G'day George,

I have to disagree with what you have presented. I'll let anyone
reading the posts decide what to accept and what to dismiss. Further,
I see little benefit is likely when you have to commence with sweeping
unsupported statements about the poster's knowledge and lead off with
a selected edit from a longer post.

Are you suggesting that a well sharpened tool will cut wood fibres
cleanily and equally at any lathe speed? Please advise which law of
physics you are relying upon that describes the energy necessary for
the cut to take place? I assume it must be independent of timber's
surface velocity and derive the energy from some other source (since
the cutting tip of the tool is stationary).

A given amount of energy is required to cut a fibre cleanly without
causing significant subsurface damage (pulling the fibre as it cuts).
Stop here and consider if this is correct or false in a real turning
exercise rather than with one cut from a freshly sharpened carving
tool. I believe it is true, others may not.

Subsurface damage is harder to repair than a clean, even rippled cut
so I'd opt for a speed that will more cleanly cut the fibres. Taking
this to the next stage, at some velocity, the energy available will be
below that necessary to cleanly cut the fibres. This follows as a
logical statement if you thought the earlier statement was considered
to be true.

You cannot keep a "carver's" quality edge on a turning tool so any
comparisons other than to compare edge sharpness of each are not
really a useful example when discussing turning. Obviously a tool
sharpened for carving will cut the fibres as you push. Sounds nice
but take a few cuts into a piece of jarrah with the tool and it won't
have such a keen edge for long.

I'm unsure what was meant by, "a couple of strange turning ideas" as I
doubt I would be alone with the views contained in the section of my
earlier post you copied.

Regards,
Alan

On Sat, 10 Sep 2005 09:03:16 -0400, "George" George@least wrote:


"Alan" wrote in message
.. .
G'day Arch,

I can't disagree with the points you make. My main reason for posting
was to refute any suggestion that speed should always be at the low
end for safety. Whilst turning at a speed too fast for a given blank
is dangerous, I don't believe turning at half the optimum speed is
significantly safer and I know the surface finish will probably be
poorer.


You haven't refuted a thing. You have demonstrated that you don't
understand the laws of physics, and you have a couple of strange turning
ideas beyond that.

As stated, more energy is available to the turning at faster speeds. Only a
dull tool cuts better at faster speed, or a tool presented to poke and rip
rather than cut and peel . Sharp tools cut well at any speed when properly
presented. The quality of the cut determines the quality of the surface
left behind. Sharpen your jackknife and whittle a bit and see if your best
cut happens at higher speed - or your carving tools. See if they don't
out-perform your turning tools even at near zero relative velocity. It's
the edge that cuts, and the timber that determines the energy required to do
the job. Velocity beyond that required to maintain a cut is unnecessary and
increases the potential for dismounts, the distance disconnecting pieces may
be thrown, and turning pressure on an improperly presented tool.

Do you find it more difficult to make a cut at the bottom of a bowl than at
its edge?