Re: Producing G code from a scan

--- In CAD_CAM_EDM_DRO@yahoogroups.com, "garagefella"
<garagefella@y...> wrote:

> Hello all,
> This is my first post in this forum so please inform me

if

> this query is in the correct place.
> I am in the process of building my own router table with the
> intention of cutting out parts from MDF ranging from 3mm up to 12mm
> thick. These parts were previously manually cut out on a scroll saw.
>
> Most of the parts currently produced are animals, santas, clowns,
> lovehearts that sort of thing, a master is cut and then traced onto
> MDF multiple times and cut out.
>
> As I know next to nothing about CAD I was wondering if there are
> windows based pgms that will generate G code from a scanned image.
> I hope it will be easy to
>
> 1 hand draw outline of a dog on paper
> 2 scan this outline
> 3 send to pgm for G code generation
> 4 send G code to Mach2 for actual machining
> or can I sent this scan to a CAD package to generate G code?
> I have mastercam and coreldraw 11.
>
> Thank you so much

Using what you already have you can get there. Draw your original
with as smooth and continious lines as possible. Scan it at 300 to
600 dpi. If your scanner supports scanning in "lineart" (B&W) mode
then do it that way. Think in terms like you were going to cut it
out on a scrollsaw and try to make individual closed objects. Once
you have it in B&W use the Corel Trace program that comes with Corel
11 and convert the bitmap to a vector so you can open it in CorelDraw.
Use the CorelDraw Node editing tools to clean it up then Export it as
a DXF file for import into masterCam.

Now for the way I would do it: Use the vector drawing tools in
CorelDraw to draw it in in electronic format (Skip all of the draw-
scan-trace-convert steps. The addition of a digitizing tablet wike a
Wacom (brand) will let your draw 1:1 with a stylus or to trace over
an existing drawing you already have and it will be in vector format.
If you are not comforatble with drawing in a vector program then scan
the drawing and inport it into CorelDraw and setup a new layer and
handtrace the bitmap (scanned image) with the vector tools in Corel.
IMO what you are trying to do is more artisitic cuts rather than
machining and there are other CAM packages that will work better for
you than MasterCam unless you have been using it a long time and are
comfortable with it's non-Windows type interface.

For simple cutting from Corel, you can save closed objects that you
want to route at different depths in Corel on to separate layers then
export them as DXF in layers and import directly into a controller
piece of software like MACH2 and define the toolpaths there. Most of
the programs you see mentioned on this group have free demo's and
many of them are low cost. Also checkout an emerging low cost (free
while Beta) piece of CAM software called SheetCam at
www.sheetcam.com. It will let you take the DXF or a HPGL (plt)
export file from Corel and setup your tools, figure the offsets and
let you define the cut speeds, lead-ins and multi-pass depths of the
vector objects, then spitout good g-code for MACH2. Give it a try.

Just rememeber with any of these tools the objective in Corel, if you
want to either carve objects at depth or cutout shapes, is to have
your vector artwork consist of groups of closed objects (something
that will take a fill color on Corel).

I would try and move away from working with pen and paper as soon as
you can, since the final goal is to get from an idea to a toolpath as
easy as possible.

There is a rich source of vector based clipart that can be used as is
or imported into Corel and modified easily to get what you want.