Ellipse Shape Distortion After Trimming with Parallel Lines

[emifactory]

Dear Support Team,

I have encountered an issue while working with sketches in Shapr3D. As shown in the attached diagram, I first draw an ellipse and then sketch two parallel lines intersecting the ellipse. After using the trim tool to remove the intersecting segments, I notice that the shape of the ellipse slightly changes. It appears to deviate from the original, mathematically correct ellipse.

Could you please clarify why this happens? I’m having difficulty understanding the cause and would appreciate any insights or guidance on how to maintain the accuracy of the ellipse during trimming.

Thank you in advance for your support.
Best regards,

[SCALEMODEL]

Interesting you point that out because I found this an issue while answering another oval question here.

If you distort an circle to an oval you get a better results.

If you create an oval and cut it in half you get better results which looks similar to circle distortion.

Same oval process was done in another software and imported in Shapr and this import looks correct.

I believe this is an issue with Shapr as you trim an oval, splines are generated and those splines are not clean.

If you distort a circle to an oval the splines are clean.

[SCALEMODEL]

So this brings another interesting problem.

LEFT is extruded oval RIGHT is circle distorted to an oval and both used to create an offset.

Oval Zoomed in misaligned to the grid

Circle turned into an oval, offset has perfect alignment.

[JST]

Fortunately the cut ellipse is not distorted, only the control points make you uncertain, but if you check it with vertically drawn chords, you can see that it is still symmetrical.
Here is an eaxmple when I draw a symmetrical airfoil from ellipse:

What’s more confusing is that it’s difficult to draw ellipses accurately, e.g. in 3 degrees, for this I now use an auxiliary line and autoconstraint,

It would be nice if the auxiliary point could be grabbed at the end of the ellipse and connected to the center and then constraint.

[SCALEMODEL]

Here is another interesting thing about the Ellipse tool.

I’m working on something very rounded, I wanted to use to ellipse tool to snap to endpoint of the center, side and top. On the PC/Mac Desktop this is possible, on the iPad/Surface Tablet this is not. I started on the iPad and had to open the same project on the Mac and draw it there, because I couldn’t accomplish the 3rd Snap on the iPad.

Note the grid is off, it is just snapping to the end points.