I'm trying to determine which of the acids we used to use, in the old days,
to disintegrate broken taps or drills. I remember when that was done
occasionally, but don't remember which acid was used. I have a friend who
has a broken drill in cast iron and I thought this might be a possibility
before we start chopping at it with carbide tools and make matters worse. It
might at least loosen it up enough to remove by hand. It's a 1/8" dia. drill
and not in too deep, about 3/16", but it's bound pretty tight.

Thanks
John



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John wrote:
I'm trying to determine which of the acids we used to use, in the old days,
to disintegrate broken taps or drills. I remember when that was done
occasionally, but don't remember which acid was used. I have a friend who
has a broken drill in cast iron and I thought this might be a possibility
before we start chopping at it with carbide tools and make matters worse. It
might at least loosen it up enough to remove by hand. It's a 1/8" dia. drill
and not in too deep, about 3/16", but it's bound pretty tight.

Thanks
John



If you find something which will disolve tool steel out of cast iron
without eating up the cast iron too, please let me know.

Think EDM...

Jeff
--
Jeffry Wisnia

(W1BSV + Brass Rat '57 EE)

"Truth exists; only falsehood has to be invented."

For that depth I'd get a solid carbide end mill and set it up in a mill.
We took out a broken EZ Out a couple weeks ago, just melted right
through it. I was quite impressed! But don't even THINK about doing it
in a drill press.

John wrote:

I'm trying to determine which of the acids we used to use, in the old days,
to disintegrate broken taps or drills. I remember when that was done
occasionally, but don't remember which acid was used. I have a friend who
has a broken drill in cast iron and I thought this might be a possibility
before we start chopping at it with carbide tools and make matters worse. It
might at least loosen it up enough to remove by hand. It's a 1/8" dia. drill
and not in too deep, about 3/16", but it's bound pretty tight.

Thanks
John



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RoyJ wrote:

For that depth I'd get a solid carbide end mill and set it up in a mill.
We took out a broken EZ Out a couple weeks ago, just melted right
through it.

By reading this, I just got an idea (not proofen to work, it just
flashed up in my confused brain).

Set the piece up in a mill, and "rubb" on the broken drill with some
hardened rod. Of course, the rod is rotating and pressed down firmy onto
the bit. It might start to melt and weld onto the broken drill. Maybe
the mill should go in reverse.
Works just like the welding process does.

Comments? Should I forget that idea?


You can use the trick to localy anneal leaf springs to get a hole in
them.


Nick
--
Motormodelle / Engine Models
http://www.motor-manufaktur.de
todays SPAMfeed:

"Jeff Wisnia" wrote in message
...
John wrote:
I'm trying to determine which of the acids we used to use, in the old
days, to disintegrate broken taps or drills. I remember when that was
done occasionally, but don't remember which acid was used. I have a
friend who has a broken drill in cast iron and I thought this might be a
possibility before we start chopping at it with carbide tools and make
matters worse. It might at least loosen it up enough to remove by hand.
It's a 1/8" dia. drill and not in too deep, about 3/16", but it's bound
pretty tight.

Thanks
John


If you find something which will disolve tool steel out of cast iron
without eating up the cast iron too, please let me know.

Think EDM...

Jeff
--
Jeffry Wisnia

(W1BSV + Brass Rat '57 EE)



You're right Jeff, it might eat up a small amount of the C.I., but in this
particular case that's not to important. The part is too odd shaped to
mount to a machine table to mill out. If we could loosen the drill slightly
I think we might be able to get it out.

I just remember that in the past there have been occasions where we removed
broken cutting tools from a base material with an acid. I don't recall
which specific acid or base material worked the best. Obviously if it eats
up your part it wouldn't be too good. I wouldn't propose doing it on a
precision machined part, that's why I thought this group might have a
suggestion or two. I've removed many broken tools over the years with left
hand drills and left hand carbide end mills, but that won't work too well in
this case.

73,
John (W7JDA)



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I've heard of nitric acid for disolving taps in AL. Bet it eats cast faster
than tool steel.

Karl


"John" wrote in message
...
I'm trying to determine which of the acids we used to use, in the old
days, to disintegrate broken taps or drills. I remember when that was
done occasionally, but don't remember which acid was used. I have a
friend who has a broken drill in cast iron and I thought this might be a
possibility before we start chopping at it with carbide tools and make
matters worse. It might at least loosen it up enough to remove by hand.
It's a 1/8" dia. drill and not in too deep, about 3/16", but it's bound
pretty tight.

Thanks
John



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Newsgroups
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=----

If I remember correctly, cast iron is more resistant than steel, to attack
by sulphuric acid. If you can fill the hole with H2SO4, you may find that it
dissolves enough of the drill to remove it. You'll have to keep trying it on
a regular basis though, as I have no idea as to how long it will take. I
could give you the usually boring warnings about strong acids and gloves and
glasses, but if you don't know enough about already, you shouldn't mess with
it at all.

Tom miller
"John" wrote in message
...

"Jeff Wisnia" wrote in message
...
John wrote:
I'm trying to determine which of the acids we used to use, in the old
days, to disintegrate broken taps or drills. I remember when that was
done occasionally, but don't remember which acid was used. I have a
friend who has a broken drill in cast iron and I thought this might be
a
possibility before we start chopping at it with carbide tools and make
matters worse. It might at least loosen it up enough to remove by hand.
It's a 1/8" dia. drill and not in too deep, about 3/16", but it's bound
pretty tight.

Thanks
John


If you find something which will disolve tool steel out of cast iron
without eating up the cast iron too, please let me know.

Think EDM...

Jeff
--
Jeffry Wisnia

(W1BSV + Brass Rat '57 EE)



You're right Jeff, it might eat up a small amount of the C.I., but in this
particular case that's not to important. The part is too odd shaped to
mount to a machine table to mill out. If we could loosen the drill
slightly
I think we might be able to get it out.

I just remember that in the past there have been occasions where we
removed
broken cutting tools from a base material with an acid. I don't recall
which specific acid or base material worked the best. Obviously if it
eats
up your part it wouldn't be too good. I wouldn't propose doing it on a
precision machined part, that's why I thought this group might have a
suggestion or two. I've removed many broken tools over the years with
left
hand drills and left hand carbide end mills, but that won't work too well
in
this case.

73,
John (W7JDA)



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Newsgroups
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=----

John wrote:
"Jeff Wisnia" wrote in message
...

John wrote:

I'm trying to determine which of the acids we used to use, in the old
days, to disintegrate broken taps or drills. I remember when that was
done occasionally, but don't remember which acid was used. I have a
friend who has a broken drill in cast iron and I thought this might be a
possibility before we start chopping at it with carbide tools and make
matters worse. It might at least loosen it up enough to remove by hand.
It's a 1/8" dia. drill and not in too deep, about 3/16", but it's bound
pretty tight.

Thanks
John


If you find something which will disolve tool steel out of cast iron
without eating up the cast iron too, please let me know.

Think EDM...

Jeff
--
Jeffry Wisnia

(W1BSV + Brass Rat '57 EE)




You're right Jeff, it might eat up a small amount of the C.I., but in this
particular case that's not to important. The part is too odd shaped to
mount to a machine table to mill out. If we could loosen the drill slightly
I think we might be able to get it out.

I just remember that in the past there have been occasions where we removed
broken cutting tools from a base material with an acid. I don't recall
which specific acid or base material worked the best. Obviously if it eats
up your part it wouldn't be too good. I wouldn't propose doing it on a
precision machined part, that's why I thought this group might have a
suggestion or two. I've removed many broken tools over the years with left
hand drills and left hand carbide end mills, but that won't work too well in
this case.

73,
John (W7JDA)



Try putting a little light oil or Kroil in the hole and then try tapping
against the flutes of the busted drill tip with a sharp punch and a
light hammer.

If it's only in 3/16" deep, I bet you can wiggle it enough to let the
oil get down into the crevices and help you make it easier to back it out.

Ay least that's what I'd try first, you can alway go on to more exotic
methods if my suggestion fails.

Jeff
-
Jeffry Wisnia

(W1BSV + Brass Rat '57 EE)

"Truth exists; only falsehood has to be invented."

I really like this idea! I wonder if the heat would cause the part you
wish to remove to expand and be more difficult to get out. Perhaps if
you did is fast. I goes without saying that you plan to run the
milling machine counter clockwise.
Good Luck!
Rick

Harbor Freight sells a very small air turbine that will take dental
drills. I have had good luck using one of those to get broken taps
out. Not real fast, but it does work on tool steel.

Dan

John wrote:
I'm trying to determine which of the acids we used to use, in the old days,
to disintegrate broken taps or drills. I remember when that was done
occasionally, but don't remember which acid was used. I have a friend who
has a broken drill in cast iron and I thought this might be a possibility
before we start chopping at it with carbide tools and make matters worse. It
might at least loosen it up enough to remove by hand. It's a 1/8" dia. drill
and not in too deep, about 3/16", but it's bound pretty tight.

Thanks
John

"John" wrote in message
...
I'm trying to determine which of the acids we used to use, in the old
days,
to disintegrate broken taps or drills. I remember when that was done
occasionally, but don't remember which acid was used. I have a friend who
has a broken drill in cast iron and I thought this might be a possibility
before we start chopping at it with carbide tools and make matters worse.
It
might at least loosen it up enough to remove by hand. It's a 1/8" dia.
drill
and not in too deep, about 3/16", but it's bound pretty tight.

Thanks
John
=----

One trick I have used in the past with quite good results is an arc
welder. Put a sleeve down the hole to protect the sides, use a
piece of mild steel with the welder set on fairly low current. Stick
the "electrode" down the sleeve until it "sticks" to the whatever you
are trying to get out. Turn the welder off - you now have an extension
on the whatever it is stuck in the hole. Actually works fairly well
many times.

mikey

"Jeff Wisnia" wrote in message
...
John wrote:
"Jeff Wisnia" wrote in message
...

John wrote:

I'm trying to determine which of the acids we used to use, in the old
days, to disintegrate broken taps or drills. I remember when that was
done occasionally, but don't remember which acid was used. I have a
friend who has a broken drill in cast iron and I thought this might be
a
possibility before we start chopping at it with carbide tools and make
matters worse. It might at least loosen it up enough to remove by hand.
It's a 1/8" dia. drill and not in too deep, about 3/16", but it's bound
pretty tight.

Thanks
John


If you find something which will disolve tool steel out of cast iron
without eating up the cast iron too, please let me know.

Think EDM...

Jeff
--
Jeffry Wisnia

(W1BSV + Brass Rat '57 EE)




You're right Jeff, it might eat up a small amount of the C.I., but in
this
particular case that's not to important. The part is too odd shaped to
mount to a machine table to mill out. If we could loosen the drill
slightly
I think we might be able to get it out.

I just remember that in the past there have been occasions where we
removed
broken cutting tools from a base material with an acid. I don't recall
which specific acid or base material worked the best. Obviously if it
eats
up your part it wouldn't be too good. I wouldn't propose doing it on a
precision machined part, that's why I thought this group might have a
suggestion or two. I've removed many broken tools over the years with
left
hand drills and left hand carbide end mills, but that won't work too
well in
this case.

73,
John (W7JDA)



Try putting a little light oil or Kroil in the hole and then try tapping
against the flutes of the busted drill tip with a sharp punch and a
light hammer.

If it's only in 3/16" deep, I bet you can wiggle it enough to let the
oil get down into the crevices and help you make it easier to back it out.

Ay least that's what I'd try first, you can alway go on to more exotic
methods if my suggestion fails.

Jeff
-
Jeffry Wisnia

(W1BSV + Brass Rat '57 EE)

"Truth exists; only falsehood has to be invented."

Expanding on that idea, if you heat it up first (propane torch should be
adequate, if you use OA, be conservative with it...) and then squirt some
WD-40 into it, it should loosen. A part of the problem is that the broken
drill is tight against the sides and it makes it difficult for the oil to
penetrate. But, if you heat the whole mess up a little, then squirt it, the
oil will cool the drill and it will contract enough that the oil can
penetrate the gap. Then proceed as Jeff suggested.

Jerry

Look in the Machinery's Handbook under Removing a broken tap. One part
nitric acid and 5 parts water.
Jim
"John" wrote in message
...
I'm trying to determine which of the acids we used to use, in the old
days, to disintegrate broken taps or drills. I remember when that was
done occasionally, but don't remember which acid was used. I have a
friend who has a broken drill in cast iron and I thought this might be a
possibility before we start chopping at it with carbide tools and make
matters worse. It might at least loosen it up enough to remove by hand.
It's a 1/8" dia. drill and not in too deep, about 3/16", but it's bound
pretty tight.

Thanks
John



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=----

" Jim Sehr" wrote in message
...
Look in the Machinery's Handbook under Removing a broken tap. One part
nitric acid and 5 parts water.
Jim
"John" wrote in message
...
I'm trying to determine which of the acids we used to use, in the old
days, to disintegrate broken taps or drills. I remember when that was
done occasionally, but don't remember which acid was used. I have a
friend who has a broken drill in cast iron and I thought this might be a
possibility before we start chopping at it with carbide tools and make
matters worse. It might at least loosen it up enough to remove by hand.
It's a 1/8" dia. drill and not in too deep, about 3/16", but it's bound
pretty tight.

Thanks
John



Thanks to everyone for the suggestions. Some of which I've not tried in the
past. It's amazing how many good ideas there are out there!

Thanks Jim, for the reference to the Machinery's Handbook. Duh, I guess I
should have thought to look there first. That's the specific info that I
was looking for.

Thanks again to all.

John



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"Tom Miller" wrote in message
...
If I remember correctly, cast iron is more resistant than steel, to attack
by sulphuric acid. If you can fill the hole with H2SO4, you may find that
it
dissolves enough of the drill to remove it. You'll have to keep trying it
on
a regular basis though, as I have no idea as to how long it will take. I
could give you the usually boring warnings about strong acids and gloves
and
glasses, but if you don't know enough about already, you shouldn't mess
with
it at all.

Tom miller

Truth is, iron won't dissolve in *concentrated* sulfuric acid, but if
there's any water present, all bets are off.

Cast iron kettles used to be used in processing sludge from silver cells, to
separate residual silver particles from the sludge, from which the rest of
the precious metals were extracted (gold and the platinum group metals).
The silver particles were dissolved by boiling the sludge in concentrated
sulfuric acid.

Harold

Karl Townsend wrote:
I've heard of nitric acid for disolving taps in AL. Bet it eats cast faster
than tool steel.

Karl



Nitric acid or a concentrated alum solution will eat the tap without
harming the aluminum. Don't know of anything that will help in cast
iron, though.

John Martin