What type of stitch gives the greatest pull strength?

[lod]

Hi Wiz, All,

I'd like to get your thoughts on what kind of stitch would be strongest for a simple lap seam.  I'm making a large inflatable tube, and would like to get a seam that's at least as strong as the material.  Thinking about using 1050D Cordura ballistic nylon.

I've seen zigzag stitches used on sails, and dual-needle straight stitches used on huge stage curtains.

Which of these would give the best strength for the 1050D Cordura, or is there another stitch that's even better?

Thanks!

[johnv474]

The difference between the major seams would be minimal.

If you want to do a handsewn saddlestitch, that would be impressively strong--stronger than nearly all machine stitches.

5 spi, 1.00 mm polyester (not nylon or linen) will provide among the strongest seams.  However, those stitches will be stronger than the leather that contains them.  So, when the seam fails it will be due to the leather and not the thread.

If you didn't care about the strongest seam you would choose a thread and leather combination where the thread broke just before the leather tore.  It is far easier to repair a few broken stitches than it is to repair torn leather. You dig?

[paloma]

what is the nature of the materials you are going to sew?

 

[Handstitched]

G'day, I have used a number of stitches for different applications, fel seams , french seams, etc. But one of the stitches I have used for strength, is the herringbone, aka "baseball stitch" using a heavy/ coarse thread, or Mox thread, a woven thread,  around 0.8 mm & 1.0mm . If its strong enough for a baseball, that gets whacked frequently, its strong enough for other applications . 

HS

[lod]

7 hours ago, paloma said:

what is the nature of the materials you are going to sew?

 

1050D Cordura ballistic nylon

12 hours ago, johnv474 said:

The difference between the major seams would be minimal.

If you want to do a handsewn saddlestitch, that would be impressively strong--stronger than nearly all machine stitches.

5 spi, 1.00 mm polyester (not nylon or linen) will provide among the strongest seams.  However, those stitches will be stronger than the leather that contains them.  So, when the seam fails it will be due to the leather and not the thread.

If you didn't care about the strongest seam you would choose a thread and leather combination where the thread broke just before the leather tore.  It is far easier to repair a few broken stitches than it is to repair torn leather. You dig?

Oh,  I should have mentioned that I'll need to do these with a machine, since there will be 100's of feet of seams.

[lod]

4 hours ago, Handstitched said:

G'day, I have used a number of stitches for different applications, fel seams , french seams, etc. But one of the stitches I have used for strength, is the herringbone, aka "baseball stitch" using a heavy/ coarse thread, or Mox thread, a woven thread,  around 0.8 mm & 1.0mm . If its strong enough for a baseball, that gets whacked frequently, its strong enough for other applications . 

HS

Wonder if herringbone can work on a lap joint, or just a butt joint?  Lap joints hold air better.

[Rahere]

You also should consider gluing the inside of the stitching.

Another thought is a rolled lap, where both edges are buried in the cup formed by the other roll. Bend your fingers and hook them together to get the idea.

[chuck123wapati]

consider the seam type also in the overall strength a double felled seam may be a better choice.

[nylonRigging]

8 hours ago, chuck123wapati said:

consider the seam type also in the overall strength a double felled seam may be a better choice.

exactly what  ( chuck123wapati  ) is saying. the seam for your application is major consideration . Just running a straight double-needle run on a double felled seam, is strongest for your description . on the opposite end of the spectrum for weakest seam, it would be a butt seam

It also Not the ..." pull strength".  like in your thread title.
You are dealing more with a ' shear loading ' and not a straight pull,  for the breaking point on the thread type strength rating . Shear Loading multiples 'greatly' the structural breaking point on thread, because the greater force on the Seam sewn is pulling lateral on both sides of the thread and seam .
.