I have a broket 1/4-20 tap in some 1/2 in steel plate.
(Last hole of 8, of course)

I can access both sides of the tap, the tap is a 4 flute tap
and has a dimple in the end
(Looks like it was setup to drill it out.)

My HSS drill bit does not even touch it.

So my thought is to go to the local machinist supply store on monday
and buy a carbide drill of the apropriate size and drill out the tap
on the drill press.

Should I drill undersize and work my way up to the proper size?
Or should I drill at the apropriate size all at once.

The part is simple and not worth taking to to an EDM shop etc.. I'll
just make another one if I have to.


I can rotate the tap back and forth abut 10 degrees with some small
needle nose. In general I've never had any luck with tap extractors,
alas if one was ever going to work at all now is the time.

Paul

I have a broket 1/4-20 tap in some 1/2 in steel plate.
(Last hole of 8, of course)

I can access both sides of the tap, the tap is a 4 flute tap
and has a dimple in the end
(Looks like it was setup to drill it out.)

My HSS drill bit does not even touch it.

So my thought is to go to the local machinist supply store on monday
and buy a carbide drill of the apropriate size and drill out the tap
on the drill press.

Should I drill undersize and work my way up to the proper size?
Or should I drill at the apropriate size all at once.

The part is simple and not worth taking to to an EDM shop etc.. I'll
just make another one if I have to.


I can rotate the tap back and forth abut 10 degrees with some small
needle nose. In general I've never had any luck with tap extractors,
alas if one was ever going to work at all now is the time.

Paul
I would think, that since you can rotate the tap back and forth a bit,
that the tap extractors made with the little metal pins just may work
for you in this situation. You may even be able to slip a couple of
little pins down into the flutes of the tap yourself, and unscrew it
with a pair of needle nose pliers. HTH.
Ken.

I have a broket 1/4-20 tap in some 1/2 in steel plate.
(Last hole of 8, of course)

I'd try a tap extractor:

http://www1.mscdirect.com/CGI/NNSRIT...PMT4NO=1738752

Best Regards,
Keith Marshall


"I'm not grown up enough to be so old!"


wrote in message
...
I have a broket 1/4-20 tap in some 1/2 in steel plate.
(Last hole of 8, of course)

I can access both sides of the tap, the tap is a 4 flute tap
and has a dimple in the end
(Looks like it was setup to drill it out.)

My HSS drill bit does not even touch it.

So my thought is to go to the local machinist supply store on monday
and buy a carbide drill of the apropriate size and drill out the tap
on the drill press.

Should I drill undersize and work my way up to the proper size?
Or should I drill at the apropriate size all at once.

The part is simple and not worth taking to to an EDM shop etc.. I'll
just make another one if I have to.


I can rotate the tap back and forth abut 10 degrees with some small
needle nose. In general I've never had any luck with tap extractors,
alas if one was ever going to work at all now is the time.

Paul

You may be able to back the tap out by reaching down into one of the flutes
with a small punch, screwdriver, whatever and rap on it with a little
hammer, turning it backwards in small increments. Barring that, I'd try a
tap extractror - the fact that you can move it back and forth 10 degrees
suggests a tap extractor might work. If you go for it with a solid carbide
drill, position the drill in a drill press or milling machine exactly over
the center of hole.

Bob Swinney
wrote in message
...
I have a broket 1/4-20 tap in some 1/2 in steel plate.
(Last hole of 8, of course)

I can access both sides of the tap, the tap is a 4 flute tap
and has a dimple in the end
(Looks like it was setup to drill it out.)

My HSS drill bit does not even touch it.

So my thought is to go to the local machinist supply store on monday
and buy a carbide drill of the apropriate size and drill out the tap
on the drill press.

Should I drill undersize and work my way up to the proper size?
Or should I drill at the apropriate size all at once.

The part is simple and not worth taking to to an EDM shop etc.. I'll
just make another one if I have to.


I can rotate the tap back and forth abut 10 degrees with some small
needle nose. In general I've never had any luck with tap extractors,
alas if one was ever going to work at all now is the time.

Paul

I had a business removing broken taps and bolts for 18 years. And I think
you might be able to use a Dremel slitting wheel to put a slot like a screw
slot in the end of the tap and then use a screw driver. If you use a carbide
drill I would try a .125 dia. Carbide does not like interrupted cuts and if
you go bigger the cut will be breaking into the flutes. Then break tap out
with a punch. If you use carbide be sure the broken tap is not moving
around in the hole .Because if it moves under load it can break the drill.
And drill from the bottom and the drilling may unscrew the tap. So leave
room for the tap to go if it does unscrew. Jim
wrote in message
...
I have a broket 1/4-20 tap in some 1/2 in steel plate.
(Last hole of 8, of course)

I can access both sides of the tap, the tap is a 4 flute tap
and has a dimple in the end
(Looks like it was setup to drill it out.)

My HSS drill bit does not even touch it.

So my thought is to go to the local machinist supply store on monday
and buy a carbide drill of the apropriate size and drill out the tap
on the drill press.

Should I drill undersize and work my way up to the proper size?
Or should I drill at the apropriate size all at once.

The part is simple and not worth taking to to an EDM shop etc.. I'll
just make another one if I have to.


I can rotate the tap back and forth abut 10 degrees with some small
needle nose. In general I've never had any luck with tap extractors,
alas if one was ever going to work at all now is the time.

Paul

with larger taps, like 1/4 inch, I've had good luck using a diamond point (I
suppose that's what you call it) in a high speed drill like dremel or an air
drill - the diamond dust on the point will cut the tap easily, just cut the
flutes off - since it's loose, cutting just one flute off ought to do the
trick. I get the "points" - whcih look like toothpics with diamond dust on
them - from a jewelry/lapidary store - they are pretty cheap (around a
dollar or so each) - lube with water if you wish
wrote in message
...
I have a broket 1/4-20 tap in some 1/2 in steel plate.
(Last hole of 8, of course)

I can access both sides of the tap, the tap is a 4 flute tap
and has a dimple in the end
(Looks like it was setup to drill it out.)

My HSS drill bit does not even touch it.

So my thought is to go to the local machinist supply store on monday
and buy a carbide drill of the apropriate size and drill out the tap
on the drill press.

Should I drill undersize and work my way up to the proper size?
Or should I drill at the apropriate size all at once.

The part is simple and not worth taking to to an EDM shop etc.. I'll
just make another one if I have to.


I can rotate the tap back and forth abut 10 degrees with some small
needle nose. In general I've never had any luck with tap extractors,
alas if one was ever going to work at all now is the time.

Paul

william_b_noble wrote:
with larger taps, like 1/4 inch, I've had good luck using a diamond point (I
suppose that's what you call it) in a high speed drill like dremel or an air
drill - the diamond dust on the point will cut the tap easily, just cut the
flutes off - since it's loose, cutting just one flute off ought to do the
trick. I get the "points" - whcih look like toothpics with diamond dust on
them - from a jewelry/lapidary store - they are pretty cheap (around a
dollar or so each) - lube with water if you wish
wrote in message
...
I have a broket 1/4-20 tap in some 1/2 in steel plate.
(Last hole of 8, of course)

I can access both sides of the tap, the tap is a 4 flute tap
and has a dimple in the end
(Looks like it was setup to drill it out.)

My HSS drill bit does not even touch it.


Check with your dentist for diamond & carbide burrs that they throw out
by the gross. They are usually happy to see them going to good use
instead of the dump. I have a lifetime supply.
Bugs
So my thought is to go to the local machinist supply store on monday
and buy a carbide drill of the apropriate size and drill out the tap
on the drill press.

Should I drill undersize and work my way up to the proper size?
Or should I drill at the apropriate size all at once.

The part is simple and not worth taking to to an EDM shop etc.. I'll
just make another one if I have to.


I can rotate the tap back and forth abut 10 degrees with some small
needle nose. In general I've never had any luck with tap extractors,
alas if one was ever going to work at all now is the time.

Paul

wrote in message
...
I have a broket 1/4-20 tap in some 1/2 in steel plate.
(Last hole of 8, of course)

I can access both sides of the tap, the tap is a 4 flute tap
and has a dimple in the end
(Looks like it was setup to drill it out.)

Assuming that you've tried to gently puch it out by using a small punch on
the flutes and failed. Only a diamond drill will work on a typical tap, but
that is in itself very chancy. A tap extractor (hah!) might work if you're
lucky. Realize that the point of a tap extractor is to save the work, not
the tap extractor. They break more than half the time. If you try that,
be sure to lubricate well and to work back and forth, very slowly and
gently. Maybe 100 times or more.
In a big shop with great tooling it would be done with an EDM
machine.

The simplest way (what I would do) is to punch it out. Do this in three
steps. First use a very small cold chisel and attack whatever is sticking
out on the broken end. You might be able to chip part of one or more
flutes that way and thereby make it easier to remove with a tap extractor.
This works about half the time. Next (if that failes) use a punch with a
slight hollow so that it can fit exactly over the center of the point of the
tap. Then whack it good and hard. Very rarely, you'll be able extract it
then. More likely, with a few good whacks you'll drive the tap out, leaving
a worthless thread and over-sized hole behind. And that's why Helicoils
were invented.

I made myself a 12" cast iron lathe face plate with about 120 3/8" x
16 holes tapped in it. Had to use the above procedure with Helicoils for
three holes.

Boris

--

-------------------------------------
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1232 Glenbrook Road on Software Testing and
Huntingdon Valley, PA 19006 Quality Assurance

TEL: 215-572-5580
FAX: 215-886-0144
Email bsquare "at" earthlink.net

------------------------------------------

--Where are you and how large is the part? I'm thinking
tapbuster...

--
"Steamboat Ed" Haas : You just can't beat
Hacking the Trailing Edge! : cruisin' in a steamboat
http://www.nmpproducts.com/intro.htm
---Decks a-wash in a sea of words---

Keywords:
In article , kens_at_sys_matrix_.net wrote:
snip
I would think, that since you can rotate the tap back and forth a bit,
that the tap extractors made with the little metal pins just may work
for you in this situation. You may even be able to slip a couple of
little pins down into the flutes of the tap yourself, and unscrew it
with a pair of needle nose pliers. HTH.

I've made a home brew tap extractor by using two sewing needles. The are
hardened & quite stiff, and just about the right size to drop into the
flutes of a tap. I've done a couple smaller taps this way, but it should
work on a 1/4-20 if you can find some large needles. A pair of pliers up
close can be used to twist them. Parallel jaw pliers would work best.

Doug White

Do you have a welder or access to one? MIG, Fluxcore or stick will work.
Weld a nut to the the stub and turn it out with a wrench. I've done this
with broken bolts, but I've heard it works with taps.

--
Ron DeBlock N2JSO
If God had meant for Man to see the sunrise,
He would have scheduled it later in the day.

Ron DeBlock wrote:
Do you have a welder or access to one? MIG, Fluxcore or stick will work.
Weld a nut to the the stub and turn it out with a wrench. I've done this
with broken bolts, but I've heard it works with taps.

I've tried this with broken 3 mm taps and a stick welder. I didn't have
any success. The weld always broke before the tap came out, and I had to
make a new part :-(.

Chris