The above is a very good point. It is easy to think you will only be dealing with 3-5 thicknesses of material, but that won't always be the case.....It might be true that all you'll need to be able to sew would be a few layers of Sunbrella, and that's what I originally thought. The last project was a simple sunscreen with D-rings at each corner resulting in three layers of fabric and four layers of webbing where the webbing for the D-rings crossed over. Three rather than four layers were achieved by a single fold-over hem and mitering the corners. Had the hem been a double fold, the corners would have been four layers with mitering and six layers without mitering....
Yesterday I was finishing the dodger up and I had one area where I was going through 17 layers of material, 3/8 th of an inch thick. This was were I had reinforced an area and a number of hems were laying on top of each other. I couldn't get the foot over the area directly and had to sew into it from an area with less layers. Now this isn't normal, but there are a number of places on the dodger with 8-10 layers of material with the 30 gauge window also in the mix.
Good luck,
Sum
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