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On 4/2/07, Victoria Welch <wrlabs@...> wrote:

I picked up a couple more of those today:



Not sure, but I suspect these are not really all that great, but such is
my ignorance of taps and Lowe's does have them locally.

I have a set of those Kobalt taps, and a set of Hanson taps from Home Depot.

The Hanson taps are much better quality IMHO. They seem to be sharper
and harder. They cut more easily. Also, some of the smaller Kobalt
taps are not concentric with their shaft, so I can't accurately use
the chuck to align the tap.

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

In case anybody's been wondering, I've been offline since I packed my
computer away on March 22nd to move. Now it's set up again, but my
in-box has 1600-odd messages, so if anyone sent me an e-mail requiring a
response, please let me know about it.

Mike Taglieri miket--nyc@...

Everyone has his reasons.
- Jean Renoir "The Rules of the Game"

I wrote a long instructional on this some years ago, which is posted on
the mini-lathe site at If
I were doing it again, I'd use a coarser abrasive, such as fine
valve-grinding compound.

Mike Taglieri miket--nyc@...

Everyone has his reasons.
- Jean Renoir "The Rules of the Game"


On Mon, 19 Mar 2007 23:20:43 -0700 Dennis Thompson <dbt@...>
writes:

On Monday 02 April 2007, charlie4_66043 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:

[ ... ]

Thanks for the pointer, checked that earlier and the pix was missing,
but I get the idea, I think that is the purpose that the drill chuck is
serving for here.

Once I get some bigger aluminum rod, I am going to make one, that drill
chuck is hard on the hands!

Thanks & take care, Vikki.
--
Victoria Welch, WV9K/7
"You need only reflect that one of the best ways to get yourself a
reputation as a dangerous citizen these days is to go about repeating
the very phrases which our founding fathers used in the struggle for
independence." - C.A. Beard

On Monday 02 April 2007, born4something 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.

:-) Nice feeling! Being able to re-do something complex does indeed
have a lot of benefits :)!

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.

These are just for adjusting screws and don't need much power, it would
be pretty easy to crush that laser pointer tube. Might be able to go
to a #42 or #41 drill for this, something to think on.

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!

I'd love to have an EDM machine (just where I would put it would require
some effort :) but for now I'll do it the hard way and be WAY more
aware of what is going on in the process :-).

Thanks & take care, Vikki.
--
Victoria Welch, WV9K/7
"Insisting on perfect safety is for people who don't have the balls to
live in the real world." -- Mary Shafer, NASA Ames Dryden

On Monday 02 April 2007, born4something wrote:

[ ... ]
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!

LOL, already doing that :-/. Got tight for time while I was out today
and decided to just use my little PCB drills to get it out since I have
to bore it out more anyway.

I'll keep them, but I sure will be circumspect about them in the future.
Got to find out what good taps are, hard to think that the one I broke
was only good for about 15-20 holes.

Thanks & take care, Vikki.
--
Victoria Welch, WV9K/7
"If you fill your heart with regrets of yesterday and the worries of
tomorrow, you have no today to be thankful for." -- Unknown

On Monday 02 April 2007, born4something wrote:

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.

Exactly what happened here.

I picked up a couple more of those today:



Not sure, but I suspect these are not really all that great, but such is
my ignorance of taps and Lowe's does have them locally.

I started on the second set of holes and the new one cut a lot better, I
suspect the old one was dull (about 15 holes in aluminum MAX?). WD40
may have helped rather than the cutting oil, not sure.

Embarrassed to admit, I used the mill to run the tap on through and
forgot I had lifted up the head and ran out of quill. Polished that
hole nicely to the OD of the tap :-/, Another lesson learned :).

Anyway, I decided to just tap another hole just above the one in the
original set with the broken tap. For the next one, I'll have all the
lessons of this mess :-).

Tested it out in the quill with the laser in it and it works just fine.
Can't get it aligned yet as I run out of adjustment - need to bore it
out more. These cheap laser pointers can be out quite a bit.

Using the screw for a power switch works well enough one just needs to
remove the button over the switch itself, which takes a little work,
buggered one of them in the process of doing that.

Going to head back in there and attempt to bore it out some more.
Hopefully I'll have enough room to get it where I can center it. I may
have to get that broken tap out somehow to do this. This prototype is
going to really be ugly :).

Fun, pix soon.

Take care, Vikki.
--
Victoria Welch, WV9K/7
"You can learn a lot from listening to people talk. Why everything I
know today I've learned from listening to myself talk about things that
I knew absolutely nothing about." - Gracie Allen

On Monday 02 April 2007 11:33, rroll99 wrote:

I was wondering if the group has a consensus about what would be a
good book for someone who wants to not only learn how to use a lathe,
but also how to properly layout, cut, drill, tap, grind bits and do
other basic machine shop operations.

a great resource is google books (be sure to check the full view books button)
like these



OK they're old books but the 7x lathes are old designs ,under powered and lightly built
just like the lathes from way back when ,very little has changed on bench lathes in the
last hundred years or so


Brian
--
"Nemo me impune lacesset"

Hi Ian,

Is this your beastie at www.realbull-machine.com/images/CJ0618.jpg
<> ? I assume those
plastic guards are a later addition. They do look more readily
fabricated to address the Sieg's issues with undersized guards.

BTW, what do you call the mess made by a Real Bull? It's not chips or
swarf! <G>

John


--- In 7x12minilathe@..., "steam4ian" <fosterscons@...>
wrote:

G'day Chris.
Thank you for getting back to me regarding Real Bull; as you may have
observed, I am full of it!
Seriously, it would be good if I and others could catalogue
differences as we come across them, eg key dimesions, feedscrew
diameters etc. It could save both you and your customers frustration.
Many of us have scraped together just enough for one lathe so can't
have a second machine to compare side by side, the only way we
discover changes is when buying replacement parts and finding they
have to be "addapted". I must admit it has made me hesitant to
lashout on upgrade parts.

I googled "china" "lathe" "manufacture" and came up with about 160
companies making lathes. I didn't get all the way through the list
but found at least 10 manufacturers of Mini Lathes, they were in
different provinces so I doubt they were were the same company. I
must admit in at least one case the machine was claimed by one
company but their picture showed a Real Bull logo on the control panel

It would be interesting to find where and how the design originated;
Chris, can you comment?.
I also suspect they are made for use in China and SE Asia for home
manufacturing (cottage industry) and not just for the hobby market.
They would be really good for this as thy could employ a family in
repetative small parts manufacture, better than starving. Even some
of the mini lathe parts could have been made by out workers on a mini
lathe.
An opportunity exists to aid struggling families in poverty areas of
under developed countries by providing them with a lathe. This
happens in India with sewing machines and pedal rickshaws where
charities exist to provide just such aid; they make an incredible
difference ("teach a man to fish and he will feed a village").

BTW, Thank you Chris for the service I have had from LMS and the
service LMS has provided to the craft and hobby.

One good turn deserves another.
Regards,
Ian

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

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 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 Rob:
I am also a newbie. I bought a 7x12 Cummins in summer of last year.
Doug Briney: The Home Machinists's Handbook, McGraw-Hill, available at Amazon.com, very basic and geared towards the beginner
South Bend Lathe Works: How to Run a Lathe, Lindsay Publications, available at The Little Machine Shop, a reedition of a 1942 South Bend Lathe Works manual, excellent for the beginner
Frank Hoose's home page, excellent for the beginner, many photographs
I hope this helps.
Gregor Stransky, San Antonio, Texas

I have one of these tool holders and I doubt that the rocker section
is a Woodruff key. It's about 40mm long and 12mm wide. I don't think
Woodruffs are that thick. It's also fairly shallow from the flat
surface to the curved portion. I think Woodruffs are much deeper than
this.

This tool holder will easily take a 1/2 inch tool bit.

John

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.

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

--- 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

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

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

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