```From: sslREMOVETHIS@loganact.com (Scott S. Logan)
Newsgroups: rec.crafts.metalworking
Subject: Re: Enco's solution, Metric vs Imperial
Date: 3 Oct 1998 14:31:55 GMT

On Sat, 03 Oct 1998 16:27:40 GMT, fred@fvfowler.com (Fred fowler III)
wrote:

>So sorry to say, Z is the vertical axis. In most practices, X is left
>to right, Y front to back, and Z up and down. It gets more complicated
>with rotary tables, indexing heads and the like, but basic XYZ has
>never changed.

Umm, Fred, sorry, but you are a little off on this one.

Z axis is ALWAYS the axis along which the primary spindle is.  With a
vertical mill, this would be the vertical axis.  With a horizontal
mill, it would be front to back, and on a Lathe, it is left to right.

The X axis is generally the axis remaining, with the longest travel,
and at right angles to the Z axis.

The Y axis is the last remaining axis at 90 degrees to the Z.

Axes U, V, and W are sub-sets of the above (U-X, V-Y, and W-Z).
Sometimes these are actual axes, such as the knee on a vertical mill
(usually the W), or sometimes, these are incremental movements of the
primary axes.

Rotational axes are A, B, and C.  A would be rotation around X, B
around Y, and C around Z.  A rotary table mounted on the table of a
vertical mill, with the plane of it's table in the horizontal plane,
would be a C axis.  If the rotary table is mounted with the plane of
the table vertical, and the face of the table pointing towards your
right, it would be the A axis.

In this discussion, Earle's situation was a lathe, so the CARRIAGE
travel being measured was actually the Z axis, although his readout
may have SAID the X.  For Earle, or anyone else here, it may be more
important to set his or her readout to say what they want it to say,
unless others will be using the machine too.  I always get confused in
programming our CNC machines.  "Left to Right" movement on our
vertical mill is the X axis, but on the Lathe, it is the Z axis.

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```