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Author Topic: Kite Seams  (Read 1537 times)
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madhabitz
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« on: November 08, 2011, 10:12 PM »

So, having done no research to find the answers on my own (I'm so ashamed).... I've been wondering why I don't see anyone sewing their kites using flat felled seams. Is it simply because it adds too much weight or drag? Done right, it seems like the sail would end up pretty flat and smooth. I can't see that it would add too much extra weight, either.

I've been so curious about this, because the seams would be so nicely finished. Is it perceived as just too much work?

Thanks for any insights all y'all might have.

Nancy
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chilese
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« Reply #1 on: November 08, 2011, 11:06 PM »

Skyburner has long been a proponent of flat felled seams.
At least when the seams are straight. Curved seams don't work.

I enjoy the look the flat felled seams create as you get a nice even line separating each panel.

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madhabitz
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« Reply #2 on: November 08, 2011, 11:55 PM »

Thanks for the info about Sky Burner using these seams. For what it's worth, you can do a flat felled seam on a curve-- it just takes a bit of finessing of the fabric. A good example of this are the crotch sections of denim jeans. There's no mistaking that flat felling is more time consuming, but with all the effort already being put into a sail it might be worth it to take it further.

Thanks John, for the info and the picture!

Nancy
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ae
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« Reply #3 on: November 09, 2011, 01:02 AM »

Spacekites in Germany uses them as well on all their kites.
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DWayne
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« Reply #4 on: November 09, 2011, 01:03 AM »

Mathias uses flat felled seams on the TNT.
IMO flat felled makes a cleaner, more finished looking seam.

Denny
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RonG
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« Reply #5 on: November 09, 2011, 03:44 AM »

Thanks for the info about Sky Burner using these seams. For what it's worth, you can do a flat felled seam on a curve-- it just takes a bit of finessing of the fabric. A good example of this are the crotch sections of denim jeans.

The problem with kite fabric, in particular ripstop polyester (i.e. Icarex) is the almost total lack of stretch.  You may as well be working with a sheet of paper.

I think Dick Barnes may have used flat-felled seams for at least some of the Pizazz panels, but I couldn't swear to it.

I played with flat-felled seams a bit on some early kites and prototypes, but it hardly seemed worth the effort.  A simple overlapped seam with a straight or 3-step zig-zag stitch is plenty strong for a stunt kite, especially if you're using a good polyester sail thread.  And unlike denim, you don't have an issue with fraying on the edge of kite fabric if you hot cut it, so concealing it in a rolled or flat-felled seam is unnecessary. 

All just my opinion, YMMV.
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inewham
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« Reply #6 on: November 09, 2011, 04:25 AM »

The fell seam solves one non existent problem on a polycarbonate fabric, in that it protects the cut which wasn't going to fray anyway, yet it introduces another in that poly can 'tear along the perforations' on a straight run of stitiching like a fell seam.

A properly taped & 3-stitch zig-zag/serpentine seam doesn't give a straight line of perforations to tear along and is stronger - I have made test pieces both ways and torn them apart to see.

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mikenchico
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« Reply #7 on: November 09, 2011, 07:37 AM »

Skyburner, which is sewn by Pam & Mike of Heads Up uses flat fell seams as pointed out and I don't recall any of their kites having curved panels.

Premier Kites also uses flat fell seams on most of their kites, it always impresses me to see that on an off-shore produced, mass production kite.

I was also impressed with Mathias's constuction on the TNT, his leading edges are even using a folded seam and multiple layers that provide a very smooth face and keep the black leading edge fabric from showing through the face, very impressive.

The third reason they are not used much is they take a bit more skill, a zig-zag stitch hides poor sewing much better, on a fell seam those two railroad tracks side by side show any waver during sewing.

Felled seams are reportedly stronger but as Ian points out probably not on the fabrics we use. With Icarex and 9460 tape sewing isn't even required except under extreme conditions (like sport kites see) there have been many articles, tests and examples of No-Sew kites made with just tape. When using Nylon the C3 tape provides a No-Sew alternative, it is used to construct racing boat sails that are not sewn. I wouldn't build a Sport Kite without the backup sewing myself but theoretically the sail panels could be constructed without sewing. The Dacron leading edges etc. do still require sewing, being a rougher fabric the tapes we use don't have enough glue to properly run into all the crevasses for a proper bond.

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AKA_MrBill
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« Reply #8 on: November 09, 2011, 07:50 AM »

The fell seam solves one non existent problem on a polycarbonate fabric, in that it protects the cut which wasn't going to fray anyway, yet it introduces another in that poly can 'tear along the perforations' on a straight run of stitiching like a fell seam.

A properly taped & 3-stitch zig-zag/serpentine seam doesn't give a straight line of perforations to tear along and is stronger - I have made test pieces both ways and torn them apart to see.


To me, being an Engineer, (see, I can spell that correctly  Wink ) this is the best reason and explanation as to why triple Zig-Zag is used.

While setting up the tension on my machine, I used a 35X magnifier to inspect the stitch. I was shocked to see that the needle had actually cut though the fabric instead of pushing the fibers aside as I had assumed.

Now after reading the above post, I understand and am quite satisfied.

Besides, I do not nearly have the skills to do flat felled seams.  Cry
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tpatter
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« Reply #9 on: November 09, 2011, 08:49 AM »

I like how it looks for sure!  Smiley

That is one of the reasons that I think most of r-sky's designs are so striking.  They don't fold, but they have a pinstripe tape section on the seams that really outlines and defines the panels.

Of, just fly kites without panels and forget about folds entirely!  Smiley
« Last Edit: November 09, 2011, 05:06 PM by tpatter » Logged

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inewham
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« Reply #10 on: November 09, 2011, 08:55 AM »

While we can justify it with engineering explanations I think the main reason came from the early kites using this technique, the Gemini and Midi 98; they had very tight curves that would have been extremely difficult to get a good fell seam on.

The Midi was right on the limit of how tight a curve could go before the bainbridge tape CM was using started puckering. Could you imagine fell seaming those curves at the end of the middle panel on a Gem  Huh

Kites like the Aviv have very gentle curves by comparison.
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wufer
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« Reply #11 on: November 09, 2011, 12:59 PM »

Three reasons.
1/. In my exceriance, in real life, simple overlap seams are strong enough for kites.

2/. People dont know, or have not taken the time, to find out how to construct a flat felled seam. The flat felled seam is a bit more complicated to work out the seam allowences.

3/. Time. Its much faster doing overlap seams, and thay are strong enough.


Derek.
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madhabitz
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« Reply #12 on: November 09, 2011, 03:01 PM »

My time is short right now, but wanted to respond to all these great posts. Thanks to all of you I have some of the history for how this evolution to zigzag stitching happened-- all legit explanations for sure.

Mr.B, the possibility of tearing is the best of reasons for using the proper needle for your fabric and one that is super sharp (the new needle I wrote about in your Vortex thread). Using a longer stitch length would go a ways to help prevent the problem, too.

While we can justify it with engineering explanations I think the main reason came from the early kites using this technique, the Gemini and Midi 98; they had very tight curves that would have been extremely difficult to get a good fell seam on.

I have to agree here-- while clipping curves can go a long way toward a successful job, extreme curves would be pretty difficult even for someone with a lot of experience.

For what it's worth, should anyone decide they're interested in trying this flat felled stuff, there are a ton of tutorials online. There are also flat felling feet that can be attached to your machine to help with the job.

I'd also like to say that it's my newbie kiter's observation that once a kite is in the air, those zigzagged seams can't be seen anyway, so it just doesn't matter worth a darn. It's just that my sewer's mind wanted to ask this question in the first place.

Thanks everyone!

Nancy
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kitebug
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« Reply #13 on: November 09, 2011, 07:43 PM »

All Fury's are sewn this way too
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Volando!
Cisco
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