[TheForge] DXF FILES

Thu May 9 22:57:01 2002

Mike,

Tiffs, BMP, JPEG, GIF are all image (raster) files.  These make the image up
from a series of dots just like an ink jet printer.  If this information was
sent to a pen plotter, the pen would move to an x,y location, the pen would
be instructed to drop down to form the dot then the pen would be lifted to
await the next command.

CAD drawings are vector.  They use lines, circles, arcs, points, solids and
polylines to create an image.  When this information is fed to a pen
plotter, the instruction is to move to an x,y location, the pen would go
down, then the pen and/or paper would move to form the line or circle or arc
..., then the pen would lift to await the next command.

As you can see, image files don't work for computer controlled cutting
equipment.  What your plasma guy needs is a vector based drawing and his
program will accept DXF (drawing exchange format) files.  In AutoCAD, you
can now insert raster image files.  You can see them in your drawing and
they will print or plot but they are not vector elements.

DXF files are supposed to be an industry standard to allow sharing data but
not all DXF files are the same.  I have not tried in AutoCAD to export to a
DXF file a drawing containing a raster image but I doubt it will work.  And
in your case it wouldn't be beneficial anyway.

PS - Shannel talked about vector sequencing in his post and the apparent
problem with random movement of his cutter.  The cutter is instructed on
each segment in the same order as how it was drawn and each line in the same
direction as drawn.  This appears to be random because we create our
drawings that way.  We may draw the top of a square then offset it for the
other side then draw each end.

The old pen plotters had a pen optimization program that helped with this
problem and it would sort the vectors to optimize the cutting.  You can do
the same thing in AutoCAD by writing out to a new file your lines and arcs
in the correct sequence.

Walt

Mike Wolfe wrote:

> I am going to try this one more time...
>
> My plasma guy would like dxf files to input my line drawings to his
> computer. I can scan my line drawings in photoshop and save them as
> tiff's, then he has to go through a mess to convert them to dxf or
> "vector"
> I would love to be able to give him a dxf file.
> At on time I received a coral draw file via e-mail and then was able to
> open it and resave it in the coral dxf. then I gave it to a laser guy
> who was able to open it and use it.
> I can open my tiff in coral and look at it and then save it , but the
> plasma guys can not open it.. Something in there program dislikes
> coral's dxf.
>
> Is there any other program that I can use to convert the tiff to a dxf..
>
> Something at reasonable price not at auto cad program prices...
>
> An I not understanding the conversion process, is  the process of taking
> a raster line drawing and converting it to a vector drawing is far more
> complicated then I think????
> Mike Wolfe
>
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