Bushwalk Australia

I was going to purchase a MLD DuoMid (and still might) but I thought I should give building one a go, due to it being more rewarding, fun and at the same time no doubt more frustrating .

I am still in the planning stages, and have yet to order the materials but here are some threads from others builds, which others may find helpful.

http://www.backpackinglight.com/cgi-bin/backpackinglight/myog_silnylon_floorless_2-person_tent.html?forum_thread_id=36355&startat=20#.Ulm5_VBmim5 - you may need to be a member to access this one

http://trailsandtracks.blogspot.com.au/2011/07/myog-pyramid-tent.html - andrewbish off this site's blog.

http://www.backpackinglight.com/cgi-bin/backpackinglight/forums/thread_display.html?forum_thread_id=42202

http://chrisroane.blogspot.com.au/2011/02/myog-10x10-pyramid.html.

There would be others and as I find them I will add them. If anyone has any other helpful links or other tips/advice to add feel free.

Next step finalise the design and order the materials.

Looks a straight forward project. I didn't realise that Andrew B had made one - his pitches very smoothly. So what weight cuben are you going to use??

Andrew A

I am starting with sil-nylon, I can't afford Cuben .

Or will you do a trial run in ripstop or Silnylon first before using the expensive Cuben?

Have you given thought to the venting and to the possibility of a hood over the entrance yet>??
Having used the Megamid in some really gnarly weather putting in a shallow triangular piece on the bottom windward edge is something worth while thinking about as are snow valances ( detachable even) if you want to use in winter above the snowline. Having had a Megamid pole break on me I would think seriously about pole construction methods if winter above the snowline is one use for the finished product even if it adds a little extra weight. I have my doubts about the strength of joined trekking poles in really bad conditions.
A pentagonal shape may be of benefit in windy conditions too; rear to the prevailing gusts; although that is speculative conjecture on my part

Hey Moondog,

I intend putting a vent in the top with mesh and sil cover, not sure of the exact design yet but it will be there. Probably won't bother with the hood over the entrance just yet, I figure I can add that later if need be. It will be a trial to see what works, which I can improve on next time, when I probably will use Cuben.


For the poles I was hoping to use walking poles (even though I don't own any yet), but I will see.

Once I build the outer I intend to make a solo inner tent for bug protection. It is a bit more of a stretch from making hammocks but you are just sewing two pieces of fabric together at a time.

Hello, I'm looking to build a pyramid tent also. My plan is to boldly go straight to cuben. I have a few questions that I was hoping to consult the great intelligence of this board for. My apologies to Simon, as I am posting in his thread (I'm not sure on posting etiquette as this is my first post, so I hope I'm not out of line?). I'm copying Jerry Adams Build.

I'm wondering why the pole cap goes outside of the tent. I thought it would make more sense to go inside?

I'm also after some pro-tips on doing the seams in cuben.
At this stage I'm deciding between 1 or 1/2 inch tape
sewing, straight, zig-zag or no sew.
sealing with seam grip or another layer of thin cuben.

Thank you in advance.

Redback, Good on you for fiddling with the ideal fabric first....thats my style.

-I agree that pole cap would go inside to avoid wearing though the outer waterproof (cuben) fabric.
-Read Zpacks site about cuben, and some of backpackinglight.....and Nuts (on this forum) did a cuben tent some years ago.
From what I've read, I'd limit sewing, and use toe where possible...1/2 " double sided on seams, reinforced with 1" single sided. If taped, you shouldn't need to seam seal
-also have a look at this site re making tie outs.
http://www.suluk46.com/

Enjoy the project.

A

Thanks for the reply. From my reading so far companies like Zpacks and six moons use a combination of taping and sewing. I still have a few weeks to complete my design before the cuben arrives.

Redback - I would agree also with the pole cap inside. I don't understand why it would be outside either. There is probably a very good reason, perhaps just that it is easier to sew on the outside.

Here is some information about sewing and using tape from Cubic Tech.

Bonding CTF3 with CT-PSA:
1. Determine the width of the seam: For many applications that use lightweight CT laminates a 0.5-inch
seam width is adequate. All seams should be tested to verify they have the appropriate properties for
the intended end-use application.
2. Before applying CT adhesive, wipe clean the surface with a solvent such as MEK, acetone or rubbing
alcohol to ensure that the bonding surface is clean and dry. Residual dirt or moisture will negatively
affect the performance of the bond.
3. Initial Bond: Peel the paper backer from the CT-PSA and apply the adhesive transfer tape to the first
laminate. Using a roller, apply firm pressure to ensure 100% contact.
4. Final Bond: Remove release liner. Apply the second laminate to the exposed PSA. Care should be
taken to apply the second laminate flatly and without wrinkles. Again, use a roller and firm pressure to
ensure complete contact.
5. The recommended cure parameters is 240°F for 10 minutes, under firm pressure, such as in a press.
Pressure should be as great as possible. Do not exceed cure temperatures of 270°F. Depending on
end use conditions and the intended performance of the seam, lower cure temperature or time may be
sufficient. In many cases curing the seam at 240°F, under firm pressure for 30 seconds will produce a
reliable bond.
NOTE: The seam will gain strength over time as the adhesive ages.

Optional stitch: If necessary, stitching may be added to the seam to improve the peel strength. Be
aware that stitching may reduce the strength of the seam because of the perforations. The stitch may
also reduce the water-tightness of the laminate; a liquid adhesive such as Seam Grip® may be applied
over the stitch to cure this. A straight stitch is recommended, 6-8 stitches per inch, 16 or 18-gauge
needle, Nylon 69 thread. Stitch no closer than 1/4-inch from the edge of the laminate.

Redback wrote:Thanks for the reply. From my reading so far companies like Zpacks and six moons use a combination of taping and sewing. I still have a few weeks to complete my design before the cuben arrives.

What weight Cuben have you chosen?

Wow, you are game redback. Have you considered starting with some stuff sacks first?
Most of the time bonding will be stronger and less prone to tear-outs.

TBH the BPL forums are much better for these questions, there are few experienced cuben fibre artists here.

Last year I used 1 mil (25 micron) polyethelyene plastic, along with a 200g bivy sack, on a long trip and worried whenever the sky looked dark. I knew my tarp would shred in real wind. So I wanted to replace this with a shelter that weighed about the same (groundsheet, tarp and bivy sack totaled 345g) but could be trusted in a storm to do more than just keep me alive. So I purchased 0.51 oz/yd² Cuben earlier this year in advance of a long trip. That trip got postponed and, lazy as I am, so did the tent making. I originally had a smaller design in mind, one that used two poles in an inverted "V" configuration, but a quick full scale mock-up proved that idea to be impractical. So I cast about for alternative designs and kept coming back to something about the size and shape of a Duomid. I have already read read everything I could find (without subscribing to BPL) on the subject, including the contents of those posted links.

So far I have only tinkered a bit but enough to be convinced that 1/2" tape, when allowed to cure for a sufficent period of time at room temperature, forms a very strong bond in shear. I trust the tape by itself to hold the seams together.

The other thing I've tried to understand is the optimal amount of curvature for the ridgelines. I'm not really sure how to figure this out short of constructing several mock-ups and even that may not work unless I do them in Cuben. I think most people just pick some number. From what I've read online 2" max deflection on each panel seems to be popular, nevermind that ideally there should be a difference between long and short panels for a rectangular 'mid. That works out to about 4" max deflection on the ridgeline itself. My old school Chouinard Megamid appears to have a catenary curve that deflects about this much so I suppose it's the "right" number, or close enough. The tradeoff is between pitch tautness (and strength) versus internal space. For me headroom is an important design constraint. I have a minimum requirement for this and the Duomid makes the cut but without a lot to spare.

A Duomid should be the fairly easy to build, or at least I imagine so. Given the width of the fabric roll minimizing how much I use will require cutting and joining 10 pieces, not including zipper attachment, top cap, zipper rain flap/hood, and tie outs.

I don't know when I'll start work so hopefully I can watch and learn more from (the mistakes of) you guys!

Orion - there is a strong possibility of mistakes in my build so I hope it helps. Mind you this project may take a while. I am so confident in my ability I am going with sil-nylon seconds. I have heard mixed reports about the seconds so it is also a chance to evaluate the quality personally.

If I was to work with Cuben I would use tape primarily, with minimal sewing (if at all). The general consensus if sewing is to use the tape first and then sew for reinforcement, however, you would then need to waterproof the holes you have made in the Cuben. Anyway that is for another time for me. Although the more I work with Cuben at home the more I get tempted to use it for my own purposes, it's a bad temptation .

Wouldn't hesitate to start with Cuben, different skills to nylon (though, yeah, a couple of stuffsacs would be ideal before launching into the tent). In the case of a tipi you are taping four- eight triangles together.. there would be ways to stuff up but it's not exactly 'art'

I'd just tape, sew where needed, Phillips Duomid close-ups might help: viewtopic.php?f=15&t=11177&p=166523&hilit=philip+duomid#p166523

I've studied those photos from Phil very carefully and like the idea of bonding the Cuben to a second Cuben layer that is sewn to a third non-Cuben fabric for places where sewing is necessary, like tie-outs. This maintains the integrity of the outer Cuben layer. I think adhesive would be better than tape in this case since you could spread it out evenly and have time to work the pieces into place instead of using a bunch of seperate strips of tape that grab instantaneously. For the zipper I've read that one can sew it directly to a strip of Cuben (perhaps doubled) without an additional layer of nylon fabric, and then bond that Cuben to the tent. I think that makes sense. The stitching I've tried with the 0.51 Cuben seems okay. The holes stretch open but I don't picture the fabric failing without reinforcement. I'm still not sure how critical finishing all of the edges is with the 0.51 Cuben. It can fray, but will it? With silnylon I've left the base of the tent I made with it unfinished, just the raw edge, and it isn't fraying. Of course Cuben isn't silnylon.

Simon, where are you getting your silnylon 2nds? I've sewn with silnylon 2nds I purchased from OWF many times and the fabric is great. It's heavier than Cuben but certainly a lot cheaper if you make a mistake. Plus you can rip out stitches, seal the holes, and go back to work. Cuben is less forgiving in that sense and of course many times more expensive. For me Cuben costs about $21 USD/m² whereas silnylon 2nds cost about $4.25 USD/m² -- Cuben is 5X the price of silnylon!

Orion - I will be placing an order with OWF in the next week or so for a heap of stuff inclduing the sil-seconds for this tent.

Okay, good to know. It will be very interesting to see how it works out for you. I've made a lot of stuff with the OWF silnylon and it does well. It doesn't seem as tough as the fabric that my Hilleberg Nallo is made out of but it is quite workable nonetheless.

Hi Simon, I've gone with 25g/m2 (0.74oz/yd) which is the slightly heavier version. I've managed to get hold of some in Orange, so I'll see how that turns out. I was going back and forwards whether to build in silnylon or cuben. The less sewing tipped me over in the end.
I have used silnylon 2nd from (BWD) DIY Gear supply and found it to be basically the same as the firsts they sell. (used for a DIY hammock)
Thanks for the advice re: stuff sacks. I think I will mess around with some to get a feel before I go and butcher 9m of cuben.

Nuts wrote:Wouldn't hesitate to start with Cuben, different skills to nylon (though, yeah, a couple of stuffsacs would be ideal before launching into the tent). In the case of a tipi you are taping four- eight triangles together.. there would be ways to stuff up but it's not exactly 'art'

I'd just tape, sew where needed, Phillips Duomid close-ups might help: http://bushwalk.com/forum/viewtopic.php ... id#p166523

Thanks for the link. The white tieouts are easy to see. The Duomid is a lovely tent. I will go for something slightly larger, as I'm quite tall.

Colin Ibbotson has uploaded his MYOG cuben tent design (and it's pretty nifty)

http://tramplite.com/2013/10/myog-cuben ... elter.html

icefest wrote:Colin Ibbotson has uploaded his MYOG cuben tent design (and it's pretty nifty)

I still don't understand the reason for that large beak opening amongst similar UL tents. Why not have it adjustable to ground level?

Isn't it?

icefest wrote:Isn't it?

Thank you so much for that link. Very good description of how he does the seams.

I was also confused, he said he didn't like how the Zpacks Hexamid didn't offer a lot of weather protection. Then he went and built one. It looks like the beak doesn't even extend down as far as the hexamid. Still a very nice looking tent.

Very nice work, it looks professional. That page had escaped my earlier searches.

The beak: I was also expecting to see a picture with it extended to the ground but there isn't one. That design wouldn't work for me I'm afraid. The other thing is the need for 6 stake points. Often the ground where I camp isn't great for stakes and I have to use rocks. My previous tent I had a design goal of only two stake points for this reason. A pyramid requires 4 and the hexamid style tents need 6.

One other thing I've wondered is why Dyneema Gridstop is used so frequently for the top cap and for other reinforcements. It's pretty heavy material, as Colin mentions, and I think it's tougher than is needed for the application. There are lighter coated nylons that would work just as well. Or am I missing something important?

Yep It really needs to be strong, my Megamid has 2 layers of heavy Cordura in the peak, a lot of strain and tension gets concentrated there. The original Megamid used LW ripstop in the peak but it used 4 layers and each layer was larger than the first so spreading the load over a great area, same on the peg points

You might be able to get away with lighter material on the outside top and restraints. I think zpacks use hybrid Cuben.
I think the design I posted can get away with 5 pegs.

Even so, a flat tarp requires 6 pegs usually but is more than 12g lighter.
Is there any reason you don't use the extra super crazy lightweight Cuben and make a tarp? Ie your original set up but with Cuben. You would have to find wind sheltered spots but would be able to cope with almost all other (summer) weather.

I'm also been having a play at making a mid, I'm currently at the "blue tarp" cut up experiment stage, still deciding on cuben or silnylon. I quite like the Luxe Minipeak 2 I just picked up cheap, all the design features are basically right for me, just want it a little bigger and a lot lighter...

The Ibbotson design has some nice detail stuff, especially regards adjustability, but I think there is always a case for being able to lower all sides of a shelter right down to the ground, bombproof mode I call it.

Moondog55 wrote:Yep It really needs to be strong, my Megamid has 2 layers of heavy Cordura in the peak, a lot of strain and tension gets concentrated there. The original Megamid used LW ripstop in the peak but it used 4 layers and each layer was larger than the first so spreading the load over a great area, same on the peg points

Really, two layers? Mine just has one. And since it's not a UL shelter to begin with, why not have a really tough fabric there? Mine shows essentially zero wear.

I wasn't thinking of using Cuben there, just maybe something lighter than Gridstop at 4.2 oz/yd². Even the 140d Gridstop is lighter by nearly 20%. I wonder what MLD uses? What's that white material in Phil's photos? Pure dyneema fabric?

icefest wrote:You might be able to get away with lighter material on the outside top and restraints. I think zpacks use hybrid Cuben.

Hybrid Cuben, very interesting.

icefest wrote:I think the design I posted can get away with 5 pegs.

He wrote that it requires 6. Which one can you leave out?

icefest wrote:Even so, a flat tarp requires 6 pegs usually but is more than 12g lighter.
Is there any reason you don't use the extra super crazy lightweight Cuben and make a tarp? Ie your original set up but with Cuben. You would have to find wind sheltered spots but would be able to cope with almost all other (summer) weather.

My original setup was just a rectangular piece of plastic with some guylines that I hoped to never use. It could never achieve "bombproof mode", as David calls it, and would require more effort to pitch and more hassle getting in and out of it. The 0.33 oz/yd² Cuben sounds like it is only somewhat more reliable than my plastic painter's tarp but 100 times more expensive. So I thought that with some effort I could have a very lightweight shelter that pitched easily, could handle a windy storm, have minimal bug netting, a door for easy access, and wouldn't shred or tear the first time I used it.

Orion wrote: Hybrid Cuben, very interesting.

He wrote that it requires 6. Which one can you leave out?
I think the centre-back, when pitched in compact mode.

Orion wrote:Hybrid Cuben, very interesting.

It's the same stuff they use in the Arc Blast packs
From the zpacks page:

Orion wrote:My original setup was just a rectangular piece of plastic with some guylines that I hoped to never use. It could never achieve "bombproof mode", as David calls it, and would require more effort to pitch and more hassle getting in and out of it. The 0.33 oz/yd² Cuben sounds like it is only somewhat more reliable than my plastic painter's tarp but 100 times more expensive. So I thought that with some effort I could have a very lightweight shelter that pitched easily, could handle a windy storm, have minimal bug netting, a door for easy access, and wouldn't shred or tear the first time I used it.

185$
http://www.zpacks.com/shelter/hexamid_pocket.shtml
It weighs less than 100g with guy lines. For that weight you will not get anything tougher/stronger.

I thought you were a SXUL kind of guy, and wanted the absolute lightest. :S