From: kurt matis (krogerma@yahoo.com)
Date: Fri Nov 18 2005 - 08:17:32 PST
Listers:
I do a lot of antique equipment restoration (I guess
lots of us do) and I encounter broken off bolts quite
often. Welding works sometimes, but if you try and do
not succeed you can end up in a worse mess that you
started with. The left-hand spiral ez-outs, by their
very design, must put pressure on the inside of the
drilled hole and thus will push the
bolt into even tighter contact with whatever the bolt
is screwed into. The fluted ez-outs are a little
better sometimes because they don't expand so much.
However, for severly rusted bolts, they just funnel
out the top part of the hole you drilled and end up
not working too well.
Several years ago I bought a set of left-handed
reamers at an auction associated with a machine shop
closing. By "left-handed", I mean reamers that are
designed to be turned in the counter-clockwise
direction to cut. There are also right-hand cutting
reamers with a left-hand spiral that are used for fine
finishing of holes. I'm not talking about these. I
bought the reamers because nobody else wanted them and
they sold for five bucks. I never imagined they would
come in so handy.
I use the reamers for bolt extraction of totally
rusted, broken off bolts as follows:
1) Center-punch hole with a transfer punch. You must
use a transfer punch to get the hole exactly in the
center of the bolt, as another lister has stated. Go
out and buy a set if you don't have any. They are
cheap now that they are made in China. Get 'em from
Enco or someplace like that. Everything is made in
China these days. They are using our steel to make
them, so you needent feel totally guilty about buying
them, I guess. I buy US-made stuff whenever I can, but
US-made goods are getting hard to find.
2)I mount my tapping fixture on the surface the bolt
is stuck in. In my case, the bolt has either been
stuck in a cylinder block or in a cylinder head and I
was able to mount the fixture in a rigid orientation
with respect to the surface. My fixture is a very
high-quality old tapper (did you notice most old stuff
is) and the column can swing 360 degrees relative to
the base. I put a drill in the tapper and then attach
my CORDLESS drill to the drive with an adapter. I use
my cordless drill, since it is the only device I have
with a limited torque capability. I then drill a hole
that is about 1/32 less than the diameter of the
inside of the female threads. In other words, if the
bolt were not in the hole, the drill would go in with
1/32 inch clearance.
3)I select a reamer which just fits in the bolt hole,
again presuming the bolt is not in there. I tap the
reamer down inside the bolt very gently. If it goes
too hard, then the bolt is probably grade 8 and you
need to drill it slightly larger using a drill that is
1/64 larger. You need to try it with the smaller
drill, first, though. You want to leave enough so the
reamer will bite and if you use the 1/64 drill first,
you might not have enough. This has been my
experience. So try the 1/32 smaller drill first, then
the 1/64 smaller if the reamer won't go in.
4)After tapping the reamer in gently, all the way to
the VERY BOTTOM of the hole you drilled, turn it out
(counterclockwise) by hand. Only exert limited force
on the reamer. One of two things will happen. It could
happen that the reamer will not turn with limited
force. If this happens and you were using the 1/32
drill, use the 1/64 and try again. If you were using
the 1/64, you will have to drill out the bolt to
exactly the diameter of the thread pitch. In other
words, use a drill that just fits in the bolt hole if
the bolt were not there. This means that all there
will be left is thread. It could also happen that the
reamer will turn the bolt out of the hole. If this
happens, all is well. The third possibility is that
the reamer will cut a hole of it's diameter and NOT
turn the bolt out. This means that there will only be
threads left in the hole. If this is the case, the
threads can normally be extracted with a pick. It is
tedious, but it can usually be done. If you can't even
get the threads out with a pick (L-shaped), then the
threads can be driven out with a bottoming tap. Since
only threads are left in the hole, they will usually
easily crumble when
the tap goes in. Of course, you need to put the tap in
a little way, then back it completely out and
wash/blow any crumbled threads out. Don't put it in
more than 1/2 turn at a time, since even if it goes
easily, you may be driving high-tensile thread pieces
into a softer substance (say an engine block). So
clear the pieces out a little at a time. When I did
this, the block was in an engine stand and I could
rotate it upside down and spray it with kerosene, then
blow it out with compressed air.
5)Why use the reamer at all? Why not just drill the
bolt out except for the threads right from the start?
First, it's very tedious to get the threads out with
either pick or tap or a combination of the two. If you
can pull the bolt out with the reamer, it's much
easier. Second, it avoids having the drill coming into
direct contact with the female threads inside the
piece (engine block in my case). Even if you hold the
drill rock-steady (or try to) it can flex a little
bit and ruin your day. I had to tap one hole one size
larger because I wrecked the threads on one. I don't
think they were wrecked already, but maybe they were,
who knows? On old equipment, one never knows for sure.
I know that all the holes were OK for bolts I used the
more complex procedure on. This procedure was used
successfully on four rusted (and broken off) head
bolts and two rusted (and broken off) bolts going into
the head.
Where would one get a left-handed reamer, you ask?
Well, as I stated I got my set at an auction. I used
to see them in the industrial supply catalogs once in
a while, but I just checked MSC and they only have
LEFT-HAND SPIRAL reamers which cut in the CLOCKWISE
direction. National Tool Grinding corp. has
left-handed reamers of various sizes.
(http://www.national-tool.com). They are pretty good
about making up a reamer to customer's specs even if
they do not have the exact size you need. They will
usually regrind one of their stock reamers to the
size/specs you want for a reasonable price (but not
cheap). They also will regrind Rotabroach annular
cutters, one of the few places I know of that does. I
have no financial interest in the company, so this is
not an advertisement.
Hope this helps.
Kurt Matis
Troy, NY
1972 m35a2
1963 Walter Tractor-Truck
--- Everette <194cbteng@bellsouth.net> wrote:
> MV] inverted "easy out".......
> Buzz wrote what years of experience has caused me to
> follow in removing
> broken bolts. I also have occacasion to remove
> broken pipe, that has broken
> off inside some sort of filling, elbow, tee,
> coupling, etc. I have found
> that the reverse twist spiral ez-outs do the same
> thing to pipe that they do
> to bolts, swell them even tighter. I use an ez-out
> that is square, and
> slightly tapered and has cutting edge on corners,
> comes in varoius sizes. I
> drive it in with hammer and then un-screw with
> wrench. Even this has failed
> a few times, it cuts inside of pipe but does not
> catch enough to unscrew the
> pipe, however, after a few attempts, stopping before
> I cut into threads of
> fitting, I can take small cutting punch and peel
> pipe away from threads,
> sometimes peel some back and the ez-out will catch
> again. This is most
> times accompained by use of penetrating oil.
>
> Everette
>
>
> Listers,
> To remove broken bolts on old equipment I assume
> that the bolt is rusted and
> that's why it broke. Especially head bolts, or
> studs, that go into the
> water
> jacket. I don't like using heat because that plays
> havoc with the temper of
> the
> metal. I've never had much luck welding on nuts
> because I couldn't get the
> proper penetration. Speaking of penetration,
> penetrating oil will break the
> surface rust bond, but after a week it only
> penetrated a few threads. If I
> can
> get the bolt or nut to move a little then I add more
> penetrating oil and
> work it
> in and out a little at a time until it comes off.
> Back to the original problem.... get the drill. If
> the part is broken off
> below
> the surface I use the proper size transfer punch to
> punch it exactly in the
> center, then follow up with a regular center punch.
> I usually start with a
> center drill, then a SHARP 1/8" drill. I use enough
> force to remove material
> but
> not so much that I bend the drill. If too much
> force is used the drill will
> bend and go off center.
> I then start using left hand drills 1/16" at a time,
> up to just below the
> tap
> hole size. If the piece is still in the threads
> then I tap the hole.
> Usually
> what happens is that as I approach the size of the
> broken piece it'll spin
> out
> of the hole.
> Forget about eze-outs they just break, then your in
> REAL trouble. The only
> time
> that I've had good results with eze-outs is if the
> bolt was new and broke
> from
> over tightening, or was sheared off. If I use
> eze-outs I like the square
> ones.
> The left hand threaded ones seem to swell the bolt
> then it is tighter.
>
> BTW buy a GOOD set of drills because if you come up
> against a class 8 bolt
> you're gonna need a good drill.
>
>
>
>
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