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idea for a UL, fabric less backpack--bamboo, carbon fiber, dyneema line--suggestions, feedback welcomed
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just Justin Whitson
(ArcturusBear)
idea for a UL, fabric less backpack--bamboo, carbon fiber, dyneema line--suggestions, feedback welcomed on 01/29/2013 22:24:07 MST Print View

I have a GoLite Jam pack, but it's a size i don't normally need or want for backpacking (70L!), and honestly i'm trying to preserve it more for my "bug out" bag should the SHTF (the reason why i got such a big pack). Anyways, this is the basic concept. Buy, or make two Bamboo oblong type rings using approx 3/4 to 1 inch diameter type bamboo poles. Take some extra carbon fiber arrow shafts that i have lying around.

Drill 4 main holes into the outside perimeter of both bamboo rings, and another one in the middle of the front roughly half way between the other two, and put the carbon fiber arrow shafts in the holes creating a basic frame. (i would glue these in as well)

Then on the back, criss cross by notching, gluing and tieing two pieces of bamboo approx. 1/4 to 1/2 in diameter. (i will probably sand them down a bit flatter too). Then do the same X pattern on the bottom of the now 3d cylindrical shape, probably using a bit thicker and sturdier pieces of bamboo than the ones on the back (at least 1/2 inch diameter).

Then take some very fine/thin and lightweight pure Dyneema/spectra type line and do some up and down V patterns around the whole thing and especially making sure to wrap around the "joints", and wrapping the bottom more than the sides. Then, put my clothes/equipment into a heavy duty type trash bag for rain protection.

Questions: What would be a good type of glue, epoxy, or the like to use to connect the carbon fiber shafts into the bamboo rings? Whatever i use for the inside, i was thinking of sealing the outside with silicone adhesive.

2nd, what kind of shoulder straps should i use? Are there some good quality, but decently priced ones that i can purchase individually? I don't plan on putting too much weight inside the pack so i don't need heavy duty type shoulder straps, but i do want some durability.

3rd, have you ever seen pre-made Bamboo loops for sale before, and where? I think the hardest part of this project would be bending the bamboo into the desired shape. I have some ideas--cutting some fresh bamboo during winter, put it in boiling water to destroy enzymes and soften it up a bit, ram out the middle inner separating joint material, bend and roast slowly over my wood stove (i don't have a propane torch and won't buy one just for this project), but honestly i would be just as happy buying pre-made loops if not too expensive!

More over, has anyone ever heard of anything like this before? It all just came to me kind of suddenly and out of the blue one night, and i couldn't sleep for thinking about it.

Just guesstimating, but i think i could get the weight to be around 17 oz at most. Bamboo may be free, already got the carbon fiber shafts, dyneema/spectra type line fairly cheap (plus i already have some, but i want to use thinner lighter stuff i think), have some silicone adhesive left over, etc and so it should be a pretty cheap project. Should i put some foam over the Bamboo X in the back for comfort, or with low weight would it be unnecessary?

Anyways, if anyone is interested, i can come up with some sketches of what i'm talking about and upload some pics.

Besides lack of innate rain protection and the possibility of snagging it easily-especially if bushwacking, what are some potential cons to such a pack?

Mark Dijkstra
(Markacd) - F
bamboo pack on 01/30/2013 06:02:09 MST Print View

Some sketches would be very much appreciated. Based on your description I picture you making some sort of clunky cage strapped to your back. Somehow I doubt that's what you have in mind.

Mark Andrews
(buldogge) - F

Locale: Midwest
CF Shafts... on 01/30/2013 06:37:25 MST Print View

Any reason not to just use carbon arrow shafts only and join them with kite connectors/ferrules???

-Mark in St. Louis

just Justin Whitson
(ArcturusBear)
feeling lazy on 01/30/2013 20:17:51 MST Print View

Ok, so i'm feeling a bit lazy and i found a pic on Google images that vaguely resembles what i'm thinking of building except it will have 4 carbon fiber arrow shafts, and dyneema cord interlaced.

http://www.google.com/imgres?imgurl=http://farm3.static.flickr.com/2594/3966370351_35c5a0ac5c.jpg&imgrefurl=http://www.flickriver.com/photos/lonqueta/3966370351/&h=492&w=500&sz=187&tbnid=mnnctmhq9p_ZOM:&tbnh=119&tbnw=121&zoom=1&usg=___crHxhM4OyzzwxIDg-jrKOdoq-w=&docid=B0i6RND8tJrYaM&sa=X&ei=s9QJUYPLMIWD0QHexID4DA&ved=0CDgQ9QEwAg&dur=11444

Yes, it will be more "clunky" than say the average internal or frameless pack, but probably not as much as you may think. I also think my initial weight estimates are a bit off. 4 carbon fiber arrow shafts should weigh no more than 2.25 oz, the bamboo hoops i could probably get down to about 5 to 7 oz total, some backpack straps (3 or 4 oz?), and the dyneema cord (i plan to use 1.4 mm thickness) should probably weigh no more than 1 to 1.5 oz total, plus .5 oz or so of glue, and whatever a small trash bag weighs (1.5oz?).

So lowest i might get it could be 14 oz and highest 16 oz i'm guessing. I'm really excited about this project.

just Justin Whitson
(ArcturusBear)
definitely a consideration on 01/30/2013 20:41:29 MST Print View

Hi Mark A., yes that would certainly be lighter and easier to make, but i only have 4 or 5 shafts that i'm willing to part with (nor do i want to buy more at this point), i think the mostly circular/cylindrical shape would be a bit more comfortable since backs are a bit concave in shape, and i (really) like the idea of using some natural and sustainable material like bamboo. I've thought of using mostly bamboo (but still with dyneema), and i may do that as another project as well since it would have more flex and give.

Who knows, maybe in the further future, i will experiment with just carbon fiber as the frame and in a more rectangular shape.



Anybody have any good suggestions for strong, durable lightweight, and relatively inexpensive backpack type shoulder straps?

Mark Andrews
(buldogge) - F

Locale: Midwest
Straps... on 01/30/2013 21:21:14 MST Print View

I would guess that hitting the salv armies and goodwills of the world for a used backpack would be the cheapest option.

-Mark

Ben H.
(bzhayes) - F

Locale: So. California
Re: feeling lazy on 01/30/2013 22:50:22 MST Print View

With only four vertical poles, only two will be against your back. That will be two flat ridges up each side of your back, then the hoops on either side will be protruding into you. It doesn't sound very comfortable to me. I think you would a lot more veritcal poles to form the cylinder you have in your mind.

Also, I agree with the above, buy a cheap backpack from goodwill and re-use the straps.

Ian B.
(IDBLOOM) - MLife

Locale: PNW
Epoxy on 01/31/2013 00:15:58 MST Print View

One of these might work for your epoxy: http://boatbuildercentral.com/products.php?cat=42#.UQoZgFrjkU4

You might be able to use a cross stitch hoop for the same weight and more or less the same strength. Another idea if your are going for something more organic may be to split the bamboo into smaller strands, soak them, wrap them around a cheap jig, wrap them with some cordage, and then epoxy them together after they've dried.

Here's a link for bamboo fly rod construction. You may be able to apply some of this to what you are doing.

http://www.thomaspenrose.com/tonkin.htm

Edited by IDBLOOM on 01/31/2013 00:23:53 MST.

just Justin Whitson
(ArcturusBear)
Thanks on 02/01/2013 14:09:41 MST Print View

Thank you for the tips, suggestions, and/or links guys. Re: the comfort factor, ideally the "hoops" i will make (i've decided to make them) will not be perfectly circular, but more oblong and so there will be flatter, but still slightly round surface that will be touching my back, and the top hoop, i plan to have slightly above my shoulders so less contact than the bottom hoop. Also, i'm hoping that the dyneema cord which will be tightly wrapped around the outside of the hoop, will provide some cushion as well. If it's not enough, then it's easy enough to glue/attach some light and small foam on the needed areas.

I did some research on bending bamboo, and apparently it's quite doable (and fairly easy) with certain methods. The one i will probably do is to get fresh cut bamboo, ram out the culm (?), plug one end with a cloth rag, fill up with sand and plug the other end, slowly but surely heat it up while bending it. I've seen people on youtube take some pretty large and thick pieces of bamboo and bend them into perfectly round shapes doing this method (rounder than i want or need).

I already tried bending some bamboo, but didn't do the extra steps of ramming out the culm (instead i put pin holes into the sides to let pressure escape) and putting sand in there, and was probably too impatient in my technique. I could get them bent fairly well, but not enough and by that point they would snap. I think the sand is key. I also wasn't using a propane torch, but my home's wood stove (i'm wondering if maybe my white box alcohol stove might work better?).

The used backpacks for straps is a good idea and one i will keep in mind. I wouldn't mind paying a little extra though, for lighter than average kinds. Btw, i've decided to use thinner/lighter dyneema cord than the one i already mentioned. Stuff is so strong, i really don't need anything but a very thin and light kind.

Thanks again, and i will keep you all updated on this, and will put up pics when it's done.

just Justin Whitson
(ArcturusBear)
quick update on 02/04/2013 17:09:21 MST Print View

Well, i spent much of Saturday on my bamboo hoop project. First found another area of bamboo, asked for permission and cut down a couple of poles, and bought some other supplies (fine sand, metal pole). Rammed out the middle stuff, packed it tightly with sand, got my woodstove a blazin, and.... FAIL again.

Yep, i got a whole new respect for those Bamboo shapers down in Central and South America, or in Asia, whom make it seem easy. But then again, i think harvesting bamboo in winter is probably not the best time for shaping/bending purposes and in late spring it would be more naturally pliable and flexible. I couldn't find a source of pre shaped stuff (unless i wanted to buy some semi-expensive pre made furniture and dismantle it)...

So... well i stumbled upon Rattan, which in some ways is similar. It's a bit heavier because it's solid and not hollow like Bamboo, but it's still lightweight and very strong and durable for it's weight. Plus, it's easier to bend/shape. Better yet, i found a supplier that sells .5 in diameter Rattan pre coiled up. For about 20 ft length coiled up, it will cost 10 dollars and some change. I'm a bit worried that drilling a 7 millimeter hole (the OD of my carbon arrow shaft) might be a bit too big for that diameter (roughly half the size) and split it...but i've heard great things about Rattan being very tough in that regard. I think i will drill a bit smaller hole and sand the rest out with my multi-purpose router tool, or by hand.

just Justin Whitson
(ArcturusBear)
change of plans on 02/13/2013 22:59:15 MST Print View

So the Rattan itself was pretty cheap, but the shipping was going to cost as much as the material, and so i said nope. I've gone with Mark's idea, and decided i could part with two more carbon fiber arrows (6 in total). I couldn't find any kind of premade connectors that would work after looking at Kite venders and the like. So i got some epoxy puddy and that's how i put the C.F. rods together.

I'm about 65% done, but i surprisingly ran out of dyneema cord already. I must have put at least 75 or so feet of it on there already. So i'm waiting on a recent order of more dyneema cord (pure dyneema, 1.4 mm size). I will probably put up a pic of the unfinished pack tomorrow.

It's hard to say what the comfort level is going to be like. It looks rightly proportioned, but until i string up the the part that will be on my back, i won't know for sure, but it seems like the cord weave will keep it off my back a bit, give it some cushion and give. Oh, btw, so far it weighs 12 oz and that's with the back pack straps. It's a little bigger than i would like, just under 3800 cubic inches of space. Basically, i just need to wrap more cord around it, and that won't add more than an 1 oz. I also ordered a lightweight silynlon large stuff sack to put my clothes, bag, food and some other stuff in, which will double as a bear bag-- that weighs .7 oz. Then a trash bag in case it rains. So i'm looking at around 14 oz total.

You guys probably think this is a crack brained idea though.... It will be if i ever fall on it, i don't think the carbon fiber rods would survive anything like that. Hey but 3800 cubic inches for 14 oz, and about 35 extra dollars i had to spend on materials that i didn't already have.. not too bad if it's halfway comfortable.

just Justin Whitson
(ArcturusBear)
pic of unfinished pack on 02/14/2013 13:29:07 MST Print View

external frame backpack

John Donewar
(Newton) - MLife

Locale: Southeastern Louisiana
Re: pic of unfinished pack on 02/14/2013 13:44:26 MST Print View

Justin,

I realize that your pack is early in the construction stage but I believe that your shoulder straps are on the wrong sides of the pack.

See the picture of the pack below for an example of what I am talking about.

Zimmerbuilt ZB4 - D40

Your S curves are turning in and they should be turning out at the bottom.

Party On,

Newton

just Justin Whitson
(ArcturusBear)
Thanks! on 02/14/2013 15:36:48 MST Print View

Arggh, you're right Newton--how did i miss that..? Thank you for pointing that out before i strung that side--would have made it a lot more difficult. Thankfully now, i just have to cut the tape on one of the straps and slide over the other one to that place.

I knew there was a reason i decided to even put up a pic of an unfinished project!

jerry adams
(retiredjerry) - MLife

Locale: Oregon and Washington
Re: Thanks! on 02/14/2013 18:04:21 MST Print View

And you want your shoulder straps closer together and at an angle so when they go over your shoulder one edge of the strap doesn't dig in. If you angle them correctly they'll be flat against your shoulder.

just Justin Whitson
(ArcturusBear)
Re: Re: Thanks! on 02/14/2013 23:42:19 MST Print View

Hi Jerry, thank you for the reply. Yeah, those are not the final positions. Right now they slide across, but when i string that side, i was planning on putting them closer together and the cord will help to fix it in position more. I may have to use some shock cord and a cord locks too--not sure.

Peter Evans
(NLslacker)
Some great inspiration. on 02/20/2013 08:10:42 MST Print View

http://74fdc.wordpress.com/2012/08/25/external-frame-backpacks-applying-the-old-ways-to-the-new-journeys/

Above is a link with a lot of unusual external frame packs: some are quite amazing and multiple-use (Chair!)
chairhatnot ultralightwow

Daryl and Daryl
(lyrad1) - MLife

Locale: Pacific Northwest, USA, Earth
Re: Some great inspiration. on 02/20/2013 20:17:47 MST Print View

Peter,

I love the link you included about external pack frames! There's much to learn just by looking at the photos.

I also liked the link within a link that led to woven backpacks.

http://74fdc.wordpress.com/2013/01/18/woven-backpacks-design-rooted-in-history-and-tradition/

Thanks,

Daryl

Edited by lyrad1 on 02/21/2013 09:42:29 MST.

Daryl and Daryl
(lyrad1) - MLife

Locale: Pacific Northwest, USA, Earth
Securing the straps on 02/20/2013 20:21:52 MST Print View

" Yeah, those are not the final positions. Right now they slide across, but when i string that side, i was planning on putting them closer together and the cord will help to fix it in position more. I may have to use some shock cord and a cord locks too--not sure."

Justin,

I addressed this "securing the sliding shoulder straps" issue on one of my packs. I'll post some photos if it is of interest to you.

Daryl

just Justin Whitson
(ArcturusBear)
Re: Securing the straps on 03/03/2013 00:52:42 MST Print View

Hi Daryl,

Yes, please do share. Thank you. The wrapped dyneema cord seems to have more or less secured them, but i'm still interested in seeing what you did.

Btw, the pack is mostly finished, i will put pics up soonish. It's surprisingly comfortable since the dyneema cord cushions, and pushes it back slightly from the back. I haven't brought it on a backpacking trip yet, or even a day hike, but plan to soon. The major potential weakness i see, is the shoulder straps since i couldn't sew them on with my machine, and taped them with tyvek tape. I could and probably should hand sew it a bit as well.