AutoCAD to Weeke

[archmill]

Good Morning... first of all im a newbie and not sure if this the right place to post this so if i am please direct me to the correct place.

Problem:

I need to cut a template for an arched door frame, our CNC router reads DXFs. I draft the arched door using the Ellipse Command. But when I trim off half of the Ellipse and offset it turns the offset Ellipse into a spline. This is no problem except when we save the drawing as a DXF it turns the offset ellipse that is now a spline into almost 1000 segments which can crash our CNC computer. We would also like to draw horizontal lines from the two half ellipses then create a polyline so that the CNC machine only has to recognize one entity instead of the thousands of points created by the spline. Is there a way to keep the offset Ellipse to fewer points without using the pellipse variable and distorting the ellipse? Or is there a way to create a polyline out of an half of an ellipse that the offset ellipse with two connecting lines?



Note:

We need to keep the ellipses concentric so they must be offset rather than two different ellipses with different axis lengths.

[rkmcswain]

I draft the arched door using the Ellipse Command. But when I trim off half of the Ellipse and offset it turns the offset Ellipse into a spline.

When I trim an ELLIPSE, it is still an ELLIPSE entity, just with a start and end angle now.



ELLIPSE Layer: "0"
Space: Model space
LineWeight: 0.000"
Handle = 65c
Length: 61.1499
Center: X = 46.3892 , Y = 69.8438 , Z = 0.0000
Major Axis: X = -28.7456 , Y = 0.0000 , Z = 0.0000
Minor Axis: X = 0.0000 , Y = -11.0014 , Z = 0.0000
Start Point: X = 74.5916 , Y = 71.9725 , Z = 0.0000
End Point: X = 18.1868 , Y = 71.9725 , Z = 0.0000
Start Angle: 184
End Angle: 356
Radius Ratio: 0.3827

[LSR]

Change the variable of ellipse.
Set PELLIPSE to 1 will draw a polyline representation of ellipse.
The default is 0 which draw a true ellipse.

[archmill]

Change the variable of ellipse.
Set PELLIPSE to 1 will draw a polyline representation of ellipse.
The default is 0 which draw a true ellipse.

its not a true ellipse when i use PELLISPE, because when i use the variable 1 and i offset the ellipse it is different with the variable 0 and it makes me wonder why theyre different.

thanks though

[LSR]

BTW, how accurate the tolerance you want in your door arched anyway?
As long as the short and long axes are correct and your elliptical arcs are
(slightly) different.

[CarlB]

Not sure what you're describing with "connecting lines".

The main problem sounds to be how your program converts splines to a multi-segment polyline(?). You can prevent that by converting splines yourself to a polyline with more manageable number of segments.

The command "FLATTEN" (Express Tools) can usually convert splines to polylines. Another option is:

"SPL2PL.VLX Converts a selection set of splines to polylines inside the drawing. No more hoops with DXF files in R12 format."

http://www.dotsoft.com/freestuff.htm

[Ako]

Have you tried copying instead of offsetting?

Dave

[archmill]

Not sure what you're describing with "connecting lines".

The main problem sounds to be how your program converts splines to a multi-segment polyline(?). You can prevent that by converting splines yourself to a polyline with more manageable number of segments.

The command "FLATTEN" (Express Tools) can usually convert splines to polylines. Another option is:

"SPL2PL.VLX Converts a selection set of splines to polylines inside the drawing. No more hoops with DXF files in R12 format."

http://www.dotsoft.com/freestuff.htm

thanks spline to polyline worked well and minimized the work although it still creates a bunch of points for the weeke. do you know any tools that can minimize the number of points but still maintains the smoothness of the arched?