It took a while but then what I was using started to slip. It grips and clamps on one side only, which allows it to rotate even when tightened. I bought this from Home Depot (about $10) and it's much better because it clamps automatically and is supported on all six sides at the same time. While I don't really like the extension above, I would rate the extension 5/5 in the link below. Spend a few bucks more to get a better quality tool and avoid the hassle.