Re: CAD Question

> From: WAnliker@...
>
> Exactly what do I need to draw for making CAM files? Does it have to be a

3D

> program, or just the different views? This is one subject that I have

never

> seen explained or discussed. Looks like another learning challenge for

one

> who sketches on napkins.
> bill

For the normal prismatic type of machined parts, made with rectangular or
cylindrical stock, the normal method is to draw the area to be cut as if
looking down from the spindle onto the vise for a mill, or at a cross
section of the part for a lathe. Nearly all milling and drilling type of
work is done with this orientation.

3D contouring with a bull or ball nosed end mill requires that you define
the shape with a minimum of a wireframe representation in 3D. The wireframe
should be oriented to the spindle, such that + Z is oriented to the Z axis
moves.

If you are cutting with a control that goes directly from DXF to cut, there
may be ways to adjust for differing depths, tools, etc, with layer or color
settings in the file. The problem with DXF direct is that eventually you
may want to cut lines or arcs in a specific order and direction, and that
can be difficult to set up in a DXF file, depending on your cad system.

When generating G-code from programs like Bobcad and Vector, the drawing
orientation is the same, but in Bobcad's case there is an option to set the
depth of cut while generating G-code, and with Vector you either draw the
geometry at the depth to be cut, or move the coordinate axes to the desired
Z height.

Both Vector and Bobcad react to a dashed line by generating a G00 rapid move
& to a solid linestyle with a G01 or G02/3 feed rate move.

Usually the top of the stock is considered to be the Z zero, as after
programming, any plus Z's will be air cuts, and any negative Z's will be in
the material. Same for lathe front of part is Z zero and to towards the
chuck is minus.

Not all people program this way, but I always recommend it for safety
reasons.


Best Regards,

Fred Smith
IMService

imserv@...
Phone: 248-486-3600 or 800-386-1670
Fax:248-486-3698