Fred, I have to agree with the other Ray H. A Polar
machine/software making a move from X(1) to X(2) must
calculate every position along the path, whereas a
Recti-linear machine merely has to say' "Am I at X(2)
yet?... no, well, then add another pulse at the X-axis."
Now, it's true, that in a Rect. machine/software,
interpolating a circular move, the program must calculate
every point on the path, but so must a Polar
machine/software. Polar machines must, of necessity be more
complex. I trained o a FANUC 120-iL Robot Welder at the
Lincoln Electric School in Cleveland, OH, a couple of years
ago, and that was one complex machine. Six axes, and four
different reference frames (points of view). Fortunately,
the programming was done via a Pendant, so it was
relatively easy... But the machine was complex. It was
really fearsome, to watch that robot welding, just thinking
about all the calculations it had to be making every few
microseconds.
RayHex
----------
From: Fred Smith <imserv@...>
To: CAD_CAM_EDM_DRO@...
Subject: [CAD_CAM_EDM_DRO] Re: Polar Coordinates CNC?
Date: Sunday, November 03, 2002 8:06 PM
--- In CAD_CAM_EDM_DRO@y..., Ray Henry <rehenry@u...>
wrote:
along that vector so in effect it is a polar move. I
can't for the
life of me see how specifying three angles and a
distance would be more
efficient or would somehow alter the fundamental
thinking about
milling or turning.
It's the machine that is simpler.
Think of a turntable (like a lazy susan) with the part
mounted in
place on the turntable. The rotation is C axis
Now place a single horizontal linear axis parallel to the
face of the
turntable (X) above the work piece, and mount a Vertical
Z axis onto
the X. (R is not a valid CNC linear axis so I will refer
to it as X.)
The machine is simplified to a single linear X and a
bearing for C.
Instead of at least 4 precision linear guide components
for a linear
gantry style machine, you reduce it to 2 (shortest
possible) plus the
bearing (Actually only 1 if you use a dove tail
arrangement like a
Bishop-Wisecarver rail). The Z axis is the same
mechanism in this
case.
