Re[10]: emc really needs a copyleft cad/cam package

Alan,

No, you're not confused. You've got it right. Funny thing is; so does
Jon E!

And the reason is WHY we don't want to use roll,pitch and yaw to
describe rotation. Most people who are familiar with R,P & Y know
that it relates to the direction we're "going", or "facing".

Jon said that: Facing(standing in front of) his BP mill, A is pitch,
B is roll, C is Yaw. You can see that a pitch down or up (from this
positions' reference, standing in front of the mill) WILL be rotation
around the mills' X axis! The others are similarly correct. And
confusing, IF you're thinking of the X axis positive being
the "faced" direction.

So if you stand at the LEFT END of the mill and look "down the
table", THEN you see roll as A, pitch as B, and yaw as C.

Notice that the AXIS definition ISN'T changing; just the CORRELATION
to R,P & Y. If we stand on a ladder and look down at the mill, we get
the third set of correlations. Three more (behind,to the right of,
ans under) will be the same as the first three with the plus/minus's
reversed.

THIS is why roll, pitch, and yaw are not used to define axes! A,B,
and C remove the possibility for mis-interpretation. And the "right
hand rule" takes it one step further, to define whether the rotation
is in the "plus" or "minus" direction. So we know whether to use G02
or G03.

Hope this helps.

Ballendo

Alan wrote:

>Jon,
>I guess I'm still getting the axis confused. Isn't A rotation around
>the X axis? And B around the Y axis, and C around the Z axis? Which
>way is the plane flying?
>Alan (probably flyin' inverted) No Scottie, we can't loop the boat!