Ask Sarah, Problems with Nuts


flank drive sockets
Don’t get 12 point sockets, those suck for rounding off bolts, unless of course you have 12 point bolts, not likely unless you have an aircraft or use a lot of super high rated AN bolts and stuff.  Get 6 point sockets with a flank drive profile.  This is the least likely to round off a nut and can even take off mildly rounded off nuts.

Maybe the best way to prevent rounding off a bolt is to use the correct tools.  I prefer to use 6 point sockets with a flank drive cam profile to remove stubborn bolts.  I don’t understand why 12 point sockets are more common but a good six point with the cam profile goes a long way in not rounding off heads.  Snap-On pioneered this sort of socket but now Craftsman and others make similar products.

sarah forst

Once you’ve rounded a nut or bolt, you’re screwed, right?  Not really, but first you need to remove it.  If a bolt extractor kit like the ones by Craftsman or Irwin doesn’t work, there are a few techniques I’ve had luck with in the past.  You can soak a rounded nut/bolt in penetrating oil like Liquid Wrench or PB Blaster (my personal favorite is Aerokroil but its kind of hard to find)  for about 5 minutes before attempting to loosen it with the closest sized open-ended wrench.  Tapping the head of the bolt after applying Penetrating oil can help as well.  Penetrating oil will reduce how much force is needed to remove the bolts.  Heating a stuck bolt until red hot with a Mapp gas or propane torch, then reapplying penetrating oil often can help break loose a badly stuck bolt.  Of course make sure that there are no other parts nearby that heat or flame might damage before trying this.

sarah forst
Stick a big flat bladed screwdriver between the flat side of the nut and the wrench for more leverage.

If the head of the bolt is impossibly rounded off you can use channel lock pliers or vice grips to grab the nut/bolt so tightly that it will twist off.  There are special channel lock pliers that have rounded jaws perfect for this kind of problem.  Or use a sharp chisel or cut off wheel to slot the top of the nut/bolt and then use a flat head screw driver to twist it out.  If it’s rounded on one side, use the blade of a flat head screwdriver as a wedge between the wrench and the flat side of the bolt for more leverage.  You can also try filing down the side of the rounded nut/bolt with a metal file until it is flat, providing two flat sides on opposite sides of the bolt head.  And as a last resort, you can always cut off the head of the nut/bolt carefully, provided you have some way to remove the remaining piece of the nut/bolt.  Obviously, never reinstall a rounded nut/bolt or one that seems it will become rounded if you look at it funny.  



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