topic Re: Problems with Shell command - Please Help ! in Fusion Design, Validate & Document Forum

Problems with Shell command - Please Help !

Monodon — Wed, 03 Jun 2020 09:55:20 GMT

Hi,

I have problems with shelling this model (attached). Every time I try to make a shell I get Error message:

"Error: The body could not be repaired after deleting faces.
Try changing the selection, or use the Delete tool in the Patch workspace to delete geometry without repairing the gap."

I tried all possible options of Shell command, and also changed thickness parameter - no result.

Please help.

Kind regards,

Mike

Re: Problems with Shell command - Please Help !

HughesTooling — Wed, 03 Jun 2020 11:05:09 GMT

The problem's probably down to the 0.1 fillets, you should try and shell before adding small fillets.

It does shell with a 0.05 offset but guess you want more than that. PS this would be simple to fix if you'd used history.

Mark

Re: Problems with Shell command - Please Help !

HughesTooling — Wed, 03 Jun 2020 11:11:15 GMT

After removing all the 0.1mm external radii I can shell at 0.5mm, the next smallest radii in the design.

Mark

Re: Problems with Shell command - Please Help !

Monodon — Wed, 03 Jun 2020 14:05:53 GMT

Dear Mark,

Thank you for your help, however I need to get final thickness = 0,15 mm. So I took different approach. I created a shell - a Form and I tried to thicken it. But here I met a problem, too while trying to Finish Form:

Warning: Form1
<b>1 Reference Failures</b><br/>Highlighted surfaces may be self-intersecting. Try modifying shape or Unwelding adjacent edges.

Please help again !

Regards,

Mike

Re: Problems with Shell command - Please Help !

HughesTooling — Wed, 03 Jun 2020 15:04:53 GMT

Sorry can't help with a form, never use them. What was wrong with the first part you attached? all you need to do is select each chain of radii and delete, shell then reapply the external radii.

You only need to delete the convex radii. See attached file with timeline, just step along the timeline to see what I did.

Re: Problems with Shell command - Please Help !

jeff_strater — Wed, 03 Jun 2020 15:06:22 GMT

@Monodon - I really don't think that the Form environment is the right one for this design. This design seems to have lots of planar and cylindrical faces on it and Form is not good for that kind of analytic geometry. Personally, I would take @HughesTooling 's advice, and remove the small fillets, do the shell, then re-apply the small fillets after the shell.

As to the problems in the form, the tool shows you where the intersecting faces are if you click on the error:

One thing to be aware of: The offset capability in Form is much different than the solid shell. It works by creating an offset control frame network, then re-fitting a TSpline surface over that network. Uniform thickness is not guaranteed, and for small offsets, it will often result in these exact kinds of intersecting faces.

Also, as Mark says: Use history, it is much easier to fix up problems when they happen if you can go back and edit features.

Re: Problems with Shell command - Please Help !

TrippyLighting — Wed, 03 Jun 2020 16:37:42 GMT

@Monodon wrote:

... So I took different approach.

Yes, but that did not work because you don't actually appear to understand what the problem is.

Sketch an arc ay 90 degrees with a radius of 2mm.

Try to offset the arc 3mm toward the inside or center of the arc. What is the geometry going to look like?

That is what you are asking Fusion 360 to do. In some circumstances, the resulting "bowtie" geometry is removed automatically and that results in a sharp edge, but the fillets on this model don't lend themselves to this.

So you either follow @HughesTooling's advise, or you need to re-think yot approach to geometry.

Re: Problems with Shell command - Please Help !

Monodon — Wed, 03 Jun 2020 18:08:47 GMT

Dear Peter,

you both are right. I tried your suggestion - it works for me. But how to delete multiple fillets when I already have a big pattern of many shapes combined together ???

Re: Problems with Shell command - Please Help !

TrippyLighting — Wed, 03 Jun 2020 18:12:41 GMT

In a design without design history, this is very labor-intensive and somewhat error-prone. Thus my recommendation to work with the timeline enabled.