Hi, All:
I have a piece of SS tubing approx 11/16 Dia that I need to thread
externally. It is critical that the threads be coincentric with the bore and
it is physically impossible to put this assembly in a lathe (It's part of
something else that does NOT come apart. I have about 4.5" of tube sticking
out to work with and need to thread the first one inch (The end that's
sticking out into the air). The surface it enters is not perpendicular and
quite rough. I can't get my mind beyond using a die to cut the threads but am
stumped on how to achieve concentricity.

Any ideas appreciated.

In article t,
Roger Hull wrote:

Hi, All:
I have a piece of SS tubing approx 11/16 Dia that I need to thread
externally. It is critical that the threads be coincentric with the bore and
it is physically impossible to put this assembly in a lathe (It's part of
something else that does NOT come apart. I have about 4.5" of tube sticking
out to work with and need to thread the first one inch (The end that's
sticking out into the air). The surface it enters is not perpendicular and
quite rough. I can't get my mind beyond using a die to cut the threads but am
stumped on how to achieve concentricity.

Any ideas appreciated.

Guide rod down the center of the tube? Give it a shoulder with a
diameter just big enough to touch the teeth of a die.

--
B.B. --I am not a goat! thegoat4 at airmail.net

In article 0001HW.BD6E4B66041FF38F01E89600
@nntp.velocitus.net, says...
Hi, All:
I have a piece of SS tubing approx 11/16 Dia that I need to thread
externally. It is critical that the threads be coincentric with the bore and
it is physically impossible to put this assembly in a lathe (It's part of
something else that does NOT come apart. I have about 4.5" of tube sticking
out to work with and need to thread the first one inch (The end that's
sticking out into the air). The surface it enters is not perpendicular and
quite rough. I can't get my mind beyond using a die to cut the threads but am
stumped on how to achieve concentricity.

Any ideas appreciated.


Is is actually necessary that the 11/16 tube be threaded?
Could you get away with threading the OD of a sleeve with
an 11/16 ID and slipping it over the tube? Weld, Loctite,
or pin to fasten it.

If the tube's wall is heavy enough, and the assembly isn't
too large to mount on a mill to groove the tube OD(or if it
is very large, a boring mill), then these might work:

http://www.meibuhr.com/thr.htm

The threads match standard bearing locknuts.

Ned Simmons

you could make a pilot that is a tight fit in the bore and threaded on the
od to start your die from , not the best but has worked for me in the past

On Wed, 15 Sep 2004 20:22:20 -0700, Ned Simmons wrote
(in message ):

In article 0001HW.BD6E4B66041FF38F01E89600
@nntp.velocitus.net, says...

Is is actually necessary that the 11/16 tube be threaded?
Could you get away with threading the OD of a sleeve with
an 11/16 ID and slipping it over the tube? Weld, Loctite,
or pin to fasten it.

Ned Simmons

Excellent suggestion! My undying thanks.

Roger Hull wrote:
Hi, All:
I have a piece of SS tubing approx 11/16 Dia that I need to thread
externally. It is critical that the threads be coincentric with the bore and
it is physically impossible to put this assembly in a lathe (It's part of
something else that does NOT come apart. I have about 4.5" of tube sticking
out to work with and need to thread the first one inch (The end that's
sticking out into the air). The surface it enters is not perpendicular and
quite rough. I can't get my mind beyond using a die to cut the threads but am
stumped on how to achieve concentricity.
If you have a CNC mill, you could locate over the tube with a CO-Ax
indicator or dial test indicator and indi-col, and then thread mill the
threads. I use a Micro-100 single row thread mill for these unusual
jobs.

Jon