Strange chamfer behaviour

[Maurizio]

hello,

we have bumped into a strange chamfer behaviour, which is new in NX9.

In the attached example, we have two solid bodies, which have the very

same geometry but one (at the right) is unparameterized while the other

(at the left) is parametric and contains a chamfer feature.

The very same draft is applied to both and, unexpectedly, I got two different

results, which doesn't make any sense to me.

I have filed an IR, and GTAC has told me that, due to an undocumented

change happened in NX9, the chamfer feature now behaves the same

way as synchronous features do.

Apart from the lack of documentation (which is a problem on its own), to me

this new chamfer behaviour is very confusing and dangerous as history-based and

non-history-based features are now mixed together.

Also, in NX9 there is seemingly no option to get back the previous kind of chamfer.

I'm curious to know the community opinion about this.

Tnx

[JohnRBaker]

OK, while I don't know this for sure, I suspect that what happened was that this was 'fixed' in response to a PR (I'll check and report back on this later).  The reason I suspect that it was after someone complained is because technically a 'Chamfer' is an edge 'treatment', the same as a 'Blend'.  Therefore, one would expect that this edge 'treatment' would remain unchanged when the edge is moved (you can verify this by replacing the 'Chamfer' with a 'Blend' and repeating the excersize).

Now I agree that perhaps, since this changed the topological behavior , that it should have been noted in the 'What's New' document, however, not to be making an accuse, but if this trully was simply someone fixing a PR, it would not have appeared as a development project and therefore there would not have been a requirement to document it.  After all, unless you were looking at the list of PR's addressed in a release, whereelse would you ever learn what changed as a result of a PR.  In other words, PR's are not typically mentioned in the 'Waht's New' document, although in this case it probably should have been.

[Jahnsen]

Hi Maurizio,

same thing happen to me last time and find the answer to that with trial and error and find it as one of the strengths of synchronous technology.

It is because the chamfer on the unparameterized one is not recognize as a chamfer.

in your model, i suppressed draft 5 and draft 6 first and then apply "Label Chamfer" on the unparameterized chamfer.

after that, I unsuppressed draft 5 and 6 and get the same result now. .

Hope this helps you.

Regards,

Jahnsen

[Jahnsen]

by the way, you may need to reorganize you history for the dependencies of the geometries

[Maurizio]

Labels are not there in NX9.

They have been introduced in NX10, to fix what seems to me a mistake.

Whatever the rationale under this change may be, the whole thing has been badly handled.

[JohnRBaker]

The 'Label Chamfer' function has been in NX since NX 7.5.  It was added so that you could edit non-parametric models and still have faces that are obviously chamfers behave like chamfers.  The same can be said for the 'Otimize Face' and 'Resize Blend' functions so that faces that are obviously rolling-ball blends behave like blends when editing a non-parametric model.

[Jahnsen]

It is available as John said.

please look at your tools again, or look in the command finder.

BTW, i'm using NX 7.5-NX10.

[Maurizio]

in NX9, Label doesn't have the Delete option that I would need to have the parameterized

body to behave as the unparameterized one, if applied before the draft, which is the behaviour

I'm used to and I wanted to restore.

Labels in NX9 do the opposite job and, as I understand, cannot help in this case.

To complete the picture, last month I submitted an IR about the same problem.

In that case (see attachment) the strange behaviour happens even where there

is no chamfer feature at all. 

I suppose some sort of unwanted labelling took place there, which caused mistakes here.

So that "feature" which has been unfortunately sneaked into the software is even bugged.

[Jahnsen]

if you need to have the parameterized body to behave in the same way as the unparameterized one. I think what you will be needing is the "Optimize Face" tool.

[Maurizio]

this would unparameterize the body altogether