Discussion in 'DIY & MYOG' started by Enzo, May 22, 2020.
I don't have any informed opinion to offer really. It's uncharted territory for me. Do any of the small manufacturers make big mids in 0.51?
That's the stuff I made my bivvy floor out of @Lempo nice to see it available again. The fiber content of 0.67 is half that of the 1.0 Zpacks use for their floor, but given how easy it is to repair I recon it's worth it for that big a weight saving
@Rog Tallbloke I don't know of any. If I had my rose coloured specs on I'd say it was because all the USA made big mids are made for snow loads....
But they are big panels, that said I think the three person duplex is 0.51 and enormous.
I reckon my 12 point tyvek teepee will handle big snow loads, but it is heavy.
And you have your knot octo for snow use, so maybe just go for it with the roomy featherweight summer palace.
Oddly enough the knot has such a cat cut that I wouldn't use it for snow. I got a 3f SL3 copy for the occasional snowy camp.
Think I'll go for it, it's definitely the biggest bang for buck.
I had a look at the MLD site, duomid is available in 0.51, but the xl and supermid etc are 0.75 and sil only.
Enzo, if you’re going big with 0.5 I think you’d better go octo.
Hi @Stumpghes, the option of 8 identical triangles would need more fabric, what's tempting is the fact there is almost no wastage. I'll have 8 seams though, central ones being perpendicular. Plan was a straight cut on those, but I wonder if a light catinary would allow a more Oct shape?
Ah, yeah, fabric waste. What about a tipi? Regarding cat curves and octagoniness, yeah, maybe, but I’m not sure with DCF. I think that cat curves create this possibility: over-tightening the ridges such that you straighten that cat curve seems to conify the entire shape, as well as slightly elongate the ridges and maybe octify a square. But I think this results in less tension on the perimeter/hem. With the Knot designs, this is no big deal because of the cat cut hems and the deformability of silnylon: the hems are are a little under-tensioned, sure, but they are not going to flap much because the part that would be under the least tension has been excised. But when I’ve tried to conify a DCF mid the price payed for coniness is loose and flappy hems.
However, unless your slants are very steep (e.g. LG Apollo) I think DCF shelters should have cat cuts. The stiffness of The material almost removes the need, but not quite. I think cat cuts allow for easier taut pitches that do not require over-tightening the ridges.
Yup agree, I think cuben needs cats to pitch drum tight.
The appeal is that a 2.7m mid is very little work for a lot of bang, I wonder if two 3f T inners would fit?
Anyhow might start cutting this weekend and work out how much more I need to order.
Pity rsbtr has run out of the seconds stuff. I'll probably get more from ex Tex to save import/postage. Be nice if they got some 1.5oz in too have packs to make!
Will you be sewing or bonding? (sorry if this has been asked already)
Enzo, won't your Octo square inner fit?
Sounds like you are going to make something similar to this: https://locusgear.com/items/khafra-dcf-b/?lang=en , which it would fit.
I dunno if my knot inner will fit, worth trying. Though I'll probably use it for a 1p palace or with my Mrs so the half inner.
That locus gear is exactly what I'm planning!
My plan is to tape the two triangles that make each panel and lap fell seam and over tape the corner seams. Given I'm using 0.51 taping alone would probably be fine but I have toys I'd like to use...
Have ordered some 9mm tape that I'll use to tape the two corner panels, then roll the seam over 180 degrees and I have a 10mm double spring guide foot for my 6mm double needle machine to form a lap felled seam. Then over tape, heavier than taped alone, but a stronger seam for sewing a tie out to, and I have 10mm mini line locs coming so they should stitch on tidy.
Looking forward seeing the end result
three sides of cut, two full triangles and one waiting for the zip to be sewn down the middle.
I have 2m of no5 aquaguard zip, any advice on how long a zip people recommend? The zip is a very significant proportion of the total weight so it makes sense to minimise length, but not to the extent of it being a pain in the ass to get in! Dimensions are 2.7 wide by 1.6m high.
The other decision is how much cat cut to put on the seams. I'm thinking an almost locus gear amount, this shelter although big enough for all four of us will probably be used for one or two (my daughter, although 7, puts God zilla to shame). So space is not at a premium, but given its 0.51, strength and wind resistance are.
Seams are 2.5m long, I was thinking 100-150mm deflection?
If someone buys my wonderful cumulus quilt that would almost pay for the fourth side of this mid, so buy away!
Looking at how my Cuben shelter pitches - I get a little 'loose' fabric along the side seams where it doesn't always pull tight/flat - I've considered putting a CAT cut along those seams in any new iteration of this design I make.
BUT I would make it a very small deflection - not more than 1cm - I think you could put too much tension along the seams if you ask the DCF to "stretch" in ways it's not designed to do. My instinct is that big CAT cuts are really for stretchy fabrics like Silnylon.
Occasionally I see a myog cuben shelter that says it doesn't use cat cuts, but generally, and in my experience as you say you get saggy seams.
Agree that heavy deflection could put extra tension on seams, but locus gear etc show it's possible with good lifespan. I'm coming around to the idea that it's shock loads from flapping that produces the highest loads, and the tauter the pitch on balance the better.
Not made enough shelters to have a good feel for it, but I'll give it a go!
Cats were discussed quite a bit in that Sarek article I linked somewhere.
I agree with Cathy. Small is beautiful with cat cuts on cuben. A big one in the main ridgeline like the Protrail Li is probably done more for aesthetic reasons. Perhaps with a bit of aerodynamics and materials economy in the equation too.
Yup read that sarek article, no numbers sadly, thanks for linking to it though.
I'll scratch my head for a week, I've asked peeps with cuben shelters to measure their deflection to get an idea.
The main downside seems to be loosing internal space, which doesn't apply to me.
Settled on 8cm deflection. Three of four sides done, should get 2.5yards more cuben to finish it off from ripstop on the 16th.
Nice. Looking forward to how it goes.
Not touched it this weekend, but still have three line locks to fit and the vent. Estimated finished weight 450g. Not perfect but I reckon a useful addition to the arsenal.
Pics of the inside for @cathyjc , with my custom trekkertent 1p inner.
It'll easily fit my knot 2p inner. But I'd be tempted to make a more state of the art inner.
If I was doing it again... Which might happen (once I've paid this one off!) I'd consider 1oz cuben to make it a winter shelter with longer lifespan, Def lower the mid panel guy points, and I'd cut the 4 panels so that it pitched as a slight octo.
Looks like you've got an enormous amount of space in the vestibule - that or the stool is "doll" sized ?
How high is the support pole ? (if you said earlier - I missed it)
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