Musing about steels for woodturners. (still way too long)
 

I started this thread late last night and figured I'd better read it
again. Before reading it put me to sleep, I remembered that softer
material can penetrate harder material at high velocity. A straw driven
into a fence post during a hurricane, etc. I've seen aluminum, wooden
and plastic knives, but I was musing about cutting wood, not about
straws in a hurricane or opening envelopes or slicing pie. :)

I hope not to mislead anyone further by adding another chapter to my
primer, but
forget tool and timber variables for now and consider the effect of
turning technic on the length of time _any tool's edge, cheap or
expensive, will remain sharp before it needs resharpening. I know from
messing about with my metal lathe that "cutting speed" is important re a
tool bit's edge life. As much or more than feed or depth of cut. I don't
see why this wouldn't apply to turning wood.

It's obvious, but important to remember that the cutting speed (how fast
the wood moves past the tool's edge) is not the same as the spindle
speed. (ok, I guess it is if the blank's diameter is the same as the
spindle's) It may not be the same thing, but spindle speed sure plays a
large part in determining cutting speed and we can control spindle speed
and thus to a large extent the life of a tool edge. To belabor the point
and not say in one word what I can usually say in ten, I think turning
at slower spindle speeds will prolong the edge life of any turning tool
and it's free and easy to do. Or you could just make resharpening easier
and more convenient and turn up the speed. Naw!

Another spec. often listed for turning tools that might confuse a few of
us is that mysterious number, the Rockwell C. This is just a number
with no units that indicates how deep the steel can be penetrated by a
ball or cone forced under a specific load. IOW, it indicates how hard
(resistance to deformation) the steel was tempered to. The higher the
number the harder the steel, usually limited by the steel becoming more
brittle.

Please remember that this is just one turner's primer. Don't take it to
the bank and try to deposit it. :)


Turn to Safety, Arch
Fortiter


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