Re: Help with routing

> Date: Mon, 18 Jul 2005 15:00:39 -0000
> From: "mikeg53549" <mikeg53549@...>
>Subject: Help with routing
>
>I have the routing out of the outside of my designs down good, like a
>plotter, but I would like to cut the oppisite out of the design now.
>In simple words I want to remove everything around my design leaving
>my design raised higher than the surrounding material.I know it is
>problably simply, but I'm a newbee.

There are a number of techniques available to create "raised" designs.

The usual terminology for a relieved background from a flat design is "pocketing".
The raised portions are called islands. This is usually referred to as 2 1/2 axis machining as
the depths of cutting are all the same, no angled or radiused surfaces are defined, and a flat
bottomed tool such as an end mill or router bit is used.

To create toolpaths with mechanical cad-cam programs, a closed chain outer boundary
is defined, and then each island is also defined with a closed contour. The outer boundary can
be any enclosing shape(s), and usually overlaps and loops are not permitted.

Some programs will automatically process "nested" islands which are enclosed inside the
contour of one or more of the islands. Nested islands are shapes such as the inside of the letter A or D.

After the pocketing toolpath is cut, a uniform depth background is created while the design
remains at the original material height. Some programs can create roughing and finish passes
to control the sizing and finish quality of the vertical sidewalls.

There are many variations on pocketing, including hatching which is most useful with decorative
laser and V-cutter techniques.

For metalworking it is usually more efficient ( approx 1/3 the spindle horsepower) to maintain
a constant climb cutting motion, and to reduce the number of vertical plunges. There are various pocketing
strategies that will reduce the number and severity( angled/arced ramping) of plunges and which
provide different kinds of cutting patterns such as Zig-Zag ( axis parallel) and spiral and/or contour parallel.

Some programs can also produce pockets with multiple depth floors and island tops.

Pocketing is often used to create the insert spaces needed for inlay, intarsia, and marquetry.

There are also several kinds of 3D relief designs, usually referred to as carvings or sculpture. These have various depths and
perspectives, both concave and convex with respect to a flat surface and are generally collected together
under the term of bas relief. The best examples of this type of CNC machined relief usually start with an accurate
3D surface model.

Some software can also create this type of carving toolpath using a bitmapped image file,
including photographs.The image file method requires image editing skills. The shades of
gray or color mixes are used to create various depths. This technique usually results in an artistic
approximation of the subject, rather than a realistic form. It creates photographic quality images
when used for lithopane which is a backlighted translucent medium.

All the relief techniques listed above, except the image file carving technique is available in Vector cad-cam
DeskCNC can also produce reliefs using most of the same techniques.

Fred Smith - IMService
THE source for lowcost cad-cam and Desktop CNC
http://www.cadcamcadcam.com/hobby