Revolve and Extrude in Solid workspace making a shell (or something)

[rnl9t]

I am modifying a solid design to take hexagonal inserts in 5 slots  instead of square.  I drew hexagons and extruded them as "join", then cleaned up some iffy edges.  So far so good.   

However, my attempt to add a conical piece at the end (to reflect what will realistically happen when a chamfer mill is used to cut it out) resulted in unexpected internal lines.  On a hunch, I tried Boundary Fill, and sure enough, that area is shown as hollow.  When I fill it, the solid body becomes a surface body.  

I shrugged that off as "Something weird Fusion 360 does sometimes" and decide I could live without the conical part in the model, and went to extruding a hexagon on a different slot.  But that extrusion now also results in a shell body, unlike the previous extrusion.

The attached screencast shows what I am talking about.  I have restarted Fusion 360 hoping that it was just a glitch, but the problem persists, and I can't make the other slots hexagonal now.

Thanks in advance for your help.

https://knowledge.autodesk.com/community/screencast/935e749f-b185-4b87-b62a-5fac17a6e281

[rnl9t]

Trying to attach screencast a second time.

[jhackney1972]

Please attach your model.

[rnl9t]

The model has a lot of stuff in it that isn't relevant, but this body is found under "Tuners" and is called "Holder Guide."

That said, I have found at least part of the problem--the holder guide itself is a shell model.  I don't know how that happened or how to reverse it.  It was solid yesterday.  If I can make it solid again it will probably be fine.

[jhackney1972]

I will have to pass on this one as I cannot understand what you want done.  By the way, why are you not using Capture Design History?

[rnl9t]

Either this design actually predates the design history feature, or is from a time when design history was new and I found it confusing and frustrating, and therefore turned it off.  I'm not sure which, but I've been working on various aspects of this particular design since 2015 and just saving new versions as I moved to different parts of it.

What is happening right now is that what should be a solid body is acting like a surface model.  If you extrude a profile through it as a cut, it doesn't have any internal faces.  That means that my attempts to cut and join are resulting in gaps (for cut) and new hollow but closed shells (for join).  If I can figure out how to make it solid again I'll be fine, otherwise I suppose I'll go back through the version history to find one where it's still solid and start over.

[jeff_strater]

this design seems to be solid.  If I do a Section Analysis, you can see its solid-ness.  However, it looks like the solid is not well formed somehow.  The surface normals seem to be backwards (which is why you can see through the solid):

I've seen cases like this in the past.

I won't have time to dig deeply into this today, but I might tomorrow.

[rnl9t]

You can see through it because it's made of polycarbonate.

But looking at the round holes at the back of the slots, I cannot see an internal (circular) face.  And if I extrude the point of the hexagon through the bottom of the slot, I don't get a triangular cut, I get just a gap that you can see through.

[jeff_strater]

you are absolutely right, @rnl9t - that confused me.  But, I think the problem is the same, but on a smaller scale - I think the faces for those holes are somehow inside-out as well, so it may be the same underlying problem

[rnl9t]

Thank you for trying to figure this out. As you can see from the center slot, it was working yesterday, so I may have just clicked the wrong thing at some point. 

[jeff_strater]

OK, back to looking at this.  Do you happen to have an older version of this design where these bad faces do not exist?  In your screencast, it's hard to tell whether the body is good before those features are added, but if so, it would be great to have a version that is ok, and a set of features that introduce the problem.

Thanks

[jeff_strater]

Made some more progress.  I'm still very interested in looking at older versions of this design (prior to the one in your screencast) to see if I can re-create this condition.  This body is pretty strange.  Fusion thinks it is a solid, but it is not really a solid.  If I unstitch it and stitch the resulting surface bodies back together, it is not a solid.  The attached video shows how I was able to repair it by building back the apparently missing surfaces.  I had to do some editing to get it down to a size that the forum would accept, so there may be some gratuitous cuts in there...

I would recommend using the timeline, if for no other reason than it would help to debug problems like this one, and would give you a way to back to a time when the design was OK, but that is certainly up to you...

[rnl9t]

Thank you for your effort. I haven’t managed to even turn my CAD computer on today but I will look through the version history when I can.  

I normally use the timeline these days, but this is a very old legacy design that I’ve never bothered to activate it in. 

[rnl9t]

Here is a still-solid body from version 104.  By version 105 it has become a shell.  I deleted the rest of the design to make it smaller.  I don't know if that will help find the issue or not, but I may simply re-save from 104 and work my way forward again rather than try to stitch the damaged body back together.

[jeff_strater]

Thanks.  I can verify that the body here is OK.  I tried a few things, but was unable to make it go bad.  If you intend to continue from this point, please check once in a while to see whether this problem re-occurs - I'd like to find out a way to make it happen if you do.