topic Re: 3 point tangent circle sketch help in Fusion Design, Validate & Document Forum

3 point tangent circle sketch help

Anonymous — Mon, 08 Feb 2016 11:24:16 GMT

I'm tring to add a 3 point tangent circle to some sketch geomertry.

Tangent snaps to the line ok but when i hover over the to adjacent radius lines the command won't finish.

This sketch is taken from a more complicated drawing so they need to be added after.

Auto Cad can easily perform this tangent - am I doing somthing wrong?

See image.

Re: 3 point tangent circle sketch help

HughesTooling — Mon, 08 Feb 2016 11:36:32 GMT

In the tool tip for 3 point tangent it says pick 3 lines so I guess that's why it doesn't work for you. You can get what you want by drawing a circle and adding the constrains yourself, I don't know why the 3 point tangent can't do this though.

Re: 3 point tangent circle sketch help

Anonymous — Mon, 08 Feb 2016 11:52:43 GMT

Mark if i create a new sketch it works, if i try it on the sketch im working on i can't even apply the constrains after?

A bit odd, the sketch in question is a section of an elipse.

Re: 3 point tangent circle sketch help

Anonymous — Mon, 08 Feb 2016 11:56:38 GMT

i've attached the file if you get 2 mins to have a look....

Re: 3 point tangent circle sketch help

HughesTooling — Mon, 08 Feb 2016 12:27:46 GMT

How were the curves made, are they projected from another sketch or imported. I drew in another pair of ellipses and trimmed in the same sketch and they work so I don't know what's odd about your curves.

Re: 3 point tangent circle sketch help

Anonymous — Mon, 08 Feb 2016 12:29:44 GMT

they were offset from an outer elipse. but not projected in.

Re: 3 point tangent circle sketch help

HughesTooling — Mon, 08 Feb 2016 12:34:00 GMT

I just exported your curves to Rhino and they are NURBS curves not ellipse in the image below my curve is showing a Elliptical and yours is the NURBS curve.

Re: 3 point tangent circle sketch help

Anonymous — Mon, 08 Feb 2016 12:40:13 GMT

mmm they were drawn in fusion, is there a way i can fix it ?

Re: 3 point tangent circle sketch help

HughesTooling — Mon, 08 Feb 2016 12:47:52 GMT

It looks like when you offset an ellipse the offset is a spline, I get the same behavior in Rhino by the way. Also it seem you can only have a tangent at the ends of splines not just where 2 curves touch.

The only thing you can do is draw 2 more ellipses to match your offset and trim back to match.

Re: 3 point tangent circle sketch help

Anonymous — Mon, 08 Feb 2016 12:52:51 GMT

interesting, I wonder if this is by design then - must be

Thanks for your effort much appreciated, at least i know why this is happening now, helps with the frustration, I can now try and work around with a new elipse as you suggested.

Cheers

Paul