开云体育

Just to share the fun.

Got my laser edge / center finder holder all turned and bored out and
started drilling and tapping (4-40) for the set screw / power switch
holes. Went along nicely up until the final one (9th) where the tap
broke.

Nothing gets it out :-(. And of course it is one of the lower
(critical) ones :-).

I tried the 4-40 tap out of my little kit from the auto parts place and
it promply turned itself into a corkscrew :-). Broke too, but it was
soft enough not to shatter and I was able to get it out with vice
grips.

Sigh. I suppose that this isn't a real big deal since this is a "proof
of concept" thing and I can rotate the holder 45 degrees and put in a
new set.

Lessons learned: When wrists get tired from doing the tapping - take a
break rather than switch hands and cheap taps are a total waste of time
and money (now I know what a cheap tap is :-).

Only a minor setback as I now have the holder itself worked out and can
easily enough duplicate it.

Not a bad day!

Take care, Vikki.
--
Victoria Welch, WV9K/7
"Windows, another fine product from the folks who brought you edlin." --
Unknown

Hi Vikki,

Ah, the dreaded broken tap. Every break is different and you do what
you need to do in your situation. It's always a good brain teaser.
In aluminium and brass I'm told alum is magical.

I recently broke a 4mm tap in a 1/2" deep hole in steel. Chemical
techniques weren't going to help steel in steel. Attempts to grab
the little protruding portion just made it crumble. It was a good
hard tap. Like yours, it was my ninth hole in a row and I thought I
had the knack. They were going smoothly. Maybe the tap fatiqued as I
was not using much force.

A while back I was asking (mainly out of academic interest) about
cutting O-ring grooves. Well, I've now cut my first O-ring groove
and a very tight face-seal type groove at that. I chucked the job in
the 4-jaw and got the broken tap on centre, confirming by peeping
through the spindle with a torch to see the reverse side. I then
ground a 1/8" HSS blank to a narrow grooving tool with heaps of
relief angle on one side to allow a really tight o-ring groove
around the broken tap. I cut a groove about 3mm deep about 1mm clear
of the tap. I then took skimming cuts at that 1mm thick island
around the tap. About one thou at a time until I was perilously
close to hitting the tap. A scriber was then poked down the tap
flutes to pry the thin remaining steel back. Instead of gripping the
tap with vice grips and having it crumble further I was able to
squash the end of some 1/4" stainless tubing to make the triangular
equivalent of a socker wrench. That distributed the load across all
three flutes and with a gentle back and forth motion I soon had
movement which gradually increased until I had it turning.

I did have some extra features on my finished product but it was
only a tool jig and I can live with that. It had toooo much work
invested to discard.

Not sure if that helps your situation. But you can never have too
many solutions in the back of your mind!

John


--- In 7x12minilathe@..., Victoria Welch <wrlabs@...>
wrote:

Just to share the fun.

Got my laser edge / center finder holder all turned and bored out

and

started drilling and tapping (4-40) for the set screw / power

switch

holes. Went along nicely up until the final one (9th) where the

tap

broke.

Nothing gets it out :-(. And of course it is one of the lower
(critical) ones :-).

I tried the 4-40 tap out of my little kit from the auto parts

place and

it promply turned itself into a corkscrew :-). Broke too, but it

was

soft enough not to shatter and I was able to get it out with vice
grips.

Sigh. I suppose that this isn't a real big deal since this is

a "proof

of concept" thing and I can rotate the holder 45 degrees and put

in a

new set.

Lessons learned: When wrists get tired from doing the tapping -

take a

break rather than switch hands and cheap taps are a total waste of

time

and money (now I know what a cheap tap is :-).

Only a minor setback as I now have the holder itself worked out

and can

easily enough duplicate it.

Not a bad day!

Take care, Vikki.
--
Victoria Welch, WV9K/7
"Windows, another fine product from the folks who brought you

edlin." --

Unknown

Using small taps freehand is guaranteed to break them. I now use a
device called a "tapdisk" and never break taps....hardly ever (don't
want to jinx myself).

I found the instructions for making the tapdisk here:


"TAP DISK
Difficult to believe that I have not posted a tip about my Tap Disk.
Every shop should have one , and use it, to prevent small tap
breakage. I have not broken a tap within the past 10 years while
using my Tap Disk and I constantly use tap sizes 0 through 6. Take a
few minutes to make one, try it and I am sure you will opt for this
taping method whenever possible.

THE DISK
Turn an Aluminum disk, 1 1/8" OD, knurl it, center drill .144" and
part it off .325" thick. Drill NO. 43 from the OD to the ID and tap 4-
40. Install a 4-40, hex head bolt, .750" long.

TO USE
Insert the tap in the Tap Disk to it's mid point. Tighten the bolt
with a 1/4" wrench. Drill the hole to be taped in the Drill Press,
Mill or Lathe. Remove the drill, fill the hole with WD-40, or your
favorite taping fluid and grip the upper half of the tap in the
chuck, just loose enough to turn freely. Lower the spindle/tap to the
work. Use your thumb and forefinger to tap the hole. The photo below
shows the Tap Disk ready to use.
Bob Shores
Ruskin FLA"



--- In 7x12minilathe@..., Victoria Welch <wrlabs@...>
wrote:

Just to share the fun.

Got my laser edge / center finder holder all turned and bored out

and

started drilling and tapping (4-40) for the set screw / power

switch

holes. Went along nicely up until the final one (9th) where the

tap

broke.

Nothing gets it out :-(. And of course it is one of the lower
(critical) ones :-).

I tried the 4-40 tap out of my little kit from the auto parts place

and

it promply turned itself into a corkscrew :-). Broke too, but it

was

soft enough not to shatter and I was able to get it out with vice
grips.

Sigh. I suppose that this isn't a real big deal since this is

a "proof

of concept" thing and I can rotate the holder 45 degrees and put in

a

new set.

Lessons learned: When wrists get tired from doing the tapping -

take a

break rather than switch hands and cheap taps are a total waste of

time

and money (now I know what a cheap tap is :-).

Only a minor setback as I now have the holder itself worked out and

can

easily enough duplicate it.

Not a bad day!

Take care, Vikki.
--
Victoria Welch, WV9K/7
"Windows, another fine product from the folks who brought you

edlin." --

Unknown

G'day Viki, John.

You have found the difference between cheap taps and better quality
taps.
I have about three sets of "cheap taps". The other day i was
attempting to cut a 8mm thread in an SS bush. The cheap taps just
would not look at the job. Fortunately I had purshased a limited
selection of Brand name taps, not top of the range but good. I
extrated ane of the better taps from its packet and set it to work.
The job was almost effortless. Forget the cheap taps unless you want
to cut a thread in
lead. As for cheap dies, I get a better job on the lathe.

I have struck it lucky with one set of truly bargain taps. A tooling
store had relocated to near my home and must have bundled eveything
together in the move and then couldn't be bothered sorting through
it. I picked up a 3/8 x 24T set of taper, plug and bottoming taps for
AUD3.00 plus some other goodies like reamers for AUD5.00.
If any one in Oz wants me to look for a specific item let me know,
you could get a bargain. There's taps and dies of odd sizes, reamer,
milling cutters (horizontal) etc.

I must have done somebody a good turn!
Regards,
Ian

Here's a link to another nifty tap alignment jig:


Taps break for several common reasons:

1. Misalignment with the hole - the jigs solve this so the tap doesn't
run into the side of the hole as it goes deeper.

2. Dry tapping - WD40 works well on aluminum, cutting oil on most
other things. Cast Iron doesn't need fluid.

3. Dull tap - taps turn hard to let you know they're dull. Often this
means a tooth is chipped, usually near the end - a little careful
grinding will make it into a nice bottoming tap :-)

The gun taps seem to work better for me than regular taps, especially
on through holes. Probably because they push the chips forward rather
than collecting them in the flutes, no need to reverse direction to
break chips. On blind holes I run the tap in until it gets hard to
turn, back it out, clean the chips out, and run it in again to finish
the bottom threads (or use a bottoming tap). Gun taps work
particularly well for sizes #10 and smaller.

John



--- In 7x12minilathe@..., "charlie4_66043" <radfordc@...>
wrote:

Using small taps freehand is guaranteed to break them. I now use a
device called a "tapdisk" and never break taps....hardly ever (don't
want to jinx myself).

I found the instructions for making the tapdisk here:


"TAP DISK
Difficult to believe that I have not posted a tip about my Tap Disk.
Every shop should have one , and use it, to prevent small tap
breakage. I have not broken a tap within the past 10 years while
using my Tap Disk and I constantly use tap sizes 0 through 6. Take a
few minutes to make one, try it and I am sure you will opt for this
taping method whenever possible.

THE DISK
Turn an Aluminum disk, 1 1/8" OD, knurl it, center drill .144" and
part it off .325" thick. Drill NO. 43 from the OD to the ID and tap 4-
40. Install a 4-40, hex head bolt, .750" long.

TO USE
Insert the tap in the Tap Disk to it's mid point. Tighten the bolt
with a 1/4" wrench. Drill the hole to be taped in the Drill Press,
Mill or Lathe. Remove the drill, fill the hole with WD-40, or your
favorite taping fluid and grip the upper half of the tap in the
chuck, just loose enough to turn freely. Lower the spindle/tap to the
work. Use your thumb and forefinger to tap the hole. The photo below
shows the Tap Disk ready to use.
Bob Shores
Ruskin FLA"



--- In 7x12minilathe@..., Victoria Welch <wrlabs@>
wrote:

Just to share the fun.

Got my laser edge / center finder holder all turned and bored out

and

started drilling and tapping (4-40) for the set screw / power

switch

holes. Went along nicely up until the final one (9th) where the

tap

broke.

Nothing gets it out :-(. And of course it is one of the lower
(critical) ones :-).

I tried the 4-40 tap out of my little kit from the auto parts place

and

it promply turned itself into a corkscrew :-). Broke too, but it

was

soft enough not to shatter and I was able to get it out with vice
grips.

Sigh. I suppose that this isn't a real big deal since this is

a "proof

of concept" thing and I can rotate the holder 45 degrees and put in

a

new set.

Lessons learned: When wrists get tired from doing the tapping -

take a

break rather than switch hands and cheap taps are a total waste of

time

and money (now I know what a cheap tap is :-).

Only a minor setback as I now have the holder itself worked out and

can

easily enough duplicate it.

Not a bad day!

Take care, Vikki.
--
Victoria Welch, WV9K/7
"Windows, another fine product from the folks who brought you

edlin." --

Unknown

Bob,

For some reason, it is not showing up in the search. Do you have a more
refined link?

Thanks
Bill

Try


--- In 7x12minilathe@..., "Bill Kenny" <billcnc@...> wrote:

Bob,

For some reason, it is not showing up in the search. Do you have a

more

refined link?

Thanks
Bill

Well if it is not one thing it is another..........
I now found the tap article, but the picture will not come up on my
Internet Explorer. Would some one down load the picture and send it to
me.
Thanks,
Dan Fuller
Carrollton, Texas
fullerdj@...

Dan,

It's not you, its the web page. The img is a broken reference. Use
your imagination. It is simply a large knurled disk that is 'clamped'
to the tap. The disk is 1 1/8" diameter and 0.325 thick. The drill
chuck is slightly loosened so the user can turn the tap using the
knurled disk (ie. the Tap Disk). This gives the operator a
better 'feel' of the force turning the tap. Easier to feel how tight
it is getting. The drill chuck is used as a centering device to make
sure it goes in straight. HTH. :)

Rance


--- In 7x12minilathe@..., "jumbo75007" <fullerdj@...>
wrote:

Well if it is not one thing it is another..........
I now found the tap article, but the picture will not come up on my
Internet Explorer. Would some one down load the picture and send

it to

me.
Thanks,
Dan Fuller
Carrollton, Texas
fullerdj@...


--- In 7x12minilathe@..., "rancerupp" <rupps@> wrote:

Try


--- In 7x12minilathe@..., "Bill Kenny" <billcnc@>

wrote:

Bob,

For some reason, it is not showing up in the search. Do you

have a

more

refined link?

Thanks
Bill

I could not get it, either.
Thanks, Ron.


---- jumbo75007 <fullerdj@...> wrote:

On Sunday 01 April 2007, born4something wrote:

Hi Vikki,

Ah, the dreaded broken tap. Every break is different and you do what
you need to do in your situation. It's always a good brain teaser.
In aluminium and brass I'm told alum is magical.

I'm going to try to track down some alum while I am out today just to
see if it actually works.

It sure does give one lots to think about, I'm pleased I just started
thinking rather than freaking out about it :-) :-)! Having some real
tools, even if smallish certainly opens a lot of doors in many ways.

I recently broke a 4mm tap in a 1/2" deep hole in steel. Chemical
techniques weren't going to help steel in steel. Attempts to grab
the little protruding portion just made it crumble. It was a good
hard tap. Like yours, it was my ninth hole in a row and I thought I
had the knack. They were going smoothly. Maybe the tap fatiqued as I
was not using much force.

Going for the 75% thread it was obvious the tiny tap was grunting down
neat the bottom of the hole. It is completely possible that the tap
could have been fatigued but I think that the real reason was that I
had the tap in the drill chuck mounted in the mill and was turning the
chuck by hand. My wrist got tired and I switched hands and am more
than a little sure I over torqued it at exactly the wrong time.

A while back I was asking (mainly out of academic interest) about
cutting O-ring grooves. Well, I've now cut my first O-ring groove
and a very tight face-seal type groove at that. I chucked the job in
the 4-jaw and got the broken tap on centre, confirming by peeping
through the spindle with a torch to see the reverse side. I then
ground a 1/8" HSS blank to a narrow grooving tool with heaps of
relief angle on one side to allow a really tight o-ring groove
around the broken tap. I cut a groove about 3mm deep about 1mm clear
of the tap. I then took skimming cuts at that 1mm thick island
around the tap. About one thou at a time until I was perilously
close to hitting the tap. A scriber was then poked down the tap
flutes to pry the thin remaining steel back. Instead of gripping the
tap with vice grips and having it crumble further I was able to
squash the end of some 1/4" stainless tubing to make the triangular
equivalent of a socker wrench. That distributed the load across all
three flutes and with a gentle back and forth motion I soon had
movement which gradually increased until I had it turning.

Sigh, it does appear impossible to get out, I futzed with it for a while
last night and tried several things. HSS tools just got screwed up
trying to turn it out and using carbide there was so much jump when the
tool contacted the remains of the tap that it accomplished nothing :-).
I was able to remove what was in the bore with the carbide boring bar
and the absolute slowest feed imaginable.

I finally was able to remove the raw edges on the outside with my
roomies lapidary diamond files (nasty surfaces poking out).

I could probably use the mill with one of the smallish PCB drills to
mill out around the tap without buggering the holder too much, but this
isn't real critical so the tap can just sit there. Other than as a
reminder, it isn't interfering with anything.

I did have some extra features on my finished product but it was
only a tool jig and I can live with that. It had toooo much work
invested to discard.

Same here, scrap isn't really available locally so everything is retail
priced. Worst case is that I turn it 45 degrees (eyeball, no indexers
or anything else, but it isn't real critical, I don't think) and remark
it for another set of holes, which I did last night.

Not sure if that helps your situation. But you can never have too
many solutions in the back of your mind!

Yes Sir, every little bit of kit that helps solve problems is always
welcome and a great addition to the mental toolbox :-).

Thanks & take care, Vikki.
--
Victoria Welch, WV9K/7
"Nothing can bring you peace but the triumph of principles." -- Ralph
Waldo Emerson

On Monday 02 April 2007, steam4ian wrote:

G'day Viki, John.

You have found the difference between cheap taps and better quality
taps.

LOL, I sure did. Watching that one tap corkscrew when trying to start
it was kind of amazing.

I have about three sets of "cheap taps". The other day i was
attempting to cut a 8mm thread in an SS bush. The cheap taps just
would not look at the job. Fortunately I had purshased a limited
selection of Brand name taps, not top of the range but good. I
extrated ane of the better taps from its packet and set it to work.
The job was almost effortless. Forget the cheap taps unless you want
to cut a thread in
lead. As for cheap dies, I get a better job on the lathe.

Slowly I learn :). Threading on the lathe, once so intimidating, I
don't think much about anymore (even the changing of the gears isn't as
scary as it once was :). Still haven't done internal, but that
shouldn't be too horrid either once I give it a go.

Unfortunately I also have three sets of cheap taps, but I know better
now :).

I was using a cutting oil to do this and I am not sure how much better
WD40 would have been, will get the chance to see on the next set.

I have struck it lucky with one set of truly bargain taps. A tooling
store had relocated to near my home and must have bundled eveything
together in the move and then couldn't be bothered sorting through
it. I picked up a 3/8 x 24T set of taper, plug and bottoming taps for
AUD3.00 plus some other goodies like reamers for AUD5.00.
If any one in Oz wants me to look for a specific item let me know,
you could get a bargain. There's taps and dies of odd sizes, reamer,
milling cutters (horizontal) etc.

I sure wish I knew what I needed, if I did I'd sure give you a list and
figure out how to pay for it. Reamers is something I keep seeing as
useful but so far I have yet (as far as I know :) actually needed them,
drills seem to be doing good enough for what I need (so far).

I did discover that drilling a 2.125" deep 1/2" hole (as big a bit as I
have) by working up from 1/4" in steps is a job on the lathe. Easy to
push that tailstock back, persistence pays :), with all this cranking
exercise my wrists will be in GREAT shape soon (I hope :-). Boring it
out after I got through with the 1/2" drill was exciting for some
reason, probably the first use of the boring bars and it came out well.

I must have done somebody a good turn!

Indeed you must have :). Without fighting through Seattle traffic from
hell, the only thing around here is consumer home supply places. Could
be worse and mail (net) order has been my savior, if slow (but no more
expensive with local taxes) :-).

Frustrating, but I really am having fun with this and I think that with
the pinhole filters that this may well work out. I remember the
frustrating of trying to do *anything* with metal before I started
learning about and acquiring tools for the purpose. To me it is indeed
magic :)!

Learning how to do all this is just so much fun, even the "bad times"
teach one something that makes the next one easier / better :)! Just
too damn cool :-) :-) :-) :-)!

Thanks & take care, Vikki.
--
Victoria Welch, WV9K/7
"Where the system is concerned, you're not allowed to
ask "Why?" --Unknown

If you haven't found alum, try a swimming pool/spa place; it's used
to lower pH. It's also used in gardening to lower soil pH.
The "trick" works because steel is acid soluble, aluminum is pretty
much acid resistant.

For small taps, the best thing I've found is a ball shaped carbide
rotary file, used freehand in a Foredom tool. If you carefully
attack the center, the rest of the tap can be picked out. A common
commercial answer is a "tap disintegrator" essentially a small EDM
unit. Frequently, there's a local shop that has one & may even be
reasonably priced.

Roy

--- In 7x12minilathe@..., Victoria Welch <wrlabs@...>
wrote:

On Sunday 01 April 2007, born4something wrote:

Hi Vikki,

Ah, the dreaded broken tap. Every break is different and you do

what

you need to do in your situation. It's always a good brain teaser.
In aluminium and brass I'm told alum is magical.

I'm going to try to track down some alum while I am out today just

to

see if it actually works.

It sure does give one lots to think about, I'm pleased I just

started

thinking rather than freaking out about it :-) :-)! Having some

real

tools, even if smallish certainly opens a lot of doors in many ways.

I recently broke a 4mm tap in a 1/2" deep hole in steel. Chemical
techniques weren't going to help steel in steel. Attempts to grab
the little protruding portion just made it crumble. It was a good
hard tap. Like yours, it was my ninth hole in a row and I thought

I

had the knack. They were going smoothly. Maybe the tap fatiqued

as I

was not using much force.

Going for the 75% thread it was obvious the tiny tap was grunting

down

neat the bottom of the hole. It is completely possible that the

tap

could have been fatigued but I think that the real reason was that

I

had the tap in the drill chuck mounted in the mill and was turning

the

chuck by hand. My wrist got tired and I switched hands and am more
than a little sure I over torqued it at exactly the wrong time.

A while back I was asking (mainly out of academic interest) about
cutting O-ring grooves. Well, I've now cut my first O-ring groove
and a very tight face-seal type groove at that. I chucked the job

in

the 4-jaw and got the broken tap on centre, confirming by peeping
through the spindle with a torch to see the reverse side. I then
ground a 1/8" HSS blank to a narrow grooving tool with heaps of
relief angle on one side to allow a really tight o-ring groove
around the broken tap. I cut a groove about 3mm deep about 1mm

clear

of the tap. I then took skimming cuts at that 1mm thick island
around the tap. About one thou at a time until I was perilously
close to hitting the tap. A scriber was then poked down the tap
flutes to pry the thin remaining steel back. Instead of gripping

the

tap with vice grips and having it crumble further I was able to
squash the end of some 1/4" stainless tubing to make the

triangular

equivalent of a socker wrench. That distributed the load across

all

three flutes and with a gentle back and forth motion I soon had
movement which gradually increased until I had it turning.

Sigh, it does appear impossible to get out, I futzed with it for a

while

last night and tried several things. HSS tools just got screwed up
trying to turn it out and using carbide there was so much jump when

the

tool contacted the remains of the tap that it accomplished

nothing :-).

I was able to remove what was in the bore with the carbide boring

bar

and the absolute slowest feed imaginable.

I finally was able to remove the raw edges on the outside with my
roomies lapidary diamond files (nasty surfaces poking out).

I could probably use the mill with one of the smallish PCB drills

to

mill out around the tap without buggering the holder too much, but

this

isn't real critical so the tap can just sit there. Other than as a
reminder, it isn't interfering with anything.

I did have some extra features on my finished product but it was
only a tool jig and I can live with that. It had toooo much work
invested to discard.

Same here, scrap isn't really available locally so everything is

retail

priced. Worst case is that I turn it 45 degrees (eyeball, no

indexers

or anything else, but it isn't real critical, I don't think) and

remark

it for another set of holes, which I did last night.

Not sure if that helps your situation. But you can never have too
many solutions in the back of your mind!

Yes Sir, every little bit of kit that helps solve problems is

always

welcome and a great addition to the mental toolbox :-).

Thanks & take care, Vikki.
--
Victoria Welch, WV9K/7
"Nothing can bring you peace but the triumph of principles." --

Ralph

Waldo Emerson

Hi Vikki,

Glad you didn't spontaneously freak out. That's a sign of maturity
and starting to get comfortable with your skills and ability to sort
things out.

I think you can get alum from a pharmacist. There are possibly
cheaper sources though.

That commonly used 75% thread figure is probably a bit tight for
most work if you don't need enormous strength. The last 2 taps I've
broken were on 75% or slightly greater (due to available drill
sizes). You mentioned the carbide tip jumping as it touched the
outside of the tap remnants. There's no way I was machining that
close as the tap was so brittle-hard. I'd change to a dremel based
grinding tool before working that close.

When all else fails, read up on EDM. Coming from an electronics
background I just KNOW I'll build one of those things one day.
There's a section in Machinery's Handbook giving a great rundown.
Check out www.modelenginenews.org/~modeng74/meng/edm for some
starter info too. There are quite viable plans around like
www.camtronics-cnc.com or www.build-stuff.com/EDMHowtoBook.htm
(that site seems down just now, hopefully temporarily). EDM would be
an interesting toy to play with, cutting obscure shaped holes in
impossibly difficult materials. Need to "drill" a square hole in
HSS? No problem!

John


--- In 7x12minilathe@..., Victoria Welch <wrlabs@...>
wrote:

On Sunday 01 April 2007, born4something wrote:

Hi Vikki,

Ah, the dreaded broken tap. Every break is different and you do

what

you need to do in your situation. It's always a good brain

teaser.

In aluminium and brass I'm told alum is magical.

I'm going to try to track down some alum while I am out today just

to

see if it actually works.

It sure does give one lots to think about, I'm pleased I just

started

thinking rather than freaking out about it :-) :-)! Having some

real

tools, even if smallish certainly opens a lot of doors in many

ways.

I recently broke a 4mm tap in a 1/2" deep hole in steel. Chemical
techniques weren't going to help steel in steel. Attempts to grab
the little protruding portion just made it crumble. It was a good
hard tap. Like yours, it was my ninth hole in a row and I

thought I

had the knack. They were going smoothly. Maybe the tap fatiqued

as I

was not using much force.

Going for the 75% thread it was obvious the tiny tap was grunting

down

neat the bottom of the hole. It is completely possible that the

tap

could have been fatigued but I think that the real reason was that

I

had the tap in the drill chuck mounted in the mill and was turning

the

chuck by hand. My wrist got tired and I switched hands and am

more

than a little sure I over torqued it at exactly the wrong time.

A while back I was asking (mainly out of academic interest) about
cutting O-ring grooves. Well, I've now cut my first O-ring groove
and a very tight face-seal type groove at that. I chucked the

job in

the 4-jaw and got the broken tap on centre, confirming by peeping
through the spindle with a torch to see the reverse side. I then
ground a 1/8" HSS blank to a narrow grooving tool with heaps of
relief angle on one side to allow a really tight o-ring groove
around the broken tap. I cut a groove about 3mm deep about 1mm

clear

of the tap. I then took skimming cuts at that 1mm thick island
around the tap. About one thou at a time until I was perilously
close to hitting the tap. A scriber was then poked down the tap
flutes to pry the thin remaining steel back. Instead of gripping

the

tap with vice grips and having it crumble further I was able to
squash the end of some 1/4" stainless tubing to make the

triangular

equivalent of a socker wrench. That distributed the load across

all

three flutes and with a gentle back and forth motion I soon had
movement which gradually increased until I had it turning.

Sigh, it does appear impossible to get out, I futzed with it for a

while

last night and tried several things. HSS tools just got screwed

up

trying to turn it out and using carbide there was so much jump

when the

tool contacted the remains of the tap that it accomplished

nothing :-).

I was able to remove what was in the bore with the carbide boring

bar

and the absolute slowest feed imaginable.

I finally was able to remove the raw edges on the outside with my
roomies lapidary diamond files (nasty surfaces poking out).

I could probably use the mill with one of the smallish PCB drills

to

mill out around the tap without buggering the holder too much, but

this

isn't real critical so the tap can just sit there. Other than as

a

reminder, it isn't interfering with anything.

I did have some extra features on my finished product but it was
only a tool jig and I can live with that. It had toooo much work
invested to discard.

Same here, scrap isn't really available locally so everything is

retail

priced. Worst case is that I turn it 45 degrees (eyeball, no

indexers

or anything else, but it isn't real critical, I don't think) and

remark

it for another set of holes, which I did last night.

Not sure if that helps your situation. But you can never have too
many solutions in the back of your mind!

Yes Sir, every little bit of kit that helps solve problems is

always

welcome and a great addition to the mental toolbox :-).

Thanks & take care, Vikki.
--
Victoria Welch, WV9K/7
"Nothing can bring you peace but the triumph of principles." --

Ralph

Waldo Emerson

--- In 7x12minilathe@..., Victoria Welch <wrlabs@...>
wrote:

On Monday 02 April 2007, steam4ian wrote:

G'day Viki, John.

You have found the difference between cheap taps and better quality
taps.

LOL, I sure did. Watching that one tap corkscrew when trying to

start

Hi Vikki,

Don't toss those cheap sets too quickly. Apart from letting you do the
easy threads (like through sheet aluminium) it's really great to have
such a comprehensive set of sizes for clearing paint and burrs out of
threads. However, if doing any serious threads I now buy a real tap
for the job. The biggest hassle is the crossover zone between easy and
serious thread cutting late in the evening where you give in to the
temptation to use the cheapy - and spend your evenings for the rest of
the week recovering the job!

John

On 4/2/07, born4something <ajs@...> wrote:

A while back I was asking (mainly out of academic interest) about
cutting O-ring grooves. Well, I've now cut my first O-ring groove
and a very tight face-seal type groove at that. I chucked the job in
the 4-jaw and got the broken tap on centre, confirming by peeping
through the spindle with a torch to see the reverse side. I then
ground a 1/8" HSS blank to a narrow grooving tool with heaps of
relief angle on one side to allow a really tight o-ring groove
around the broken tap. I cut a groove about 3mm deep about 1mm clear
of the tap. I then took skimming cuts at that 1mm thick island
around the tap. About one thou at a time until I was perilously
close to hitting the tap. A scriber was then poked down the tap
flutes to pry the thin remaining steel back. Instead of gripping the
tap with vice grips and having it crumble further I was able to
squash the end of some 1/4" stainless tubing to make the triangular
equivalent of a socker wrench. That distributed the load across all
three flutes and with a gentle back and forth motion I soon had
movement which gradually increased until I had it turning.

What about this idea: Grind a "backwards" boring bar, then do this
procedure with the lathe in reverse. When you get to the tap, it
might unthread. If you're lucky.

Regards,
Mark
markrages@gmail
--
Most of the time,
for most of the world,
no matter how hard people work at it,
nothing of any significance happens.
-- Weinberg's Law

FWIW, my usual remedy for broken taps in something I have too much tim
into to just remake:

I haven't had luck using alum, try nitric acid (it can be diluted, no
need to play around with concentrated stuff if you are not familiar
with proper acid handling procedures)

If it's a through hole, plug the bottom with some putty or other acid
proof sealer then add the acid to the top of the hole with an eye
dropper till it's full. Wait an hour or so then drain and rinse it
then see if the tap is loose enough to remove (it may have already
been reduced to a mush by then if the acid is not too weak). If it's
still tight, just keep repeating the procedure till it comes out.

If your part was aluminum, you can just go ahead with the tapping
using a new tap. If it was steel, the hole will likely be enlarged
and you will need to drill it oversize and plug it with a steel insert
(piece of rod) which can be epoxied, soldered, or press fitted in
place then re-drill and tap. If you are using solder or epoxy you
need to take the temperature of the parts operation into consideration
and select one that will work at that temperature without melting
(usually not a consideration, but something to be aware of if you're
working on gun parts or other potentially high temp stuff). You could
also thread a larger bolt into the new hole then cut/mill/turn it off
flush and re-drill and tap for the smaller size.

Concentrated nitric acid can be dangerous to work with and diluting
any concentrated acid can be dangerous (slowly add acid to water, not
water to acid, or it can explode in your face). Try to find some
already dilute acid if you are not familiar with handling concentrated
acids. A chemist should be able to prepare a dilute solution for you.

Hi Mark,

Nice concept but I'm pretty sure my tap was too brittle hard for
that. When it initially broke it left a stump protruding. It
crumbled like glass when I tried to grip it. It actually broke on a
forward cut, not a reverse chip-breaking action. That meant I still
needed to break the chips before it would back out. No way that was
going to happen by catching it on a reverse cutting exercise with
just one small point of contact.

But I still like your thinking. :-)

John


--- In 7x12minilathe@..., "Mark Rages" <markrages@...>
wrote:

On 4/2/07, born4something <ajs@...> wrote:

A while back I was asking (mainly out of academic interest)

about

cutting O-ring grooves. Well, I've now cut my first O-ring

groove

and a very tight face-seal type groove at that. I chucked the

job in

the 4-jaw and got the broken tap on centre, confirming by

peeping

through the spindle with a torch to see the reverse side. I then
ground a 1/8" HSS blank to a narrow grooving tool with heaps of
relief angle on one side to allow a really tight o-ring groove
around the broken tap. I cut a groove about 3mm deep about 1mm

clear

of the tap. I then took skimming cuts at that 1mm thick island
around the tap. About one thou at a time until I was perilously
close to hitting the tap. A scriber was then poked down the tap
flutes to pry the thin remaining steel back. Instead of

gripping the

tap with vice grips and having it crumble further I was able to
squash the end of some 1/4" stainless tubing to make the

triangular

equivalent of a socker wrench. That distributed the load across

all

three flutes and with a gentle back and forth motion I soon had
movement which gradually increased until I had it turning.

What about this idea: Grind a "backwards" boring bar, then do this
procedure with the lathe in reverse. When you get to the tap, it
might unthread. If you're lucky.

Regards,
Mark
markrages@gmail
--
Most of the time,
for most of the world,
no matter how hard people work at it,
nothing of any significance happens.
-- Weinberg's Law

Hi,

I stayed clear of using acide on a steel job but I guess if you use
it strong enough that the job doesn't take days then you can keep an
eye on progress and stop it before it destroys everything.

Anyone resorted to sulphuric acid? It just happens that I keep a
supply of concentrated sulphuric on hand for some titrations I use
in measuring the output of ozone generators I manufacture.

John


--- In 7x12minilathe@..., "fkunc" <fjk@...> wrote:

FWIW, my usual remedy for broken taps in something I have too much

tim

into to just remake:

I haven't had luck using alum, try nitric acid (it can be diluted,

no

need to play around with concentrated stuff if you are not familiar
with proper acid handling procedures)

If it's a through hole, plug the bottom with some putty or other

acid

proof sealer then add the acid to the top of the hole with an eye
dropper till it's full. Wait an hour or so then drain and rinse it
then see if the tap is loose enough to remove (it may have already
been reduced to a mush by then if the acid is not too weak). If

it's

still tight, just keep repeating the procedure till it comes out.

If your part was aluminum, you can just go ahead with the tapping
using a new tap. If it was steel, the hole will likely be enlarged
and you will need to drill it oversize and plug it with a steel

insert

(piece of rod) which can be epoxied, soldered, or press fitted in
place then re-drill and tap. If you are using solder or epoxy you
need to take the temperature of the parts operation into

consideration

and select one that will work at that temperature without melting
(usually not a consideration, but something to be aware of if

you're

working on gun parts or other potentially high temp stuff). You

could

also thread a larger bolt into the new hole then cut/mill/turn it

off

flush and re-drill and tap for the smaller size.

Concentrated nitric acid can be dangerous to work with and diluting
any concentrated acid can be dangerous (slowly add acid to water,

not

water to acid, or it can explode in your face). Try to find some
already dilute acid if you are not familiar with handling

concentrated

acids. A chemist should be able to prepare a dilute solution for

you.

Hi again,

I just had a reply from Doug who sells EDM books via that (broken)
link below. He's still in business but his ISP has had his site down
for a few days and he's spitting chips over it. So if you're keen to
check the couple of projects he has either wait or contact me for
his email. His older publication uses a stepper motor but the later
one is based on a servo motor and probably easier to source the bits
for.

John


--- In 7x12minilathe@..., "born4something" <ajs@...>
wrote:

Hi Vikki,

Glad you didn't spontaneously freak out. That's a sign of maturity
and starting to get comfortable with your skills and ability to

sort

things out.

I think you can get alum from a pharmacist. There are possibly
cheaper sources though.

That commonly used 75% thread figure is probably a bit tight for
most work if you don't need enormous strength. The last 2 taps

I've

broken were on 75% or slightly greater (due to available drill
sizes). You mentioned the carbide tip jumping as it touched the
outside of the tap remnants. There's no way I was machining that
close as the tap was so brittle-hard. I'd change to a dremel based
grinding tool before working that close.

When all else fails, read up on EDM. Coming from an electronics
background I just KNOW I'll build one of those things one day.
There's a section in Machinery's Handbook giving a great rundown.
Check out www.modelenginenews.org/~modeng74/meng/edm for some
starter info too. There are quite viable plans around like
www.camtronics-cnc.com or www.build-stuff.com/EDMHowtoBook.htm
(that site seems down just now, hopefully temporarily). EDM would

be

an interesting toy to play with, cutting obscure shaped holes in
impossibly difficult materials. Need to "drill" a square hole in
HSS? No problem!

John


--- In 7x12minilathe@..., Victoria Welch <wrlabs@>
wrote:

On Sunday 01 April 2007, born4something wrote:

Hi Vikki,

Ah, the dreaded broken tap. Every break is different and you

do

what

you need to do in your situation. It's always a good brain

teaser.

In aluminium and brass I'm told alum is magical.

I'm going to try to track down some alum while I am out today

just

to

see if it actually works.

It sure does give one lots to think about, I'm pleased I just

started

thinking rather than freaking out about it :-) :-)! Having some

real

tools, even if smallish certainly opens a lot of doors in many

ways.

I recently broke a 4mm tap in a 1/2" deep hole in steel.

Chemical

techniques weren't going to help steel in steel. Attempts to

grab

the little protruding portion just made it crumble. It was a

good

hard tap. Like yours, it was my ninth hole in a row and I

thought I

had the knack. They were going smoothly. Maybe the tap

fatiqued

as I

was not using much force.

Going for the 75% thread it was obvious the tiny tap was

grunting

down

neat the bottom of the hole. It is completely possible that the

tap

could have been fatigued but I think that the real reason was

that

I

had the tap in the drill chuck mounted in the mill and was

turning

the

chuck by hand. My wrist got tired and I switched hands and am

more

than a little sure I over torqued it at exactly the wrong time.

A while back I was asking (mainly out of academic interest)

about

cutting O-ring grooves. Well, I've now cut my first O-ring

groove

and a very tight face-seal type groove at that. I chucked the

job in

the 4-jaw and got the broken tap on centre, confirming by

peeping

through the spindle with a torch to see the reverse side. I

then

ground a 1/8" HSS blank to a narrow grooving tool with heaps of
relief angle on one side to allow a really tight o-ring groove
around the broken tap. I cut a groove about 3mm deep about 1mm

clear

of the tap. I then took skimming cuts at that 1mm thick island
around the tap. About one thou at a time until I was perilously
close to hitting the tap. A scriber was then poked down the tap
flutes to pry the thin remaining steel back. Instead of

gripping

the

tap with vice grips and having it crumble further I was able to
squash the end of some 1/4" stainless tubing to make the

triangular

equivalent of a socker wrench. That distributed the load

across

all

three flutes and with a gentle back and forth motion I soon had
movement which gradually increased until I had it turning.

Sigh, it does appear impossible to get out, I futzed with it for

a

while

last night and tried several things. HSS tools just got screwed

up

trying to turn it out and using carbide there was so much jump

when the

tool contacted the remains of the tap that it accomplished

nothing :-).

I was able to remove what was in the bore with the carbide

boring

bar

and the absolute slowest feed imaginable.

I finally was able to remove the raw edges on the outside with

my

roomies lapidary diamond files (nasty surfaces poking out).

I could probably use the mill with one of the smallish PCB

drills

to

mill out around the tap without buggering the holder too much,

but

this

isn't real critical so the tap can just sit there. Other than

as

a

reminder, it isn't interfering with anything.

I did have some extra features on my finished product but it

was

only a tool jig and I can live with that. It had toooo much

work

invested to discard.

Same here, scrap isn't really available locally so everything is

retail

priced. Worst case is that I turn it 45 degrees (eyeball, no

indexers

or anything else, but it isn't real critical, I don't think) and

remark

it for another set of holes, which I did last night.

Not sure if that helps your situation. But you can never have

too

many solutions in the back of your mind!

Yes Sir, every little bit of kit that helps solve problems is

always

welcome and a great addition to the mental toolbox :-).

Thanks & take care, Vikki.
--
Victoria Welch, WV9K/7
"Nothing can bring you peace but the triumph of principles." --

Ralph

Waldo Emerson