Mar 15, 2014 at 2:41 pm #1314434
Here is a sneak peak at my latest project: A Bamboo External Frame Backpack.
It’s a work in progress and I’m still tinkering with it, but I hope to have it ready very soon.
It is made of bamboo poles and paracord lashings. The straps to hold the gear to the frame are nylon with plastic buckles. No metal involved at all. The pad for the back is multi-use: The pad can be removed from its pouch through a Velcro opening so it can be used as a sit pad during breaks and as extra insulation under my feet in my hammock or in my tent.
The top can be loaded with either a large or small bear canister.
The bags will be 20 liter waterproof drybags with roll top closures. I ordered some gray ones so I don't have such a "rainbow" effect with the multi-colors. The nylon straps that hold the bags are affixed to two vertical poles running down the middle of the frame. They won’t slip because there are several holes running along the poles and the straps are tied into place. The holes make it adjustable so I can shift the fixed points along different points along the poles.
I’m experimenting with adding a loop for holding a water bladder for drinking on the go. Should be easy, but don’t know if it will swing too much and be annoying.
It can be set up with or without a sturdy hip belt. It’s not necessary to have one, but the heavy duty belt does help with higher weights. The problem is that my hip belt–a military MOLLE belt–weighs a whopping 16 oz. So, I’m trying to avoid using that or find an alternative that sets up similar to the MOLLE.
A special thanks to Daryl Clark whose lightweight external frame packs inspired me to jump into this project. His help with previous projects was invaluable. And a big thanks to Henk Smees (aka "The Flying Dutchman") for his input and sharing his external fame creation with me. I borrowed quite a bit from his pack design.
Pack Back:Mar 15, 2014 at 3:40 pm #2083026
@wildtownerLocale: Grand Canyon State
Very cool — it reminds me a bit of a LuxuryLite.
Have you thought about replacing the paracord with strips of cane (like you would use for a woven cane chair)? You soak the cane strips in water to make them malleable, then you tightly wrap the bamboo, and the cane actually continues to tighten as it dries. Trim it to fit, wood glue the end, and it'll be stronger, more durable, and lighter than with the cord. You can google cane furniture repair supplies to find the cane strips (something like this: http://www.hobbyshopamerica.com/commonwealth-basket-fine-2-5mm-chair-binder-cane-refill-for-kit-200f-fc.html?gclid=CNfpnOnMlb0CFcURMwodemMALA).
Really nice work!Mar 15, 2014 at 4:02 pm #2083033
@funnymoLocale: Sunshine State
REALLY cool project, I must say.
Questions about the pad pocket/back panel: Does it move away from your back when packed? Is it enough padding along the frame?
Also, what does the pack weigh?
ToddMar 15, 2014 at 4:05 pm #2083034
Nice job Michael.
I'm glad you posted it so others can learn from your efforts.Mar 15, 2014 at 5:02 pm #2083047
Cool project! Gossamer Gear sell 4 oz hip belts.Mar 15, 2014 at 5:33 pm #2083053
It's as if Jansport had located on Gilligan's Island.Mar 15, 2014 at 5:36 pm #2083055Mar 15, 2014 at 7:18 pm #2083079
@ Valerie: Thank you so much. I had not considered your suggested method for the joints. I will have to experiment with that. It’s very appealing since it uses more bamboo instead of synthetics. I did consider a resin process such as some of the bamboo bikes because it’s strong, but I decided against it because of cost, hassle, mess, etc.
@ Todd: I’m not sure if I understand what you mean by “move away from your back,” but the pad protects against the two *inside* vertical poles and the bottom horizontal pole. The hip belt also helps as an additional cushion for the bottom pole. The two *outside* vertical poles are 13 inches apart and the pad does not do anything for those. The pad hangs between those two outer vertical poles. But those outer poles do not make contact with my back. It is not a factor. I have added some additional padding to the back panel to make it extra comfy, especially at my lower back where the most contact is made.
I knew someone at BPL would ask about weight. Mea Culpa…I don’t know. I did not start weighing the individual pieces and it's a bit cumbersome with my small digital scale to weight it accurately. I have a feeling I’m not done with this thing and will try to make it lighter where I can. I will hold off on weighing it for now and report back if there is enough interest. For now, all I can say is: It’s the lightest MYOG bamboo backpack I’ve ever encountered…Sorry, not trying to be a smarty. I’ll get some weights sometime after doing more testing and tinkering.
@ Daryl: And THANK YOU for all of your very, very helpful input. It simply wouldn’t have been right not to acknowledge your help.
@ Ian: I have a Mariposa and I like their hip belt. And I did try using lighter alternatives, but I should elaborate. The MOLLE belt has straps that are affixed to a rigid panel on the back of the belt. These things are designed to hold very heavy military packs, like the ALICE. I mimicked the ALICE pack connections with paracord on the bottom horizontal pole so the MOLLE belt would work as it was designed to work. I guess what I’m looking for is some way to repeat that effect but with a much lighter version.
@ David: Your comment made me laugh. Thanks. Part of this project was just to see if it would work and have some fun. I really like bamboo, so there you go.
@ John Abela: You hit the nail on the head. Those two packs certainly played a role in inspiring this pack. Indeed, I was about to make a Molly Mac replica with some modifications when I went in a slightly different—more traditional—path for this external frame.
MichaelMar 15, 2014 at 7:22 pm #2083080
I would love more feedback on this project, especially any thoughts on improvements.
Does anyone have any suggestions on lightweight cordage that would hold knots well for the purposes of this pack, i.e. lashings and holding the joints? I prefer black or green, but some of the stuff out there is neon orange or bright green. I'm trying to avoid that, if possible. Also trying to keep the price down. Overall, this was a pretty low budget project and making adjustments will add to costs–but I do want it to work.
And, any assistance with a hip belt alternatives that would achieve the criteria I mentioned above with regard to mimicking the MOLLE belt/ALICE pack connections, but in a lighter version, would be fantastic.
MichaelMar 15, 2014 at 9:18 pm #2083120
The strength to weight of bamboo is high enough that it was used as ski poles before aluminum.
Three years ago, I saw bamboo used all over China in traditional housing, furniture, musical instruments, cooking utensils, all manor of light construction and, most incongruently, as scaffolding during the construction of high-rise steel-reinforced concrete high rises.
We were told that there are many species of bamboo and some are used for food, some for structural work, etc. If, as a westerner, you grab a piece of bamboo willy-nilly, it might be like someone new to wood working attempting to build furniture from eucalyptus, airplane wing ribs from ironwood, use pine for cooking, and balsa in a post-and-beam house.
Don't take that as a criticism, I certainly don't know any better myself. But whatever you're able to achieve in your first effort, could be optimized greatly with better materials.Mar 15, 2014 at 9:25 pm #2083123
>"Does anyone have any suggestions on lightweight cordage that would hold knots well for the purposes of this pack, i.e. lashings and holding the joints?"
I saw the 550 cord and thought of that as an obvious place to save weight. I'd use 75- to 150-pound test braided fishing line. I carry 25-foot lengths as a part of a UL fix-it kit. Lashings, replacement shoelaces, fishing line, etc. PM me if you want me to throw a hank of it in the mail to you. You'd want to wear gloves when cranking on it, but you can make joints that are quite strong and weight about 1/8 of what that parachute cord does.
Here it is in black at one cent per foot for 100-pound test:Mar 16, 2014 at 6:54 am #2083170
@ David: Thank you for the generous offer. I'll send you a PM. Never would have thought of using fishing line and I'd love to try it out. I'm also kicking around the idea of trying Zing It and other similar lines.
MichaelMar 16, 2014 at 7:41 am #2083179
Thanks for the line suggestion. I just ordered some.
David and others,
After lashing something do you have any suggestions for knots or other means of securing the end(s) of the line? My knots tend to loosen up over time. I've even resorted to taping the ends down.
DarylMar 16, 2014 at 10:22 am #2083224
Here is a tutorial from Hedgehog Leatherworks that I use for lashing:
I have learned quite a bit from his videos.
MichaelMar 16, 2014 at 12:55 pm #2083265
@cameronLocale: Idaho Falls
We built tents like this using a modified square lashing technique.
A lot of people make this knot more complicated then it needs to be. What we did was easier and in my opinion plenty strong.
Step 1 – Fold your rope length double
Step 2 – Put the folded end around one piece of bamboo and pass the loose ends through it to make a "slip knot"
Step 3 – Wrap the doubled over strong tightly as shown in square knot diagrams
Step 4 – Separate the two strands. Pass one under the wrapped cord and keep the other loose. Now the two strands can be pulled in opposite directions
Step 5 – Pull the two strands at tight as possible and tie them off.
I tried finding a diagram of our technique online but couldn't. The normal boy scout way looks more complicated. The closest I could find was the Japanese Mark II square lashing.Mar 16, 2014 at 1:43 pm #2083284
Michael and Luke,
Thanks for the info. Helpful.
Here's a video that might be close to what Luke was describing?Mar 16, 2014 at 2:39 pm #2083299
Thanks, Daryl and Luke. I like that method in the video, too.
MichaelMar 16, 2014 at 2:58 pm #2083303
I've had good success with a "constrictor knot" – a clove hitch with an extra twist, which helps with slipperier synthetic cordage.
which especially helpful and easy with the starting point, but it can also be used as a the ending point to secure the line, albeit harder to take up all the slack. Once snug enough, you can apply a dap of glue to make it permanent.
If you have two lashings near each other, you can tie a loop on the end of each line with a bowline and then run another line multiple times between the two loops. That gives you a pulley-like effect, more mechanical advantage, and gives a point where you retighten everything in the future.Mar 16, 2014 at 3:08 pm #2083308
Thanks. I made a copy and will tape (tie?) it to the spool of fish line you recommended when it arrives.Mar 16, 2014 at 3:21 pm #2083316
Another approach would be to drill the cross members with a hole saw matching the verticals' diameter. Then rest the verticals in the 180-degree and compress the left vertical towards the right vertical with a turnbuckle snugging up fishing line between the two verticals. Here's someone else's concept where the joint is snugged up locally, through the use of a peg as an attach point:
This would eliminate the overlapping the bamboo, keep the load closer to the back, and reduce the weight a bit. I think it also be stronger – you would be using the compressive strength of the bamboo and the tensile strength of the line, rather than relying on the friction between the pieces of bamboo in a square or diagonal lashing.Mar 17, 2014 at 11:49 am #2083533
Other than the fishing line that David suggested, can anyone suggest lighter alternatives for the lashings that will hold knots very well?
MichaelMar 17, 2014 at 1:06 pm #2083561
There's braided nylon line that works well. NOT mason's line – Mason's line is twisted, not braided and doesn't stay together well and is more slippery. But the braided stuff is available in about the same size as the mason's line. I square-lashed 200 feet of 1-inch rope into a cargo net for one of our playgrounds (about 81 square lashings) 10 years ago using that braided nylon line. 10 years out in the weather and it is still fine. The bumps on the braided line make it more frictional – easier to pull on and easier to hold knots. It is MUCH easier to work with because it doesn't untangle so quickly at the cut ends.
It can be a little hard to find at a Home Depot. They'll have 10-15 options of twisted Mason's line, but 0 or 1 braided options. Commercial fishing supply shops always have it because it is used in mending and constructing fishing nets.Mar 17, 2014 at 6:38 pm #2083668
80-pound dacron fishing line, 25 feet = 5.1 grams
braided nylon line (mason's line thickness, but braided, 25 feet = 10.4 grams
550-cord, possibly heavier than some stuff sold as para-cord, per 25 feet = 55 grams.
edited to add: upper left on scale: 25-feet of 80-pound fishing line. Upper right: 300 yard spool of same. Middle left:25-feet of braided nylon twine. Bottom: spool of same. Middle right: 6 feet of 550-para-cord.Mar 17, 2014 at 9:07 pm #2083721
Thanks for the post.Mar 17, 2014 at 9:10 pm #2083723
Yes, thank you David. You're like a one-man Home Depot!
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