How to modify sketch with coincident constraints ?

[Anonymous]

Dear forum members,

I am trying to chamfer the corners of a square plate. I could do that in 3D with the chamfer commande, but that would clutter the timeline more. Also, I want to practice modifying sketches, as that is something I have difficulty with.

What you see is the bottom right corner of a square. I used fillet on the top left corner. The proper way to contunue was probably to fillet the three other corners and constrain them with three symmetry constraints, which I tested and worked.

[image should be here]

However, what I did first was to mirror the original fillet, correct the mirrored cornder and mirror both corners again. I was able to painstakingly mostly correct corners 2 and 3, but am stuck on 4, shown above.

The goal is to keep only the arc of the corner.

I would expect the proper procedure would be to delete the offensive coincident constraints in the corner, move the straight line end points to the arc end points and apply new coincident constraints. However, that doesn't work.

A workaround would be to delete the lines and draw them again and that is something I have been doing a lot with Fusion 360 : not change things, but delete and start over. In addition, that may destroy the extrusion assiciated with the sketch area.

Is there a proper way of making that modification and if so, how ?

[davebYYPCU]

Something strange there,

make the rectangle, Fillet / Trim the corners, add the chamfer lines,

make the curve Construction, or disappear.  Dimension the vertical and horizontal lines.

when you fillet a corner it should trim the corner lines back to it,  of course mirror the arc won't do that.

but you need the new chamfer lines first else the profile will be replaced and not updated.

Might help....

[Anonymous]

Sorry, but I don't understand your explanation.

[MoshiurRashid]

Hi @Anonymous  

I hope you are well. I have created a screencast for you to about the sketch. Click here to watch the screencast 

Additional: For chamfer, you can just attach a line between the two lines creating corner and dimension it.

[TheCADWhisperer]

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@Anonymous wrote:

I am trying to chamfer the corners of a square plate. I used fillet on the top left corner. 

However, what I did first was to mirror the original fillet, 

The goal is to keep only the arc of the corner.

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I am confused about your true goal.

Is it for fillet corners

or is it for chamfer corners?

Either way, there is no need to trim lines.

Attach your *.f3d file here and I can demonstrate several (easy) techniques.

[davebYYPCU]

No need to trim does not apply to all of us, 

2d profile cutters need trimmed lines for at least, time and material nesting considerations.

Fillet command does trim those intersections, this example has used mirrored arcs, which is one way to define 45 degree chamfers.

Might help....

[Anonymous]

I made a vocabulary error. I wasn't trying to chamfer, but to fillet. Sorry for the confusion.

The corner shown was not obtained by mirroring with a diagonal, but by mirroring twice, first with a vertical line and then with a horizontal line, both through the center of the square.

This seems to be a bad example, as there are better ways of filletting identically in the 4 corners. Trim has worked well to get rid of the sharp corner.

What I am having difficulty with is modifying lines or points that are on top of each other and constrained. It is often hard to convince Fusion 360 to move a line or its end point, as illustrated in the example : Fusion 360 stubbornly refused to separate the end points of the sides at the corner.

The latest update is reported to have solved some issues with constraints.