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Elliptical Arc

hrwind

New member
This one has been bothering me for awhile now. I feel stupid for asking this question.

Is there a way to create an elliptical arc (the arc only) in the sketcher in Creo? I used Inventor for awhile, and it had this feature. The ways I've found to do this are the following:
*Drawing an ellipse and trimming away the things I don't want.
*Putting and elliptical fillet on a corner.
 
There is no direct method to sketch an elliptical arc within sketcher environment. However, you can create an elliptical curve (either full or partial) using parametric equations.
 
Construct a spline with 3 points. The end points at the major dia of the ellipse and the middle point at the minor dia.
Double click on the spline. Select control polygons
The first span from the endpoint should have a length equal to the minor radius * 0.6
The middle point should have a distance from the center line equal to the minor radius * 1.4
 
I like mgnt8's solution. Save it as a sketch and insert it when needed. Set the size of one of the radii to 1 so all you have to do is change the scale. Really want to get trick map key it and add it to the drawing tool bar.
 
Just create a regular Ellipse then use the Divide Entity Trim tool from the Dynamic Trim flyout to trim out the portion you want. If you want an exact quarter ellipse you can snap on the quadrant points with the divide tool. I can't Believe it took PTC so loang to allow Ellipses to be created or rotated at an angle smaller than 90 degrees.

That was only possible with 4 conics and way too many constraints during the Wildfire period. Good thing they decided to add that capability to the other ones PTC created in Wildfire 5 which copied many useful features from the SolidWorks sketcher. SolidWorks can now do conics good thing they now both have good sketchers. I'd highly suggest against using the Spline workaround due to instabilities and inaccuracies it will give.

It's a nice suggestion by mgnt8 and was the only way to attempt conics on SolidWorks before 2013 release but it did not work too well.
 

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