When you’re tensioning a fabric structure, it’s difficult to pull the fabric close enough to the attachment point to connect the permanent hardware.
A compactly built rigging block can pull the fabric closer than a come-along.
“Say you have a 50-foot-by-50-foot fabric structure with four points,” says Charles Duvall, principal at Duvall Design, Portland, Maine. “If you’re using a come-along to close up the distance, the hardware itself can take up a couple of feet, so you can’t pull the point close enough to connect it. I like rigging blocks. Blocks pass the line multiple times over a pair of pulleys; if you have five passes of the line, you get a five-to-one pulling advantage. When you’re rigging a structure, you can put a block in there that has a total width of one foot, so you can open up the block to five feet and then close it down to one foot.”
Duvall has improved the utility of rigging blocks even further.
“Even blocks sometimes take up more space than I like,” he says. “Nowadays there’s specialty high-tech rigging line available that’s very thin, very high-strength, and very slippery. So I invented a block with very few moving parts (that uses this thin rigging line) that cuts the average space in half.”
Sustained wind creates vibration, and
the resonance can cause turnbuckles
Some turnbuckles have notched barrels with springs, which prevent the turnbuckle from turning unless the spring is pulled out. Others have a nut that can be tightened down. A simpler solution, however, is to use rigging tape, which works on the same principle as plumbers’ Teflon® tape. “It looks like electrical tape, but has no sticky side,” explains Duvall. “But when you stretch it around [hardware], it sticks to itself in layers.”