http://www.metalworking.com/DropBox/...ding_setup.pdf

I don't cut internal threads that often (usually tap), but when I do,
it takes me forever to remember how to set the lathe up correctly.
There was an excellent discussion on this topic on the Chaski Board
recently.

I made this chart which I've uploaded to the metalworking.com drop box.
Harold Vordos graciously corrected all my mistakes and as always, I
appreciate his willingness and ability to teach the craft so well.
Hopefully, this will help someone else.

George

gglines wrote:

http://www.metalworking.com/DropBox/...ding_setup.pdf

I don't cut internal threads that often (usually tap), but when I do,
it takes me forever to remember how to set the lathe up correctly.
There was an excellent discussion on this topic on the Chaski Board
recently.

I made this chart which I've uploaded to the metalworking.com drop box.
Harold Vordos graciously corrected all my mistakes and as always, I
appreciate his willingness and ability to teach the craft so well.
Hopefully, this will help someone else.

George

What the 'L' -- you had one too many:

http://www.metalworking.com/DropBox/...ding_setup.pdf

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

gglines wrote:
http://www.metalworking.com/DropBox/...ding_setup.pdf

I don't cut internal threads that often (usually tap), but when I do,
it takes me forever to remember how to set the lathe up correctly.
There was an excellent discussion on this topic on the Chaski Board
recently.

I made this chart which I've uploaded to the metalworking.com drop box.
Harold Vordos graciously corrected all my mistakes and as always, I
appreciate his willingness and ability to teach the craft so well.
Hopefully, this will help someone else.



George,

There are two more positions as alternates for starting inside the hole
and coming out, which is not a fun thing to do.
They are both for the back side of the hole, with feed to the left:

RH with the tool down, forward rotation.
LH with the tool up, in reverse.

In both cases, the compound is aligned the same as for RH external
threads, pointing to the left--I would call it going from 5 o'clock to
11 o'clock, generally the most convenient position.

You can cut RH, LH, internal and external with the compound in this
position--just flip the toolbit appropriately.

So it's always the left side of the cutter doing the chip removal, and
the right side is just taking an extremely fine shaving as the tool is
fed in a half a degree more to the right than straight along the
thread's left flank.

Ken Grunke




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"Ken Grunke" wrote in message
...
gglines wrote:
http://www.metalworking.com/DropBox/...ding_setup.pdf

I don't cut internal threads that often (usually tap), but when I do,
it takes me forever to remember how to set the lathe up correctly.
There was an excellent discussion on this topic on the Chaski Board
recently.

I made this chart which I've uploaded to the metalworking.com drop box.
Harold Vordos graciously corrected all my mistakes and as always, I
appreciate his willingness and ability to teach the craft so well.
Hopefully, this will help someone else.



George,

There are two more positions as alternates for starting inside the hole
and coming out, which is not a fun thing to do.
They are both for the back side of the hole, with feed to the left:

RH with the tool down, forward rotation.
LH with the tool up, in reverse.

In both cases, the compound is aligned the same as for RH external
threads, pointing to the left--I would call it going from 5 o'clock to
11 o'clock, generally the most convenient position.

You can cut RH, LH, internal and external with the compound in this
position--just flip the toolbit appropriately.

So it's always the left side of the cutter doing the chip removal, and
the right side is just taking an extremely fine shaving as the tool is
fed in a half a degree more to the right than straight along the
thread's left flank.

Ken Grunke

Threading as you suggest is not a good idea. The pressure of the cut has
the ability to propel the carriage ahead of the lead screw, causing a
drunken thread. Feed of the compound should *always* be in the same
direction as the cut, which avoids the problem by loading the cut against
the lead screw. That is, and has always been, the reason for setting the
compound on different sides, depending on the nature of the thread involved.

Harold

Harold & Susan Vordos wrote:


In both cases, the compound is aligned the same as for RH external
threads, pointing to the left--I would call it going from 5 o'clock to
11 o'clock, generally the most convenient position.

You can cut RH, LH, internal and external with the compound in this
position--just flip the toolbit appropriately.

So it's always the left side of the cutter doing the chip removal, and
the right side is just taking an extremely fine shaving as the tool is
fed in a half a degree more to the right than straight along the
thread's left flank.

Ken Grunke


Threading as you suggest is not a good idea. The pressure of the cut has
the ability to propel the carriage ahead of the lead screw, causing a
drunken thread. Feed of the compound should *always* be in the same
direction as the cut, which avoids the problem by loading the cut against
the lead screw. That is, and has always been, the reason for setting the
compound on different sides, depending on the nature of the thread involved.

Harold



If I understand you correctly, you're referring to the pressure on the
right side of the cutter which is taking only a minute (myNOOT) shaving?
It can't be very much, if you're advancing the compound only a little
for each pass as generally recommended.

Are you saying that the compound should be set at 30 degrees, instead of
29.5?

In my suggestion, the compound is *always* fed in the direction of cut,
it's just set a half degree in from 30 degrees. The advancement into the
left flank of the thread is so miniscule at that angle, that it barely
cuts on that side.

Ken Grunke


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"Ken Grunke" wrote in message
...
Harold & Susan Vordos wrote:


In both cases, the compound is aligned the same as for RH external
threads, pointing to the left--I would call it going from 5 o'clock to
11 o'clock, generally the most convenient position.

You can cut RH, LH, internal and external with the compound in this
position--just flip the toolbit appropriately.

So it's always the left side of the cutter doing the chip removal, and
the right side is just taking an extremely fine shaving as the tool is
fed in a half a degree more to the right than straight along the
thread's left flank.

Ken Grunke


Threading as you suggest is not a good idea. The pressure of the cut
has
the ability to propel the carriage ahead of the lead screw, causing a
drunken thread. Feed of the compound should *always* be in the same
direction as the cut, which avoids the problem by loading the cut
against
the lead screw. That is, and has always been, the reason for setting
the
compound on different sides, depending on the nature of the thread
involved.

Harold



If I understand you correctly, you're referring to the pressure on the
right side of the cutter which is taking only a minute (myNOOT) shaving?
It can't be very much, if you're advancing the compound only a little
for each pass as generally recommended.

Are you saying that the compound should be set at 30 degrees, instead of
29.5?

In my suggestion, the compound is *always* fed in the direction of cut,
it's just set a half degree in from 30 degrees. The advancement into the
left flank of the thread is so miniscule at that angle, that it barely
cuts on that side.

Ken Grunke

I'm sorry, I apologize. When I re-read your original post, I realize I
misinterpreted your comments as threading from the inside to the outside
(that was on my mind). *You clearly stated the opposite.* The two methods
suggested are, indeed, proper, but I would hesitate to use them unless I was
threading a through thread.

I would take exception to your statement about the difficulty of threading
from the inside to the outside. My first attempts to do it were a result
of the horrible difficulty of threading to a shoulder when chasing a 1"-8
inside thread. The bore was deep, near two inches. It was far easier to
start the thread in the relief that was permitted than it was to pull the
half nuts at the precise moment when threading such a course thread. I
guess it's all in what one gets used to! g

Harold

Harold & Susan Vordos wrote:
"Ken Grunke" wrote in message
...

Harold & Susan Vordos wrote:


In both cases, the compound is aligned the same as for RH external
threads, pointing to the left--I would call it going from 5 o'clock to
11 o'clock, generally the most convenient position.

You can cut RH, LH, internal and external with the compound in this
position--just flip the toolbit appropriately.

So it's always the left side of the cutter doing the chip removal, and
the right side is just taking an extremely fine shaving as the tool is
fed in a half a degree more to the right than straight along the
thread's left flank.

Ken Grunke


Threading as you suggest is not a good idea. The pressure of the cut

has

the ability to propel the carriage ahead of the lead screw, causing a
drunken thread. Feed of the compound should *always* be in the same
direction as the cut, which avoids the problem by loading the cut

against

the lead screw. That is, and has always been, the reason for setting

the

compound on different sides, depending on the nature of the thread

involved.

Harold



If I understand you correctly, you're referring to the pressure on the
right side of the cutter which is taking only a minute (myNOOT) shaving?
It can't be very much, if you're advancing the compound only a little
for each pass as generally recommended.

Are you saying that the compound should be set at 30 degrees, instead of
29.5?

In my suggestion, the compound is *always* fed in the direction of cut,
it's just set a half degree in from 30 degrees. The advancement into the
left flank of the thread is so miniscule at that angle, that it barely
cuts on that side.

Ken Grunke


I'm sorry, I apologize. When I re-read your original post, I realize I
misinterpreted your comments as threading from the inside to the outside
(that was on my mind). *You clearly stated the opposite.* The two methods
suggested are, indeed, proper, but I would hesitate to use them unless I was
threading a through thread.

I would take exception to your statement about the difficulty of threading
from the inside to the outside. My first attempts to do it were a result
of the horrible difficulty of threading to a shoulder when chasing a 1"-8
inside thread. The bore was deep, near two inches. It was far easier to
start the thread in the relief that was permitted than it was to pull the
half nuts at the precise moment when threading such a course thread. I
guess it's all in what one gets used to! g

Harold



Harold, I completely agree with your exception, at least when threading
under power.
I don't have a very big lathe (Emco Maier Compact 8) so 8 tpi is pretty
big for me.
For that size and for any blind hole, I thread using a crank on the
outboard pulley so a carriage travel to the left into the bore isn't a
problem, I can set up a carriage stop.
But an 8 tpi hole can get pretty tiring after a while! :-)
Thanks,

Ken Grunke


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"Ken Grunke" wrote in message
...
Harold & Susan Vordos wrote:
"Ken Grunke" wrote in message
snip---


I'm sorry, I apologize. When I re-read your original post, I realize I
misinterpreted your comments as threading from the inside to the outside
(that was on my mind). *You clearly stated the opposite.* The two
methods
suggested are, indeed, proper, but I would hesitate to use them unless I
was
threading a through thread.

I would take exception to your statement about the difficulty of
threading
from the inside to the outside. My first attempts to do it were a
result
of the horrible difficulty of threading to a shoulder when chasing a
1"-8
inside thread. The bore was deep, near two inches. It was far easier
to
start the thread in the relief that was permitted than it was to pull
the
half nuts at the precise moment when threading such a course thread. I
guess it's all in what one gets used to! g

Harold



Harold, I completely agree with your exception, at least when threading
under power.
I don't have a very big lathe (Emco Maier Compact 8) so 8 tpi is pretty
big for me.
For that size and for any blind hole, I thread using a crank on the
outboard pulley so a carriage travel to the left into the bore isn't a
problem, I can set up a carriage stop.
But an 8 tpi hole can get pretty tiring after a while! :-)
Thanks,

Ken Grunke

Ah!! That's very different! I always thread under full power, including to
a shoulder, internally, when it's called for. My method of keeping out of
trouble is to make a pencil line on the boring bar, which is my reference to
which I disengage the half nuts. It's surprisingly accurate, although when
you're chasing a coarse thread it requires your undivided attention.

Not long ago I chased a three pitch auger for Susan's wheat grinder, a
replacement for the original, which broke. It was made of cast iron. The
auger started and ended inside a full diameter, so there was no runout. I
had to pull out on one end, but the starting end I used a starting groove, a
duplicate of the radius of the auger. The auger was made of 17-4PH
stainless, with a left hand "thread". It's surprising how closely you can
pull out when necessary. I ended up with a very nice transition from auger
to straight shaft in a relatively short distance. A picture is available
if you're interested.

Harold

replying to gglines, Sarah Allen wrote:
Can you supply a copy of the chart? I'm not able to open PDF.

--
for full context, visit https://www.polytechforum.com/metalw...he-384987-.htm