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Question about using a magnetic drill press on curved tanks
I was working on a propane tank down at the Port of Savannah last Thursday. Had to drill 16 holes for a patch plate on a curved section. My mag drill kept slipping off the curve no matter how tight I set the magnet. Ended up having to tack weld a flat plate on first just to hold the drill. Anyone got a trick for keeping a mag drill from sliding on a curved surface without having to weld something on first?
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ivan4018d ago
Not sure this is as big a deal as people make it out to be. I've drilled plenty of curved tanks with a mag drill and never had that problem. If the magnet's strong enough and you make sure the surface is clean and dry, it usually holds fine. Maybe your magnet was dirty or the tank had oil or something on it. I'd also check the drill's base for flatness. A lot of guys blame the curve when it's really just a worn out pad or a weak magnet. Welding a plate seems like overkill unless you're in some crazy windy or slippery spot.
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Dang, that's a tricky spot to be in. Instead of tack welding a whole plate, you could try cutting a piece of 1/8 inch thick sheet metal to match the curve's radius as close as possible. Clamp it tight with a couple of good C-clamps on each side of where you need to drill, that gives the mag drill a flat surface to bite into without needing to weld. If the curve is really tight, you can even use a piece of rubber roofing membrane or a rubber mat under the sheet metal to help it grip the tank better and stop it from sliding around. Just make sure your clamps are on solid and you're not putting too much pressure on the drill while it's running, or it'll still want to kick off. That saved my bacon on a few rusty boiler jobs where I couldn't weld.
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