Re: Contour Machining, was Optimizing cutting paths, was Traveling Salesman

--- In CAD_CAM_EDM_DRO@y..., "Fred Smith" <imserv@v...> wrote:

>
> Pocketing is a 2D operation. 3D is called kellering, profiling
> surfacing, or just 3D roughing, sometimes 3D cutting strategies are
> included with pocketing, but for the most part these are not really
> pocketing, but a different animal, and that animal has LOTS of
> different varieties. Lathe roughing is also a specialized form of
> pocketing.
>
> The contouring method of pocketing is actually quite easy as it is

a

> series of offsets from the outer contour(a closed planar shape),
> something that most Cam software can do fairly well. It gets a bit
> complicated with islands, but you just treat the island as a
> peninsula with a very small isthmus, and multiple islands as a
> peninsula with several areas(nearly islands) connected by very

small

> isthmi.
>
> The cuts actually originate in the center of the part and finish at
> the side walls of the pocket, just reversed from how they are
> developed.
>
> Horizontal or zig-zag pocketing is the other major 2D area clearing
> method. Like contour pockets, it is a 2D process. Both will

result

> in tool pickups if blind canyons are created in the contour

designs.

> Some people use hatching as zig-zag pocketing, if their CAD system
> will all them to be interpreted as lines.
>
> Best Regards,
>
> Fred Smith

Good post Fred.
If your cad system will support zig-zag pocketing from hatching or if
you CAD/CAM system can alter the machining angles then choose the
longest paths to get the lowest times and the best cutting paths.

Incidently not nit picking <bg> but pocketing is a 2 1/2D operation.
If it were just 2D you would get no Z moves.

John Stevenson.