Re: [CAD_CAM_EDM_DRO] RE: Paper dwgs, was programming by hand

----- Original Message -----
From: <dougrasmussen@...>
To: <CAD_CAM_EDM_DRO@egroups.com>

> Another thing about electronic files..there isn't any guarantee
> they'll anymore right than a paper drawing. Just had one today, the
> dimension on the drawing said one thing and the inherent dimension in
> the drawing file was different?? Every see CAD files where the
> entities that would represent a tool path are not connected? They
> appear connected on the screen and on paper, but they might have
> larger end gaps than the CAM program can automatically compensate
> for. I see that one all the time.
<much snip>

Virtually every CAD file sent to me has so many errors (line disconnects,
holes placed incorrectly, etc.) that I have to -

1. Redraw them from scratch so the CAM will accept them, or
2. just print them out and program by hand.

The problem stems from widespread lack of Proper training, even among
professional draftsmen. When the colleges first started teaching CAD they
were not fully aware of it's potential. The instructors tended to teach
"board" habits, such as changing a dimension by editing the number instead
of changing the actual feature. Line disconnects often come from sketching
a line so it looks right instead of entering coordinates. Many tech school
grads don't even understand cartesian coordinates.

How many of you are still getting drawings with the archaic "do not scale
drawing" in the title block? Give me a minute to put on my flame suit. If
the drawing is done correctly (so as to be at all useful as a CAM drawing)
then it should be to scale. I used to fight this battle by scribbling "DRAW
TO SCALE" across any such drawing and sending it back to the drafting
department for rework. Made a lot of enemies this way. It doesn't help
that today's drafting department managers and tech school instructors were
trained in methods that don't work anymore.

Doug