I've been plugging away on my 'mid project and got it far enough along to put it up this morning. I just hemmed the bottom edge and sewed on the line locks. Still have some more details to get done- something to tie the doors open, some extra guy outs, mid panel pull out, etc.

The best guy line I had on hand that would work in the line locks was para-cord. No ideal, but the rest of my z-line is too thin for the line locks to work. And this was my first time pitching a 'mid shelter- plus my hex shaped footprint, made it a bit of a learning experience.

My first attempt netted me less than satisfactory results. I went with this unconventional design because of its economy of fabric and amount of sewing, but how well it would pitch was at risk. So, after playing with the tension on the guy lines, I finally gave up and went inside to eat breakfast. I was a bit on the upset side, since it was about $75 spent and a great many hours of time spent, for something I'm just going to want to re-do. Doing over gets closer to the "it would have been cheaper to just buy a duomid" point.

So, a bowl of raisin bran later, and time to reflect on where the fabric was the most slack I realized my center pole was too short. So, I went scrounging around in the garage hoping to find some 1/2" pvc pipe. No luck- but I did fine some 1/2" sprinkler risers. I went out, loosened all the guy lines, pulled out the center pole, stuck the makeshift pole-jack in place and re-tensioned it with much more satisfactory results. I still think with a bit more practice I will be able to get an even tighter pitch.

One thing I did not expect, though I should have, was the amount of tension across the zipper. I place a side release buckle along the bottom hem like MLD does, but since it's a hex shape, the area of greatest tension is about 12" up from the bottom hem. I feel like I wasted a ton of money on the waterproof zipper. The tension is enough to make it possible to see daylight through the zipper teeth. I may end up placing a 2nd side release buckle there...





One thing I didn't like that much with 'mid tents is how open they are to the elements when the door is open. I saw a few ideas thrown around on the forums so I thought to give one of them a try. So, I sewed in a couple extra flaps of fabric and another zipper (more weight!), so with a third pole it can open up like this-



In this mode it is absolutely cavernous. I originally wanted to use separating zippers so the awning panel would be removable, but I could not find separating zippers long enough. The awning is much flatter than I expected. I maybe could give it a bit more slope with some adjusting of the guy lines. What I don't want to happen is for water to pool up there, and then leak through the zipper.



peak reinforcement and "pole jack"



I bonded the guy out reinforcements and then sewed them. I'm pretty happy with the results.



I hope the images show up properly- I'm trying to imbed them from my picasa album. If that doesn't work, I'll have to download all the photos and attach them the hard way (vbulletin for the win). Too bad these forums don't have a preview post option... :(

eidt- only two of the pics worked.. What is the deal with that?

BM

Edited by Ultra_Magnus on 03/23/2012 16:32:31 MDT.

I can see 6 pictures now, so whatever was going wrong appears to be solved.

What material did you use for reinforcing the peak?

How much was the catenary cut on your door? I'm going to be making a tent myself pretty soon (materials are underway) and I would like to avoid overtensioning my doors.

Thanks!

I think the problem with the pictures might have been with Google- when I right-clicked the image in my picasa album and selected "copy image location" and then tried pasting it in a new tab of my browser, some of the pictures wouldn't load... weird...

Anyway- I had some left over dyneeem-x gridstop from Thru Hiker that I used for the peak reinforcement. I designed it in my CAD program at work (don't tell my boss!) and generated flat patterns that way. I printed the peak patter out 100% scale, pinned it to the fabric and cut it out like that (pacman shape). I rolled it into a cone, sewed it together, and stuck in in the peak of the tent- pinned it and sewed to the tent. It was difficult running all that fabric through my wife's little sewing machine (shallow throat). I'm not sure if it needs more stitching or not...

I didn't cut any cat curves (lazy). Any curvature you see is from fabric stretch. My projects are leading up to eventually building a big 11' square 'mid. For that one I don't think I'll be able to avoid cutting cat curves.

BM

Thanks for the reply. I have one more question. What did you use for bonding the tie outs? I'm guessing you used diluted silicone, but what were the proportions of silicone to mineral spirits?

Looks awesome, great design. What is the weight and/or what do you think the finished weight will be?

Yeah, I used a mixture of silicone and mineral spirits but I have no idea the ratio and I'm too cheap to purchase the BPL article on bonding silnylon, so I just winged it. I had a can of leftover diluted silicone from when I DIY sil-coated a tarp project I made from un-coated ripstop (super cheap Walmart 2nds) that thickened quite a bit in the can. The consistency was like, uh, maybe as thick as hair gel? It was pretty goopy... I tested it on some scraps first and was satisfied with the strength so I just went for it. I was able to peel apart my test pieces with enough force, but that was with trying to peel it. In a direct shear load, with the stitching holding the edges down, I think it will be more than adequate.

One thing though, I should note, is that I did not pay any attention to the bias of the fabric reinforcement patches. Under load, they want to stretch in different directions than the fabric it's bonded to which strains the bond. I think it would be better to match the patch bias with the fabric before bonding.

I didn't have a very big area to work- so I bonded three or four at a time, and when they dried I moved on to the next area. It was slow going...

BM

I'd go with the geodesic kiddie dome in the background for my base camp shelter, but that's me.

But seriously, Beautiful work!

Whoa. I actually have never seen a pyramid shelter deployed like that (tipped up). I guess it may be common practice among mid users, but it is new to me. I had never thought of using creative fair weather pitches with a mid. You could add a few yards of nanoseeum netting to one side to provide for bug coverage with the tipped pitch. Then, in good weather, for just a few added ounces, you'd have a giant bug-free palace. It looks great, UM.

It's about 550g (1lb 3.5oz) w/o guylines... I'm going to sew on a few more guy out points and some mid panel pullouts, so that'll add a bit more weight, but not much, and that plus seam sealing... I dunno- how much that'll add in total.

I'm a bit paranoid about wind load. Not so much the fabric but the stakes themselves. I intend to use this mostly in desert conditions and the soil here is really hard and crumbly, and doesn't hold on to stakes very well. The more stakes there are to carry the load, the less chance they'll rip out of the ground in a good gust. I should mention the wind blows here a LOT. Winds with constant 30-40mph gusts are pretty common. I don't intend to use all the guy outs all of the time, but if it's windy I'd stake out the one side facing the wind pretty well.

I went back and forth with the bug netting. My wife won't sleep in anything but a fully enclosed shelter, so I decided instead of perimeter netting to eventually make a inner net tent- plus I like modular shelter options.

Thanks for all the compliments.

BM

Nice work. Can't you use the side opposite the zipper as the awning in the open pitch?

the "open" pitch option is fantastic!

Great job on the mid. I especially like the open pitch...almost ready for a big flat tarp, huh. Nice hybrid idea : stormy- hunker it down : want a view- open it up.

Dave

P.S. want any info on bonding silnylon - shoot me a PM. I'm still using a totally bonded 10 x 10 flat tarp.

Link to 10 x 10 bonded tarp : http://www.backpackinglight.com/cgi-bin/backpackinglight/forums/thread_display.html?forum_thread_id=51361&skip_to_post=514846#514846

Edited by dmgoody on 03/24/2012 20:49:07 MDT.

Enjoyed the pictures showing how well you crafted the taut canopy.

There is something like a pic preview by using the last listed forum, the User Test forum.

You can check the articles here for the one on bonding silnylon. The author later posted that the adhesive was silicone glue, as distinguished from silicone sealant. It may be distinction without a difference, but the glue seems to work better. Hope that's not from 'placebo effect.'

I've put it up twice now. It does take a bit of practice to get it set up neatly, but it is a lot easier than pitching a flat tarp (my first sewing project). I'm sure a rectangular mid would be a lot easier to pitch than my hex shape- but it adds so much extra room.

I was sitting inside of it yesterday and I noticed points of light coming in around the perimeter of the peak reinforcement. Upon closer inspection it appears as though the stitching is being over stressed. It has not seen any wind loads yet either. I had a similar issue with my flat tarp on the ridge-line reinforcements (just sewn- not bonded) and to fix it I ripped all the stitching out and sewed in much larger reinforcements made from 70d ripstop.



I don't think its going to fail outright- but it irritates me enough to make me want to fix it. Ripping out the peak reinforcement is simple enough job but I have to figure out how I want to fix it. Would just making a larger reinforcement be sufficient? Right now it started out as an 8" diameter circle. Would a 10" diameter reinforcement (extending 1" further down from the peak) be enough? 12" diameter? It'd be pretty difficult now, but should I bond on some silnylon like I did at the guy-outs and then sew on the Dyneema? I guess another option that wouldn't require any ripping of anything would be to make a 2nd Dyneema reinforcement some amount larger than the one that's in it, like 10 or 12", and sew it on the outside of the tent, effectively sandwiching the silnylon between the layers of Dyneema. At least in that case with they Dyneema on the outside, even if the stitch holes in the silnylon opened up a bit, it would be less likely to leak because the water would flow off the Dyneema like roof shingles, if that makes sense.

I put the reinforcement on the inside because it "seemed" to me that it would be stronger that way, but maybe not. The reinforcement on MLD's Duomid doesn't look very big and I can't imagine they have strength issues. I've seem pics and videos of them holding up to crazy winds.

Anyway - at least I know what to look out for when I do my 11' mid.

BM

Nice looking tent, well done

"I don't think its going to fail outright- but it irritates me enough to make me want to fix it."

Ha ha ha - I know what you mean

I saw that I have not answered your question in another topic
I did not dilute the silicone.
Not so good for the strength I think.
Maybe you can use flowable silicone (permatex flowable silicone windshield and glass sealer?)

Edited by Ivo on 03/29/2012 22:53:42 MDT.

Your shingle effect won't work properly with the dyneema inside. Any water soaking through will drip off the reinforcement patch directly into the center of your shelter.

You could probably just seem seal the reinforcement threads. The silicone will provide extra strength and distribute the forces on the thread holes a bit. It'll also of course provide weatherproofing too.

So- you just smeared straight silicone caulking on the silnylon? Was it difficult getting an even coating?

Again- very nice job on that. It looks really nice. I still can't for the life of me understand WHY OH WHY I didn't bond on a 2nd layer in the area where the reinforcement went before I closed up the last seam... Doing that now would be considerably more difficult, but maybe I can manage with a well thought out work area and some careful prep work.

Flowable silicone sounds like a good option. I'll look out for that at my auto parts store next time I'm there...

Dustin- when I referring to the shingle affect I meant if the dyneema reinforcement was sewn on the outside of tent. I think I started rambling a bit in my last post (more thinking out loud) and can see how that may have been misunderstood...

BM

I used a putty knife.
I think it is possible to strengthen the top.
Remove the dyneema.
Turn the shelter inside out and put a triangular piece of cardboard or something similar
in the top so that the silnylon is stretched and flat.
Use a circular patch of silnylon for the top ..
The point of the peak is in the center of the patch.
Glue the two parts together. (without air bubbles)
Then apply glue to the rest of the patch.
Glue the rest of the patch to the shelter (without air bubbles).
Glue and fold the protruding part inward
and sew along the outside to secure.
You repeat with another layer on the other site if you want.
I hope you understand my explanation.

Yeah, you make prefect sense. I was thinking of something along the same lines. I think I'll go ahead and make a template for the reinforcement in case I find some time to tackle it this weekend.

While I'm doing all that I might also take the time to bond the mid panel pull-outs as well...

Thanks,
BM

Edited by Ultra_Magnus on 03/30/2012 17:51:30 MDT.