"Harold and Susan Vordos" wrote in message
...

"Jerry Foster" wrote in message
om...
What is the material? I have a hunk of steel round of indeterminate
ancestry (probably hot rolled...) that cuts like a piece of concrete
and,
no
matter what I do, I can't get a decent finish on it. OTOH, other
materials
cut beautifully, using the same setup...

Jerry


Chuckle!

Hot rolled? That's not a material, it's a method of producing material.
It could be 1020 or 4340 just as easily.

From the description, what you have is chrome-moly. It likes to tear and
will usually yield a good finish only when run fast enough with carbide.
If you're using carbide and getting a finish that varies between shiny
spots
and torn spots, you're likely using the wrong grade of carbide and
experiencing premature tip failure.

Harold.


I understand "hot rolled" is a method, not a specific material. My basic
point was, however, that different materials cut VERY differently and, if
you try to use materials of "indeterminate ancestry," you never know quite
what you are getting into. And, for the benefit of the original poster of
the question, unless you know what the specific material is, it is difficult
to suggest an approach to machining it (or even if it can be satisfactorily
machined for the application...).

But hot rolled steels are, in general, much less uniform in hardness (hard
spots and soft spots) and tend to machine poorly. Most of the more
"machinable" steels are cold rolled. Your friendly metal dealer will tell
you he mostly sells cold rolled steels to machine shops and (cheaper) hot
rolled steels to welding shops...

Jerry