Simple! The short answer is: just like you'd do it with a piece of paper -- instead of rotating 180 degrees and taping, you rotate 60 degrees and glue it. It's got a hexagonal cross section, so the faces should still match up.
Long answer: you make a prototype out of wax or soft rubber. You could even use a pencil for this part. Lay a pencil in plaster-of-paris, let dry. Wax the top surface (or even butter it) and pour more plaster in. When it dries, you have the injection mold for a belt. Split the mold, get the pencil out, clamp the mold together again, and pour in a very soft rubber (or a soft metal for that matter).
Take your part out of the mold; shave off the flashing (mold artifacts) and cut both ends square. If it's soft rubber, no problem: bend it around so the ends are close to each other. Turn one end 60 degrees, apply J-B Weld or superglue, and press the ends together. You now have a Mobius Hexagon -- the solid actually only has one face, approximately 6 times the length of the original molded object. Trace it if you don't believe me!
You could use this object if your application doesn't require much load-bearing, but most pulleys have to be pulled pretty tight, so this loop is just your prototype -- it still has a seam that could separate.
Take this loop and make a mold from it. You can lay a spliced carbon-fiber rope loop into the mold before injecting hard plastic, and now you've got a cable-reinforced composite cable with no seams that makes 1/6 of a twist each time it goes around. Much less fatigue for both cases I mentioned above, plus its faces get used as sidewalls 1/3 of the time, pressure faces 1/6 of the time, and go unused 1/2 the time. Possibly better wear and tear!
Long answer: you make a prototype out of wax or soft rubber. You could even use a pencil for this part. Lay a pencil in plaster-of-paris, let dry. Wax the top surface (or even butter it) and pour more plaster in. When it dries, you have the injection mold for a belt. Split the mold, get the pencil out, clamp the mold together again, and pour in a very soft rubber (or a soft metal for that matter).
Take your part out of the mold; shave off the flashing (mold artifacts) and cut both ends square. If it's soft rubber, no problem: bend it around so the ends are close to each other. Turn one end 60 degrees, apply J-B Weld or superglue, and press the ends together. You now have a Mobius Hexagon -- the solid actually only has one face, approximately 6 times the length of the original molded object. Trace it if you don't believe me!
You could use this object if your application doesn't require much load-bearing, but most pulleys have to be pulled pretty tight, so this loop is just your prototype -- it still has a seam that could separate.
Take this loop and make a mold from it. You can lay a spliced carbon-fiber rope loop into the mold before injecting hard plastic, and now you've got a cable-reinforced composite cable with no seams that makes 1/6 of a twist each time it goes around. Much less fatigue for both cases I mentioned above, plus its faces get used as sidewalls 1/3 of the time, pressure faces 1/6 of the time, and go unused 1/2 the time. Possibly better wear and tear!
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i was thinking flat belt only.
genius.
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