Re[11]: emc really needs

Terry wrote:

>after a long discussion with my daughter concerning the coordinate
>systems and axis names used in computer graphics it is somewhat
>clearer now why they use the axis names that they do. the camera is
>like an airplane.

Yes. And like an airplane, the "camera" can "fly" around the part.
So, as we've been saying roll, pitch, and yaw make sense when you
know the "point of view". But the point of view can change... And
hopefully our PARTS are not "flying around" the shop... :-)

Unless we're building small aircraft, anyway :-)

(more coments threaded below)

>in cnc
>axis a is parallel to x axis b is parallel to y axis c is parallel
>to z

The A,B,and C axis are NOT parallel to their respective linear axis,
they are perpedicular to it! If you think of the rotary axes as
circles, disks, or "targets", the attending linear axis is like an
arrow through the target (though not necessarily through the center)

>in cnc
>x axis is the axis with the most travel. depending on machine this
>maybe left-to-right, front-to-back.
>z axis is always the cutting tool axis.

Correct, except that sometimes the axis properly called X has a
shorter TRAVEL than Y. In this case, the machine structure will allow
this shorter X axis to accomodate LONGER MATERIAL than the Y axis,
which will be limited in length (of material handled) by the machine
structural parts.

Say you have a flat bed, gantry machine. The gantry travels toward
and away, say 36 inches. The axis ON the gantry has a travel of 48
inches. Z axis is not pertinent to this discussion, and can be any
travel length (it is defined by the fact it carries the tool).

Now, if we want to machine some stock 60 inches long (or more), we
can't lay it "crosswise" on the table; it will likely overhang and
prevent the gantry travel. But if we put it lengthwise on the table,
we will be able to work it in 36 inch increments, up to its' full
length. So towards and away,36" in this case, is X. And the 48" left
to right travel is Y.

Hope this helps.

Ballendo