SUL External Frame / 1-1-2009I started making another SUL External Pack Frame on New Years Day. My goal is a frame similar to the modified Harrier Frame I have been working on but that weighs closer to one pound or less. The old frame was made to carr

[Bill Fornshell]

I started making another SUL External Pack Frame on New Years Day. My goal is a frame similar to the modified Harrier Frame I have been working on but that weighs closer to one pound or less. The old frame was made to carry 40 to 60 pounds. The new frame may carry the same amount but I hope it is not by me. For a normal 3 to 5 day resupply schedule I don't think I would ever need to carry more than 15 to 20 pounds. There are times when I might want to carry up to 10 days worth of food. This frame should do that easy.

I was talking to Grant at Gossamer Gear the last week of 2008. I had read about the new pack they are coming out with that will have bent aluminum stays. I was curious about how they were bending the aluminum tubing. I told him I had never had much luck at bending aluminum tubing. Grant is currently bending the stays. He is using 1/4" 6061-T6 tubing. He talked me through how he was doing it. I decide to give it a try.

I bought some 3/8" (GG is using 1/4") 6061-T6 aluminum tubing and have bent my first two tubes. I am happy so far with how they turned out. The bending process is a bit slow as I needed to try and only bend a little at a time. The jig I made only helped get me started. The rest of the bending was more or less bent "free hand". I may have spent about 45 minutes on the two tubes. The second one went faster as my technique improved. The tubing I am using weighs about 1.4 grams per inch. The total weigh of the tubes that I bent weigh 32.7 grams or 1.15 ounces each. The bent tubes are 24.5 inches long. The actual length might change a bit.

To answer one question before it is asked. The 3/8" aluminum tubing I used weighs 1.4 gram per inch vs the 1/4" at 1.1 gram per inch. I would only have saved about 0.4 ounce if I had gone with the 1/4" tubing.

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I have made one more piece and this should be all the aluminum tubing I have to bend for this frame. This piece is more or less a half circle and will be used near the hip belt area. It weighs about 18 grams or 0.63 of an ounce and was all bent "free hand". It was much harder then the other two pieces to bend.

This first part has gone much faster than It thought it would. Now I need to take a bit of time and plan out the rest of the frame.

These are the two frame sections of the of the modified Harrier Frame. I am using the basic design of the modified Harrier Frame for the new frame but trying to reduce the weigh.

The top part weighs 469.2 grams or 16.5 ounces.

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The bottom part weighs 440 grams or 15.52 ounces.

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Next group of pictures – 12 Jan 2009

I have continued working on my new External Frame and it is ready for the Hip Belt, Shoulder Straps and Pack Bag. This frame is the first of my bent tubing frames and each next version should get a bit lighter. I would like to get the total weight of the External Frame, Bag, Shoulder Straps, Hip Belt etc down to 16 ounces or less.

The finished Frame weight is 12.5 ounces. A have put the Cuben Pack Bag on the frame for something to carry. The Cuben Bag was the one I made as a Winter Bag and has a few extra features that a normal bag would not have. That may add as much as one ounce extra weight. With the 2.5 ounce Cuben Bag the current total weight is 15 ounces. My guess is that the finished ready to carry setup will be about 20 ounces.

I will admit that I got a bit caught up in the Frame Design but decide to just go along with it on this one.

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New External Frame With a Cuben Pack Bag.

The Cuben Pack Bag weighs 2.5 ounces . This frame / bag combination is just a test so I have a bag to put stuff in when I start carrying the frame to see how it works.

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[s k]

Of fire!, fever!, and fitful frustration!, pricked by revelation! Life at Skunkworks Steamrolling.

Nice developments, Bill, and thanks for the view.

[t.darrah]

A great example of a MYOG project, very very nice. Keep up the good work Bill.

[Joe Clement]

Did you ever think about bending the side stays to a pivot point on your hips, kind of like the old Jansport D5 did with the velocity arms?

[Bill Fornshell]

Hi Joe,

I just went back to one of my first threads here about External Frames to get a couple of pictures of my old Jansport frame. I just discovered all those pictures are gone. It seems that album on my Photobucket account is gone.

Anyway is this what you are calling "velocity arms"?

If it is I call that part of the hip belt.

Dug these out of my files. This is my old Jansport pack:

[Joe Clement]

That is it. Eddie Bauer used to sell a pack, and instead of those arms, they just made the side tubes on the frame longer, and bent the to attach to the belt where the Jansport does. Always fascinated me for some reason. Those packs like that sure carry well.

[Bill Fornshell]

Hi Joe,

I had a couple of phone conversations with Skip Yowell co-founder of Jansport a couple of years ago about the "wing things" they used to have on their packs.

This is where I am going with this version of my New Frame using the "wing things" idea:

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[Bill Fornshell]

The new Frame is ready for a pack bag and some testing. Frame weight as shown in this picture is 17.63 ounces. The winter Cuben Pack Bag at 2.5 ounces would give me a temporary total weight of 20 ounces.

I will be working out a design for a Cuben Pack Bag to use on the New Frame.

I have been wearing the new Frame walking around in my house. It fits nice.

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[Bill Fornshell]

The picture with the pack bag is something I made to test a new material that I have recently discovered. It a woven material that is strong, almost light – 3.4 ounces per sq yard, very strong and almost free. It cuts and sews on the easy side. It is not some form of tyveck.

I think it might be strong enough to work as a material for a cheap bushwacking pack. I am going to made several packs in different sizes and try and get them tested under some harsh conditions.

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[Jim Colten]

Bill,

I seem to recall that one of your earlier objectives with a framed pack was to keep the pack bag away from you back to allow perspiration to evaporate.

Has that fallen by the wayside?

[Bill Fornshell]

Hi Jim,

My goal is still a framed pack that will push away from my back. I will be trying to add that feature back in over time with the follow on versions. Some of that feature maybe in the way I finish my hip belt. One idea I have will require some of my Primitive blacksmithing skills. It will involve shaping some aluminum.

I wanted to work out my Aluminum Tube Bending technique with this frame.

I also want to try and get this frame design lighter before I have to add any additional weight to open up the window across my back.

[David Erekson]

Bill, you can't expect to mention some new fabric and not give us the name. Inquiring minds want to know. Also, the Texas Hill Country brush should give your plenty of "harsh condition" testing. Good luck.

[Patricia Combee]

Bill, very nice work. Nice pictures. I do love external frame packs and still use one on occasions. I hope your project really takes off. I expect you would have quite a few sales to BPL members.

[Kevin Egelhoff]

Bill,
I just came back from a nice vacation to see your new posts. Very impressive work!!
Looking forward to hearing the full test report!
When you first went down this path months ago and I talked about making a new all carbon back stay support I figured it would only take a few weeks to knock something out … well, about 4 months now and I finally made the first prototype to test out. This first unit is WAY over kill and soo stiff that you can't flex it one little bit along the spine. The sides that wrap around the waist seem just about right for the flex and weight. I used honeycomb along the spine to be really light and stiff but used way too much carbon fiber. Current weight is about 240 grams and I think I can reduce the weight to about 160 to 180 grams pretty easy. I hope to make version two in the next few weeks if I can find some time….. Once perfected, I hope to load up about 40 lbs in the Gossamer Gear pack and see how it feels. Right now, it fits my back perfect and has about a half inch gap molded into the middle section of the back for a little air flow. I originally thought I would need wider wings at the top like you have to hold the pack out but found the single attachment point to "hang" the pack from the top center seems to work well. At least in the office carrying 15 lbs. 30 to 40 lbs. might change the way it works and feels?
I will probably add a small piece of foam padding at the top of the stay where the carbon rest at the base of the neck. Other then that, I don’t think I need any extra padding or support. ???
Would love to hear your thoughts and insight before I go for version #2.
Kevin

[Kevin Egelhoff]

Completed frame on pack:
Wouldn't this be a NICE complete pack with your 2.5 oz cuben pack connected to a carbon stay weighing about 7 oz!!!

[Bill Fornshell]

Hi Kevin,

That is looking really good. I like the way your design has worked out. Do you have a side view picture of the frame?

I have always though a truly light External Frame or Hybrid Frame / Pack would have to use Carbon Fiber in some form.

I have never tried to work with Carbon Fiber.

I may try a design similar to yours but use bent aluminum tubing and some sheet aluminum to stabilize the tubes. It may not be as light as Carbon Fiber but would use what I know how to work with. Add a Cuben Pack Bag and who knows how light it might be.

You are on the right track.

[Kevin Egelhoff]

Thanks Bill.
If I can get a few little bugs worked out I will see if I can build an extra one for you to play with. This prototype is based on a 190 lb 6'2" person but I think we could trim the top and see if you can make it work. If I make the waist section a little more flexable I think you could sinch the waist belt tight enough to maybe fit your waist?
Here is a picture showing the stay directly on the back without the pack so you can see the shape better.
I might see if I can get him to model the entire set-up and shoot another photo. Loading up the pack with 40 lbs will be the real test. I might have to do a hour long hike tomorrow at lunch time to see what needs to be revised.

[Kevin Egelhoff]

Added two more photos showing the pack/stay combo. You can see the area in the second photo that I think I would add a small piece of foam too. Right now it fits perfect but I'm sure a heavy load and several hours would make this a hot spot. This is also the area that would be trimmed to fit a shorter torso. The MAJOR problem with a design like this being one size does NOT FIT EVERYONE !!!
Kevin

[Don Meredith]

Very sexy carbon frame ideas there. Its pretty user specific but there are a lot of thermoplastics that would be nearly as stiff as carbon and could be custom fit after warming them up. This is essentially what Osprey is doing with the thermo-fit hip belts. The thermoplastic is just wrapped in padding and fabric. I'd LOVE to have one of these to play with.

Do you think the potential hot spot you mentioned could be addressed by spooning the top out away from your back on a smooth radius?

[Kevin Egelhoff]

Don,
The tooling I made could be revised to add a radius on ALL the apparent sharp edges. The basic tooling took a LONG time to make. In a perfect world I would have a nice aluminum tool made to fit several different back and waist sizes. Thermo materials would be nice to play with but I don't have access to it. I added a very thin and light piece of foam to the section close to the neck and plan on testing out the pack tomorrow at lunch time!

Bill,
Looking forward to seeing the direction your new pack frame heads and hearing about some heavy weight testing.

[Bill Fornshell]

Hi Kevin,

Thanks for posting the new pictures.The side pictures look like the frame follows the curve of your spine nice.

If you recall some of the pictures on my original External Frame Thread I used a lot of the perforated Thermo Plastic. The type I was using worked easy but I don't think it would be strong enough for something like your frame without some type of backup support.

I don't understand how you made the frame.

Using my name and the term "heavy weight" in the same sentence almost made me laugh. Heavy to me would normally be 3 to 5 days food and a sub 5 – 6 -7 – or 8 pound gear list. I think I know what you mean however, heavy use. Hiking long enough at one time to really stress the frame / bag setup and see how it holds up.

[Dale Wambaugh]

I've wondered about making a pack using the water reservoir as the frame. Gerber (as in Gerber knives) has made a hydration pack with a rigid reservoir that gave me the idea.

It could be internal or external. For an external reservoir, the strap attachments could be molded in and air channels could be designed in as well. It seems that an internal reservoir would need a snug fitting sleeve or some sort of velcro attachment to tie it all together and vector the weight to the hip band. Working some I-beam structures into the reservoir would help with rigidity too.

Gerber 70 ounce reservoir

[Kevin Egelhoff]

Bill,
I was thinking about your opening statement about taking 10 days worth of food on a long trip being considered "Heavy Weight". The 9 day trip I did in Sept. had 18 lbs of food in a 2 lb bear canister. 20 lbs. felt pretty heavy when adding that to my 6 lb. base weight and then adding another 2 lbs of water. I figure if we test these packs out with heavier loads and they feel good, then anything lighter is only going to feel even better! I know you don't typically carry ANY loads close to that weight but thought you were thinking about doing a long unsupported hike?
I really think I can try and get the carbon stay down to 5 to 6 oz. and then will look at making a 4 oz., heavier weight Cuben bag and see if I can get the entire pack weight less then 10 oz. and carry a 30 to 35 load comfortably.

[Kevin Egelhoff]

Got a chance to test out the new Carbon frame today carrying 34 lbs. I added a small piece of foam at the neck portion and a small piece of foam at the middle lower back portion. I filled up a 5 gallon hard plastic water jug about 3/4 full and weighed it. 34.0 lbs…. and dropped it into the pack. It fit like a glove but the water sloshes around since it wasn't all the way full!! I know a correctly loaded pack would place the weight much closer to your back and wouldn't be in a super hard plastic containter but this quick and easy test still felt really good. I only got out and walked for about 40 minutes and want to try and actually get the pack weight up to 40 lbs. and do a longer hike in the next few days. Then I will take the weight down to a reasonable 15 lbs. and see how it feels. Thinking this might work out really well at light and heavy weights! Then, I will look at making a superlight carbon stay in version #2.
Bill, Hope you don't feel like I'm taking over your post. Just thought you and I are working along the same path here.

[Matthew Roberts]

Kevin:

Great work on a great idea. I'm enjoying watching your progress. Thank you very much for sharing the updated pictures of your idea.

I've often wondered about incorporating the bladder into the frame. It would seem to me that carrying the water weight on the hips would be the most well-centered location for this weight. 3L would be enough for me, and my hips would give me a low center of gravity. I go through water like a fish :)

…My idea consists of a hip bladder that can be used for day hikes. The mould-able thermoplastic bladder formed for your hips was a great suggestion. For backpacking, slide the carbon fiber spine into a slot at the top of the hip bladder and clip on the cuben fiber backpack.

[Author]

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