Re: Polar Coordinates CNC?

--- 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.

The intriguing part is how to accurately position the work piece
because there are no straight edges to indicate, away from the
central X axis. I'm thinking of mounting a vise. How to indicate it
in, is a much different thought process if only one horizontal axis
is linear. I guess you could indicate one face, set zero degrees,
rotate 180 degrees and tram for centrality, or rotate 90 degrees and
use an edge finder to set the X distance and angle to a part edge. I
would guess that you would want to have an axis transform for the
vise to avoid going nuts trying to mount it square to the X axis.

Logically it's the same as setting X & Y, but it's still a mind
twister.


Fred Smith - IMService