Flange problem

[oldenjon]

Hi everyone, let me start off by saying that I'm new to Fusion 360. I've watched a few videos on YouTube but haven't found an answer for the issues I'm having. 

I'm designing an aluminum box using the flange / sheet metal functions, and using a symmetric edge to close the gaps at the corner. The aluminum is 2.5mm thick. The idea is to have the short sides wide enough that the edges of the long sides are not visible from a profile view. 

The first problem is that after I've set the appropriate symmetric edge for the short sides and created a flange on the adjacent long sides, the cutout at the base of the short side becomes stepped. How do I avoid/correct this?

The second problem is that if I try to close the gap with a symmetric edge on the long sides in an exact manner, the corners look continuous and I get errors. Is there a minimum clearance? 

The last question I have is what determines the corner radius of a bend? The width and k-factor of the material used?

[TheCADWhisperer]

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@oldenjon wrote:

Hi everyone, let me start off by saying that I'm new to Fusion 360.

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I recommend that for now you forget the sheet metal tools.

Model up the part as best you can using the standard tools

and then

File>Export and Attach the *.f3d file of your attempt here.

Someone will demonstrate how to best model the sheet metal part.

[carl.j.barker]

Here is one method I use to close corners on sheet metal. It usually solves the problem and doesn't use any tricks.

Pay as much attention to the settings in the sheet metal rule as to the modelling operations, especially mitre size and 2 bend  intersection.

[oldenjon]

I assume you are using a template and using the sheet metal bend feature to construct a box? I haven't figured out how to do that yet. I followed a tutorial and the extra lines I drew for bends disappeared when I used the flange feature to create a component. 

[carl.j.barker]

No, just the flange tool and extrudes.

Download it and have a look.

[oldenjon]

Oh I see, you use the unfold or create flat pattern function.

I am able to match all sheet metal rule properties shown in the snapshot you attached except I left k-factor at 0.5 because the material I'm using is aluminum not steel, and the relief size for the 2-bend intersection is locked at thickness * 4.0.

I experimented with constructing a box this way. One thing I noticed is that the edges of each flange are slightly shorter than the dimensions of the base, even though I set the bend position to 'outside'.  Why is that? I can't proceed until I get the edges consistent with the dimensions of the base. 

For example, I was not able to add a symmetric edge to the short sides in order to cover the edges of the adjacent sides. I was however able to add a flange to the edges set a 0° which has the same effect. Problem is I don't know how long to make them now. It would be 2.5mm but the reduced edge length means I need to add a bit. 

[TheCADWhisperer]

Attach file.

[oldenjon]

https://a360.co/2VAJefk 

Here is an example. The base is 150 x 300mm.

After using the sheet metal rules I described in the previous post, you can see that the edges of the created flange are just under 150mm and 300mm. About .014mm shorter. If that is a result of the corner settings, it's fine. I just need to know exactly how much shorter they are so that I can add flanges to the short sides. It's somewhat important because I need to use the edge as a reference for placing holes. 

[carl.j.barker]

Did you download the model I attached to my post?

It shows how to use extrude->to object to close the gaps. You don't need to know the size fusion does it for you. You only need to examine the first 5 items in the time line, the rest has nothing to do with this problem.

[oldenjon]

Yes I'm afraid I don't really understand it. I don't know what the profiles or object selected are. 

*edit* never mind I get it. thanks!

[TheCADWhisperer]

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@oldenjon wrote:

*edit* never mind I get it. thanks!

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@oldenjon 

You should mark @carl.j.barker example as the solution.