i know this is a long shot, but does anyone know a good low budget way to weld fabric? maybe i'm just crazy, but thread and seam seal just seems way too heavy. i can get a strong (but ugly) seam with an iron and some aluminum foil, but it weakens the fabric next to the seam which then rips under stress. any ideas?
What kind of fabric are you trying to weld? Heat will, in most cases do exactly what you have experienced. Stitching and seam sealing is usually the most effective way of joining. I have had luck with using a product called Goop. It can be had at stores like lowe's or Home depot in the adhesives section. I wouldn't use it where stress is involved but could be used for mending a rain fly but not to build something as a eg. chair seam where weight would pull it apart. I used it to glue hook and loop onto the edge of my hammock to attach a removeable bug net. I would do a test on a small piece of fabric in question and give it the stress test to see if it will fail.
Loc: Central Texas
Heat and sonic welding always weaken the fabric. A wide variety of glues work much better than welding. However, conventional stitching is still the strongest method for conventional woven or knit fabric.
Low budget welding? Not that I have ever seen. The commercial rigs start at about $20,000.
you can get SewFree, the same adhesive the big guys use. I'm not sure who is carrying it right now. It will take some monkeying around with jerry rigged irons to get the same results. Keep in that the big guys do a lot of die cutting with templates, to get such clean cuts to meld. It's cool stuff, but I wil tell you this. If you make something with welded seams, you pretty much eliminate the ability to repair or alter it. That stuff simply cannot be undone cleanly.