Re: How to go from 2.5 D to real 3 D ??

Tom,

The 2.5 & 3D definitions are not fixed in stone. They mean different
things to different people.

Here's my understanding for 3 axis machines....

A 2.5D machine is one that can only make LINEAR moves while moving
X, Y, and Z simultaneously. Most controllers can do 2.5D.

A 3D machine is one that can CIRCULAR interpolate (cut an arc) using
the Z axis in combination with X and Y. In other words cut an arc
using Z, in a plane other than XZ or YZ. Circular interpolation in
the XZ or YZ plane is not considered 3D. Most controls can't do this
simultaneous 3D.


Helical interpolation might be a cloudy situation. That's used in
thread milling among other uses. XY circular interpolation plus
simultaneous linear Z. I don't consider this 3D, it's a special
situation added to controllers mainly for thread work.

Another cloudy situation which some controls support, program an XZ
or YZ plane circular interpolation, then insert an axis rotate
(around the Z axis) statement prior to executing the interpolation.
That's 3D, but only very high end controls have a way to directly
program the path without the axis rotation statement.

BTW axis rotation is a very powerful feature in a controller. For
instance, to mill a hemi-spherial pocket, mill an arc in XZ plane
into the workpiece, rotate around Z axis a small increment, and
repeat the arc statement. With a couple of lines of Gcode the
complete hemi-sphere can be milled.

Doug



-- In CAD_CAM_EDM_DRO@y..., tom.kay@n... wrote:

> Hi All

(snip)

>
> I think I get the concept about what's 2.5 D and what's 3D. In 2.5

D,

> you do some x-y movements, then stop, lift the tool in the z axis,
> then stop, and do more x-y cutting. In 3D, all three axes can move

at

> once. Or 4, if you have a rotary device.
>

(snip)