On 6 August 2018 at 03:36, Gene Heskett <[email protected]> wrote:

> Tool paths (corrected) are I assume to be the nearest of the 8 positions,
> or are those actually calculated from data in the tool table (and fussed
> about if obviously wrong I hope.

Tool radius correction is based entirely on the stated tool
orientation in the tool table.
It take no account of the stated front and back angles.
If you want an orientation 2 tool with the cutter flanks pointing back
in to the work then Axis will cheerfully render that for you while at
the same time the motion planner will do radius compensation for an
orientation 2 tool.

The tool controlled point can only be at 9 positions relative to the
centre point of the tool tip radius. This has very little to do with
the flank angles. It is more related to which quadrants of a notional
full-circle tool are in use.
For example orienation 2 (right hand facing and turning) expects to be
touching at 12-o-clock when moving purely in Z and at 9-o-clock when
facing in X. If moving in some combination then the tool will be moved
a little bit closer to the work to compensate for the gap between the
controlled point and the tool tip that exists between those two
tangents.

For the vast majority of lathe work cutter comp is not important. The
positions of  shoulders and absolute diameters are unaffected. Tapers
will end up a little fatter than drawn and both external and internal
fillets will have extra material. The latter vary rarely matters, and
the former normally seem to need some tweaking-to-fit anyway, so I run
with cutter-comp turned off nearly all the time.
If I was machining accurate spheres then things would be different.


-- 
atp
"A motorcycle is a bicycle with a pandemonium attachment and is
designed for the especial use of mechanical geniuses, daredevils and
lunatics."
— George Fitch, Atlanta Constitution Newspaper, 1916

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