I built a picnic table several years ago. It took a hit from the snow
plow this winter. It's worth repairing, but I can't undo the carriage
bolts. The square part of the bolt head strips the wood when I put a
socket on the nut. Next weekend I'll try pounding a screwdriver under
the head parallel to the surface of the wood to engage a flat side of
the square. What do you experts do?
I take that to mean the bolt is counter-sunk? If so, how did that happen? I
mean whatever you used to counter-sink the bolt should be the same device
used to remove it.
If it's a carriage bolt, it has a nut somewhere. Can you attack it from that
I believe that Liz is saying that when she turns the nut, the bolt
turnes with it and the square under the bolt head reamed out the wood,
possibly because the nuts are a bit corroded onto the bolts.
If the nuts are accessable, she could buy a nut cracker and split them
so they'll slide off the threaded part of the bolts, then drive the
bolts out enough to grab the head and pull. Then buy some new nuts to suit.
Sears sells nutcrackers, and so do most auto parts stores:
Since the carriage bolt heads are apparently above the surface given the
comment about the screwdriver, the easiest thing to do is to use a
hacksaw (or angle grinder with cutoff wheel) and make a slot in the bolt
head for the screwdriver.
It isn't a 'rust problem'. Carriage bolts in wood that has been
exposed to weather will almost invariablyi strip out the wood. The
wood has less holding power than it takes to turn the nut. BTDT and
got the t-shirt many times.
The 'nutcracker' is about the best and quickest solution.
Every carriage bolt in wood I have seen have been set at least flush
if not a bit counteersunk into the wood. There is nothing there to
grab. Vice grips on the exposed thread is a possibility but will
screw up the threads, might allow unscrewing enough to get the
vicegrips onto the head and then force the nut over the screwed up
Happens all the time.
Basically, you have to cut off the bolt at the "hex" end.
If a washer was used under the hex nut, you can try a hack saw or a powered
version of the same (a "saws all").
The next step down is to drill out the volt from the "hex" end. When the
nut gets loose, you drive out the bolt.
The "final answer" is to grind off the hex nut with whatever power grinder
you can get in there.
"Sometimes" you can get a nut off with an impact wrench. Or you can "fix"
the flush end with glue and after the glue sets try turning the nut again.
Carriage bolts just are not designed for most soft woods. When you torque
down, you often bring the head below the surface of the wood. Folks also
tend to drill a hole that a little oversized for starts and soft woods
simply fail to hold the square all too often.
Where you NEED them because of the nearly flush surface they provide, you
might give them a little help with a drop or two of glue.
If you don't NEED them, use regular bolts with good sized washers.
Coincidentally: Just today took two, well rusted such bolts out in
order to reuse a piece of wood.
Couldn't shift the nuts; although one started turning around the whole
The nuts, with washers were fortunately not recessed into the wood.
The head ends of the coach bolts were virtually flush with the wood.
Used a hacksaw to cut into the square nuts at an angle I could reach
holding the pieces of wood firmly, until I could split the nuts apart
and beat them off with a small cold chisel and hammer.
If nuts had been recessed would probably have sharpened up a bigger
cold chisel and split the nut with sharp blows of the hammer.
One trick is to have something very firm and heavy below; so the force
of the blows on the cold chisel cutting edge really impacts the nuts
and cuts into them.
Bolt threads are rusty as anything but despite the rough treatment
breaking the nuts off, one of the two bolts, to our surprise, looks
I'm in the Dremel/anglegrinder camp- cut/grind the nut off & drive out
But if I was really reaching for a good excuse to buy a wire-feed mig
welder [or knew someone with one] I might try tack welding a nut on
top of the carriage bolt. Weld inside the nut - don't overheat.
HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.