90 degree bar clamps and threaded rod slippage

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For H-1.1s, when you're using the bar clamps to hold threaded rod, it helps to wrap a bit of sand paper around the rod to really secure it in place.

I use a piece of 320 or 400 grit sandpaper, 1/2 inch wide and 2-3 inches long. Fold the strip in the middle, then wrap it around the rod before putting on the clamp pieces. The sandpaper ensures that nothing slides.