Isn't it funny how the brain latches onto things better when they're stripped down? I've noticed the same thing with cooking, like reading a grandma's handwritten recipe card makes way more sense than some fancy food blog with a life story before the ingredients. Old stuff just gets to the point.

That curved shell is the whole problem, the magnet only grabs maybe 20 percent of its face on a 6 inch pipe. I ran into the same thing on a 48 inch header and what saved me was a wrap chain with a ratchet binder, the kind you'd use for tie downs. You loop it around the pipe, hook it to the base of the drill, and crank it down until the slack is gone. The chain takes the side load so the magnet just keeps the drill from tipping. Takes about two minutes to set up and it works on any size round. One tip, put a scrap of rubber under the chain where it crosses the weld seam so it don't slip on you.