help sketching smooth curve/arc/fillet

[jeremyparks]

Requirements:

The three outside edges need to be 5 inches and at 120 degree angles.  The inside geometry just needs to be visually appealing (smooth arc and good proportions).

I have a few questions and would appreciate advice:

1. What is a good way to have a smooth curve around three sides of an object that doesn't have 90 degree inside corners.  I used the fillet command just to get something to show.

2. My sketch is still blue (not fully constrained) but not sure what constraint I'm missing.

3. I was left with two bodies after mirroring it.  How do I get one body for the current component?

also - is .f3d the best file format to share here?

[JDMather]

1. See attached.

2. 

Your sketch showed as fully constrained when I opened your file?

3. Combine

>also - is .f3d the best file format to share here?

Yes.

[jeremyparks]

Thank you for the quick reply.

I didn't know about that preference, just learning and watching videos, expected the fully constrained sketch to turn black.

The combine makes sense - select the two bodies, join, don't keep tool.

Looking through the timeline of your design it appears you:

sketched the complete shape with a symmetry constraint (nice how that created symmerty when adding fillets later)

extrude

fillets

Is it better to make fillets after the extrude instead of on the sketch?

I wasn't clear on this - I was trying to make a continuous arc connecting the legs, ie - no flat spot between the legs.  Is there a precise way to do that, or is it trial and error?

[TheCADWhisperer]

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@jeremyparks wrote:
...I wasn't clear on this - I was trying to make a continuous arc connecting the legs, ie - no flat spot between the legs.  Is there a precise way to do that, or is it trial and error?

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No trial and error needed - see possible solutions depending on design intent.  (I didn't know whether you wanted all flat spots removed - or only those at the angles.)

It is almost always better to add fillets as placed features rather than as sketch entities, but given your design intent it should be done in sketch.

[jeremyparks]

I was trying to achieve what you did in Rev3 - creating one continuous arc between the two 120 degree angles (just to learn how).  Once I got that arc smooth I was then going to decide what looked good as a transition from the arc to the bottom curve.  The arc can be moved up to add more radius on the bottom.

Looking at your sketch of Rev3 I can't determine which tool you used to accomplish the smooth arc.  Do you mind sharing how you did it?

[TheCADWhisperer · Accepted solution]

Turn on your sound.

[jeremyparks]

TheCADWhisperer,

Thank you for the screencast.  That does match my design intent.  As a side bonus I learned some constraints that I've not been using.  I figured a circle might hold the answer.  I haven't used the midpoint constraint or the trim tool.  I tried all the arc tools, splines, fillet, and conic curve.  It makes sense how you solved it.  The inside portion (curves and fillets) only needs to look good.  So being able to move the circle radius to get a nice looking shape is good.

I have not shared files with anyone.  This exercise also gave me a reason to better learn A360.

What a great community, a thanks to you and JDMather for getting me in the correct direction.