Changing the number of calculation points AutoCAD recognizes on curves

Hi everyone,

Can anyone please tell me if there is a command that allows you to
control the amount of calculation points AutoCAD uses or recognizes on
a curve ?

I created a cam curve with some third party software and used 10
calculation points per each degree of cam rotation. However, after
importing the DXF file into AutoCAD, It does not seem to be using
anywhere near that many calculation points, and if you zoom in a
little, you can really see how the curve is pieced together between
the calculation points. If AutoCAD were using all of the calculation
points, the cam curve would be much smoother.

If I convert the curve to a polyline and then use the fit command,
then the curve gets smoother. Also, I can run a spline through the
calculation points that AutoCAD displays and the curve seems smoother.
In any event, it would be best if I could first get AutoCAD to
recognize and/or use 10 calculation points per each degree of cam
rotation as I originally intended.

I prefer to keep using AutoCAD 14 for this as I prefer the layout for
2D stuff, but I have access to AutoCAD 2007 if really needed.

Thanks for your help.
John

 

Try viewres and set the value to, say, 1000 and see if that's suitable for
your purpose.

Brian.

 

Hi Brian,

The viewres comman won't change the number of points along the curve.
I'm not concerned with how the image "looks" on a screen, I'm
concerned with accuracy of the curve and CAD file so the CNC machine
can be accurately programmed and accurately make the part. When I snap
to the points along the curve in AutoCAD, there are not 10 calculation
points per each degree of cam rotation as I wanted.

Thanks
John

 

AutoCAD is pretty good about respecting data that comes in via DXF, so
is it possible that the third-party software is not exporting all those
points to the DXF file? You might check to see if there are settings in
that software to control something like this: minimum distance between
points, maximum points per polyline -- something like that?

-Bill

==========

 

I go along with Bill's response here. I use R14 and have never had any
problem with dfx files sent to a laser cutter.

You are zooming into the curve within R14, but what is displayed isn't
what the file actually contains; just what R14 displays. For example, if
you have fastzoom active, then the display is visually short on apparent
''curviness'', if you see what I mean.

On way to check is to look at the dxf file in a text editor - Notepad if
it's a short file; Wordpad if it's alrge file. You can check the number of
points in the file itself. There's info in the AutoCAD manuals on the
format of the dxf file.

Brian.

 

I go along with Bill's response here. I use R14 and have never had any

There would be no problems here either except that this part requires
higher precision & in this case more points means more precision.

I understand the difference between viewing screen pixels and the
mathematics of a CAD file. It has nothing to do with what's displayed
on screen, it has to do with the mathematics of the CAD file, i.e. the
number of points I can "snap to" along the curve. The number of points
I want simply are not there. I don't think the software exported all
the points to the DXF file.

Thanks
John