I bought a heavy sandbag which is supposed to be able to be dropped. Given the good ratings it has, I assume it had a manufacturing fault as the seam exploded the first time I dropped it.

enter image description here

Luckily, as insurance I bought this sewing awl, that comes with waxed thread that is thicker than what the sandbag is sewn together by.

Will this thread be suitable, and can you please point me to the best stitching method/pattern for repairing this seam, given that I only have this awl to hand?

Edit: I also have 50mm wide nylon webbing to hand, perhaps I can use that to reinforce the seam?

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    That's not a sewing machine. It's an awl. – csk Apr 11 '20 at 4:07
  • @csk thanks, fixed. I'd never heard of them before so thought it was a name specific to that brand. Any ideas on the repair? – Griffin Apr 11 '20 at 9:15
  • You could add a band of the nylon webbing around the bag horizontally. That would prevent it from expanding at the bottom when dropped. It looks like that's what burst the seam in the first place. – csk Apr 11 '20 at 20:26

The way I see it, even the base material is not cut / prepared really properly. Even if you make a very good stitching, there is a chance that the material itself will fail during the next "shocking experiences".

I would do it in two steps:

  1. stitch as good as possible, to make sure that the sand will stay inside. Please stitch each layer individually, for increased strength;
  2. Wrap the area with strong ribbons (let's say, similar with the safety belts in cars; similar to wearing belts for pants). Be sure that the belts close with good quality metal, not with cheap plastic.

You can try a strong fabric glue (example). Might not be pretty, but it gets the job done — really depends on what you're using the bag for.

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    Welcome to Arts & Crafts. Nylon is one of a few materials that are very difficult to glue for a bond that adheres permanently and handles serious stress (like dropping a heavy sandbag). The kind of glue you linked to is good for many other fabrics, even nylon for less demanding requirements, but won't give a secure enough bond on nylon for an application like this. There are a few specialized glues designed for nylon and other "ungluable" polymers that might be strong enough. (cont'd) – fixer1234 May 16 '20 at 5:11
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    They often involve a more complicated process, like surface prep, using activators and heat, and can take up to a month for the bond to reach full strength. I'm not sure how often they're used for "structural" applications (where the joint needs to have strength, flexibility, and longevity similar to the material being bonded). Still, your basic idea isn't bad. Consider doing some quick research on gluing nylon for high-strength requirements, and modifying the answer to recommend a glue that is likely to hold up to the demands of the application. – fixer1234 May 16 '20 at 5:11

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