Well, I've broken off my second 5-40 tap in cast iron (model steam
engine). One I got out with an extractor - the second one I've
buggered up so much my only hope is to drill it out.

I've read a number of posts about drilling them out with carbide bits.
When I look in KBC, Wholesale Tool, etc., I see solid carbide jobber
bits for 10 bucks or so in size 39. Will one of these do it? Because
I also see a "square die" carbide bit that specifically mentions
drilling out taps - but it's $35...

If I need the $35 bit, so be it. But, if a regular carbide jobber bit
will do it, I would obviously rather go that way.

TIA,
Wally

Wally Blackburn wrote:
Well, I've broken off my second 5-40 tap in cast iron (model steam
engine). One I got out with an extractor - the second one I've
buggered up so much my only hope is to drill it out.

I've read a number of posts about drilling them out with carbide bits.
When I look in KBC, Wholesale Tool, etc., I see solid carbide jobber
bits for 10 bucks or so in size 39. Will one of these do it? Because
I also see a "square die" carbide bit that specifically mentions
drilling out taps - but it's $35...

If I need the $35 bit, so be it. But, if a regular carbide jobber bit
will do it, I would obviously rather go that way.

TIA,
Wally
I don't think it is possible to drill out a tap. We always EDM them out.

"tomcas" wrote in message
...
Wally Blackburn wrote:
Well, I've broken off my second 5-40 tap in cast iron (model steam
engine). One I got out with an extractor - the second one I've
buggered up so much my only hope is to drill it out.

I've read a number of posts about drilling them out with carbide bits.
When I look in KBC, Wholesale Tool, etc., I see solid carbide jobber
bits for 10 bucks or so in size 39. Will one of these do it? Because
I also see a "square die" carbide bit that specifically mentions
drilling out taps - but it's $35...

If I need the $35 bit, so be it. But, if a regular carbide jobber bit
will do it, I would obviously rather go that way.

TIA,
Wally
I don't think it is possible to drill out a tap. We always EDM them out.

Yep! Taps don't lend themselves to being drilled. Even if you can get a
drill started, if it's anywhere near the edge and sees a path of lesser
resistance, it probably won't stay in the tap. You're most likely to ruin
your part if you try, and be out the cost of the drill, which will break
much like glass. Your absolute best bet is to find a shop that has an EDM
and hope they'll give you a hand. Who knows, you might find a kind
hearted soul that takes pity on you and does it as a favor.

I'm curious how you're breaking taps in cast iron. It taps quite easily,
so you might give some thought to what you're doing if you've broken two
taps. If it's by bottoming, be sure to clear chips often and approach the
bottom of the hole very cautiously, assuming you can't drill any deeper to
get the depth of thread you desire. Let us hear how this turns out.

Good luck!

Harold

What size drill did you use for your tapped hole? Try a few thousanths
bigger, it won't affect thread strength and will make your job easier. I
have had luck making a forked tool to fit the flutes of the tap and back it
out but that's SMALL, you'll need a jewler's saw, some O-1 drill rod heat
treated just right, and a lot of luck. I think it helps if you burry some
chicken guts in the back yard during a full moon.
--

"Wally Blackburn" wrote in message
om...
Well, I've broken off my second 5-40 tap in cast iron (model steam
engine). One I got out with an extractor - the second one I've
buggered up so much my only hope is to drill it out.

I've read a number of posts about drilling them out with carbide bits.
When I look in KBC, Wholesale Tool, etc., I see solid carbide jobber
bits for 10 bucks or so in size 39. Will one of these do it? Because
I also see a "square die" carbide bit that specifically mentions
drilling out taps - but it's $35...

If I need the $35 bit, so be it. But, if a regular carbide jobber bit
will do it, I would obviously rather go that way.

TIA,
Wally

I've removed some that small by "drilling", using a worn old carbide endmill
(3/32 should do for a #5) in my milling machine. Setup over the center of
the hole and raise the knee slowly up onto the endmill. By doing it gently,
you should be able to core the tap, leaving it as bits to be picked out of
the hole. It takes some patience to get through it, but it can be done.

Good luck.
John Sullivan
http://jamlab.home.att.net


"Wally Blackburn" wrote in message
om...
Well, I've broken off my second 5-40 tap in cast iron (model steam
engine). One I got out with an extractor - the second one I've
buggered up so much my only hope is to drill it out.

I've read a number of posts about drilling them out with carbide bits.
When I look in KBC, Wholesale Tool, etc., I see solid carbide jobber
bits for 10 bucks or so in size 39. Will one of these do it? Because
I also see a "square die" carbide bit that specifically mentions
drilling out taps - but it's $35...

If I need the $35 bit, so be it. But, if a regular carbide jobber bit
will do it, I would obviously rather go that way.

TIA,
Wally

Well, I've broken off my second 5-40 tap in cast iron (model steam
engine). One I got out with an extractor - the second one I've
buggered up so much my only hope is to drill it out.

I've read a number of posts about drilling them out with carbide bits.
When I look in KBC, Wholesale Tool, etc., I see solid carbide jobber
bits for 10 bucks or so in size 39. Will one of these do it? Because
I also see a "square die" carbide bit that specifically mentions
drilling out taps - but it's $35...

If I need the $35 bit, so be it. But, if a regular carbide jobber bit
will do it, I would obviously rather go that way.

TIA,
Wally


Carbon steel or HSS? Carbon steel taps can often be shattered by striking with
a punch. Depends on how much of the tap is in the hole, though.

John Martin

Great day, a 5-40 tap.. Heck I can't even see things that small
anymore yet alone try and drill one out. Are you using a vise to
secure the part your tapping or a tapping jig? I find myself breaking
smaller taps (not as steady as I used to be) when in the sizes less
than 1/4" so all my small tapping jobs go in a tapping jig if
possible. No more holding it in one hand and working the tap wrench in
the other.


Visit my website: http://www.frugalmachinist.com
Opinions expressed are those of my wifes,
I had no input whatsoever.
Remove "nospam" from email addy.

Skipping school, I decide to respond to what (Wally
Blackburn) fosted 15 May 2004 16:09:46 -0700 in rec.crafts.metalworking , viz:
Well, I've broken off my second 5-40 tap in cast iron (model steam
engine). One I got out with an extractor - the second one I've
buggered up so much my only hope is to drill it out.

I've read a number of posts about drilling them out with carbide bits.
When I look in KBC, Wholesale Tool, etc., I see solid carbide jobber
bits for 10 bucks or so in size 39. Will one of these do it? Because
I also see a "square die" carbide bit that specifically mentions
drilling out taps - but it's $35...

If I need the $35 bit, so be it. But, if a regular carbide jobber bit
will do it, I would obviously rather go that way.

My limited experience drilling out taps (or screws) is to use a left handed
drill bill and a reversible drill. What doesn't drill out may back out by it's
lonesome.
OTOH, it sounds like what you need more than anything else is a rigid setup
and a slow feed to minimize the deflection. You may have some problems there
with a hole too large for a 5-40 thread. In which case, drill and tap a larger
hole, turn a nd thread a cast iron plug, insert it, and drill and tap the plug.
(We did that with a lathe at the school. The shifting level for the speeds was
worn "a bit" (gears were engaging only half way.) Shift the detent hole and
violins: it's good for another fifty years!


tschus
pyotr

--
pyotr filipivich.
as an explaination for the decline in the US's tech edge, James
Niccol wrote "It used to be that the USA was pretty good at
producing stuff teenaged boys could lose a finger or two playing with."

may I suggest an approach that actually will work, and will cost you under
$5 total?

go to a lapidary store and buy some diamond drills - they cost about a
dollar each. Diamond will cut the tap just fine - you want the kind that
looks like a toothpick with diamond dust all around it - use the to cut the
flutes off the tap - power it with a high speed drill of your choice. if
possible, put the assembly under water so the diamonds stay cool.

I know this works, I've done it several times - I usually destroy one
diamond drill for every 1.5 taps.

bill

"Wally Blackburn" wrote in message
om...
Well, I've broken off my second 5-40 tap in cast iron (model steam
engine). One I got out with an extractor - the second one I've
buggered up so much my only hope is to drill it out.

I've read a number of posts about drilling them out with carbide bits.
When I look in KBC, Wholesale Tool, etc., I see solid carbide jobber
bits for 10 bucks or so in size 39. Will one of these do it? Because
I also see a "square die" carbide bit that specifically mentions
drilling out taps - but it's $35...

If I need the $35 bit, so be it. But, if a regular carbide jobber bit
will do it, I would obviously rather go that way.

TIA,
Wally

On Sun, 16 May 2004 01:47:33 GMT, "John Sullivan"
wrote:

I've removed some that small by "drilling", using a worn old carbide endmill
(3/32 should do for a #5) in my milling machine. Setup over the center of
the hole and raise the knee slowly up onto the endmill. By doing it gently,
you should be able to core the tap, leaving it as bits to be picked out of
the hole. It takes some patience to get through it, but it can be done.

Good luck.
John Sullivan
http://jamlab.home.att.net

If you can score a lefthanded carbide drill bit, it tends to help as
does use of a carbide lefthanded endmill.

Often times it will back out the tap after a certain point.

Gunner



"Wally Blackburn" wrote in message
. com...
Well, I've broken off my second 5-40 tap in cast iron (model steam
engine). One I got out with an extractor - the second one I've
buggered up so much my only hope is to drill it out.

I've read a number of posts about drilling them out with carbide bits.
When I look in KBC, Wholesale Tool, etc., I see solid carbide jobber
bits for 10 bucks or so in size 39. Will one of these do it? Because
I also see a "square die" carbide bit that specifically mentions
drilling out taps - but it's $35...

If I need the $35 bit, so be it. But, if a regular carbide jobber bit
will do it, I would obviously rather go that way.

TIA,
Wally


That rifle hanging on the wall of the working-class flat or labourer's
cottage is the symbol of democracy. It is our job to see that it stays
there.
- George Orwell

Tom Gardner wrote:

What size drill did you use for your tapped hole? Try a few thousanths
bigger, it won't affect thread strength and will make your job easier. I
have had luck making a forked tool to fit the flutes of the tap and back it
out but that's SMALL, you'll need a jewler's saw, some O-1 drill rod heat
treated just right, and a lot of luck. I think it helps if you burry some
chicken guts in the back yard during a full moon.
These are commercially available, go down to #4, and have worked pretty
well for me in the past.
http://www.waltontools.com/catpdfs/W...Extractors.pdf

Wally Blackburn wrote in message
om...
Well, I've broken off my second 5-40 tap in cast iron (model steam
engine). One I got out with an extractor - the second one I've
buggered up so much my only hope is to drill it out.


Nobody has suggested that if it's a carbon-steel tap, you could heat the
part & tap and let them cool, and the tap will be softer - if you're gonna
drill it, softer is w-a-y easier...

No one mentioned that if the tap is broken off in an aluminum
block (can't be that lucky) that the tap can be eaten out with
acid.

^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Keep the whole world singing. . . .
DanG


"jtaylor" wrote in message
...

Wally Blackburn wrote in message
om...
Well, I've broken off my second 5-40 tap in cast iron (model
steam
engine). One I got out with an extractor - the second one
I've
buggered up so much my only hope is to drill it out.


Nobody has suggested that if it's a carbon-steel tap, you could
heat the
part & tap and let them cool, and the tap will be softer - if
you're gonna
drill it, softer is w-a-y easier...

You could us inductive heating to take the temper out of the tap....
Then drill it out...

"Kevin Beitz" wrote in message
m...
You could us inductive heating to take the temper out of the tap....
Then drill it out...

Not if it's HSS.

Harold

Son-of-a-bitch!!! I didn't know, cool!!!

--
There are 10 kinds of people...Those that understand binary and those that
don't
"tomcas" wrote in message
t...
Tom Gardner wrote:

What size drill did you use for your tapped hole? Try a few thousanths
bigger, it won't affect thread strength and will make your job easier.
I
have had luck making a forked tool to fit the flutes of the tap and back
it
out but that's SMALL, you'll need a jewler's saw, some O-1 drill rod
heat
treated just right, and a lot of luck. I think it helps if you burry
some
chicken guts in the back yard during a full moon.
These are commercially available, go down to #4, and have worked pretty
well for me in the past.
http://www.waltontools.com/catpdfs/W...Extractors.pdf

"Tom Gardner" wrote in message
.com...
Son-of-a-bitch!!! I didn't know, cool!!!


DITTO!

Harold


--
There are 10 kinds of people...Those that understand binary and those
that
don't
"tomcas" wrote in message
t...
Tom Gardner wrote:

What size drill did you use for your tapped hole? Try a few
thousanths
bigger, it won't affect thread strength and will make your job easier.
I
have had luck making a forked tool to fit the flutes of the tap and
back
it
out but that's SMALL, you'll need a jewler's saw, some O-1 drill rod
heat
treated just right, and a lot of luck. I think it helps if you burry
some
chicken guts in the back yard during a full moon.
These are commercially available, go down to #4, and have worked pretty
well for me in the past.
http://www.waltontools.com/catpdfs/W...Extractors.pdf

"Tom Gardner" wrote in message
.com...
Son-of-a-bitch!!! I didn't know, cool!!!

DITTO!

But with reservations. I am familiar with tap extractors, but they are
also prone to failure, all depending on how or why a tap is broken. If
you've broken a tap by loading the flutes with chips, you can pretty much
forget an extractor. They also can let you down big time when you've
bottomed a tap in a hole. They work very best for fools like us that
break a tap by bending it. Ever notice how taps don't bend well? g

Harold



--
There are 10 kinds of people...Those that understand binary and those
that
don't
"tomcas" wrote in message
t...
Tom Gardner wrote:

What size drill did you use for your tapped hole? Try a few
thousanths
bigger, it won't affect thread strength and will make your job easier.
I
have had luck making a forked tool to fit the flutes of the tap and
back
it
out but that's SMALL, you'll need a jewler's saw, some O-1 drill rod
heat
treated just right, and a lot of luck. I think it helps if you burry
some
chicken guts in the back yard during a full moon.
These are commercially available, go down to #4, and have worked pretty
well for me in the past.
http://www.waltontools.com/catpdfs/W...Extractors.pdf

On Sat, 15 May 2004 23:43:37 GMT, tomcas
wrote:

Wally Blackburn wrote:
Well, I've broken off my second 5-40 tap in cast iron (model steam
engine). One I got out with an extractor - the second one I've
buggered up so much my only hope is to drill it out.

I've read a number of posts about drilling them out with carbide bits.
When I look in KBC, Wholesale Tool, etc., I see solid carbide jobber
bits for 10 bucks or so in size 39. Will one of these do it? Because
I also see a "square die" carbide bit that specifically mentions
drilling out taps - but it's $35...

If I need the $35 bit, so be it. But, if a regular carbide jobber bit
will do it, I would obviously rather go that way.

TIA,
Wally
I don't think it is possible to drill out a tap. We always EDM them out.

EDM is the best way to do this, but a "christmas tree" carbide burr in
a high-speed (at least 50K RPM) air tool will do the job.

Harbor Freight sells a small high speed grinder that is air driven.
It is much like a dentists drill. I got a bunch of used dental drills
from my dentist and have used them to drill out small taps. Not fast
but it works. The little air grinder is cheap and the dental drills
cheaper.

Dan



Don Foreman wrote in message . ..

EDM is the best way to do this, but a "christmas tree" carbide burr in
a high-speed (at least 50K RPM) air tool will do the job.

(Wally Blackburn) wrote in message . com...
Well, I've broken off my second 5-40 tap in cast iron (model steam
engine). One I got out with an extractor - the second one I've
buggered up so much my only hope is to drill it out.

I've read a number of posts about drilling them out with carbide bits.
When I look in KBC, Wholesale Tool, etc., I see solid carbide jobber
bits for 10 bucks or so in size 39. Will one of these do it? Because
I also see a "square die" carbide bit that specifically mentions
drilling out taps - but it's $35...

If I need the $35 bit, so be it. But, if a regular carbide jobber bit
will do it, I would obviously rather go that way.

TIA,
Wally

Pneumatic 1/8" die grinder and a diamond burr does it for me. I've
done 4-40s in the past, takes a steady hand and good lighting. You
cut the center out of the tap from the side(s) and pick the pieces
out. I've never, ever, had good luck with any sort of tap extractor,
the taps are usually siezed in the material and those itty-bitty
fingers have absolutely no chance to back the thing out without
snapping across. Since I've gone to using a tapping jig with
bushings, I don't break taps, large or small, anymore. I can't
understand breaking taps in cast iron, though, that stuff is usually
one of most free-cutting materials there is. You might have hit a
chilled spot or aren't cleaning the tap out enough. One way to do
blind holes is to fill them with cutting wax, I use Castrol brand,
then tap them. The extruding wax pushes the cuttings out of the hole.
The wax can be cleaned out with a blast of brake cleaner, if needed.

Stan

First of all, thanks to everyone for all of their suggestions. A few
people had questions and some wanted to know how it turned out:

A lot of people wanted to know "How did you break off 2 taps in cast
iron?" Well, I am first to admit when Ido something stupid - the
second one was me being stupid, but the first one snapped off easily
and without warning. I know when I've gotten lazy and pushed
something harder than I should. You know, "One more half-turn and
then I'll clear out the chips". But the first one must have been hard
spot in piece or defective tap. I ended up getting it out with a tap
extractor - further evidence that it was not going in too tight when
it broke.

The second one, well, I, um, kind of tried to learn how to use a
Tapmatic I bought at an auction by starting with a 5-40 tap on a blind
hole...probably not my brightest move. I wasn't precise when I
drilled the holes and one was not as deep as the others. The tap
bottomed and snapped in a heartbeat. Yes, I could've had the clutch
on the Tapmatic set lighter, but I did not. This bad boy was in there
- I couldn't get the fingers of the extractor in. I heated this one
up with the torch. I didn't really expect it to help much, but it
softened it considerably. I was able to drill it out with a
combination of a 3/32" carbide end mill and a regular old drill bit.

Now, how to avoid breaking off teeny-tiny taps in the future? Well, I
took an evening and some pieces from the scrap bin and made a small
tapper! Check it out at:

http://www.wallyblackburn.com/tapper

Nuthin' fancy, but it works fine. The large brass knob gives me more
than enough power to tap small holes but keeps the "feel" of the cut.

Thanks again,
Wallace





(Wally Blackburn) wrote in message . com...
Well, I've broken off my second 5-40 tap in cast iron (model steam
engine). One I got out with an extractor - the second one I've
buggered up so much my only hope is to drill it out.

I've read a number of posts about drilling them out with carbide bits.
When I look in KBC, Wholesale Tool, etc., I see solid carbide jobber
bits for 10 bucks or so in size 39. Will one of these do it? Because
I also see a "square die" carbide bit that specifically mentions
drilling out taps - but it's $35...

If I need the $35 bit, so be it. But, if a regular carbide jobber bit
will do it, I would obviously rather go that way.

TIA,
Wally