Frame Modification
12 November 2007
This is my latest in a long line of home made External Pack Frames. This one uses a few parts from a Mountain Hardwear Harrier pack.
I made a new hip belt that is mostly foam stabilized with thin plastic sheet. The shoulder straps are also new and made from a very strong and very special Cuben Fiber (6.25 ounces per sq yard) by itself.
The modified Frame weighs 17.67 ounces. The stock Harrier frame weighted 55.65 ounces.
The stock Harrier pack bag at 3600 cubic inches weighs 34.86 ounces empty and I will make a new bag out of Cuben Fiber. The new Cuben Fiber Pack Bag will be very light.
I am using the stock Harrier pack bag for testing the frame. The bag (with stuff in it) and frame weigh 21 pounds. I am walking 2 miles twice a day to test the frame.
If this frame works out it might be used for something like an AT long hike next year.
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It is going on two years since Mountain HardWear introduced its "EXODUS Pack Series.
I started this entry on my BLOG back in May 2006. I like a lot of the features of the EXODUS Pack Series except that it is heavy - by my standards anyway. It has sat in Draft form since then and I am taking a little time now to clean out all my "half-started entries. I have made two newer versions of an external frame using a few ideas from the EXODUS packs. I will try and add them to this BLOG before the end of the year (2006).
Mountain Hardwear EXODUS Pack Series:
Two EXODUS Frames.
(NOTE: Most of the following was taken from MH information.)
1. Motive Frame:
The Motive frame is designed for active backcountry and off-trail use. Motive's free-floating design allows unrestricted mobility for technical activities. For use with medium loads.
2. Cruiser Frame:
The Cruiser frame is designed for traditional backpacking and trail-oriented use. The Cruiser's center stay provides excellent stability and support for heavier loads.
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NOTE - (From Bill):
1. I think the only difference between the two frames are the lower part of the frame sheet area. It looks like the lower cross piece on the Motive connects to the upper part of the frame sheet the same way the lower part of the Cruiser does. If you had one of the frames you might be able to get the parts to change the frames from one to the other and back. That would give you one frame that could work both ways with a quick parts change.
2. Notice the points on far sides the top part of the frames. This is what the pack bag slips over when you put it on the frame. Straps on both sides of the bottom of the bag pull it down and the pressure hold it. The lower straps attach to the bottom of the frame.
3. If you could buy other size pack bags you could swap out a larger bag for a smaller bag or the other way around.
4. I would just sew me a new SUL pack bag out of some Cuben Fiber.
5. I weighed the Maestro - med. The frame alone was 3 pounds 12 ounces. The bag alone was just at 2 pounds. Total weight was just as MH lists it - 5 pounds 12 ounces. Being that close to a pack that was that heavy made my blood pressure go up.
6. There is a lot of room to lighten the pack/frame system. I would really like to have one to put on a diet if I could get it free or at a really good discount.
7. I used a copy machine to enlarge all the pictures post here.
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Pack Detail:
The Mini Frame:
This piece of molded polycarbonate is the backbone of the EXODUS system. It is engineered to have great vertical stiffness (keeping the loaded pack bag under control) while having torsional flexibility (allowing it to move with you when you twist your torso). Also built in to the Mini Frame is the ability to adjust the pack's torso length. You can either custom-fit the length to one lockable setting or allow the adjustment to ride free so the frame can adjust to your movements on the fly.
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The U-Bar:
The U-Bar connects the yoke of the harness to the main frame. This does two things: it holds the yoke in its correct, load-bearing shape, and it allows you to adjust the upper body-to-pack geometry. What's more, it lets you do the adjusting on the fly.
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The Fit-Lock Harness:
You can mold our yoke-and-belt system so that it fits the contours of your neck, collar, shoulders, hips, and waist. Then lock that fit into place. The harness stays in that setting until you decide to readjust it. High density foam and polycarbonate overlay hold this body-fitting shape, so load is transferred evenly. Think of how hard it would be to hold a cup of coffee if the handle were a floppy piece of fabric. That's what packs with non-structural shoulder straps are asking you to do.
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Scandium Tubes:
Heat-treated Yunan Scandium tubes attach to the Mini-Frame and transfer load to the waist belt. These advanced alloy tubes are very light and have high compression strength combined with just the right amount of flexibility to absorb a bit of shock and to allow the aforementioned torsional flex.
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The Pivoting Waist Belt:
While wearing most packs, bending over to tie your shoes is virtually impossible. That's because you are strapped in to a structure that does not bend where you do. Our pivoting waist belt changes that. Its two pivoting joints leave the belt free to tilt forward or back when your hips do. Now you can bend forward to tie your shoes or bend back to reach for a hand hold without having your pack fight you all the way.
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Bill,
ReplyDeleteThanks for the additional b&w spec photos at the bottom.
- Sam
What weight of cuben fiber do you use in your tarps (oz/yd)? I am looking to put together a tarp, but I've only seen .48 oz/yd and .33 oz/yd out there, while Ron from Mountain Laurel says .6 oz/yd has a good balance of durability and weight. Is there a good source of .6 oz/yd cuben out there? Thanks in advance!
ReplyDelete- Six2
Bill, I've been watching development of your frame pack ideas for a couple of years. Great stuff. I've just ordered an Outdoor Products Dragonfly kid's pack with a small plastic frame - $40 from Campmor. I'm interested in attaching a very lightweight waterproof bag to it with shockcord. Currently I have a couple of POE's wytex bags that are used for the BPL arctic pack but I think a cuben bag would ultimately be the way to go. I also plan on lightening up the plastic frame by cutting away uneccessary parts and lighthening the straps and belt. Ultimately I may jump into the fray of joining carbon fiber and aluminum tubing together but the Dragonfly frame is a simple way for me to get started.
ReplyDeleteI also have an idea of making an x pattern carbon fiber frame by putting the 2 cross members under tension using a mesh back panel. Picture a minature mesh tent floor with the 2 tent poles attached at the 4 corners but with no tent body. Shoulder straps could attach to the mesh panel and a lightweight cuben pack bag could attach to the CF poles. I suspect this could all be done with less than a pound of materials.
I don't know how to sew (yet?) so will likely tape together any parts made of cuben. Seems to have worked for folks though I understand you sew cuben.
One question I have is, do you know if it has worked to use tape joining cuben with Momentum or other fabrics. I noticed a fellow named Robert Merrick had mentioned it in your consolidated cuben thread on BPL. I'm too cheap to shell out the $25 to be able to post on BPL so was hoping you had heard if it worked to tape these 2 fabrics together.
Thanks for your creativity.
Best,
Todd Schulke
Bill, Just saw the "under a pound" goal. I'm in awe.
ReplyDeleteAnyway just got the frame from the Outdoor Products Dragonfly. Haven't purchased a scale yet but I'm guessing about 1.5 pounds with hipbelt and shoulder straps. Maybe it's a little more. Right out of the box no less. I've attached the 10 oz dry bag with cord. It's not bad. But I want to get lighter with the frame. After my last comment I made a rare trip to REI and noticed most of the big pack makers have a ventilated X frame though they are much more complicated that what I have in mind. I ran across this website that illustrates the concept well - http://www.kk.org/cooltools/archives/000348.php
I still believe a rectangular piece of mesh providing tension to bow out the X of carbon fiber poles will make the foundation of a very comfortable, cool pack frame that a cuben bag could be attached to. After thinking more about it, I think it might be possible to get down to the half pound range. Have you ever tried anything like this or do you see any obvious pitfalls?
Thanks for your time.
Best,
Todd Schulke
Bill, Back again. I've been messing around with the small Coleman and Outdoor products frames. They are nice and comfortable with light pack bags and allow for flexible mounting for various bag types. But, of course, they end up being on the heavy side - 30 oz before hacking. It might be possible to get one down to about a pound.
ReplyDeleteI've also stripped down a couple of kids aluminum frame packs. Seems like 12-16 ounces is possible for just the frame. A little better but obviously not superlight.
I just ran across the extensive thread you and others created on BPL. I feel like I'm treading ground that you and others have already covered. I had dreamt up a heavily perforated carbon fiber sheet idea that would mimic the simple structure of an aluminum H frame but a much less weight. I was thinking about an attachment system similar to Coleman or Molle. But I noticed a similar idea was outlined in the aforementioned thread. I also ran across this new stripped down version of the Molle frame but it's also over 1.5 pounds http://www.downeastinc.com/1606.html,
http://www.downeastinc.com/MiniMe/MiniMe.html
I've kind of come full circle back to a simplfied version of the H frame - one that resembles you carbon/titanium efforts a bit but that are more traditional. Vertical carbon struts with 3 curved or bent small diameter round aluminum cross pieces. The trick is how to efficiently join the 2 together. I think a light version of the fittings Jansport uses might be best. Looked on kitebuilder but didn't see the perfect thing. I'm thinking simple is best - the frame only needs to keep the bag off my back and supoort 15-20 pounds max (with water - usually much less). Mesh back pad and maybe even a mesh waistbelt would do the trick. Enough for now.
Thanks again for all your innovation.
Todd Schulke
Bill, Back again. I've been messing around with the small Coleman and Outdoor products frames. They are nice and comfortable with light pack bags and allow for flexible mounting for various bag types. But, of course, they end up being on the heavy side - 30 oz before hacking. It might be possible to get one down to about a pound.
ReplyDeleteI've also stripped down a couple of kids aluminum frame packs. Seems like 12-16 ounces is possible for just the frame. A little better but obviously not superlight.
I just ran across the extensive thread you and others created on BPL. I feel like I'm treading ground that you and others have already covered. I had dreamt up a heavily perforated carbon fiber sheet idea that would mimic the simple structure of an aluminum H frame but a much less weight. I was thinking about an attachment system similar to Coleman or Molle. But I noticed a similar idea was outlined in the aforementioned thread. I also ran across this new stripped down version of the Molle frame but it's also over 1.5 pounds http://www.downeastinc.com/1606.html,
http://www.downeastinc.com/MiniMe/MiniMe.html
I've kind of come full circle back to a simplfied version of the H frame - one that resembles you carbon/titanium efforts a bit but that are more traditional. Vertical carbon struts with 3 curved or bent small diameter round aluminum cross pieces. The trick is how to efficiently join the 2 together. I think a light version of the fittings Jansport uses might be best. Looked on kitebuilder but didn't see the perfect thing. I'm thinking simple is best - the frame only needs to keep the bag off my back and supoort 15-20 pounds max (usually much less). Mesh back pad and maybe even a mesh waistbelt would do the trick. Enough for now.
Thanks again for all your innovation.
Todd Schulke