I ran across a similar problem to the guy with the aluminum the other day.
During my lathe experiments to make a pivot pin for my knife I discovered I
didn't have any stainless nuts the right size for my pin. No big deal I
thought. I'll just make one. I drilled out a piece of the same stainless
bolt I used to make the pivot pin and then tried to tap it. Holy cow. Talk
about tight. Never could get all the way down to the free spin section on
the tap. I did get far enough to get it on my pin, but it started me
thinking. Is there a best way to drill work hardening materials to minimize
hardening so you can tap it easily?

There are a bunch of little tools and fixtures I have in my gonna build it
when I need it plans that will require drilling and tapping as part of the
assembly.

Bob La Londe wrote:
I ran across a similar problem to the guy with the aluminum the other
day. During my lathe experiments to make a pivot pin for my knife I
discovered I didn't have any stainless nuts the right size for my pin.
No big deal I thought. I'll just make one. I drilled out a piece of
the same stainless bolt I used to make the pivot pin and then tried to
tap it. Holy cow. Talk about tight. Never could get all the way down
to the free spin section on the tap. I did get far enough to get it on
my pin, but it started me thinking. Is there a best way to drill work
hardening materials to minimize hardening so you can tap it easily?

There are a bunch of little tools and fixtures I have in my gonna build
it when I need it plans that will require drilling and tapping as part
of the assembly.

Very sharp drills, feed it hard, about 20-30 SFPM for HSS drills, heavy oil.


--
Steve Walker
(remove wallet to reply)

On Jan 5, 7:10*pm, "Bob La Londe" wrote:
I ran across a similar problem to the guy with the aluminum the other day..
During my lathe experiments to make a pivot pin for my knife I discovered I
didn't have any stainless nuts the right size for my pin. *No big deal I
thought. *I'll just make one. *I drilled out a piece of the same stainless
bolt I used to make the pivot pin and then tried to tap it. *Holy cow. *Talk
about tight. *Never could get all the way down to the free spin section on
the tap. *I did get far enough to get it on my pin, but it started me
thinking. *Is there a best way to drill work hardening materials to minimize
hardening so you can tap it easily?

There are a bunch of little tools and fixtures I have in my gonna build it
when I need it plans that will require drilling and tapping as part of the
assembly.

When tapping stainless, use the next size larger drill. Threads will
still hold quite well, and you will avoid the scars from broken taps.

Paul

wrote:


When tapping stainless, use the next size larger drill. Threads will
still hold quite well, and you will avoid the scars from broken taps.

Paul


NOW ya tell me. Too late, of course.
This thread would have saved me several taps this summer trying to tap stainless
to add fittings...

But now I know!

--

Richard Lamb
http://www.home.earthlink.net/~cavelamb/


"The clock of life is wound but once, and no man has the power
to tell just when the hands will stop, at late or early hour...
Now is the only time you own. Live, love, toil with a will.
Place no faith in time. For the clock may soon be still."

On Jan 6, 6:53*am,
wrote:

When tapping stainless, use the next size larger drill. Threads will
still hold quite well, and you will avoid the scars from broken taps.

Paul
--


This will give you a lot of information on machining stainless
steels. A lot of the information also applies to any machining.

Guide to Machining Carpenter Specialty Alloys

http://www.cartech.com/productliterature.aspx

Dan

spaco wrote:
Yes, and now try to take that nut off! A rule of thumb is to never use
a nut of the same stainless material as the bolt.

Sometimes it can't be helped. Years ago I worked
on some high vacuum gear. All stainless fasteners.
The easy fix is a small drop of some kind of lubricant.
All I had was some vacuum grease, but it worked fine.