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I am looking to buy a cheap lathe to do the following work.
I will be working on some 10" long pipe under 3/4" diameter.
I need to make small sections of it thinner ( face?), and be
able to cut the pipe to length ( part? )

I am specificaly interested in THREADING, I NEED to be able to
make 14x1 left hand thread.
Are the cheapo harbor freight ones suited to this? Which is the
best to buy?
This lathe will be LIGHTLY USED, I do not need an industrail
machine. I am simply wondering what INEXPENSIVE lathe can perform
the task and HOW to perform the threading task ( what gear set up ect ).
Harbor freight has 2 7x10 lathes listed that look identical,
there is a $10 price diferance...... which is better? what is the
diferance? Will either do the required task?

A couple of questions.

When you say "I need to make small sections of it thinner" do you
mean make the outside smaller or the inside larger?

When you say a "14x1 left hand thread" do you mean a 14mm diameter
piece with a 1mm pitch?

These answers will held decide what you need.

As far as the 7x10 lathe it will be to short for a 10" long piece.

Paul M

--- In 7x12minilathe@..., "harleyknall" <knall@...>
wrote:

I am looking to buy a cheap lathe to do the following work.
I will be working on some 10" long pipe under 3/4" diameter.
I need to make small sections of it thinner ( face?), and

be

able to cut the pipe to length ( part? )

I am specificaly interested in THREADING, I NEED to be able

to

make 14x1 left hand thread.
Are the cheapo harbor freight ones suited to this? Which is

the

best to buy?
This lathe will be LIGHTLY USED, I do not need an industrail
machine. I am simply wondering what INEXPENSIVE lathe can

perform

the task and HOW to perform the threading task ( what gear set up

ect ).

Harbor freight has 2 7x10 lathes listed that look

identical,

there is a $10 price diferance...... which is better? what is

the

diferance? Will either do the required task?

Just to get the terminology down for lathe work -

Turning - reducing the diameter of the work.
Facing - reducing the length of the work from an end.
Parting - cutting work off on the lathe.
Boring - enlargening a hole in the work.
Centre-drill - a special bit that cuts the seat for the tailstock
centre. It is also used for precisely starting drilling operations
since it's short and rigid.

- That should be enough

Since you're working on pipe 10" long, I would suggest getting at
least a 7x12. Work much longer than 8" gets really tricky on the
7x10. The 7x12, despite the numbers, is actually a full 4" longer
than the 7x10.

3/4" and slightly larger diameters will fit fine through the spindle,
so theoretically you could work on one end of a very long pipe. But
the stock 3" chuck will on only pass 5/8" work. 4" chucks almost
universally pass 3/4" work though.

I don't know the American market for these lathes very well, but a lot
of people like the cumminstools.com 7x12 for the amount of accessories
they get. The steady rest is useful for working on very long stock
too, replacing the tailstock. It's probably available somewhere else
a little cheaper though.

Threading is no problem at all. If you buy just about any US lathe,
it'll be equipped to make perfect imperial threads. Usually the gears
used will be 40-65-35 gears. The metric leadscrew minilathes can
approximate a 14 TPI pretty well too. Making left hand threads is
pretty simple as you just drive the leadscrew backwards - no trouble
at all, just flip a shifter.

That said, 14 TPI is pretty steep and can get pretty hairy on any
lathe pretty quickly. So something that course is best done by
turning the lathe with a hand crank rather than by power. Usually
it's a pretty simple matter to just make your own hand-crank for the
spindle out of scrap, etc.

Which gets us to the crux of the matter. All the 7xs, with the
possible exception of one of the nice tuned up 7xs like the Micromark
7x14 (6" longer than the 7x10), are best described as "lathe kits
assembled for your inconvenience" While you can take them out of the
box and start turning, it won't be very nice and you won't enjoy it.
This is why these lathes are so popular among us hobbyists as we
actually enjoy spending time tuning them up and dialing them in. If
you don't enjoy fiddling with machines you just want to get straight
to work, spend 2 or 3 times more money and get a real lathe.

Either way you go, the operation sounds pretty straight forward to me.
I'll explain how I would do it on my 7x10, presuming I could fit the
work between the centres. I'm also going to presume that I'm making a
few different length pieces but only a few different ID pipes. Clearly
OD is our choice.

1). Make some top-hat shaped pieces out of aluminium (or
what-have-you) to make caps to fit each ID pipe I'm using. Probably
about 3/4 inch long, centre-drilled to fit the tailstock. The thin
portion of the top-hat will closely fit the ID of the pipe, and the
flange will 'cap' it and allow the pipe to be held by the dead centre.
Here's how their made simply:

1.1). Set the AL stock so it's sticking out of the chuck about 1".
With a left-hand turning tool set squarely in the toolpost, turn down
the stock cutting from tailstock end toward the chuck end, stopping
after about 5/8". Make light cuts to this point until the pipe just
slips over it. Lay a file at an angle on the end of the work, and
form a quick chamfer (slight point) to make inserting the plug easier.
Then with the cutoff tool set square, cut the stock off 1/8"-1/4"
past the turned down part, forming a flange.

1.2). Remove what remains of the stock and mount the top-hat in the
chuck, flange side out. There will be a nib left over from parting,
you can file it off or simply face the whole top-hat with the turning
tool. Finally, centre drill the peice with a centre-drill bit held in
a tailstock chuck.

1.3) A word of warning here - these are not "precision" unless you
indicate the part with a dial indicator when you chuck it a second
time. You can expect 0.002-.005" error if you don't.

2) Get cutting pipe. Cut your peice about an inch longer than you
need it. About 1" of an end will be held in the chuck and is
essentially unworkable without some serious juggling. Cap the other
end with your new cap and fit the tailstock and dead centre. Turn
down your pipe to the OD you want as close to the chuck as you dare.
If bits of the top-hat flange are in the way, just blast through them.

3) Back off the tailstock far and part off the pipe, loosing the
chucked end. Remount the pipe so it's only sticking out of the chuck
1-1.5" (assuming it fits through the headstock & chuck). Chamfer the
end of the pipe with a file or with the threading bit set at 45
degrees (appx.) to make the pipes thread on easily. Setup and cut the
threads (whole other lesson!).

4) Flip pipe, face to desired length using turning tool, then repeat
step #3.


I hope that explains it. As you can see, lathe work (and most machine
work really) involves a lot of setup. This is why machine shops
charge so much less for batches than 1-offs. Also, you see how half
the time you setup for a job, you begin by making tools. Sometimes
you end up making tools to make the tools!

-Paul Moir

G'day Paul,
Just to say what you said is great.
Making tools, to make tools, to make tools..........
One good turn deserves another.
Regards,
Ian
--- In 7x12minilathe@..., "Paul Moir" <paul.moir@...>
wrote:

Just to get the terminology down for lathe work -

Turning - reducing the diameter of the work.
Facing - reducing the length of the work from an end.
Parting - cutting work off on the lathe.
Boring - enlargening a hole in the work.
Centre-drill - a special bit that cuts the seat for the tailstock
centre. It is also used for precisely starting drilling operations
since it's short and rigid.

- That should be enough

Since you're working on pipe 10" long, I would suggest getting at
least a 7x12. Work much longer than 8" gets really tricky on the
7x10. The 7x12, despite the numbers, is actually a full 4" longer
than the 7x10.

3/4" and slightly larger diameters will fit fine through the

spindle,

so theoretically you could work on one end of a very long pipe. But
the stock 3" chuck will on only pass 5/8" work. 4" chucks almost
universally pass 3/4" work though.

I don't know the American market for these lathes very well, but a

lot

of people like the cumminstools.com 7x12 for the amount of

accessories

they get. The steady rest is useful for working on very long stock
too, replacing the tailstock. It's probably available somewhere

else

a little cheaper though.

Threading is no problem at all. If you buy just about any US lathe,
it'll be equipped to make perfect imperial threads. Usually the

gears

used will be 40-65-35 gears. The metric leadscrew minilathes can
approximate a 14 TPI pretty well too. Making left hand threads is
pretty simple as you just drive the leadscrew backwards - no trouble
at all, just flip a shifter.

That said, 14 TPI is pretty steep and can get pretty hairy on any
lathe pretty quickly. So something that course is best done by
turning the lathe with a hand crank rather than by power. Usually
it's a pretty simple matter to just make your own hand-crank for the
spindle out of scrap, etc.

Which gets us to the crux of the matter. All the 7xs, with the
possible exception of one of the nice tuned up 7xs like the

Micromark

7x14 (6" longer than the 7x10), are best described as "lathe kits
assembled for your inconvenience" While you can take them out of

the

box and start turning, it won't be very nice and you won't enjoy

it.

This is why these lathes are so popular among us hobbyists as we
actually enjoy spending time tuning them up and dialing them in. If
you don't enjoy fiddling with machines you just want to get straight
to work, spend 2 or 3 times more money and get a real lathe.

Either way you go, the operation sounds pretty straight forward to

me.

I'll explain how I would do it on my 7x10, presuming I could fit

the

work between the centres. I'm also going to presume that I'm

making a

few different length pieces but only a few different ID pipes.

Clearly

OD is our choice.

1). Make some top-hat shaped pieces out of aluminium (or
what-have-you) to make caps to fit each ID pipe I'm using. Probably
about 3/4 inch long, centre-drilled to fit the tailstock. The thin
portion of the top-hat will closely fit the ID of the pipe, and the
flange will 'cap' it and allow the pipe to be held by the dead

centre.

Here's how their made simply:

1.1). Set the AL stock so it's sticking out of the chuck about 1".
With a left-hand turning tool set squarely in the toolpost, turn

down

the stock cutting from tailstock end toward the chuck end, stopping
after about 5/8". Make light cuts to this point until the pipe just
slips over it. Lay a file at an angle on the end of the work, and
form a quick chamfer (slight point) to make inserting the plug

easier.

Then with the cutoff tool set square, cut the stock off 1/8"-1/4"
past the turned down part, forming a flange.

1.2). Remove what remains of the stock and mount the top-hat in the
chuck, flange side out. There will be a nib left over from parting,
you can file it off or simply face the whole top-hat with the

turning

tool. Finally, centre drill the peice with a centre-drill bit held

in

a tailstock chuck.

1.3) A word of warning here - these are not "precision" unless you
indicate the part with a dial indicator when you chuck it a second
time. You can expect 0.002-.005" error if you don't.

2) Get cutting pipe. Cut your peice about an inch longer than you
need it. About 1" of an end will be held in the chuck and is
essentially unworkable without some serious juggling. Cap the other
end with your new cap and fit the tailstock and dead centre. Turn
down your pipe to the OD you want as close to the chuck as you

dare.

If bits of the top-hat flange are in the way, just blast through

them.

3) Back off the tailstock far and part off the pipe, loosing the
chucked end. Remount the pipe so it's only sticking out of the

chuck

1-1.5" (assuming it fits through the headstock & chuck). Chamfer

the

end of the pipe with a file or with the threading bit set at 45
degrees (appx.) to make the pipes thread on easily. Setup and cut

the

threads (whole other lesson!).

4) Flip pipe, face to desired length using turning tool, then repeat
step #3.


I hope that explains it. As you can see, lathe work (and most

machine

work really) involves a lot of setup. This is why machine shops
charge so much less for batches than 1-offs. Also, you see how half
the time you setup for a job, you begin by making tools. Sometimes
you end up making tools to make the tools!

-Paul Moir


--- In 7x12minilathe@..., "harleyknall" <knall@> wrote:

I am looking to buy a cheap lathe to do the following work.
I will be working on some 10" long pipe under 3/4" diameter.
I need to make small sections of it thinner ( face?), and

be

able to cut the pipe to length ( part? )

I am specificaly interested in THREADING, I NEED to be able

to

make 14x1 left hand thread.
Are the cheapo harbor freight ones suited to this? Which

is the

best to buy?
This lathe will be LIGHTLY USED, I do not need an industrail
machine. I am simply wondering what INEXPENSIVE lathe can

perform

the task and HOW to perform the threading task ( what gear set up

ect ).

Harbor freight has 2 7x10 lathes listed that look

identical,

there is a $10 price diferance...... which is better? what is

the

diferance? Will either do the required task?