Draft Bug
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John Hackney, Retired
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You used an Extrude to create the angled corners in the original model and a chamfer to create them in the second. They will react differently to the Draft command with the chamfer adjusting to the Draft where the Extrude will not.
John Hackney, Retired
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As I said, the Extruded features will not be affected by the Draft operation because it is a sketched base feature where the Chamfer will be affected because it is a placed feature and will be influenced by the Draft.
John Hackney, Retired
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this looks like a bug to me also. if draft is going to modify previous features instead of working an the obvious way visually, it should have a type setting like offset faces does-
@Phil.E ?
Hi,
1. When I get into a design like this, I can't see how a chamfer was created which leads to irritation and the subsequent (time-consuming) search for causes.
It should also be noted that it is repeatedly pointed out that fillets, chamfers ... should not be created in sketches, but as features.
2. I have never seen a draft pull adjacent surfaces along with it.
3. The same phenomenon also occurs with Move > Face > Rotate
can you give an explanation of this
günther
I can explain what is happening here. Whether it is a bug or a feature is probably a matter of opinion. It is intentional, I will say that. I apologize up front - this might get long.
what is at play here: Chamfer and Fillet operations are handled differently during "local operations", which include Face Draft, or Move Faces. The main reason for this is: if you want to move this face to the right:
The fillet is the problem. You cannot move that face with the fillet in place. So, what Fusion does is:
- find and remove all relevant fillets (and keep that info)
- move the face
- reapply the fillets
The same is done for Chamfer, being a similar operation to Fillet (select an edge, Fillet/Chamfer it, which removes the edge, and replaces it with a new surface).
Most of the time, it works without any surprises. But, there are cases where it does, and you have found one of those.
Anticipating the next question, I've created a similar case with Fillet instead of Chamfer (the body on the left has a sketch fillet, while the one on the right has a fillet feature).
As you can see, both behave the same. Why is that? Well, it turns out that Fillets are easy to identify: tangent faces, probably cylindrical/conical/toroidal. Chamfers, however, are not. So, in your case, the one on the right is correctly being identified as a Chamfer (because it is), so is treated as one. On the left, it is ambiguous. I'm not even sure it should be considered a Chamfer. It might just be an angled face. In this case, maybe it should, but that might be only because the one next to it is the same, and that is a Chamfer.
Anyway, you asked why. That is why.
Jeff Strater
Engineering Director
@jeff_strater wrote:
... It is intentional, I will say that. ...
...meaning the team has made a decision on behalf of the user. That decision addresses 90% of the use cases.
For the other 10% it is undesirable behavior. In essence we'd like to have a choice and sensible defaults.
Disclaimer: percentages were chosen arbitrarily. Actual situation might be worse 😉
