If you need to bend a sheet of thin metal (e.g., tin), draw on the fold line using a ruler and a cutter, a deep scratch (groove). After that, the metal will easily bend on the drawn line, the fold will be very accurate, running strictly at right angles. The cutter is fabricated out of a piece of saw blade for metal, a length of about fifteen centimeters. One end of the wind izoljatsionnoj with a tape, the second sharpened on an electric grindstone so that the tip turned a sharp "tooth", which is cut through the metal.
To bend thick metal harder. Gently Pat on the fold line with a chisel, natuba sheet to about half its thickness. Bottom under the anvil, or any other suitable size flat and heavy piece of metal. For smooth curl you'll need a long flat surface with a clear angle, e.g., metal area, clamped in a Vice or placed at the edge of the concrete slab, stairs, etc.
Lay the sheet on the area to cut the groove came just at its edge, firmly press. Then begin to gently bend, evening bend with a hammer. The deeper cut groove, the easier it is to bend the sheet. However, carefully bend a thick and large sheet metal is quite difficult, it requires some experience. Desirable assistant, two the job done a lot easier.
If you need to bend sheet metal ring, do this by tapping the surface with a hammer. Strikes apply on lines parallel to the bend lines. The sheet will bend stronger, carefully prostukivanie edge – the bend radius should be the same in all its points. When the ends of the sheetand, zagnuvshis, will meet back to back, they can be welded, or prilepite, after which finalize the shape of the resulting ring.