Help Needed - Offset / Parametric Model

[toddbg]

I'm trying to make a few sketches of a small parts bin.

The first sketch I made I offset by a set amount.

I copied the whole thing and built in parameters instead of the dimensions.

I made a second copy and then tried to use parameters to size it further down, and it broke the sketch.Then I started looking at how to do an offset of an offset, ok, seems like you can't.

so, is there a way to take the original sketch outline and offset it by a new amount, and have the *offset line* become an independent sketch object to use elsewhere?

What I am trying to achieve is sketch the top portion of a bin and offset for wall thickness.

I then want to sketch the bottom portion of the bin that would have the outer line be an offset of the first offset plus a tolerance amount.

E.g.

Sketch primary object = A

thickness = 1.6mm

tolerance = 0.5mm

• Sketch 1

  • Primary Line = A

  • Inner Line = OFFSET (A) by (thickness)

• Sketch 2

  • Primary Line = OFFSET (A) by ((thickness)+(tolerance)) AS (B)

  • Inner Line = Offset (B) by (thickness)

Thanks in advance!

Left hand = original sketch. Right hand = dimensions changed to parameters

Sketch 2 using the parameters with a formula broke the corners

Ultimately I am trying to make small bins for storage and want them to be parametric so that I can just say "Give me a new bin that is 3 units wide by 2 units long and is half height so it can stack.

image of the STL I am using as a base design.

[davebYYPCU]

Parameters and blue sketch lines, - lots of accidents looking for a place to happen.

Black lines are required in your case.

Chamfer the model.

How I would do it, you are working too hard.  Your solids are right of my timeline.

Step up my timeline, edit features to find where your parameter settings have been used where I could.

Might help.....

[toddbg]

interesting.
That is close, but the rim to bottom should be a chamfer not a bevel.

I realize I might be over complicating things, but part of it is that I am trying to understand parametrics and fully constraining a model.

Any thoughts on what the problem is with the original sketches and how to get around that?

[etfrench]

Offsets add constraint icons to the sketch.  Simply delete the icons to make the offset independent.

[davebYYPCU]

Chamfer / Bevel same thing, fillets at the waist transition area are stronger, and the least of your problem.

You or Fusion were dimensioning corner points, 

Your problems stem from not fully defined.  Black geometry required for Parameter reliability.

Might help....

[toddbg]

I decided that applying the chamfer after the extrusion would make more sense.
I set up the first rectangle, extruded that and then sketched on the bottom the inner rectangle, then extruded that.
Parameters are assigned to the extrusions.
Then chamfered as needed and then applied a shell with the parameter there.

I think I have the parameters all set, the only problem at this point is the chamfers are not behaving the way I would expect for the corner chamfers connecting to the edge chamfers.

I may have the order of operations off?

Thoughts?

Appreciate the help.

[davebYYPCU]

Yes and no.  It's the geometry that Fusion has to operate with, your result is what you asked Fusion for and not what humans would expect.

The reason is the two differing distances involved here, showing 2 chamfers of 1mm, and the order of operations does change the result but not the underlying geometry.

Change lower chamfer to 2.77mm for the expected result.

Might help....

[toddbg]

Interesting.
How did you do that?
I changed the order of operations and made the corner chamfers, then chamfered the bottom.
When I went to chamfer the transition I keep getting errors and cannot mimic what you have done.
If I select the overhang face I can only go 1mm, if I select the "inner" edges then it doesn't go all the way, same thing if I select the outer edges.

Selecting both throws everything off.

Thanks again for all the help!

[davebYYPCU · Accepted solution]

Do what?

The middle chamfer is the last one, and one chamfer, at (Tolerance + Thickness or 2.10). 

Pick one loop, and that depends on where you want the material change to be (lower or) higher than the sketch.

Blue sketch articles should keep you awake at night.

Might help....