bobgengeskahn
member
Registered: 04/28/04
Posts: 139
Loc: Redwood City CA
Has anyone tried working with composite materials for a pack frame? The idea came to me to build my own small composite pack boat, but I do not want to spend a whole lot of money on Carbon fiber, that and carbon fiber is not the best in the outdoor world (very sensitive to stress fractures and UV). The idea came to me to try Tyvek and the filler material that is typically used with carbon fiber to try make a rigid pack frame (or possibly even a canoe if its rigid enough). Has anyone here experimented with this or any composites?
The only concern I might have in trying it is that carbon fiber tends to absorb the resin, where as I fear that tyvek will just layer it instead of absorbing it and becoming hard. Maybe kite tyvek since it is softer? I don't know, it has been a long time since I have played with Tyvek...
Edited by bobgengeskahn (05/27/0801:29 AM)
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~Shaun T. KG6TNB tech. redwood city CA
finallyME
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Registered: 09/24/07
Posts: 2710
Loc: Utah
I think Tyvek would be a bad choice. All it is is spun HDPE which does not like to stick to stuff. You usually have to corona treat it to stick to an epoxy. It melts at a low enough temperature that it is great for heat sealing.
If you plan on dropping your pack a lot, or throwing it off a cliff, any composite would be a bad choice. If carbon fiber won't work in your application because of stress fracture, then I wouldn't be surprised that any other composite won't work for the same reason. However, if it is just the cost, try replacing it with fiber glass. More detail on what you are trying to do would also be helpful.
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DJ2
member
Registered: 01/06/02
Posts: 1348
Loc: Seattle, WA
I use carbon two vertical pieces of carbon tubing as the primary struts in my home made pack. Have had several years of use with no breakage. You can see my frame in the Make Your Own Section of this website under DJ's Frame Pack-updated.
I've had carbon fiber poles break in tent usage. When using them in my pack, however, they are only slightly bent and therefore less likely to break.
I also fill the ends of the tubing with a fiberglass rod and protect them with nylon plumbing tees. This prevents end splitting.
I've tested my pack by dropping it many times, on purpose. It has never broken. The steps I described above plus the flexible nature of my design see to protect it.
Two vertical struts, weighing about 1 ounce each, are more than adequate for supporting 40 lbs of weight.
Has anyone tried working with composite materials for a pack frame? The idea came to me to build my own small composite pack boat, but I do not want to spend a whole lot of money on Carbon fiber, that and carbon fiber is not the best in the outdoor world (very sensitive to stress fractures and UV). The idea came to me to try Tyvek and the filler material that is typically used with carbon fiber to try make a rigid pack frame (or possibly even a canoe if its rigid enough). Has anyone here experimented with this or any composites?
The only concern I might have in trying it is that carbon fiber tends to absorb the resin, where as I fear that tyvek will just layer it instead of absorbing it and becoming hard. Maybe kite tyvek since it is softer? I don't know, it has been a long time since I have played with Tyvek...
Check out Granite Gear Packs. They have been using composites for their backpack suspension for 12 years (started in 1996). The benefit is that they can engineer "flex zones" into the backpanel. I believe composites are the future of internal frame packs.
The material they use isn't carbon fiber (they tried it in their big 7000 cu.in. packs because of CF's stiffness), but they went away from it due to the expense and durability issues. Now they use what they call Tepex and Topoflex, a high-end (meaning best quality), continually reinforced thermoplastic. This material has proved to be very durable and holds it's shape far better than any metal. In fact you can bend the framesheet in half, leave it for several days, and it will return to the exact shape in an instant. It's amazing stuff! I have never seen a frame sheet break or crack.
The other thing I like about it is that it has a 3-D shape to it which allows for a better fit. Aluminum stays and plastic framesheets can't do this. By using the 3 flex zones (bottom is flexy to absorb the trail shock of each step, middle is semi-flexy to bend with the body but support the load, and the top is fully rigid to allow the load-lifter straps to help comform the backpanel to fit perfectly on anyone's back), Granite Gear has made their packs to perform far superior to an aluminum stay/plastic frame sheet pack. You simply can't (or nobody has) developed a way to put flex zones in aluminum. Actually that would be foolish since aluminum can stay permanently bent and will eventually fail if bent too much. It's pretty cool stuff <img src="/forums/images/graemlins/cool.gif" alt="" />.
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bobgengeskahn
member
Registered: 04/28/04
Posts: 139
Loc: Redwood City CA
Quote:
Quote:
Has anyone tried working with composite materials for a pack frame? The idea came to me to build my own small composite pack boat, but I do not want to spend a whole lot of money on Carbon fiber, that and carbon fiber is not the best in the outdoor world (very sensitive to stress fractures and UV). The idea came to me to try Tyvek and the filler material that is typically used with carbon fiber to try make a rigid pack frame (or possibly even a canoe if its rigid enough). Has anyone here experimented with this or any composites?
The only concern I might have in trying it is that carbon fiber tends to absorb the resin, where as I fear that tyvek will just layer it instead of absorbing it and becoming hard. Maybe kite tyvek since it is softer? I don't know, it has been a long time since I have played with Tyvek...
Check out Granite Gear Packs. They have been using composites for their backpack suspension for 12 years (started in 1996). The benefit is that they can engineer "flex zones" into the backpanel. I believe composites are the future of internal frame packs.
The material they use isn't carbon fiber (they tried it in their big 7000 cu.in. packs because of CF's stiffness), but they went away from it due to the expense and durability issues. Now they use what they call Tepex and Topoflex, a high-end (meaning best quality), continually reinforced thermoplastic. This material has proved to be very durable and holds it's shape far better than any metal. In fact you can bend the framesheet in half, leave it for several days, and it will return to the exact shape in an instant. It's amazing stuff! I have never seen a frame sheet break or crack.
The other thing I like about it is that it has a 3-D shape to it which allows for a better fit. Aluminum stays and plastic framesheets can't do this. By using the 3 flex zones (bottom is flexy to absorb the trail shock of each step, middle is semi-flexy to bend with the body but support the load, and the top is fully rigid to allow the load-lifter straps to help comform the backpanel to fit perfectly on anyone's back), Granite Gear has made their packs to perform far superior to an aluminum stay/plastic frame sheet pack. You simply can't (or nobody has) developed a way to put flex zones in aluminum. Actually that would be foolish since aluminum can stay permanently bent and will eventually fail if bent too much. It's pretty cool stuff <img src="/forums/images/graemlins/cool.gif" alt="" />.
Actually that is very similar to what I had in mind (as far as a pack frame goes, thanks to DTape for the Canoe info). I remember first looking into the granite gear packs a while ago, and really liking their frames, but at the time I did not realize that they are actually composites.
I have a kind of 3D shape in mind, similar to the new Mountain Hardwear packs and a little like the Granite Gear stuff. Maybe if I can find sketches from way back when I'll scan them in and post them...
_________________________
~Shaun T. KG6TNB tech. redwood city CA
Well they are in the 4th production generation of the MOLLE frames, most of the issues from being a plastic frame have been dealt with for durability and impact resistance, still not perfect however.
bobgengeskahn
member
Registered: 04/28/04
Posts: 139
Loc: Redwood City CA
interesting... i wonder if it would work with the issue Alice packs. I'm in the reserves and that might actually be worth getting to replace the one I have because the one they issue is, um, terrible to say the least lol
_________________________
~Shaun T. KG6TNB tech. redwood city CA
Coleman had the 1st "composite" pack frame and it was very nice. It was made of fiberglass reinforced resin (Delrin methinks) ans flexed with the wearer.
The military did use some frames like this for a while for special ops troops's ALICE packs. Much better than the original ALICE frames. Then the military went to internal frame packs with aluminum stays.
Dana Designs and other pack makers have used composite carbon fiber frame rods as well, mainly in combination with aluminum maiin frames.
Eric
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DJ2
member
Registered: 01/06/02
Posts: 1348
Loc: Seattle, WA
That's what I use. I buy the carbon fiber shafts from a kite store.
My primary aim in a lightweight frame is to transfer all of the pack's weight to the waist belt. An inverted U made of these shafts does the job and, even with fittings, wieghs only about 3 ounces total.
Registered: 05/02/06
Posts: 208
Loc: Rock Springs, WY
Background: worked in engineering department for a leading composites manufacture of parts for medical, wind energy, mass transit and ag. equipment
i think fiberglass frame sheets would work great. to start you will need to find a resin that is flexible. use sheets of fiberglass mat for your structure then saturate the mat with resin. you can get mat that is woven like fabric or felted ( lots of random strands in different directions) the different woven mats provide for strength or flexibility in different directions and by layering them you can create a sheet with any characteristics you desire.
i also like the granite gear packs and own a latitude vapor, but their frame sheet is not really a composite or a fiber reinforced plastic, it is a solid thermoplastic sheet with different holes punched in it to create flexible and stiff areas, possibly with some solid filler material in the matrix, still a great design but not quite the same.
any questions on how to work with fiberglass let me know.
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