On Tue, 23 Apr 2013 09:55:45 -0400, Ed Huntress
wrote:

On Tue, 23 Apr 2013 09:40:16 -0400, Ned Simmons
wrote:

On Mon, 22 Apr 2013 12:27:00 -0400, Ed Huntress
wrote:

On Mon, 22 Apr 2013 07:59:29 +0700, J.B.Slocomb
wrote:

On Sun, 21 Apr 2013 12:06:48 GMT, wrote:

The rod needs to be smooth except for the threads. I will check the die, it
was $40 which is all I know about it. I did taper the end. It will be used
on a boat, not sure what as this is something for my father. But it can't
stain the wood. I do have a woodworkers lathe which I assume is useless. My
father is 90 so I am just trying to keep him happy.

If it is for a boat then use 316 stainless as it is far more
"stainless" than other common stainless :-)

As for threading. Try to file the end of the rod that you are planning
on threading. If a file cuts it easily than your problem is the vise
not the threading.


On 20-Apr-2013, wrote:

Looking for 1/4" metal rod I can thread. These will be attached to wood so
rusting or staining can be a problem since they will be outside. Got a
piece of stainless, the softess I could get but it is too hard to thread,
have a good vise but with all the pressure It won't hold in the vise. Even
bought a new die and tapered the end first. Had tried aluminum but it
makes
dark stains. Not into metal stuff so don't know what to look for. Maybe
something coated? Thanks.

As JB says, 316 stainless if you want it to be stain-free.

I didn't notice if this is for fresh water or salt, but if it is for
salt water use and it has any load on it, anything but 316 will
develop stress-corrosion effects that can drive you nuts. Even if
strength isn't an issue, a stressed piece of 304 in salt water will
probably get rust spots or streaks on it.

Sure you're not mixing up stress corrosion and crevice corrosion? Both
304 and 316 are prone to stress corrosion. 316 does resist crevice
corrosion and pitting better than 304.

Stress corrosion is blamed for rusting of sailboat rigging and similar
applications. It's not something I learned from materials science but
rather something I learned as a sailor. I don't know what the
mechanism is. But the story is that 304 gives problems, and 316 does
not. I've seen it, but the descriptions come from experieced boating
people I've known, not from materials scientists.

I worked in boatyards for several years after college, then ran a
custom marine hardware fab business for several more years. It drove
me nuts that it seemed the answer to every materials question was "316
SS," even from folks I had a lot of respect for.

This is what the corrosion volume of the ASM Handbook says regarding
304/316 and stress corrosion:
"The common austenitic grades, AISI types 304 and 316, are
especially susceptible to chloride SCC."

But it also says that stress corrosion is generally not a problem in
the environment that standing rigging is typically exposed to:
"Stress-corrosion cracking is generally not a concern when austenitic
or ferritic stainless steels are used in atmospheric
exposures. Several austenitic stainless steels were exposed to a
marine atmosphere at Kure Beach, NC. Annealed and
quarter-hard wrought AISI types 201, 301, 302, 304, and 316 stainless
steels were not susceptible to SCC."


As far as cosmetic rust spots go in a marine environment, for stuff
out in the open and above the water line, the finish can make a bigger
impact on rust spotting than the the difference between 304 and 316.
It's tough to distinguish between 304 and 316 for parts that are
highly polished and not exposed to stagnant water.

I don't have experience with that, but I'll take your word for it.
Passivating and the quality of the steel are issues, too.


--
Ned Simmons