Re: [CAD_CAM_EDM_DRO] Re: Software options

On Jun 25, 2006, at 5:45 AM, turbulatordude wrote:

> I'm not positive, but I think the terms we use are
>
> CAD, this is the drawing part. Corel would fit here although it is
> not called a 'C.A.D.' program.

Correct. You can call Corel a CAD program, as it technically
qualifies (it is a drawing program), but it lacks some features a
typical CAD user would want.

>
> then a Post-Processor. this converts the file from whatever format to
> G-code (for machineing) or to Gerbers (for PCB work)

Not so correct. What you're describing here is CAM. CAM ("Computer
Assisted Machining") takes a CAD drawing (or solid model) and
generates G-Code. The operator of a CAM program specifies stock and
tool information and selects cutting strategies for the part, the
program then computes tool paths and generates the G-code from there.
In some cheaper CAM programs you have to provide a lot more help with
the tool path (some to the point of drawing the path yourself).

The post-processor is a part of the CAM process. Most CAM programs
actually output an intermediate format (specific to the CAM program),
then a post-processor converts that data to the actual G-code. Often
this process is hidden and aside from specifying which post-processor
to use, the operator is unaware of the post-processing. This is done
so that specific post-processors can fine tune the G-code for
specific CNC controller or machine requirements (like which G-codes
are OK to use).

>
> lastly, CAM or Computer Aided Manufacturing. This is where Mach2/3,
> TurboCAD, EMC and others come in.

These programs are CNC controllers, not CAM programs. CNC Controllers
read G-code and actually control the machine to execute the
instructions in the G-code.

>
> The post-processor part takes the drawing file and fixes it. it
> allows a person to add cutter compensation, to tweak tool paths, to
> take a roughing cut, then a finish cut....

Again, these are all part of the CAM cycle.

>
> the CAM just takes the g-code and sends it to the machine. I'm not
> sure if CNC or NC or DNC is the more appropriate term for the software
> that looks at each line of the code and then sends those signals to
> the machine.

CNC controller here ("Computer Numeric Control"). NC means "Numeric
Control" and implies there isn't a computer in the loop (old NC
machines were driven by punched paper tape). DNC is a type of program
that interfaces a PC to a CNC controller. DNC ("Direct Numeric
Control" or "Distributed Numeric Control") is typically used with
industrial CNC machines where someone sitting in an office can dump G-
code directly to a CNC machine sitting on the shop floor (the
"Direct" version, might even feed G-code one line at a time). More
sophisticated DNC systems allow one PC to operate multiple CNC
machines simultaneously (ie: you could run an entire shop floor from
your desk, this would be "distributed numeric control)".

In industrial machines, the CNC controller is generally embedded into
the machine (often just a PC inside the box, but it could be anything
that can eat G-code). Programs like Mach3, EMC and TurboCNC turn a
conventional PC into a CNC controller.

Peter