Rounded Bolt Extraction – need help!

Beau Posted July 11, 2020 Share Posted July 11, 2020 (edited) Not sure if this is the right forum – feel free to move this thread if necessary. I’ve run into a rusty bolt that I cannot remove. It has a rounded head and is recessed. I’m looking for advice on how to remove it. See the attached photo. It’s an M10 bolt (14 mm head size) fastening a cross-brace to the frame under my car. The bolt head is recessed into the cross brace so I need to use a socket or similar (wrench or vice grips won’t work here). The head is rounded enough that all my 14 mm sockets slip very easily, but it’s still too large for a 13 mm to fit. Closest SAE socket would be 17/32″, which is not a standard size. I’ve already tried using 2 different bolt extractors (the kind w/spring loaded pins and the spiral socket kind), but they didn’t work. I also tried a hammer and chisel to “spin” the bolt, but because of the angle I don’t think this is very effective. I got the chisel to bite into the head a bit, but it’s not at a good angle. This might come in handy later. Okay so the real question is what else can I use to grab the bolt head tight enough? Most online articles say to heat it up good then turn it with vice grips or similar, but that won’t work here. I bought a torch so I’ll try heating the bolt up to hopefully loosen it up (break the rust bonds), but I still need to grab the bolt to turn it after that. I’m not sure what else I can do here. Some options I’ve thought of, but haven’t tried yet. Would any of these work or just waste of time? Can I somehow grind or chisel the bolt head to allow either a 13 mm socket or one of the extractors to bite better? E.g. chisel some detents into it and use a smaller socket? Not sure if this will help. I could buy a sacrificial 13 mm socket and grind out the inside of it with a dremel until it fits snugly (effectively creating a 13.5 mm socket). Tough to do accurately. Can I shim the inside of a 14mm socket somehow to make it a tighter fit? I would need some very thin steel bar or maybe stack some foil or steel wool, other material to create a better bite? Or similarly, could I fill the 14 mm with some JB Weld or Epoxy or something and let it set overnight to get a good fit on the bolt? I could grind a slot into the bolt head so I could turn it with a flat head screwdriver, but I doubt I could get enough torque on it that way. Maybe after heating it up enough this would work. I could weld on a sacrificial nut – well, not me, but someone could for me. I would need to ask a favour or take it to a shop. How difficult would that be since the bolt is recessed? Would one need a MIG welder or special skill to be able to do this? My very last resort is to cut the brace off with an angle grinder or saw, then remove the bolt with big vice grips or something, but I really don’t want to do that as the brace cost $$. Any advice is appreciated! Edited July 11, 2020 by Beau typo Link to comment Share on other sites More sharing options…