[Randy333]

I need to do some thread milling, never did it before!! I need to cut
2- 1-1/4"-11.5 NPS exteranl threads, a 1-3/4"-16 external and a
1-7/8"-18 internal thread.

I found a thread mill for 11.5 NPS but in the catalog it's listed as
internal only, why? Any place I can get this at under $300 bucks that
MSC wants?

Remove 333 to reply.
Randy

[F. George McDuffee]

On Fri, 13 Jan 2012 16:01:25 -0500, Randy333
wrote:

I need to do some thread milling, never did it before!! I need to cut
2- 1-1/4"-11.5 NPS exteranl threads, a 1-3/4"-16 external and a
1-7/8"-18 internal thread.

I found a thread mill for 11.5 NPS but in the catalog it's listed as
internal only, why? Any place I can get this at under $300 bucks that
MSC wants?

Remove 333 to reply.
Randy
====================
If these are one off you may consider a single point tool or
boring bar with formed cutter. Slow machining but cheap
tooling. Should also be good for special profile threads
like stub acme or buttress.

See

http://www.homemodelenginemachinist....p?topic=9964.0

http://www.cnczone.com/forums/tormac...d_milling.html

http://www.practicalmachinist.com/vb...source-151206/

and a bunch more. Google on single-point "thread milling"
for 55.8k hits.


--
Unka' George

"Gold is the money of kings,
silver is the money of gentlemen,
barter is the money of peasants,
but debt is the money of slaves"

-Norm Franz, "Money and Wealth in the New Millenium"

[anorton]

"Randy333" wrote in message
...
I need to do some thread milling, never did it before!! I need to cut
2- 1-1/4"-11.5 NPS exteranl threads, a 1-3/4"-16 external and a
1-7/8"-18 internal thread.

I found a thread mill for 11.5 NPS but in the catalog it's listed as
internal only, why? Any place I can get this at under $300 bucks that
MSC wants?

Remove 333 to reply.
Randy

I have never done anything like this either, but I could see that a tool
meant to cut right-hand internal threads would work better for left-hand
external threads than right-hand external (think about the slope direction
of an external thread versus and internal as you look at it from the
cutter's point of view.)

[F. George McDuffee]

On Fri, 13 Jan 2012 15:17:38 -0600, F. George McDuffee
wrote:

On Fri, 13 Jan 2012 16:01:25 -0500, Randy333
wrote:

I need to do some thread milling, never did it before!! I need to cut
2- 1-1/4"-11.5 NPS exteranl threads, a 1-3/4"-16 external and a
1-7/8"-18 internal thread.

I found a thread mill for 11.5 NPS but in the catalog it's listed as
internal only, why? Any place I can get this at under $300 bucks that
MSC wants?

Remove 333 to reply.
Randy
====================
If these are one off you may consider a single point tool or
boring bar with formed cutter. Slow machining but cheap
tooling. Should also be good for special profile threads
like stub acme or buttress.

See

http://www.homemodelenginemachinist....p?topic=9964.0

http://www.cnczone.com/forums/tormac...d_milling.html

http://www.practicalmachinist.com/vb...source-151206/

and a bunch more. Google on single-point "thread milling"
for 55.8k hits.
==============
For some videos see
http://www.youtube.com/watch?v=pQ83XRgRCyg
http://www.youtube.com/watch?v=nQgjmRyfNCs
http://www.youtube.com/watch?v=w54DywBujVU

external thread milling on a mill
http://www.youtube.com/watch?v=Dlz0EUq6k9M

home made lathe insert thread mill
http://www.youtube.com/watch?v=TUaNEgoKgKw


--
Unka' George

"Gold is the money of kings,
silver is the money of gentlemen,
barter is the money of peasants,
but debt is the money of slaves"

-Norm Franz, "Money and Wealth in the New Millenium"

[Bob La Londe[_2_]]

"Randy333" wrote in message
...
I need to do some thread milling, never did it before!! I need to cut
2- 1-1/4"-11.5 NPS exteranl threads, a 1-3/4"-16 external and a
1-7/8"-18 internal thread.

I found a thread mill for 11.5 NPS but in the catalog it's listed as
internal only, why? Any place I can get this at under $300 bucks that
MSC wants?

Remove 333 to reply.
Randy

JTS Machinery has single point thread mills at a fair price last time I
looked. Might be slower, but it will work.

[Jon Elson[_3_]]

F. George McDuffee wrote:

On Fri, 13 Jan 2012 16:01:25 -0500, Randy333
wrote:

I need to do some thread milling, never did it before!! I need to cut
2- 1-1/4"-11.5 NPS exteranl threads, a 1-3/4"-16 external and a
1-7/8"-18 internal thread.

I found a thread mill for 11.5 NPS but in the catalog it's listed as
internal only, why? Any place I can get this at under $300 bucks that
MSC wants?

Remove 333 to reply.
Randy
====================
If these are one off you may consider a single point tool or
boring bar with formed cutter. Slow machining but cheap
tooling. Should also be good for special profile threads
like stub acme or buttress.

There are single-row thread mills that can do a fair range of thread pitches
with one tool. They generally are cheaper than true threadmills, too.
I have a small Micro-100 single row threadmill, and it works great.
I have only done internal threads, but I think that tool should be able
to do either.

Jon

[[email protected]]

On Fri, 13 Jan 2012 16:01:25 -0500, Randy333
wrote:

I need to do some thread milling, never did it before!! I need to cut
2- 1-1/4"-11.5 NPS exteranl threads, a 1-3/4"-16 external and a
1-7/8"-18 internal thread.

I found a thread mill for 11.5 NPS but in the catalog it's listed as
internal only, why? Any place I can get this at under $300 bucks that
MSC wants?

Remove 333 to reply.
Randy

eBay is my friend. Taks time, but i buy threadmills for peanuts. I
needed 1.5mm for an RPD receiver. Just scored four brand new ones for
$99.

For external, get an insert threadmill holder and inserts. You can get
the holders any day of the weed on the bay. You may have to buy the
11.5 NPS insert from MSC.

Karl

[MadHatter]

On Jan 13, 1:01*pm, Randy333 wrote:
I need to do some thread milling, never did it before!! *I need to cut
2- 1-1/4"-11.5 NPS exteranl threads, a 1-3/4"-16 external and a
1-7/8"-18 internal thread.

I found a thread mill for 11.5 NPS but in the catalog it's listed as
internal only, why? *Any place I can get this at under $300 bucks that
MSC wants?

Remove 333 to reply.
Randy

I'm going to guess that it pertains to the smaller percentage of
thread when cutting internal. If that is correct, then using a thread
mill designed for internal cutting should produce a truncated root
when used to mill external threads.

[MadHatter]

On Jan 13, 1:23*pm, "anorton"
wrote:
"Randy333" wrote in message

...

I need to do some thread milling, never did it before!! *I need to cut
2- 1-1/4"-11.5 NPS exteranl threads, a 1-3/4"-16 external and a
1-7/8"-18 internal thread.

I found a thread mill for 11.5 NPS but in the catalog it's listed as
internal only, why? *Any place I can get this at under $300 bucks that
MSC wants?

Remove 333 to reply.
Randy

I have never done anything like this either, but I could see that a tool
meant to cut right-hand internal threads would work better for left-hand
external threads than right-hand external (think about the slope direction
of an external thread versus and internal as you look at it from the
cutter's point of view.)

You would use the same tool to mill either left or right hand
threads. The only thing that changes is the direction of the helix.

[anorton]

"MadHatter" wrote in message
...
On Jan 13, 1:23 pm, "anorton"
wrote:
"Randy333" wrote in message

...

I need to do some thread milling, never did it before!! I need to cut
2- 1-1/4"-11.5 NPS exteranl threads, a 1-3/4"-16 external and a
1-7/8"-18 internal thread.

I found a thread mill for 11.5 NPS but in the catalog it's listed as
internal only, why? Any place I can get this at under $300 bucks that
MSC wants?

Remove 333 to reply.
Randy

I have never done anything like this either, but I could see that a tool
meant to cut right-hand internal threads would work better for left-hand
external threads than right-hand external (think about the slope direction
of an external thread versus and internal as you look at it from the
cutter's point of view.)

You would use the same tool to mill either left or right hand
threads. The only thing that changes is the direction of the helix.
------------------------------------------------------------------

I see you are right. As an amateur machinist I was under the mistaken
impression that thread mills with multiple cutting rows had a helical pich
to them like taps.

Looking into the reason for different internal and external cutters I see
that the UTS spec has different profiles for internal and external threads.
I guess you could cut both with the same cutter if you did not mind extra
open space at the root of the external thread.
http://en.wikipedia.org/wiki/File:IS...Dimensions.svg