Dimensions

The other day, I think it was Wednesday, I fiddled around with finding out some dimensions for my first prototype.  I mainly took the sleeping bag as the design driver since it is the the most important gear piece for me.  I care that it not get too compressed.  I want it to stay as lofty as possible, really, but it needs to be protected.  Therefore it needs the protective stuff sack and the current design is the one I should start with.  I wrapped the tape measure around the current one and figured out the tightest circumference I would want to hold.  I used that to find the diameter of 7".  So that is where I am going to start with the width of the pack.  I also always put the sleeping bag in the bottom of the pack so I just need a curved bottom of the pack.  A nice fit will be nice because the Six Moon was a little too big and I always had to stuff clothes in there to get  a well compacted back pack.  It was frustrating because I never had a well figured out plan with how to stuff things in there all the time and I know that it was awkwardly crushing the sleeping bag or etc...  This will be a nicely welcomed change.  It's simple, it requires zero thought to put together, and I can use the clothes to wrap around all the awkwardly shaped items like the cook pot, the food.  (That reminds me that I need to make a new stuff sack for food.  Something lightweight that fits inside the pack well.)  Is it really only the cook pot?  Heh, beers at some point for sure.  Oh, and the water bag or bottles, maybe the poncho if I use it.  That lends me to believe that I can get away with a much smaller pack.  The only things that take up any real space are the sleeping bag, the down jacket, food, and the cook pot/fuel.  Actually, at some point it will be the bear can but I need to come up with other ideas for that later. I do like the idea of the bear can on the outside of the pack.  That lends me to believe I can make the pack the right size for everything and figure out a way to strap it on.  I can tackle that issue later, though.

Strap Testing

I know that I am going to be trying a lot of different strap ideas or configuration.  Instead of sewing the straps into the seems of the pack, I need to sew in another sheet of fabric that extends out an inch or two from the seem down the side of the pack.  This will allow me to easily get different configurations of the straps without having to actually take apart the side seems.  I'll only need to remove the straps themselves.

That works for the sides down near the base of the pack but where the straps connect to the top of the pack, I am going to just sew them into the back of the pack.  They are easy enough to get at to take apart anyways.

Sewing

No internet for almost a week but finally it was fixed today.  Someone literally drove down the street and caught the cable wire and tore it out of the house.  The funny part is that the AT&T people that came that day when the street was blocked off, didn't even fix it.  They cut the wire and left it like that.  What morons.  The guy that came out today was cool but obviously was pissed at the laziness of others.

I put the sewing machine together today and figured out how to use it.  I tried a few different stitches in hope of finding something that works well.  I had to play around with the tension of the threads(obviously a common activity).  I guess I could say that I have a pretty good idea how this thing works.  Now I need to get some basic dimensions put together and find some fabric to use and get a basic test model built.  I think that using old sheets or equivalent will mimic the type of fabric that I want to use for my initial design, so I think this could be a good place to start to see what happens.  Well that's not true.  I think pillow case material which is a little thicker is probably the better option.  I feel like sheets might be too thin to hold any serious weight.  Than again, I'm not trying to carry any serious weight.  I'm trying to build a semi-working prototype that I can learn how to sew on and get some basic idea what I am doing.  This will ensure a working model essentially that I can build a more functional prototype off of.  It's a learning curve and I need to slow(or quickly)  build all of my skills to get towards the major goal of a functional CDT pack.

Pack Testing

Yesterday, I filled up the Six Moon pack that I had with basically everything that I take with me on a long distance hike.  Except for the food; I didn't really have any of that lying around.  Instead I filled up a gallon jug with water.  Since Harley was coming with me, I figured that I could get rid of some of it somewhere through the couple of hours we would be gone.  I tried out a configuration of my new strap idea.  It wasn't the best test model because the geometry and the straps themselves were a little uncomfortable but the concept was certainly proven.  I had some issues with the straps being too tight around my neck.  It wasn't bothersome enough to prevent me from hiking for over an hour like that but in the future I am going to need a wider platform.  That will allow the straps to really hug onto the middle trapezius muscles.  Geometry will correct the right fit so that there is no digging into the shoulders, as commonly seen on current packs when carrying loads for extended periods of time. 

The pack weight itself, though, felt good.  It was really weird at first.  I could tell that something was off.  My side to side movements felt weird and when I bent over (especially to the side) the pack was strangely centered.  The pack weight didn't shift at all on my body.  It was more upright and didn't rotate with me.  There was no moment of inertia there needed to move the pack with my body.  When I got back up, it was easier.  There was less strain on my muscles to do so.  I guess a good way to picture it is when you bend over with your pack on, there are times when you feel that pack is going to keep going and pull you down with it.  I didn't get this sensation nearly as much.  I know that I have worn packs for over 3000 miles now but this was different and once I got used to it, I wasn't a huge fan of going back.

I put the pack on the way it was intended after this test phase and it just didn't feel right.  Something was out of place.  The weight felt alright on my shoulders but not good enough.  I was expecting to put it back on the right way and fall back in love with it but I didn't.  I wanted to take the pack back off and put the configuration back to what I was testing.  That's a really good sign because I think a few geometry changes can shore things up for me and ensure that the pack will fit me properly.

I also came up with idea to figure out how to design the ideal pack for my body.  I think the best way is going to be tracing my body while it's up against a mirror.  I can have a roommate of mine draw the outline on the mirror while I stand right next to it.  It's an easy and simple way of "tracing" the profile of my back.  Then I can begin to figure out what shape I need to make it.  A good contoured fit like the Jam had is going to be more comfortable on the shoulder and hips.  The higher friction area on the back will help keep some of the load off those areas directly.  And a nice snug pack will ultimately be most comfortable.  The problem with that may be the wicking away of sweat off the body.  The right fabric will need to be chosen.  In the ultralight community there is no room to add the weight to add vents, plus the closer the load is to the back, the less it will pull the body backwards.  I want the center of gravity as far forward as possible.  Otherwise, the pack is just pulling you backwards as you need to pull it forwards, as you walk.

Design thoughts

I took my little pack and loaded it up with some weight to see how the straps felt.  It wasn't enough weight though.  Maybe 10 lbs.  I guess that's a significant amount when compared to my real pack weight but really not enough to thoroughly test it out.  Either way, the bag felt really comfortable.  The straps are the real problem, though, they loosed up too easily and that's mainly because they are these thin maybe 1/2" wide straps that don't have enough friction to prevent the slippage.  Tomorrow I am going to get my packs out and load them up with all my weight and test some things out.  I want to play around with the straps a bit and also get some basic dimensions for a size and fit.  Just a rough outline that I can start with so that I can start thinking about putting together a basic design.  Having the packs all loaded up will give me the information that I am looking for in regards to strap design.  The ideas I have here are the main focus I have for an improved design.  I actually feel kind of dumb for not realizing that I could have done this 2 days ago to figure out the initial feasibility and basic structure that I need to think about next.

It's good to be focused on working on this each day.  The blog has really helped keep my attention locked in.  I feel that I have to write about something every other day or so.  Therefore I need to constantly be productive even if it's brainstorming while I am busy or working all day on a 3-D model.