Blog — Slim Pack

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Slim Pack behind the scenes: One More Thing

Is it "One More Thing" worthy? Probably not, but it is in the literal sense of being a single additional item. Based on feedback from early Beta testers, I made the straps on the Slim Pack rather long to accommodate a variety of body types. So even though the volume of the pack is small, it fits a wider array of people. And it’s easier for anyone to get on and off. But with that change came some later feedback from my #1 Beta tester (my wife), which was that the straps dangled a bit too much if cinched tight on a smaller body. This was a bit more pronounced given the straps are made from hefty 1.5” seat belt webbing rather than the traditional thin nylon.

How to address this? Shorten the straps and it won’t fit some people… keep them long and the ends will dangle. It initially seemed like a mutually exclusive decision for how to design it. In those cases, the options are usually either to identify the best possible default or make something that the user can adjust. But the length wasn’t easily modified by end users given that the ends need to be melted so they don’t fray and then sewn so they don’t slip out of the clip.
Slim Pack Strap Keeper Minimal Perfect Backpack

Then I remembered all of the specialized components which are used extensively throughout the Slim Pack. To select them, I had browsed the catalogs of several manufacturers and the array of pieces available was vast. Sure enough, I found several options of pieces that could do the job and ordered samples of 4 different types. Once I received the samples, one stood out as clearly superior. Though it was twice as expensive as the other options (and I’d need 2 per pack), it had a quality feel and excellent design.

Strap Keeper for Slim Pack Minimal Perfect Backpack

Normally used for military applications, this component is created with a 2-part mold from Acetal plastic. According to DuPont™, this material has the “stiffness and strength needed in parts designed to replace metal.” The finished piece has a slotted back and spring loaded clip to efficiently manage the extra material. But if you’d prefer not to use it, you can remove the strap from the front of the clip or remove the Strap Keeper completely.

For the Kickstarter project, this introduced another challenge… several hundred of the packs were already complete and packaged up. So in the days leading up to Christmas, with the help of my wife and (sort of) with the help of my son, we took each pack out, attached the clips, and packaged them back up again. It took the better part of 3 days, but I felt good knowing that each and every backer would be able to enjoy the Slim Pack to its fullest.

Adding Strap Keeper to all inventory already completed

I’m really happy with this finishing touch, as it helps the bag stay looking neat and polished during use no matter the size of the person using it or how they’re adjusted. I hope you enjoy it too!

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Slim Pack behind the scenes: Components

Following up on the previous post about patterns and dies, the steel versions have arrived from the die makers. Making dies is a long tradition best done by master craft people, which is why I use a small business out of Texas for almost all of my die work. Why Texas? Some of the most complicated dies are used to cut leather used for horse saddles, Texas still has lots of horses, and so the tradition and skills there run a bit deeper than in Silicon Valley!

Slim Pack Perfect Backpack Dies for cutting

That said, they’ve modernized to the point that I can send them die lines output from Illustrator which get CNC cut onto a board which is used to shape the steel.

When my dad asked me, "How long does it take to make each pack?", I had to honestly say I didn’t know yet. More quizzical than accusatory, he replied with a look that seemed to say- “Isn’t that something you would know?” In fact, I did know how long it took to make some of Slim Pack prototypes… they ranged from 3 to 10 hours each and have cost up to $1000 for a single prototype just in labor. But this is because changes and refinements are being made during the construction process. New patterns are being made, production documentation is being generated, and sometimes it’s simply exploration. On many occasions, we would produce 3 prototypes at once with 3 different ways to solve a problem, so that we could compare them.

During production, the challenge is to systematize and standardize the process in order to improve efficiency. Meanwhile, since we’re using such expensive materials, we also need to reduce mistakes as much as possible at each step in the production process. This was a large reason for investing in producing dies for each piece of soft shell material. Normal materials are much easier to cut and the penalty for error is a lot lower. If you make a mistake at the time of cutting, you’re only out a few dollars for the cost of the fabric. But if you make a mistake cutting layers of Soft Shell material, it could be a loss of a few hundred or even a few thousand dollars.

Slim Pack Perfect Backpack Pockets

To further optimize efficiency, the backpack production is separated into individual components. For example, all of the interior front pouch ripstop nylon can be cut and assembled to produce the pockets. The key loop and clip is also attached at this stage.

Meanwhile, the shoulder straps, back, sides, front and zippers can each be produced concurrently in batches. This also helps with quality since each individual assembly can be inspected before it’s included into the bag. Any mistakes are isolated to that particular piece and only perfect pieces are used in the final pack.

Slim Pack Perfect Backpack Final Assembly

The final assembly step then goes rather quickly… and can honestly be put in the hands of the most experience seamstresses. Many of the top seamstresses in the shop have 12-15 years experience with this same company and have been sewing much longer than that. They have an amazing ability to maintain both speed and focus.

The packs go through the shop in batches like this… starting with 10 or so to get things moving, then 50 to refine the processes, then 100, 250, and 500.

Slim Pack Perfect Backpack Components

The goal is that each batch takes less time than the last while quality is maintained or improved. And as the team becomes more and more familiar with the produce, optimizations continue, sometimes for months.

So how much time does it take to make one bag, anyway? Well, this is calculated per batch according to “shop time” and the number of sewers and cutters allocated. Sometimes time studies are conducted for each step and then divided out. So once the first batch of 50 are done, I'll have an idea for those, but hopefully the next batch will go more quickly, and we'll have a really good idea of how to improve.

Is there something you’d be interested in learning about the process to make a Slim Pack? Let me know in the comments below...

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Slim Pack behind the scenes- Patterns and Dies

Coming from an Industrial Design background where most products are injection molded, it’s been interesting for me to learn about how soft goods are produced. In fact, during my design phases, I used several 3D modeling techniques, both physical and digital, to arrive at the form of the Slim Pack.
Foam Model
Then an interesting translation had to take place to determine exactly how the form could be made using only flat fabric. During the prototyping phase, much of this was happening on paper. The first patterns were printed from Adobe Illustrator on my computer onto Tyvek. (Most designers would use card stock manila paper for this but I use Tyvek because, well, the wallets.) These are easy to tweak and adjust while iteration is happening.
Tyvek Patterns
Once the patterns are final, they’re translated onto Mylar plastic. Sometimes sewing notes are written right on these patterns as instructions and alignment grooves are usually included to line up multiple pieces precisely. When it comes time to produce an item, the patterns are used to hand trace the shapes onto the material to be used. If only one item is being made, each pattern may be cut out by hand with whatever tools make sense depending on the complexity of the shape.
The next step of cutting is when say 5-10 units are being produced at once. In that case a stack of the fabric can be clamped together and cut at once using a fabric saw. Appearing very similar to a normal hand held jig saw with a thinner blade, very precise cuts can be made through many layers of fabric.
Mylar Pattern
Even if you were producing 50 or possibly 100 items or more, it may still make sense to cut things in this way, just repeating the process to make more pieces. This is especially true if the item is made somewhere in which labor is very inexpensive.
In order to produce the 1000+ Slim Packs for Kickstarter backers, we’re using the larger scale production technique of die cutting. For this process, a separate steel die needs to be created for each piece. This is an expensive process done by skilled craftspeople, but once the proper pieces are made, it improves both precision and efficiency. 
Therefore, I’ve decided to have dies made for almost every piece of the Slim Pack. The initial cost to produce the tooling will probably be right around $3k but I feel that it’ll make the product better as well as give us our best shot at completing the project on time. I'll let you know how they look once we receive them!
Stay tuned for more updates along the way... is there something you’d like to see in a future behind the scenes update? Let me know in the comments!