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What type of seam do tent manufacturers use?
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jerry adams
(retiredjerry) - MLife

Locale: Oregon and Washington
Re: standard book on 04/09/2012 07:53:50 MDT Print View

Yeah, curved seams different story, but I've never had problem with straight seams.

I was thinking of words like "bugger" which I believe is mildly profane, not what you were saying : )

David Scheidt
(dscheidt) - F
Re: Re: standard book on 04/09/2012 10:48:41 MDT Print View

I use a scroll hemmer foot:

Similar things are available for most home machines. Works a treat, though not as well as a bed mounted folder does.

Mark Dijkstra
(Markacd) - F
Foot on 04/09/2012 11:12:48 MDT Print View

I actually have one of those feet for my machine. I tried using it, but it didn't work that well with silnylon. I had to redo the whole seam because the material wouldn't do what it was supposed to do. Maybe I just need to practice with it, but that will have to wait until I make a stuff sack or some other inexpensive project.

Ultra Magnus
(Ultra_Magnus) - F
Re: seams on 04/09/2012 11:19:15 MDT Print View

@Samuel- "Problem is - the faux felled seam defeats the purpose of lap or flat felled seams; in that it does not have the stitches in both seams going through four layers of fabric. Once the canopy is stretched taut, the faux felled seam, unlike the lap felled seam, will present one line of needle holes that is not backed up by additional layers of fabric. The only thing keeping the water out is the sealant. With the true felled seam, the needle holes in both stitch lines go through four layers of fabric, instead of just one layer. This does not show so well on your diagram, as you are showing the material X-sections in a less than taut position."

As still a beginner MYOG'er I'm still learning for myself what works and why, and what doesn't and why, rather than just listening to what so and so said to do one whatever tutorial I'm reading. What you wrote is EXACTLY what I've been experiencing and coming to realize for myself. When I pitch my last 'mid tent project nice and taut, and can see light coming through the stretched out stitch holes on the first row of my "faux" felled seams. In practice, it may not really be a problem- I guess I'll find out over time, but it just doesn't seam "Kosher" to me. I first had issue with the "faux" seam on a dry sack I was trying to make (more for the practice with some remnants of material than actually trying to make a dry sack)and found if I stuffed it full, the holes opened up. No matter how much seam sealer you put on there, it won't plug holes, at least not for long.

This is what prompted me to post a thread asking about taping silnylon seams, which I'm still not sure if I'll try. The mess could be substantial, and a sloppy job could make my nice tent project look a lot less nice, or it could end up looking down right ghetto.

But- after reading your post I had to answer the call of nature, and while sitting on my porcelain thinking chair I had an idea- what if you sew a normal "faux" felled seam, but for the first seam set the machine to its longest stitch setting, with the thread tension a bit on the low side. My machine, by total luck of the draw as neither my wife or I knew anything about sewing machines when we got it (Janome Gem gold, $60 used) has the ability to sew with wicked low thread tension, I mean, sloppy slack in the stitches low if I want to. After doing the 2nd seam, do a third just about 1/16 - 1/8" from the first, sewing through (hopefully) all four layers of fabric. Then, try to pull out that first "temporary" seam. I'm think that's called a basting stitch. Getting the thread out from inside of the seam could be a problem, esp. of your final stitch ran across it by mistake at any point. In some cases it might be impossible to get it out, but I think it'd be worth a try. Even if it was stuck in there, it might not be really all that visible. I might try it on some scrap and see how it goes...

Anyway- thanks for the great post...


jerry adams
(retiredjerry) - MLife

Locale: Oregon and Washington
Re: seams on 04/09/2012 11:45:14 MDT Print View

"As still a beginner MYOG'er I'm still learning for myself what works and why, and what doesn't and why, rather than just listening to what so and so said to do one whatever tutorial I'm reading."

Well put

And sometimes I'll decide something does or doesn't work but later change my mind

Kevin Beeden
(captain_paranoia) - F

Locale: UK
mock vs true flat-felled seam on 04/09/2012 11:50:41 MDT Print View

I'm not sure if there's actually much difference in seam loading between a mock and true flat-felled seam. After all, in both seams, there's still a line of stitches between the seam and the main body of the fabric. When loaded, this line of stitches will open up. I think the benefit of a true felled seam is that the other layers of fabric in the seam hold the stitches more perpendicular to the fabric, which I think reduces the chances of seam ripping, either fabric or thread.

Harald Hope

Locale: East Bay
beautiful on 04/09/2012 13:34:53 MDT Print View

Samuel, beautiful work, do you have a thread here with pics on that tent, I don't want to pull this topic off topic, but I'd love to see a lot of closeups of your work there on the green tent, especially seams and key joints and connections, inside and out. I'm not to the point of being able to make a tent, but I'd love to see what others have done, especially with such an excellent outcome.

Roger, thanks for the input, I'll still try the hemmer presser foot on silnyon to see how it works, slipping, as indicated above, would be what I'd expect though, but if I have to pin to do it well, that's fine, I'll do it, it's just the lazy hacker in me wondering where I can avoid unnecessary work in the end, heh. But necessary stuff, no problem.

Peter, thanks for confirming what struck me as kind of obvious, if you pull at basically one single layer, which is a standard edge of a faux felled seam, not, I realized reading your comments, even two layers, that's totally different than having one seam press down, creating friction of the top layer, onto the next layer, onto the rest of the layer. I know that friction holds are radically stronger than the actual connector alone, thread, screws, etc, from experience, so conceptually that makes total sense. Excellent argument for making true felled seams on especially a tent.

I've had the same experiences with ironing in the folds, but I haven't been able to test durability, ie, if I damaged the silnylon by ironing it, but good point re making sure to only iron the actual fold, I was sloppy in that regard.

One thing I've started to see re myog is that I can do stuff with sewing, by not worrying about speed or efficiency, in terms of stronger seams that take a long time to sew, so it's possible to really exceed standard production techniques in some cases, since my time is free for me, give or take.

Roger Caffin
(rcaffin) - BPL Staff - MLife

Locale: Wollemi & Kosciusko NPs, Europe
Re: beautiful on 04/09/2012 16:16:17 MDT Print View

> re myog is that I can do stuff with sewing, by not worrying about speed or
> efficiency, in terms of stronger seams that take a long time to sew, so it's possible
> to really exceed standard production techniques in some cases,
Absolutely true. Commercial pack seams are usually a single line of stitching: mine have a faux felled seam and are taped as well. My way would not be commercial, but the result is MUCH better.

In practice I avoid the felled seam on the critical parts of my tents by using different designs.


Ultra Magnus
(Ultra_Magnus) - F
Re: Re: beautiful on 04/09/2012 16:18:43 MDT Print View

"In practice I avoid the felled seam on the critical parts of my tents by using different designs."

Could you elaborate a bit? I'd love to see some alternate techniques for joining strength critical panels of fabric...


Harald Hope

Locale: East Bay
second on 04/09/2012 20:01:56 MDT Print View

I second that, can you show some pictures of your tent seams and other things Roger, would be interesting to see how you solved the problems.

I know I realized when I was ripping apart my first pack project due to design errors, it hit me, man, this thing would never have failed on the seams. Materials, maybe, but not the seams.

Sam Farrington
(scfhome) - M

Locale: Chocorua NH, USA
All is not what it seams on 04/09/2012 22:34:49 MDT Print View

If the iron is hot enough, it will go through the silnylon like butter. What a mess. The temp needs to be just hot enough to make a good crease without melting.
Even at that temp, however, if the iron slips over the fold and onto the single layer of fabric, you can have damage to the fabric which is clearly visible. It starts to shrink and harden. Not what you want in a tent canopy.

Thanks for comments. But mea culpa. I was so focused on providing evidence that the ironed crease technique works, that I neglected to mention that the project was a fly, not an entire tent. The tent was a friend's Hubba. Phase 1 was making carbon poles, which dropped 5-6 ounces. Phase 2 was the silnylon fly, which dropped another 5-6 ounces. Phase 3 was to be a silnylon or 1.26 oz Cuben floor, but we broke up. Since you asked, here is the only other photo taken:


Here is a diagram of the mock or faux felled seam:

Faux felled seam

Please note where the stitch holes will be exposed in one layer of fabric when tention is applied. Yes, you can remove the first seam, and stitch #3 where indicated, but you will still be left with the bloody exposed holes.

I wonder what nifty ideas Roger will have for us. Have tried to come up with simpler methods, but none worked as well as the lap for flat felled seam - with the exception of the bonding approach for Cuben that I mentioned. That could be used with silnylon and sil glue also, I suppose. Haven't tried it, because for sil to sil, I have found that bonding reduces the elasticity of the fabric in the seam, creating wrinkles ad nauseam on the canopy. This doesn't happen if an unbonded seam is sewn, and then carefully sealed with a thin coat of sealer.

Edited by scfhome on 04/09/2012 22:35:55 MDT.

Roger Caffin
(rcaffin) - BPL Staff - MLife

Locale: Wollemi & Kosciusko NPs, Europe
Re: Re: Re: beautiful on 04/10/2012 01:36:36 MDT Print View

Hi Magnus and Harald and Sam

5621S2 Red tent Snowy River, When Things Go Wrong
This is my winter tent - featured in When Things Go Wrong. It has to be strong.

The panels are small so there is basically no need for an unsupported high-strength seam. Yes, there is a seam along the ridge, but that is really not under any significant tension. Where the tension does happen is at the pole seams. A lot of engineering went into those seams. This is a diagrammatic cross-section.

Pole Seam for tents
The black circle is a carbon fibre tent pole.
The yellow at the bottom is the inner tent, held up by the green and teal bits of Velcro or hook&loop tape. Yes, it is strong in shear like that.
The dark blue lines are of course stitching.

The top red loop is the pole sleeve in the fly. I have little patience with designs which have the fly free-floating, not sleeved into the fly. You can see how the pole sleeve goes right through the fly to anchor the inner tent - which incidentally includes the bathtub groundsheet. The connection is important, as our weight helps keep the tent down, although the guy ropes are always sufficient.

The two red bit at the sides are the fly. They have no less than three lines of stitching. These are important.

The lowest (pale blue) is the first one: it holds the pole sleeve folded and serves as a guide for the next two. It uses light Rasant 120 thread and long stitches.

The middle one (medium blue) attaches the bits of the fly to the pole sleeve. When sewing this all the fabric edges line up together (by design), the layers are pinned in the seam zone, and this line of stitching goes next to the first one. It too uses Rasant 120 thread and long stitches.

The top line of stitching is the strength line. I fold each of the edges of the fly back for reinforcement so I am sewing through a double layer of silnylon at each side. I use shorter stitches and stronger Rasant 75 thread, and the line of stitching is again next to the previous ones.

I run a small bead of sealant along the corners on the outside of course. But with all the layers and the tight sewing, not much water gets through without the sealant.

Is this complex? Does it take me some time to do? Yes. But the tent can take a violent 100 kph storm all night without flinching. Do I care about the extra sewing time? :-)
Is the design really meant to handle pole sleeves? Yes. Would you use it for a tarp ridge? No.

Hope this helps
PS: why did I camp in such an open exposed position? Well, at the time in the evening I was having trouble seeing my feet in the fog ...

Edited by rcaffin on 04/10/2012 01:41:47 MDT.

Ivo Vanmontfort
(Ivo) - MLife
glue/sew silnylon parts on 04/10/2012 03:02:09 MDT Print View

It is posible to glue sil to sil without wrinkles
if you use a catcut.
My copy trailstar is a combination of bonding and sew technics.
I used a large (240 cm) pu foam plate and ... yes, pins.

Van lijmen/kleven silnylon panden

After this step you can sew the first seam without using pins.
If there is silicone on the wrong side of the seam, then tear it open up to the seam.
Then, glue again and sew the second seam.
In the corners you sometimes have to skip using glue.
Otherwise, the seams are too thick

Ultra Magnus
(Ultra_Magnus) - F
Re: glue/sew silnylon parts on 04/10/2012 11:24:25 MDT Print View

Roger- that is some beautiful work and some seriously bomber sewing...

Ivo- what are you using to glue the silnylon? What kind of work space do you need to do the job? How long does it need to stay undisturbed until the glue sets up?


Ivo Vanmontfort
(Ivo) - MLife
glue and sew on 04/10/2012 13:25:55 MDT Print View

I used pure silicone (eg aquarium silicone sealant).
I have no Permatex flowable silicone.
I think that would be an advantage.
I get a nice flat, strong seam but the shelter weighs about 3 oz more
than the original.
The tie-outs are glued to.
Must say that the apex is too heavily executed.
I gave me about 3 to 4 minutes to distribute the glue
with a putty knife.
Waited a while to let the silnylon relaxing and pressed the layers
together with a wooden bar.
Took a cup of coffee and began to sew.
Give it five minutes.
I protected the foam with brown plastic tape.
Residues hardened silicone can be removed easily.
Working on the floor is not convenient.
A table is useful.
Is it not long enough, support the foam plate with a few long wooden bars.
link with extra photo's of the making

Edited by Ivo on 04/10/2012 16:36:18 MDT.

Ultra Magnus
(Ultra_Magnus) - F
Re: glue and sew on 04/10/2012 17:40:59 MDT Print View

Sorry! I'm a little slow on the uptake sometimes and always bad at remembering names. You replied and explained this process to me on my post about forming the peak of a 'mid shelter... But thanks again for taking the time to explain it again...

I'm afraid of doing a big project like that. It seems it could be really easy to make a mistake and have the whole mess get out of control and ruin the project. Maybe I'll try in on a smaller piece of fabric and see how it goes. It just seams (pun) to me that you would need to be pretty neat and precise in the application of the silicone to get an even, consistent seam...


Roger Caffin
(rcaffin) - BPL Staff - MLife

Locale: Wollemi & Kosciusko NPs, Europe
Re: Re: glue and sew on 04/10/2012 20:33:24 MDT Print View

I did try glue&sew, but before the silicone sealant set completely. The result was NOT pretty: the silicone adhesive stuck to the eye of the needle and the thread, and the whole lot ended up a serious mess very quickly!

Once the sealant has set it would be OK, but you would need to make sure the layer was very thin. I had problems keeping everything aligned exactly too.


Sam Farrington
(scfhome) - M

Locale: Chocorua NH, USA
seams on 04/10/2012 21:50:28 MDT Print View

Thanks for your seam construction post. It is another one of yours that I will copy and refer back to often.

The shelter looks gorgeous in the photo, but in the close up, there is some puckering along the seams. With careful sewing at not too much tension and sealing afterward, there can be almost no puckering, which may or may not translate to wrinkles. The time I tried bonding, just a little puckering on the seam significantly reduced the tautness of the canopy. Sorry for being such a fussbudget.

The clouds finally opened, and it dawned that maybe that aquarium sealant, unlike silicone glue with a hardener in it, will allow a silnylon seam to stretch along with the fabric. Will have to try some. Thanks. Edited on 4/12/12

Edited by scfhome on 04/12/2012 23:02:51 MDT.