In this video I'm going to take a look at a few techniques
for removing broken bolts or broken studs which are deep within a hole.
So I've got a stud in that hole that needs removing
we've also got a sheared bolt just
there that needs removing. If you see that
all of these are below the surface.
Then on this sump we have actually got a sheared bolt just there.
The danger with trying to remove
a stud like that or a broken bolt
is the fact that the surrounding
material is much softer than the bolt
itself so obviously this is made from
aluminium and the bolt is made from steel
so the aluminium is much softer.
Before you attempt to remove
any broken bolt there are a couple of things that
you can do that can make it easier. One
of the first things you should do is try
to shock it now I'm actually going to
use a spring-loaded punch to do this so
I'm just going to give that a few gentle taps.
If you don't have a spring-loaded
punch like that you can use a
traditional punch just give that a few
gentle taps with a club hammer and that
can help to free the broken bolt.
can also apply some heat obviously you
have to be careful if you're using
burning gear because you can quite
easily melt the aluminium.
You can also use some spray penetrant
there is a good chance that will help.
One thing that you could use is a hinge
sighting drill they have a spring loaded
part there which exposes the drill bit
that will actually prevent the drill bits
from catching the side of the material
which you are trying to remove the
broken bolt from. In sighting drills are
normally used like that, you'll position
your hinge where you want it then you
can simply use that to drill your pilot holes
that will ensure they are dead central.
However I'm not going to use it
for that I'm going to use that to ensure
that I can drill dead in the center of a
sheared bolt.
Take a look at that one for example you can see that that is in very
bad condition if you try to use a normal
drill bit on there you would have no
slipping off and damaging the aluminium thread.
For the first bolt I'm going to
swap the drill bit over and I'm going to
use a left-handed drill bit so I'm just
going to push that in there I'll then
tighten the grub screw
and then I'll
screw that back together.
The actual drill bit that I'm using is a
bit shorter than the one that I've taken out
so I'm actually just going to remove the spring from that
and that will still centre the drill bit.
So if we try that in
the end of the shaft you can see that
it's a very good fit and we're not going
to actually damage the internal threads on that.
You can of course use a regular
right handed drill in a hinge sighting drill
but that will then mean that you
will need to use a screw extractor afterwards.
So I'm now going to flick the
drill in to reverse and then we're going
So you can see that the left handed drill
bit actually started to bite into that
and it actually extracted it from the hole.
If we take a look in there you
can see that the threads are not damaged at all.
A big problem with removing a broken bolt
that is deep in a hole
is that you don't want to damage
the threads in the surrounding material.
I've actually made these which are
socket head bolts and I've actually
drilled a hole down the center of those
using a lathe and I've actually made an
M12, M10 and an M8.
So we can now take this we can actually screw that
into the hole where the damaged or
broken bolt is until that is tight and
then we can tighten up the nut that
will prevent that from coming loose
just gently nip that up and again I'm
actually going to use a left-handed
drill bit. The beauty of a left handed
drill bit is that when it bites into
the material there's a chance that it
will remove the broken bolt.
So I'm just
going to put some cutting paste on the
end of that and ensure the drill
is in reverse
You can see that that has now started
so I'm going to remove the bolt
and we should have an indentation in the bolt
so that should ensure that we don't
actually damage the threads on the
aluminium and we should now be able to
proceed and there is a chance that we
will be able to remove this.
Let's give that a spray with some spray penetrant
and I'll just try again.
It's not actually been moving the bolt
that time but we have got it far enough
forwards now and in a deep enough
hole to try a screw extractor.
So I'm now going to take a screw extractor I'll just tap that in there
I'm just going to take
a small adjustable, I would normally use a
a tap wrench but it is at work.
This time we've actually got that moving.
It moves a little bit more, it has actually slipped out again.
These are not the best quality
screw extractors that you can get these
were a very cheap set.
I'm just going to go to the next size up.
I'm just going to tap that in,
and as you can see that has successfully
removed the damaged bolt.
I'll just prove to you that none of these threads
have been damaged. We can now take an M10
bolt and we can easily screw that back in there.
With this one you've got
absolutely no chance at all of starting
the drill bit on it because it's not at all flat.
So the chances are that you'd
skid off there and you'd actually end up
damaging the threads. So I'm just going
to give that a spray. I'm now going to
take the socket head bolt that I've drilled a hole
through the center, I'm going to screw
that in there until it touches the broken
bolt, I'm going to run the nut down and
I'll just nip that up.
I'm going to use
a cobalt drill bit for drilling the bolt
because these are very tough. What we
don't want to do is go too deep into it
because you don't want to drill into the aluminium.
So I'm just going to apply
some cutting paste then I'm going to
proceed to drill the hole.
I'm now going to remove that and we'll see how deep in we have gone.
So you can now see that
we've got that hole started and it is
dead in the center of the bolt.
Now that we've got the hole started in the dead
center we can now continue to drill that
without the guide in or if you aren't
confident about doing that
you can always put the guide in.
So I'm now going to take some more cutting paste
and I'm going to proceed to drill the hole.
So we've drilled approximately seven to
eight millimeters in that bolt. What we
don't want to do is go too far in there
and go through the actual aluminium casting.
So I'm actually just going to try
the screw extractor on that now.
I'm just going to tap that in using the hammer
and then I'm just going to undo that
using the adjustable spanner.
It does actually look like that has bit.
Normally I would use a tap wrench for doing this
but unfortunately it is at work.
As you can see that has been removed successfully.
We will now just try a regular
M12 bolt back in there
just to prove that the threads have not been damaged.
You can see that that goes in there perfectly.
Obviously before you go
putting any bolts back into components
like this it's a good idea to give them
a good coating using some copper grease
or anti-seize compound.
If you do that
you can virtually guarantee that the
next time you come to remove the bolts
they're not going to seize up and
they're not going to snap and you will
be able to remove them very easily.
So that's a couple of techniques that
you can use to remove bolts that have
been broken deep in holes.
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