[Stupendous Man]

I have a lot of 2 inch by 8 TPI internal threads to cut in cast aluminum,
both left and right hand, and just got the missing parts for an "on end"
style bar thats been in the cabinet for years. I remember someone saying
that they prefer leave the compound 29 degree angle out of it and just use
the cross feed.
Hows that compare to the traditional method for smooth threads?
--
Stupendous Man,
Defender of Freedom, Advocate of Liberty

[Ed Huntress]

"Stupendous Man" wrote in message
...
I have a lot of 2 inch by 8 TPI internal threads to cut in cast aluminum,
both left and right hand, and just got the missing parts for an "on end"
style bar thats been in the cabinet for years. I remember someone saying
that they prefer leave the compound 29 degree angle out of it and just use
the cross feed.
Hows that compare to the traditional method for smooth threads?
--
Stupendous Man,
Defender of Freedom, Advocate of Liberty

When you cut threads by feeding straight in, you're cutting both flanks of
the thread at once. That produces twice the tool load for a given depth of
cut.

If you have a good lathe, your tools are sharp, and you're cutting aluminum,
it may work just fine. But cutting clean internal threads depends on getting
things pretty close to right, so the extra tool load is something to watch
out for if you get some chatter.

--
Ed Huntress

[Steve Lusardi]

In addition to Ed's comment, formed carbide tools have insufficient
clearance for cutting aluminum. You will have much less tool drag and
loading using HSS. Making good threads easier to acheive. Please refer to
Ed's comment on machine size and set up stiffness.
Steve

"Ed Huntress" wrote in message
...

"Stupendous Man" wrote in message
...
I have a lot of 2 inch by 8 TPI internal threads to cut in cast aluminum,
both left and right hand, and just got the missing parts for an "on end"
style bar thats been in the cabinet for years. I remember someone saying
that they prefer leave the compound 29 degree angle out of it and just use
the cross feed.
Hows that compare to the traditional method for smooth threads?
--
Stupendous Man,
Defender of Freedom, Advocate of Liberty

When you cut threads by feeding straight in, you're cutting both flanks of
the thread at once. That produces twice the tool load for a given depth of
cut.

If you have a good lathe, your tools are sharp, and you're cutting
aluminum, it may work just fine. But cutting clean internal threads
depends on getting things pretty close to right, so the extra tool load is
something to watch out for if you get some chatter.

--
Ed Huntress

[Lew Hartswick]

Stupendous Man wrote:
I have a lot of 2 inch by 8 TPI internal threads to cut in cast
aluminum, both left and right hand, and just got the missing parts for
an "on end" style bar thats been in the cabinet for years. I remember
someone saying that they prefer leave the compound 29 degree angle out
of it and just use the cross feed.
Hows that compare to the traditional method for smooth threads?

Just today had to try using the cross feed to deepen the threads on
a student job. It is a "turn between centers" (sort of a test) and
with the chuck off to use a center in the spindle it is impossible
to reach far enough, with the compound at 60deg (Clausing/Metosa
have the angles "other way round"), toward the headstock. So I
tried it on the required 3/4 - 16 thread and using .010 infeed
up to .080 and .005 after that ( diameter infeed measure) per pass.
Came out OK. Good sharp HSS bit.
...lew...

[DoN. Nichols]

On 2008-04-22, Steve Lusardi wrote:

"Ed Huntress" wrote in message
...

"Stupendous Man" wrote in message
...
I have a lot of 2 inch by 8 TPI internal threads to cut in cast aluminum,
both left and right hand, and just got the missing parts for an "on end"
style bar thats been in the cabinet for years. I remember someone saying
that they prefer leave the compound 29 degree angle out of it and just use
the cross feed.
Hows that compare to the traditional method for smooth threads?

[ ... ]

When you cut threads by feeding straight in, you're cutting both flanks of
the thread at once. That produces twice the tool load for a given depth of
cut.

In addition to Ed's comment, formed carbide tools have insufficient
clearance for cutting aluminum.

That depends. If by "formed carbide" you mean the ones which
bolt the flat of the insert to the side of the tool holder, I'll agree,
depending on the combination of thread pitch and diameter. With 2"
diameter, the clearance angles required for both left and right hand
will be less than for the same 8TPI and 1" diameter.

However -- the "laydown" style of threading tool inserts deal
with the clearance angle by offering a selection of anvils to go under
the insert. Each one has a different angle, in 0.5 degree steps, so you
can achieve a good clearance angle for most combinations of pitch and
diameter.

You will have much less tool drag and
loading using HSS. Making good threads easier to acheive. Please refer to
Ed's comment on machine size and set up stiffness.

Assuming that you grind the HSS to the proper clearance angles
for that specific thread -- requiring two of them if you are cutting bot
left-hand and right-hand threads of the same pitch.

Enjoy,
DoN.

--
Email: | Voice (all times): (703) 938-4564
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
--- Black Holes are where God is dividing by zero ---

[Stupendous Man]

I have a laydown set, but it's too small for this job, and I am the whole
labor force of a small shop, so buying "one time" tooling isn't happening
when I can do it another way.
I started doing them yesterday using a TPMA style insert, 10 Deg. rake and
it's doing a good job and has plenty of clearance
http://catalogs.shoplocal.com/jlindu...r=715&fsid=715

I had hoped that ignoring the crossfeed might be a nice shortcut but am
doing it the way I know. It takes me 15 passes to get there, plus the items
are irregular castings so I have to bore each in the same chucking. Too bad
I can't fit the Valcut trepanning tool into the tailstock and have enough
clearance.Good thing I get paid by the hour.
--
Stupendous Man,
Defender of Freedom, Advocate of Liberty

[John Martin]

On Apr 22, 2:04*am, "Ed Huntress" wrote:
When you cut threads by feeding straight in, you're cutting both flanks of
the thread at once. That produces twice the tool load for a given depth of
cut.

If you have a good lathe, your tools are sharp, and you're cutting aluminum,
it may work just fine. But cutting clean internal threads depends on getting
things pretty close to right, so the extra tool load is something to watch
out for if you get some chatter.

--
Ed Huntress

Of more importance is that cutting on one flank loads the cutter
against the lead screw. Cutting both flanks at once, the carriage can
float instead on being driven by the leadscrew, and you can end up
with a drunken thread.

John Martin

[Ed Huntress]

"John Martin" wrote in message
...
On Apr 22, 2:04 am, "Ed Huntress" wrote:
When you cut threads by feeding straight in, you're cutting both flanks of
the thread at once. That produces twice the tool load for a given depth of
cut.

If you have a good lathe, your tools are sharp, and you're cutting
aluminum,
it may work just fine. But cutting clean internal threads depends on
getting
things pretty close to right, so the extra tool load is something to watch
out for if you get some chatter.

--
Ed Huntress

Of more importance is that cutting on one flank loads the cutter
against the lead screw. Cutting both flanks at once, the carriage can
float instead on being driven by the leadscrew, and you can end up
with a drunken thread.

John Martin

Maybe you can answer something that's bugged me for a long time, John: Why
do the traditional lathe books say you should advance the cut when cutting
Acme threads by plunging straight in, rather than on the appropriate angle
for cutting one flank at a time? I don't recall ever having seen an
explanation.

--
Ed Huntress

[Stupendous Man]

Thanks guys. I got 25 pieces done today, only 3 more days to go!
--
Stupendous Man,
Defender of Freedom, Advocate of Liberty

[John Martin]

On Apr 23, 11:07*am, "Ed Huntress" wrote:
"John Martin" wrote in message

...
On Apr 22, 2:04 am, "Ed Huntress" wrote:





When you cut threads by feeding straight in, you're cutting both flanks of
the thread at once. That produces twice the tool load for a given depth of
cut.

If you have a good lathe, your tools are sharp, and you're cutting
aluminum,
it may work just fine. But cutting clean internal threads depends on
getting
things pretty close to right, so the extra tool load is something to watch
out for if you get some chatter.

--
Ed Huntress
Of more importance is that cutting on one flank loads the cutter
against the lead screw. *Cutting both flanks at once, the carriage can
float instead on being driven by the leadscrew, and you can end up
with a drunken thread.
John Martin

Maybe you can answer something that's bugged me for a long time, John: Why
do the traditional lathe books say you should advance the cut when cutting
Acme threads by plunging straight in, rather than on the appropriate angle
for cutting one flank at a time? I don't recall ever having seen an
explanation.

--
Ed Huntress- Hide quoted text -

- Show quoted text -

Some may say that, some don't.

Machine Tool Operation, Burghardt:

"5. The side of an Acme thread is 14 1/2 deg., therefore move the
compound rest 14 1/2 deg. to the right when cutting a screw, to the
left when boring an internal thread. Set the thread stop and feed for
successive cuts by moving the compound-rest handle."

Perhaps the audience has something to do with it. Most of the machine
tool books were written by and for guys using big, heavy lathes. The
heavier the carriage, the less likely it is to jump ahead due to soft
spots in the work or the alignment of the planets. With a lighter
lathe, and less friction and mass in the carriage, it becomes more a
factor.

John Martin

[Ed Huntress]

"John Martin" wrote in message
...
On Apr 23, 11:07 am, "Ed Huntress" wrote:
"John Martin" wrote in message

...
On Apr 22, 2:04 am, "Ed Huntress" wrote:





When you cut threads by feeding straight in, you're cutting both flanks
of
the thread at once. That produces twice the tool load for a given depth
of
cut.

If you have a good lathe, your tools are sharp, and you're cutting
aluminum,
it may work just fine. But cutting clean internal threads depends on
getting
things pretty close to right, so the extra tool load is something to
watch
out for if you get some chatter.

--
Ed Huntress
Of more importance is that cutting on one flank loads the cutter
against the lead screw. Cutting both flanks at once, the carriage can
float instead on being driven by the leadscrew, and you can end up
with a drunken thread.
John Martin

Maybe you can answer something that's bugged me for a long time, John: Why
do the traditional lathe books say you should advance the cut when cutting
Acme threads by plunging straight in, rather than on the appropriate angle
for cutting one flank at a time? I don't recall ever having seen an
explanation.

--
Ed Huntress- Hide quoted text -

- Show quoted text -

Some may say that, some don't.

Machine Tool Operation, Burghardt:

"5. The side of an Acme thread is 14 1/2 deg., therefore move the
compound rest 14 1/2 deg. to the right when cutting a screw, to the
left when boring an internal thread. Set the thread stop and feed for
successive cuts by moving the compound-rest handle."

Perhaps the audience has something to do with it. Most of the machine
tool books were written by and for guys using big, heavy lathes. The
heavier the carriage, the less likely it is to jump ahead due to soft
spots in the work or the alignment of the planets. With a lighter
lathe, and less friction and mass in the carriage, it becomes more a
factor.

John Martin

Maybe. I just never could see why they'd recommend the angled cut for 60
deg. threads, and then the straight-in cut for Acme. It seems to me that the
Acme is going to produce a much heavier load on the tool.

I've only cut 10 tpi Acme threads (because I have only one Acme tap, and
it's 10 tpi), and it's not a big deal on my South Bend to cut those. But
bigger, coarser ones would be a real challenge.

--
Ed Huntress

[Bruce in Bangkok[_3_]]

On Wed, 23 Apr 2008 23:38:00 -0400, "Ed Huntress"
wrote:


"John Martin" wrote in message
...
On Apr 23, 11:07 am, "Ed Huntress" wrote:
"John Martin" wrote in message

...
On Apr 22, 2:04 am, "Ed Huntress" wrote:





When you cut threads by feeding straight in, you're cutting both flanks
of
the thread at once. That produces twice the tool load for a given depth
of
cut.

If you have a good lathe, your tools are sharp, and you're cutting
aluminum,
it may work just fine. But cutting clean internal threads depends on
getting
things pretty close to right, so the extra tool load is something to
watch
out for if you get some chatter.

--
Ed Huntress
Of more importance is that cutting on one flank loads the cutter
against the lead screw. Cutting both flanks at once, the carriage can
float instead on being driven by the leadscrew, and you can end up
with a drunken thread.
John Martin

Maybe you can answer something that's bugged me for a long time, John: Why
do the traditional lathe books say you should advance the cut when cutting
Acme threads by plunging straight in, rather than on the appropriate angle
for cutting one flank at a time? I don't recall ever having seen an
explanation.

--
Ed Huntress- Hide quoted text -

- Show quoted text -

Some may say that, some don't.

Machine Tool Operation, Burghardt:

"5. The side of an Acme thread is 14 1/2 deg., therefore move the
compound rest 14 1/2 deg. to the right when cutting a screw, to the
left when boring an internal thread. Set the thread stop and feed for
successive cuts by moving the compound-rest handle."

Perhaps the audience has something to do with it. Most of the machine
tool books were written by and for guys using big, heavy lathes. The
heavier the carriage, the less likely it is to jump ahead due to soft
spots in the work or the alignment of the planets. With a lighter
lathe, and less friction and mass in the carriage, it becomes more a
factor.

John Martin

Maybe. I just never could see why they'd recommend the angled cut for 60
deg. threads, and then the straight-in cut for Acme. It seems to me that the
Acme is going to produce a much heavier load on the tool.

I've only cut 10 tpi Acme threads (because I have only one Acme tap, and
it's 10 tpi), and it's not a big deal on my South Bend to cut those. But
bigger, coarser ones would be a real challenge.

I have roughed out large acme threads using the compound and finished
them with a form tool. But my guess (for whatever it is worth) is that
the reason you usually plunge cut acme threads is because they are
easier to measure that way. If you grind the tool correctly you just
jam her right in there until the calipers just slip over root diameter
and you're right.

The 60 degree threads are easy to eyeball because when they get pretty
sharp they are almost done.

Remember that a lot of the procedures were developed when things just
weren't as accurate or easy to measure. One example: Once you chucked
up a piece of stock you never, never, never, took it out of the
machine until it was finished and parted off. It was just too damned
hard to get it back in the chuck running true.


Bruce-in-Bangkok
(correct email address for reply)

[Ed Huntress]

"Bruce in Bangkok" wrote in message
...
On Wed, 23 Apr 2008 23:38:00 -0400, "Ed Huntress"
wrote:


"John Martin" wrote in message
...
On Apr 23, 11:07 am, "Ed Huntress" wrote:
"John Martin" wrote in message

...
On Apr 22, 2:04 am, "Ed Huntress" wrote:





When you cut threads by feeding straight in, you're cutting both
flanks
of
the thread at once. That produces twice the tool load for a given
depth
of
cut.

If you have a good lathe, your tools are sharp, and you're cutting
aluminum,
it may work just fine. But cutting clean internal threads depends on
getting
things pretty close to right, so the extra tool load is something to
watch
out for if you get some chatter.

--
Ed Huntress
Of more importance is that cutting on one flank loads the cutter
against the lead screw. Cutting both flanks at once, the carriage can
float instead on being driven by the leadscrew, and you can end up
with a drunken thread.
John Martin

Maybe you can answer something that's bugged me for a long time, John:
Why
do the traditional lathe books say you should advance the cut when
cutting
Acme threads by plunging straight in, rather than on the appropriate
angle
for cutting one flank at a time? I don't recall ever having seen an
explanation.

--
Ed Huntress- Hide quoted text -

- Show quoted text -

Some may say that, some don't.

Machine Tool Operation, Burghardt:

"5. The side of an Acme thread is 14 1/2 deg., therefore move the
compound rest 14 1/2 deg. to the right when cutting a screw, to the
left when boring an internal thread. Set the thread stop and feed for
successive cuts by moving the compound-rest handle."

Perhaps the audience has something to do with it. Most of the machine
tool books were written by and for guys using big, heavy lathes. The
heavier the carriage, the less likely it is to jump ahead due to soft
spots in the work or the alignment of the planets. With a lighter
lathe, and less friction and mass in the carriage, it becomes more a
factor.

John Martin

Maybe. I just never could see why they'd recommend the angled cut for 60
deg. threads, and then the straight-in cut for Acme. It seems to me that
the
Acme is going to produce a much heavier load on the tool.

I've only cut 10 tpi Acme threads (because I have only one Acme tap, and
it's 10 tpi), and it's not a big deal on my South Bend to cut those. But
bigger, coarser ones would be a real challenge.

I have roughed out large acme threads using the compound and finished
them with a form tool. But my guess (for whatever it is worth) is that
the reason you usually plunge cut acme threads is because they are
easier to measure that way. If you grind the tool correctly you just
jam her right in there until the calipers just slip over root diameter
and you're right.

The 60 degree threads are easy to eyeball because when they get pretty
sharp they are almost done.

Remember that a lot of the procedures were developed when things just
weren't as accurate or easy to measure. One example: Once you chucked
up a piece of stock you never, never, never, took it out of the
machine until it was finished and parted off. It was just too damned
hard to get it back in the chuck running true.


Bruce-in-Bangkok
(correct email address for reply)

'Sounds possible. I'll have to look into the old books sometime to see if
there's any comment on it. I really miss having access to the old
McGraw-Hill library, which contained all of the _American Machinist_
references back to the 1870s. I don't think their metalworking library even
exists anymore.

--
Ed Huntress

[John Martin]

On Apr 23, 11:38*pm, "Ed Huntress" wrote:
"John Martin" wrote in message

...
On Apr 23, 11:07 am, "Ed Huntress" wrote:





"John Martin" wrote in message

...
On Apr 22, 2:04 am, "Ed Huntress" wrote:

When you cut threads by feeding straight in, you're cutting both flanks
of
the thread at once. That produces twice the tool load for a given depth
of
cut.

If you have a good lathe, your tools are sharp, and you're cutting
aluminum,
it may work just fine. But cutting clean internal threads depends on
getting
things pretty close to right, so the extra tool load is something to
watch
out for if you get some chatter.

--
Ed Huntress
Of more importance is that cutting on one flank loads the cutter
against the lead screw. Cutting both flanks at once, the carriage can
float instead on being driven by the leadscrew, and you can end up
with a drunken thread.
John Martin

Maybe you can answer something that's bugged me for a long time, John: Why
do the traditional lathe books say you should advance the cut when cutting
Acme threads by plunging straight in, rather than on the appropriate angle
for cutting one flank at a time? I don't recall ever having seen an
explanation.

--
Ed Huntress- Hide quoted text -

- Show quoted text -
Some may say that, some don't.
Machine Tool Operation, Burghardt:
"5. The side of an Acme thread is 14 1/2 deg., therefore move the
compound rest 14 1/2 deg. to the right when cutting a screw, to the
left when boring an internal thread. *Set the thread stop and feed for
successive cuts by moving the compound-rest handle."
Perhaps the audience has something to do with it. *Most of the machine
tool books were written by and for guys using big, heavy lathes. *The
heavier the carriage, the less likely it is to jump ahead due to soft
spots in the work or the alignment of the planets. *With a lighter
lathe, and less friction and mass in the carriage, it becomes more a
factor.
John Martin

Maybe. I just never could see why they'd recommend the angled cut for 60
deg. threads, and then the straight-in cut for Acme. It seems to me that the
Acme is going to produce a much heavier load on the tool.

I've only cut 10 tpi Acme threads (because I have only one Acme tap, and
it's 10 tpi), and it's not a big deal on my South Bend to cut those. But
bigger, coarser ones would be a real challenge.

--
Ed Huntress- Hide quoted text -

- Show quoted text -

Not at all sure who your "they" is, Ed. As I quoted, Burghardt - who
is certainly among the top few most widely read of the machine tool
writers - said to set the compound to the flank angle and feed with
it.

Bruce may be on to something with regard to the measurements. For 60
degree V threads, with the compound set to 30 degrees, it's pretty
easy to figure the compound feed necessary to hit full thread depth -
it's the same as the pitch. No fussing with trig tables.

Again, though, it seems that not all the writers said the same thing.

John Martin

[Ed Huntress]

"John Martin" wrote in message
...
On Apr 23, 11:38 pm, "Ed Huntress" wrote:
"John Martin" wrote in message

...
On Apr 23, 11:07 am, "Ed Huntress" wrote:





"John Martin" wrote in message

...
On Apr 22, 2:04 am, "Ed Huntress" wrote:

When you cut threads by feeding straight in, you're cutting both
flanks
of
the thread at once. That produces twice the tool load for a given
depth
of
cut.

If you have a good lathe, your tools are sharp, and you're cutting
aluminum,
it may work just fine. But cutting clean internal threads depends on
getting
things pretty close to right, so the extra tool load is something to
watch
out for if you get some chatter.

--
Ed Huntress
Of more importance is that cutting on one flank loads the cutter
against the lead screw. Cutting both flanks at once, the carriage can
float instead on being driven by the leadscrew, and you can end up
with a drunken thread.
John Martin

Maybe you can answer something that's bugged me for a long time, John:
Why
do the traditional lathe books say you should advance the cut when
cutting
Acme threads by plunging straight in, rather than on the appropriate
angle
for cutting one flank at a time? I don't recall ever having seen an
explanation.

--
Ed Huntress- Hide quoted text -

- Show quoted text -
Some may say that, some don't.
Machine Tool Operation, Burghardt:
"5. The side of an Acme thread is 14 1/2 deg., therefore move the
compound rest 14 1/2 deg. to the right when cutting a screw, to the
left when boring an internal thread. Set the thread stop and feed for
successive cuts by moving the compound-rest handle."
Perhaps the audience has something to do with it. Most of the machine
tool books were written by and for guys using big, heavy lathes. The
heavier the carriage, the less likely it is to jump ahead due to soft
spots in the work or the alignment of the planets. With a lighter
lathe, and less friction and mass in the carriage, it becomes more a
factor.
John Martin

Maybe. I just never could see why they'd recommend the angled cut for 60
deg. threads, and then the straight-in cut for Acme. It seems to me that
the
Acme is going to produce a much heavier load on the tool.

I've only cut 10 tpi Acme threads (because I have only one Acme tap, and
it's 10 tpi), and it's not a big deal on my South Bend to cut those. But
bigger, coarser ones would be a real challenge.

--
Ed Huntress- Hide quoted text -

- Show quoted text -

Not at all sure who your "they" is, Ed. As I quoted, Burghardt - who
is certainly among the top few most widely read of the machine tool
writers - said to set the compound to the flank angle and feed with
it.

I don't remember which books, John. It may have been the Atlas or South Bend
lathe books. If I think of it I'll look for it and see what they say. It's
been years since I've looked.


Bruce may be on to something with regard to the measurements. For 60
degree V threads, with the compound set to 30 degrees, it's pretty
easy to figure the compound feed necessary to hit full thread depth -
it's the same as the pitch. No fussing with trig tables.

Again, though, it seems that not all the writers said the same thing.

John Martin

--
Ed Huntress

[Bruce in Bangkok[_3_]]

On Thu, 24 Apr 2008 05:59:54 -0700 (PDT), John Martin
wrote:

On Apr 23, 11:38*pm, "Ed Huntress" wrote:
"John Martin" wrote in message

...
On Apr 23, 11:07 am, "Ed Huntress" wrote:





"John Martin" wrote in message

...
On Apr 22, 2:04 am, "Ed Huntress" wrote:

When you cut threads by feeding straight in, you're cutting both flanks
of
the thread at once. That produces twice the tool load for a given depth
of
cut.

If you have a good lathe, your tools are sharp, and you're cutting
aluminum,
it may work just fine. But cutting clean internal threads depends on
getting
things pretty close to right, so the extra tool load is something to
watch
out for if you get some chatter.

--
Ed Huntress
Of more importance is that cutting on one flank loads the cutter
against the lead screw. Cutting both flanks at once, the carriage can
float instead on being driven by the leadscrew, and you can end up
with a drunken thread.
John Martin

Maybe you can answer something that's bugged me for a long time, John: Why
do the traditional lathe books say you should advance the cut when cutting
Acme threads by plunging straight in, rather than on the appropriate angle
for cutting one flank at a time? I don't recall ever having seen an
explanation.

--
Ed Huntress- Hide quoted text -

- Show quoted text -
Some may say that, some don't.
Machine Tool Operation, Burghardt:
"5. The side of an Acme thread is 14 1/2 deg., therefore move the
compound rest 14 1/2 deg. to the right when cutting a screw, to the
left when boring an internal thread. *Set the thread stop and feed for
successive cuts by moving the compound-rest handle."
Perhaps the audience has something to do with it. *Most of the machine
tool books were written by and for guys using big, heavy lathes. *The
heavier the carriage, the less likely it is to jump ahead due to soft
spots in the work or the alignment of the planets. *With a lighter
lathe, and less friction and mass in the carriage, it becomes more a
factor.
John Martin

Maybe. I just never could see why they'd recommend the angled cut for 60
deg. threads, and then the straight-in cut for Acme. It seems to me that the
Acme is going to produce a much heavier load on the tool.

I've only cut 10 tpi Acme threads (because I have only one Acme tap, and
it's 10 tpi), and it's not a big deal on my South Bend to cut those. But
bigger, coarser ones would be a real challenge.

--
Ed Huntress- Hide quoted text -

- Show quoted text -

Not at all sure who your "they" is, Ed. As I quoted, Burghardt - who
is certainly among the top few most widely read of the machine tool
writers - said to set the compound to the flank angle and feed with
it.

Bruce may be on to something with regard to the measurements. For 60
degree V threads, with the compound set to 30 degrees, it's pretty
easy to figure the compound feed necessary to hit full thread depth -
it's the same as the pitch. No fussing with trig tables.

Again, though, it seems that not all the writers said the same thing.

John Martin

Shoot man! you don't need to measure it just eye ball it :-)

Reminds me of the part time job I took with a gunsmith in Shreveport
LA. The first job he gave me was to make a couple of stub axles to
weld in a piece of sch 80 pipe to make a boat trailer axle. I roughed
out the first one and set up the threading tool. Roughing pass,
finishing pass - upps just a little tight so made a light cut to
finish. Parted it off and started the second one. Got it ready to
thread, set the tool; first pass, second pass, tried the nut and
parted it off. Finished!

An hour or so later the Boss sidled over and sort of out of the corner
of his mouth asked me, "how'd you know those nuts were going to fit on
them axles?" I looked him right in the eye and said, "experience."

I tell you, from that day on if I said it went this a way then the
Boss pointed and said Go!

Probably if I'd a told the truth and said "blind luck", he wouldn't
have been so impressed :-)


Bruce-in-Bangkok
(correct email address for reply)

[Mark Rand]

On Thu, 24 Apr 2008 20:51:35 +0700, Bruce in Bangkok
wrote:




An hour or so later the Boss sidled over and sort of out of the corner
of his mouth asked me, "how'd you know those nuts were going to fit on
them axles?" I looked him right in the eye and said, "experience."

I tell you, from that day on if I said it went this a way then the
Boss pointed and said Go!

Probably if I'd a told the truth and said "blind luck", he wouldn't
have been so impressed :-)


Bruce-in-Bangkok
(correct email address for reply)



ROFLMAO :-)


Mark Rand
RTFM