3alarmer

...not certain you've used an impact wrench in a circumstance like this. It's not like going at a lug nut on a car wheel, and the bicycle itself tends to move around easily. So the business end of the tool either slips out or can damage the little teeth in the BB fitting (they are either aluminum or plastic.) So it might work, but you're way better off bolting the tool to the sealed unit spindle with a properly sized bolt and some fender washers, putting either an adjustable or (better) properly sized box end wrench on the tool, and hitting the wrench with a mallet or hammer. Plus you get to use a hammer.