Thinner than the round carriage bolt, sure, but not countersunk as a
plow bolt is in a plow share. A scoop could still catch the edge of an
Indeed, the application is the key; I was speaking of the wagon bed
usage of the previous poster re: common usage of a carriage bolt and
commenting that, _IF_ (the proverbial big if) there were the thickness
for the countersink a plow bolt could be make totally flush w/ the floor
(or even slightly under) and avoid the scoop catch problem entirely.
Never seen it, however (altho certainly have a multitude of plow bolts
on the planters and other tillage implements even though w/ no- and
low-till practice of today the number of different implements that
actually turn the soil is far fewer than used to be 30 years ago)...
I don't know squat about plow shares, but I have used Grade 8 fender
washers and hex bolts to "counter sink" (read: "dent") boards so that
the elevator bolts will be flush with the surface.
If the wood is too hard the elevator bolts tend to break before
"counter sinking" themselves, but a hex bolt and Grade 8 fender washer
will usually get the job done.
Carriage bolts also have better aerodynamic properties than hex head
bolts. Not as good as elevator bolts, but certainly better than hex
When using hex head bolts and aerodymics need to be considered, always
ensure that a point faces into the wind, not a flat side.
Sometimes a air impact gun will get them as it "hammers" the nut a
bit. If you are putting these in wood make sure you don't drill the
hole bigger than the bolt. You want square part to be forced into the
hole. Metal backets for docks usually have square holes so that
carrage bolts work with them. If you have a round hole in metal then
you want to use hex head.
On removal, try an air impact. Hold with a pair of vise grips, weld a piece
off rebar to the top, or slide a screwdriver under it so the turning of the
bolt wedges the screwdriver tighter. If they are corroded, a SawZall or
grinder may be the only way. Reinstall them with an air impact. It will
tighten them a fraction of a turn at a time, and possibly get what you want.
Use lock washers.
If it doesn't have a plain rounded head with a square collar/neck
it is no longer a carriage bolt -- it becomes a very large "machine
at that point once you can use some sort of tool on the head of the
Dude, it sounds like the wood on your dock supports is starting
to get mushy and rotten around the carriage bolts...
If this is a dock you take apart every year to store, you could
salvage what you have by installing some kind of metal guide
tube for the bolts into the wood with epoxy to prevent further
You could epoxy the bolts in place but depending on how your
dock is put together that might make taking it apart impossible...
The best way to remove stuck nuts off bolts you can replace
is to use an oxy-acetylene torch and burn them off if you have
one and know how to use it properly...
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