Cannot get replace face to work

[Anonymous]

It doesn't help that I don't entirely understand the command, but I've gotten all but one of the faces I wanna replace to work, after many hours of trying. No matter what I do, however, this large curved face will not replace to a flat one. The surface body I'm using for the face is "face for knurled grip", the sketch that controls the elevation of the surface body is "sketch for replace face side grip". And yes, I'm aware of the red thing in the timeline. The curved circle face finally replaced, and then inexplicably turned into an error.  The surface body for that is "face for taurus", and the sketch that controls the body is "taurus face flatten". If you could help me with that as well, I'd really appreciate it.

[TheCADWhisperer]

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@Anonymous wrote:

 And yes, I'm aware of the red thing in the timeline. 

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There are multiple unresolved issues indicated in your Timeline.

But perhaps more important for now - many of your sketches are not fully defined, especially your very first sketch - the very foundation of your design.

I recommend that you start over from scratch using what was learned from this attempt.

Stop after completion of each and every new sketch and Attach your file here for suggestions from the experts here.

[Anonymous]

What an absolutely disrespectful reply. Sketches do NOT need to be fully defined, contrary to popular opinion. The yellow is just downstream failures that I got tired of fixing. I am not starting over. It took weeks to do this. I had to do a lot of changes and it broke stuff. You know as well as I do that yellow is really minor, easily fixable stuff. I gave clear instructions about what sketches and bodies were involved. I didn't ask that people make the thing perfect, just fix the one issue that I have tried for hours and can't.

[davebYYPCU]

.... I’d really appreciate it. 

I don’t think so.

[Anonymous]

Sorry, what is that supposed to mean? He did the exact opposite of what I requested, criticized me as a designer, and then told me to start over. And I'm supposed to be grateful for that?

[davebYYPCU]

Statement of fact with a recommendation, and you ark up,

we volunteer to be criticised for advice freely given? Not me.

Where is the appreciation you intimated would be forthcoming?

[jeff_strater]

@Anonymous - can you help me understand better what you want to replace with what?  I get that "face for knurled grip" is one of them, but is that the "source face" or the "target face"?

A quick explanation of how Replace Face works might help understand when it succeeds and when it fails.  Here is a classic case for Replace:

Here, I want to replace the top face of this truncate pyramid with that curvy face.  To do this, Fusion will have to remove the top face of the pyramid:

then, extend the side faces until they intersect the replacement face:

trim both the replacement faces and the extended faces, and stitch it all back together:

In this case, you can see, because of the angles, I did not have much left of the replacement face, but it all worked.  Replace Face automates this for you.

Reasons why it can fail:

• adjacent faces cannot be extended enough to reach the replacement face.  In this case, if I had put that surface much higher, the extension would have degenerated to a point, and failed
• adjacent face extension fails for another reason.  Face extension of curvy side faces can fail
• cannot self-trim all the faces for various reasons
• if the replacement face is not big enough for the extended side faces, things cannot be stitched back together (usually requires the replacement face to be a bit over-built)

Hope this helps.

[Anonymous]

If you call the nonsense that he gave me advice, fine. I don't. That was the elitist way of saying "nope, not helping you, but I'll make fun of you for free". I know exactly what he meant, and I know exactly what you meant. But you were not so rude, so I didn't give you rudeness back.

Those errors keep happening, and they are not related to the issue at hand. They are a result of changing something else, and I got tired of fixing them when they are extremely minor. Yellows are just lost projections (at least in my case), and I got tired of relinking it. The red is at the end of the timeline. It's red, but before it broke I got the face replaced to a flat one, which is what I need. I wasn't about to change it back.

Perhaps you saw that as helpful, but it is the exact opposite. And when someone is rude to me, I don't let it slide. I call it out. And I'm well aware people do not like me for doing that.

I want to be finished with this project and move on to the next. I'm doing this for a friend, remotely, and I've put at least two weeks of work into getting this grip right. I'm not starting over.

[Anonymous]

Sure Jeff, thanks.

I apologize for not giving all the details. The surface body is the target face. The source face is the face I have split on the curved side of the grip. The large one. I know there are two over there, but I am trying to get them both to be flat, and offset down a smidge. All the commands seem to work, sans replace face.

When you say "extend the side face, do you mean like, offset up where the old face used to be? I do understand a bit of how it works, maybe not completely I guess? I have the surface bodies close or below the surface, so they don't extend up and ruin the look I want.

Maybe the new face is in a different angle plane than the old face. Could that cause it to fail?

[jeff_strater · Accepted solution]

Thanks, @Anonymous - now I think I understand the failure.  I had to try this out for myself, because I did not know if it would work or not, and it does not.  I don't think you can "replace" a face produced by Split Face like that.  At least it failed in the simple cases I tried:

And, this is why:  Looking above in my explanation of what Replace does, the first thing is to delete the source face.  Then, the adjacent edges of the target face are extended.  But, in the case of a split face, those adjacent edges are not going in the right direction.  In my simple case, extending those would just fill in the hole again:

and, in your case, if I delete the source face, and extend the adjacent edges, they do not go towards that plane, they go towards the middle, and will not intersect that planar face.  Plus the hole in that face is going to cause problems as well.

Hope that makes sense.  If you had split the body instead of the face, then it might be possible, because there would have been side faces that point toward the plane.

[Anonymous]

I got rid of the split face, and used a split body instead. It seemed to have much more success, but I am having problems recessing the face enough, because when I go low enough, the original face is still there as well. I try to patch it, and I can't grab the edge to make the patch. I think I am going to have to go with an only an offset recess for the face.