How to create concentric eclipses

mitch_b708

My approach was to add points to each end of the ellipse and create a center line. Then create a second ellipse, add points to each end of the second ellipse, and constrain those points such that the second ellipse has the same long axis. Repeated for the short axis and then add dimension constrains, so that one ellipse is larger all around by a constant amount. It seems a bit complicated. Maybe there is a simpler method?

Here's an example:

https://cad.onshape.com/documents/4e2cfdd35f47ab69d75e1e22/w/baba9ba860aaa65f1c71be44/e/e2d7c96ff2fb6310b373286f?renderMode=0&uiState=62d9bec978b96711ee8e88ae

NeilCooke

Use the offset tool?

mitch_b708

Fantastic. Thank you. 

NeilCooke

Use the offset tool?

S1mon

Making a second ellipse 2 x N wider and 2 x N taller only produces an N offset at the major and minor axis. 

Offsetting an ellipse by N doesn't create another ellipse (except if the "ellipse" is a circle).

What exactly are you trying to do?

mitch_b708

Fantastic. Thank you. 

mitch_b708

S1mon said:

Making a second ellipse 2 x N wider and 2 x N taller only produces an N offset at the major and minor axis. 

Offsetting an ellipse by N doesn't create another ellipse (except if the "ellipse" is a circle).

What exactly are you trying to do?

Actually, I did notice the the shape made with the offset tool looked a little funny. I manually drew another ellipse from the same center point and eyeballed it to orient it with the shape made by the offset and then I could see the difference. Even though the difference is small, I sorted didn't care for the shape for some reason. It seemed "blunter" on the ends. Maybe there is something visually pleasant about a pure ellipse.

What I am making is a plate with a few controls (potentiometers and switches). The plate will lay flat on the wood with the back of the controls suspended in a routed opening. BTW, this is a plate to hold the controls for an electric guitar body.

I'm using OS as a 2D tool. I print out the shapes full size and use them to make the plate and a template to rout the opening under the plate.

Since I didn't like the look of the "almost" ellipse. I may try using a negative offset, because I only care (aesthetically speaking) about the shape of the plate because that is what people see.