Specifying ellipse parameters

[Anonymous]

Is there a way to sketch an ellipse in Fusion 360 in such a way that you create the following parameters in the parameter table: length of the major axis, length of the minor axis, and a focus on the major axis?

Given the current sketching function in Fusion 360, I can't seem to do this. Maybe I'm missing something. At best I can currently create a single axis length, and an angle of axis off the origin. I can create a point along the ellipse, but that position does not seem to get recorded.

[James.Youmatz · Accepted solution]

Hi,

You can define parameters with custom equations. Take a look at the below screenshot that I created for more clarification.

I've created a sample file that contains a sample ellipse based on those equations. To quickly walk you through my process after I created the equations:

1. Create parameters for major and minor axis
2. Create parameter with custom equation for focus length, calculated from major/minor axis.
3. Create an sketch with an ellipse.
4. Manually enter the parameter names in the dimension field,
5. To create the focus point insert a point on the major axis.
6. In the sketch menu, select Sketch Dimension and click the point you created and the center point of the ellipse.
7. Manually enter the parameter name for your focus length in the dimension field.

http://a360.co/1IZIMft

Hopefully this helped solve the problem, and feel free to let me know if you have any more questions or if you need me to clarify more. I'm more than happy to help!

Cheers,

[James.Youmatz]

Hi @Anonymous,

Just wanted to check in with you and see if the method that I posted worked for you? If so feel free to accept those answers as solutions so other Fusion 360 users experiencing similar issues can benefit from this thread!

Thanks,

[Anonymous]

Thank you. My problem is how do I apply thos parameters to a particular drawing? I can create an ellipse with the drawing tool with one axis in the parameter table. How do I apply the other axis and foci to that ellipse?

[Anonymous]

Actually, your solution will work for me. I was hoping that I could physically create foci on the drawing in addition to the axes. That said, I did have a problem using the expression. For me, the sqrt() function would not accept parameters of any type. If I used fixed values for Major_Axis, and Minor_Axis the expression was accepted. Doing it exactly the way you did it below the formula is red flagged.

Strange.

[James.Youmatz]

Hi @Anonymous,

You actually can create the foci on the ellipse you sketch. I went ahead and made a screencast detailing how I created my ellipse using the Parameters table. As far as your invalid expression for the focus, can you send me a screenshot showing your expression that gets red flagged? Did you make sure to check that the output of your expression would be unitless? As you can see in my example, my Major Axis and Minor Axis parameters are in inches. Therefore if I create my focus equation, I will need to divide by the normalized factor which would be dividing the parameters Major Axis and Minor Axis by "1 in". Please note that in my expression I divided my parameters by 2 instead of 1 in order to express Major Axis/Minor Axis as a radius, not a diameter.

Here is a link to the screencast showing how to add your axis and foci:

http://autode.sk/1J3HVbN

Hopefully this helps and send a screenshot of your expression if it gets red flagged again. Also, feel free to ask any more questions you have, I'm more than happy to help!

Thanks,

[Anonymous]

That was it. I did not know units had to be specified in the formula. Thank you!

[Anonymous]

Hi. Is posible to change from parameters ( like in your cast video ) the ellipse curvature 1/4- from convex to concav? And how ?

Thank you.