What type of seam do tent manufacturers use?
- This topic has 47 replies, 2 voices, and was last updated 2 years, 5 months ago by
.
-
Jim,
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.Harald,
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:
All,
Here is a diagram of the mock or 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.
Hi Magnus and Harald and Sam
OK.
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.
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
Cheers
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 …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
Timothy Clarke can not submit replies even though he’s a member
Screenshot of what it’s supposed to look like
Timothy Clarke’s response that he’s not able to post so I’ll just copy paste it:
Hi Jerry, I am quite excited to hear your thinking on seams. I am heading in the same direction as you describe (using a multi-folded straight grain to stabilize the seams formed from bias cut fabric. I don’t know if it is wise to feel so good about someone else agreeing with oneself. It could be the blind leading the blind. Nevertheless, it is heartening to hear the ideas expressed by you. It means that I know that you will eventually understand what I am on about.
My most recent tents have addressed the bias grain stretch issue by wrapping the bias within the straight for the first line of stitching.
The process described briefly within in:
https://timtinker.com/ultralight-tent/
Yes, I now agree with you that a third line of stitches would be easy to do and add to the strength, even though I never had any leakage or failures over many years of use.
My cutting and sewing are tricky and tedious when compared with yours. So I am keen to do less cutting and less seaming where possible and make it as simple as possible without compromising strength, leak resistance and a taut tent shape. I don’t even want to cut cat-curves, never have, hope I never will as that is just giving in to gravity!
Do you have a sketch or photo of ’2 – I put a strip along each of the 4 ridges.’
Independently, in my mind and sketches, I was thinking of a 2 time folding, giving 4 layers and incorporating it into the lay flat seam. Could go to 6 if required
I aim to make seams that are about 7mm wide. I would start with a 28mm wide strip and fold it in two and glue it together with very thin silicone rubber, just to make it easy to manage in the next step.
Next with the neat rounded edge facing left I would introduce the two bias-cut tent panel edges (from the left) and fold the strip, in half, around those edges and pin them together or even better glue them together at the starting point. The bias edges will be covered by the tape and the tapes two raw edges will eventually be covered by the ????? flat seam when the seam is laid flat for the second row of stitches. It will have all the features of a Mock Felled Seam, including the ’Gerry’s Third Line’. However, it will also have ’Tims and Gerry’s straight grain strength’ embedded within the seam. Am I making sense?
I have ordered some Grosgrain seam tape from China for the seams, but I would much prefer the multi-folded tent fabric to provide that strength with softness. Your success is encouraging. I have even considered adding glued 100lb Dyneema fishing line into the folded and glued strip!
If the tensile strip needs to be stronger, then 6 or more layers can be used.
I don’t know if you agree with me, but I would not be surprised if you do. I find the multiple layers of sewn thin fabric sew nicely and the thickness gives the seam resilience. I think the resilience comes from the stitches being more able to stretch along the seam, almost like zig-zag stitches do.
Later, I will send a photo of a crude sketch to supplement my inadequate words describing my proposed seam. I am certain that our thoughts are running somewhat similarly, and we are both very open to new ideas without resorting to defensive dogma.
I also have posted on a simple way of linking the tensile forces of the tent panels and particularly the seams to a simple tubular apex hem that easily allows the use of almost any tent pole or dare I say no tent pole at all. There is a detailed post on the subject, and it makes cutting and sewing easy and tolerant of errors and ends up with infinite strength, uses only tent fabric and looks great even for a crappy sewer like me:
A load bearing hem for the apex of pyramid tents
https://timtinker.com/an-innovative-apex-hem-for-pyramid-tents/
Look at any of my tent tops and they look good weather a thick tree branch or a skinny pole or no pole at all.
Also, my design differed from yours with a little wall. It means a smaller footprint, make the single tent pitch high as a palace or down low for storm survival as in the above photos. It adds sewing complexity, but I have a plan to eliminate this.
With your tent layout for cutting the equal triangular panels, why did you cut the 8 when you could have cut 3 at twice the size plus 2 halves (from each end of the stip) that would join at the zipper?
This would nearly halve the cutting and stitching.
I have been having conversations with a Candian who has made a wonderful tent with only three panels cut, sewn and taped on this basis, These taped bias seams form the tent’s structural stays to the ground. The straight grain section of each panel have secondary ridges formed in them and extra fabric sewn on to reach the ground. (Similar to your special cutting to maintain ground contact but on steroids.) A very nice tent, but you and I like the efficiency of a square tent. However, I think his design has some lessons for our square tents and his design can easily be scaled up or down. More on that later.
I sent the email Re: my access to reply/commenting to BPL, as you suggested. I got a robotic nice reply indicating that a real response would follow (as usual). Not holding my breath waiting!
I think I have ideas to contribute to forum discussions and as far as I can tell I am constructive and polite even when I have silly comments from fools or worse.
Do you think a group of forum participants such as Roger and yourself and some other respected members could partition for this action on my behalf? I promise to behave myself.
Kind regards,
Tim
- You must be logged in to reply to this topic.
