the handles for the duffel bag. It should be possible to build the two smaller bags on any sewing machine.
Step 4: Cutting the Material
CONSIDER STOCK DIMENSIONS
The vendors we use carry 54" wide rolls of Dyneema, and they sell it by yard. That means you get 54" wide by 36" sections (or longer in three-foot increments). Tyvek comes in 108" wide rolls and they sell it by the foot. The Robic XL nylon comes in 68" rolls and they sell it by the yard. All of our vendors send the material folded up in a box rather than wound around a roll.
Our first step in bag design is to set the dimensions to minimize waste. As the most expensive material, the Dyneema roll dimensions determine our bag dimensions. In the beginning, I tried all these fancy formulas for dimensions, setting target internal dimensions for the bag and then working backwards to include seam allowance and other factors--but I'm too sloppy at cutting and sewing and this isn't press-fit cabinetry.
Now, I simply divide the 54" roll width as follows for each bag:
- pencil/passport case
- Goal is to cut panels that are 9" wide by 10" tall
- Cut a 10" tall strip off the roll,
- Cut that strip into six 9" x 10" sections
- Creates a flat case that is roughly 9" wide by 4.25" tall.
- Goal is to cut panels that are 18" wide by 21" tall.
- Cut a 21" wide strip off the roll
- Cut that strip into three 18" x 21" sections.
- Creates a flat case that is roughly 16" wide by 10" tall.
- Goal is to cut panels that are 27" wide by 36" tall.
- Cut the 54" wide by 36" stock section in half to create two 27" x 36" sections.
- Creates a bag that is roughly 10" wide by 18" long by 7" tall.
CUTTING THE MATERIAL
Our favorite way to cut with the hotknife is to use the large flat metal engraving bed that came with our laser cutter. We pin the dyneema sheet down on top of the metal plate with magnets (magnetic pin backs from conference badges) and then quickly zip the hotknife along the marked line. For a heat-safe cutting surface, you can also use a big pane of glass.
After I've cut the exterior Dyneema panel for the duffel bag, I cut the Tyvek middle layer and and the interior panel of Dyneema or nylon slightly big. I find the most square edge of the outer Dyneema panel, and attach it to the most square edges of the Tyvek and inner material layers with double-sided basting tape. I lay the composite panel flat on the metal engraving bed and trim away the excess with the electric hotknife.
Step 5: Prepare the Panels and Attach the Zippers
Starting with the blank panels, consider whether you want to add any patches or nametags--as it gets much harder to do once you attach the zippers.
For example, I found dozens of vendors selling inexpensive military "name tapes", a narrow embroidered fabric name tag that can typically fit a dozen letters or so. They come in all kinds of colors, from the most stealthy camouflage patterns to ninja black-on-black to color patterns that are easy to read from far away. We went with the white letters on navy blue ripstop nylon.
Another relatively inexpensive way to personalize your gear is to invest in a custom woven labels. I designed the label in Adobe Illustrator in the "center fold woven label" style so it would have our logo on the front and a short message on the reverse. I saved the file as an EPS. Wunderlabel charged US$100 for 300 labels (one hundred labels would have been just a few dollars cheaper) and delivered the labels in a couple weeks. I didn't have time to do much price-shopping so there may be cheaper service. Anyways, it's amazing how a little tag turns a home-made bag into an official Real Thing.
ATTACH THE ZIPPERS
The steps for attaching the zippers are as follows:
- mount the zipper slider on the zipper tape. This can be tricky, especially with the tiny #3 zippers. See the video for a quick HOWTO.
- cut the zipper tape to length with a half-inch margin on either end
- create stops on either end of the zipper by sewing folded pieces of binding tape across each zipper end. Make sure the opening of the fold faces the outer edge of the zipper.
- attach one edge of the zipper to the panel with basting tape using an inside-out fold
- sew the first edge of the zipper in place
- attach the other edge of the zipper to the panel with basting tape and a similar inside-out fold
- sew the other edge of the zipper in place
Now you should have a tube of dyneema with a zipper seam.
Step 6: Sew the Sides to Complete the Flat Top-Zipper Case!
Attaching the zipper is the hardest part of the basic gear bag. Now you simply need to cut some loops out of binding tape for the side of the bag, and stuff them inside the fold along the unsewn edge of the bag (see video). Then you run a stitch down each side of the bag.
Flip the bag inside out. Create a zipper pull--we use bright yellow thread. You're finished!
Step 7: Waterproofing
If you want to go the extra mile, you can tape the seams on the inside of the bag with single-sided Dyneema tape to make the bag waterproof! This step has the added bonus of sealing down the loose threads for added durability.
Trim the exposed seams to just under 1/4 inch. Trim the Dyneema tape to the size of the seam, peel off backing and stick in place.
Step 8: Laptop/document Case Notes
The construction for this design is very similar to the pencil/passport case, with a few minor differences.
Follow steps 4 and 5 for the pencil case construction, these steps are the same but with the larger fabric. For step 6, sewing the side seams, there is a minor difference. In the pencil/passport case the zipper is positioned directly on the top fold. However, for the laptop case design, position the zipper about 1/2" below the top fold.
Step 9: Duffel
Construction for the duffel bag is more involved than the previous two bags, but it's worth it!
Start by cutting out the three layers of body fabric as described in step 4. Attaching them together with basting tape around the edges. This step will save you many headaches down the road.
Cut two 15" strips of 2" wide nylon webbing. These will become the handles. Measure out 9 inches centered on the 15" strip. Fold the sides inward and sew in place across the 9 inch section. (see above)
Use the "Strap Alignment jig" linked above to determine where on the fabric to attach the straps. First, mark the center of the long edge of the fabric. Align the center of the jig (notched) with the center of the fabric, and align the bottom of the jig with the bottom of the fabric. Mark where the outer 4 notches of the jig are located. Second, lay the strap on top of the jig and scrunch until the left and right edges are aligned with the edges of the jig. This will elevate the sewn part of the strap. Mark the two outer notches on each side of the jig, this will note where to sew. Repeat on both sides.
Align the notches on the fabric and the strap. Sew a a square between the notches and to the thickness of the strap. Then sew the diagonals connecting the corners of the square. Repeat this on both sides of the strap and both edges on the fabric, 4 sewn boxes in total.
Next, prepare the zipper. Cut it to the length of the short side of the fabric, 27 inches. Cut a scrap piece of dyneema fabric to 2" x 6". Fold this piece in half to be 2" x 3" and tack this to the open end of the zipper. Optionally: tack both sides of the dyneema scrap at a greater width than the zipper. This will lift the scrap and create a "garage" for the zipper head to pull into. (see above)
Sew the zipper along the edge as described in step 5. This will make a long tube.
Flatten out the tube and align the zipper to the center. (see above) Sew along the open sides which will make a closed rectangle. Similar to step 6, insert a loop of the binding tape aligned the zipper sandwiched in the middle of the seam. This will make a useful pull tab for the zipper.
Open the zipper and fill the bag with some air. Working one corner at a time, position the bag as shown above. Flatten out a corner and move around until the seam is centered in the 90 degree angle. Mark a line, perpendicular to the seam at the lowest point of the box seam from the strap, (see above) approximately 3 inches from the corner. Sew across marked line and trim. Repeat on all 4 corners.
Turn the bag inside out and you're done!
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