Need advice on bent sheet metal design

[Anonymous]

Hey all, I'm still very much a beginner with CAD and Fusion and I'm not sure of the fundamental approach to creating a design from a single piece of sheet metal with multiple bends. My understanding is I can't just sketch it out as a single, flattened component and then add the bend lines/angles (though, oddly, I know Fusion can "flatten" your design once you've finished it - too bad it can't do the same in reverse). So, how would I sketch and model the object?

For example, assume I want to create an M shape from a 1" wide, 12" long strip of sheet metal that incorporates 3 bend points and four 3" legs. I can't simply create a single extrusion that's 1" wide and 12" long and add bend lines and angles at 3", 6" and 9" (wouldn't that be great though?). So I start by sketching the first leg of the M (3" long, 1" wide). Now what do I do for the next leg of the M? Do I need to create a new 1" wide, 3" long sketch on the appropriate plane and extrude that object? Or do I simply create a 3" long flange at an angle starting from the end of the previously-extruded leg? And do the same for the remaining two legs?

I hope my question makes sense. Just trying to understand the logical approach for doing this type of design work. Thanks!

[Anonymous]

Switch over to the Sheetmetal workspace. Under Create, Flange simply bend the edge of the first leg and use the arrow or arc manipulators to pull out to the required length and angle.

Repeat for the other 2 bends.

I found it helps to draw the M on perpendicular plane to serve as a guide.

[carl.j.barker]

Using the sheet metal workspace. First start a new component (#ruleone). then sketch your 'M' as an open profile and use the flange tool to create a contour flange.

[Anonymous]

Hard to find but its also possible to change all the Sheet Metal settings.

Things like material, thickness, bend radius K factor etc, can be be found under Sheet Metal Rules.

It hidden away about half way down in the Modify Menu.

You will need to expand the side arrows in each category.

Then hover near the Title heading to activate the Edit icon.

I will do a short Screencast to demonstrate. 

[TheCADWhisperer]

There is a bit more involved (Bend Radius, Thickness, Bend Allowance), but the attached might give you some ideas.

In general, you start with Design Intent, what are you intended final form dimensions for the part.

Sometimes this runs counter to standard stock size.

Bending metal stretches the material towards the outside if the bend and compresses material towards the inside of the bend.  Typically the neutral plane - no stretching or compression - isn't in the center of the Thickness.

[Anonymous]

Thanks for the feedback. My “M” example was a poor one - too simplistic to get the answer I’m looking for. Assume a more complex shape with multiple bends and bends-from-bends. Say, perhaps, an origami swan for example. How would you sketch it out in 2D before doing all the extrusions/flanges?

I’m really hoping someday Fusion supports bend lines.

[TheCADWhisperer]

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@Anonymous wrote:
Say, perhaps, an origami swan for example.

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Model in finished form as best you can and then Attach the *.f3d file here and I’ll demonstrate how to create using sheet metal tools.

[Anonymous]

Let's try this as a fictional example. I sketched out a rudimentary metal chair in "flattened" form. It has a square seat and four triangular legs that bend down and then are bent from the center line to form 90-degree angles (so the legs form an L shape). There is a small flange that extends out from the seat at 45 degrees upward and then the seatback extends straight up from there. I've highlighted the bend lines in the sketch below. In a perfect world, I'd be able to take this exact sketch in Fusion, indicate which lines are bends, specify the angles for each bend line, and voila, sheet metal chair design finished. Since Fusion is unable to do that (though my understanding is Inventor can), I don't know what the correct Fusion approach would be for this design.

[TheCADWhisperer]

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@Anonymous wrote:

..., I don't know what the correct Fusion approach would be for this design.

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The correct Fusion approach would be to model the design in the finished form that the customer will purchase.  (Then Fusion will generate the necessary Flat Pattern automatically.)

Do you know what your customer wants?

Can you sketch by hand the design that the customer wants (like you did for your flat example)?

[Anonymous]

Let’s take the imaginary chair example. So on my primary sketch I’d only have the chair seat as that’s the only component that exists on the 0-degree plane? Then I’d do new sketches on the other planes for the legs and seat backs? And if so, how do I make, say, on of the chair legs a 90-degree flange coming off the seat?

[TheCADWhisperer]

The easiest way for me to demonstrate is -

forget for now that it is sheet metal.

Model the design as best you can with the standard tools.

Then I can demonstrate how to use the Sheet Metal tools to get an appropriate design.