Amazing constraint behavior

[lnonnato]

Hello friends,

I've faced this amazing problem when trying to reproduce another user's question.

In a sketch, I have two straight lines that intercept at a defined angle. I then fillet the intersection, using a conic and trimming the lines. Up to now, all is OK - Fusion automatically inserts a coincident constraint between the end of the lines and the conic extremities.

If I change the lines angle, however, everything goes havoc. The lines get disconnected and I  have now 4 coincident constraint gliphs, two at the conic's ends and one at one end of each straight line. I have no idea to which elements these points are "coincident".

I attach a screencast.

Cheers,

Luiz

[donsmac]

Add Tangent Constraints where the conical curve meets the straight sections. 

[HughesTooling]

The problem is the coincident constraint is between the line and the end of the conic spline, when you trim there's no automatic coincident made between the end points the constrain is still the end of the conic and the line. Like this example the line and the point are coincident but don't even touch.

If I don't highlight the constraint the point at the end of the line doesn't even show, which is a bit misleading.

Mark

[HughesTooling]

---

@donsmac wrote:

Add Tangent Constraints where the conical curve meets the straight sections. 

---

Ah I see if you add the tangents before you trim it works how you'd expect.

Mark

[lnonnato · Accepted solution]

Dear Mark,

Thanks for both your messages. I can see now what is happening.

As you mention, it' s not possible to add the tangent constraint after I trim the lines (there is an overconstrained error). I cannot imagine why this error appears, specially since the lines are not welded together (my original problem).

On the other hand, it will take some time for me to digest the fact that two elements can be coincident but not touch one another ...

Cheers,

Luiz