Re: [CAD_CAM_EDM_DRO] How to Program a CAD / G-code/Machine commands freesource code?

Alan:

>>>Writing a CNC controller program can be quite

challenging (I know, I wrote one)!

:) , I think we're in a small group. Hard to express to those that havent just how much it takes from you.
but without the pioneers like yourself, where would any of us be..

Thanks,
Art
www.artofcnc.ca

Videos And Support Forums http://www.machsupport.com
Users Map: http://www.frappr.com/machsupport

----- Original Message -----
From: Alan KM6VV
To: CAD_CAM_EDM_DRO@yahoogroups.com
Sent: Thursday, August 23, 2007 12:50 PM
Subject: RE: [CAD_CAM_EDM_DRO] How to Program a CAD / G-code/Machine commands freesource code?


Hi Elwolv,

If you are going to write a CNC controller program, then Check out the
TurboCNC and CNCpro lists, both also on Yahoo. There is source code
available for these. Writing a CNC controller program can be quite
challenging (I know, I wrote one)!

The CAD part is different task, usually a separate program. You might
consider generating a DXF file (standard) first, then post-process to Gcode.

Structure? You make your own. LISTS. Try to keep the contours in ordered
lists of coordinates. Think of the cutting DIRECTION. You'll need offsets
for cutter diameter. Do this, and you can generate Gcode (or DXF) files
from them.

Yes, WAY too many questions at one time! And probably more depth then you
can hope to achieve in a reasonable time. Start by using a free CAD
package; write the CNC controller. Or vice-versa. Nurbs? Do you really
want to go there right away?

What is your project for? A Science Fair project perhaps? Your own use?
Search the internet!

Alan KM6VV
SherlineCNC list

> hello;
>
> thanks to Dan Hudgins for referencing this forum for my project.
> I building a micro CNC machine
> I want to write SW for simple CAD front /to G-code / to Machine commands
>
> the information regarding the programming is very limited to some
> g-code description.
>
> I think those steps are needed to complete a sw for a cnc?
>
> 1- data structure in the CAD part, I can build a simple CAD GUI, but
> what is the concept for the data structure.
> do we make all the input from the mouse as line and arc as was
> suggested to me. then use these in a data list to create G-code
> listing that can be reviewed by the use?
>
> 2- how does the milling of a surface is translated from a CAD data
> structure to a G-code.
>
> what is the data structure for a cad surface suitable for translation
> to g-code? line and arc will not represent surface shape milling.
> Extrusion will allow a line or arc to be shaped and we can define that
> structure as a way to be translated into many lines and arcs to match
> the shape.
>
> what is the data structure for extrusion to can be translated to
> G-code easily?
>
> 3- usually it is the format of the cad output that translated to
> g-code. the only reason to have a cad data structure (or format
> output to file) is to allow the automatic translation to G-code.
> the reason of g-code translation step is to allow the user to review
> and correct the automatic translation. or to allow the use of direct
> g-code if needed for simpler shapes
>
> 4- examples of how to translate g-code to machines codes?
>
> I have seen some old very elementary pascal simple incomplete sample
> for the parallel port. the translation is for a simple single line or
> arc motion. which was is straight forward with some thought to it for
> efficiency.
>
> since G-code is a line and arc operation then we can connect between
> cad structures and g-code translation as each is a name for subroutine
> that contains the machine code to perform the motion according to the
> motor controller specifics needs as step and direction for parallel
> port as specific rs232 serial port commands for a commercial
> controllers needs.
>
> 5- how to work out the surface data structure into motion into tens of
> lines or arcs motion to create a surface from a g-code?
>
> g-code will give only line and arc. so we need to create tens of
> g-code lines and arcs. is there is efficient way to do that or that
> simple brute force with a very long list of lines showing the g-codes
>
> do we put the g codes in a loop which represent the structure some how
> to change the x,y,z as needed for each line.
>
> or we use a straight line operations where the z change for every step
> (within the line) to make a curved surface. how do we automate such
> a loop = how do we have a formula to give the surface height for a line?
>
> as I see now brute force is not suitable for surface. do we use Nurbs
> operation to represent a line analytically then we use that equation
> to give the z for the curve shape?
>
> is that why Nurbs is used in surface application.
>
> 6- but simple engraving SW does not use Nurbs, what is the concept
> they use in the SW? for engraving.
>
> 7- what available free codes are available in the community to use or
> review?
>
> those are lot of question, but your help is welcomed
>
> elwolv
>






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