Direct modeling help 2

[cowski]

Attached is a chunk of an unparameterized file that I am working on. I would like to offset the highlighted planar face by -8mm and have the highlighted blends move with the face (reattach after the planar face is offset). I have been unsuccessful even after consulting the help files and trying various combinations of options. I have even tried to delete the blend faces so I could use the trusty 'offset face' command, but still no luck.

So, is this possible? Am I asking too much? Is something wonky in the geometry? (it passes validation tests, but there is something strange going on in the opposite face near the corner).

File version is NX2.

 

[JohnRBaker]

OK, attached is your part modified as you say you needed it.

As to what I did, you are correct, the Direct Modeling tools of NX 2 were not able to either offset the face nor could it delete the 'blends' so that a more conventional offset could be done.

I then opened your model in NX 5 just as a sanity check and the same issues confronted me.

So I finally opened your file in NX 6 and while I was not able to offset the face directly, I was able to delete the 'blends' with the new NX 6 Synchronous Technology tools and then it was easy to offset the face 8mm and then added the blends back to the model. I finally exported the solid from NX 6 as an NX 2 compaptible Parasolid model and then imported that model into an NX 2 part file, which is the file that I've attached.

Note that there was some good reasons why this part was presenting the problems that it did. To start with, those 'blends' are not really blends, they were b-surfaces and as such are difficult is not impossible to update like a blend would have during a face offset operation. You can see that this is the case by performing an Information -> Object on those 'blend' faces. And to see what a true blend looks like in a Parasolid model, perform those same checks on the faces of the model that I've attached to this note.

Anyway, you've got a model now that should meet your needs. However, if this is the sort of work that you expect to be doing often, you should really consider moving up to NX 6 since the changes made, in what are now called the Synchronous Technology tools, are extensive and many editing cases that could not be handled in the past are now much easier to address.

Let me know if this was what you were expecting.

John R. Baker, P.E.
Product 'Evangelist'
NX Design
Siemens PLM Software Inc.
Cypress, CA

http://www.siemens.com/plm

http://www.plmworld.org/museum/

To an Engineer, the glass is twice as big as it needs to be.

 

[JohnRBaker]

Sorry, I forgot the part file :-(

Here it is.

John R. Baker, P.E.
Product 'Evangelist'
NX Design
Siemens PLM Software Inc.
Cypress, CA

http://www.siemens.com/plm

http://www.plmworld.org/museum/

To an Engineer, the glass is twice as big as it needs to be.

 

[hudson888]

Cowski,

This isn't going to work for a couple of reasons but I've cobbled a couple of solutions as parasolids so that you'll get an understanding of where my explanation is headed.

Firstly you probably tried to use offset, move region or replace face in your models. I also found they wouldn't work and I soon realised what was stopping it was a radius on the shoulder that you probably think isn't involved with the problem.

The oldest that I have loaded is NX-3 I could load NX-2 but it would be a lot of bother just for this. If you have a later version loaded what I'm doing should work equally well in NX-2 as I'm not taking advantage of any new features in the software. So I could create models for you containing a little more info than just these parasolids.

To start with I managed to remove all the radii from the edges, using a combination of replace faces and simplify body features. In the case of this model there is a 3mm radius at the base of the upstanding shoulder and a 1mm radius running along the edge. This was easy enough to find out with a bit of quick checking. Whenever you have trouble and need to find a solution simplifying the problem is a good place to start. By removing the radii you're stripping the model down to its bare bones so that there aren't so many variables contributing as to why it won't work and you can therefore target the root cause. Look at the parasolid call chunk.x_t and compare it with your model. See if you can figure why that flat face still won't offset by 8mm.

The answer is hinted at in the built up parasolid called chunk_possibile.x_t there is a much smaller radius on the upstanding shoulder.

What occurred was that the original blend which was either variable or resulted from a free form construction was too large at the tangents. Any offset exceeding 3mm causes the surfaces to come apart that the corner. In fact the geometry isn't great to start with in the version of the data that I'm working with.

Anyway the problem is that at 8mm offset that corner is unresolved so the geometry isn't possible.

Let me know if this makes sense.

Cheers

Hudson

 

[hudson888]

I need to wear my glasses more I was answering for an offset of +8mm instead of -8mm. Ignore that my previous answer makes no sense.

Have a look at the attached. I found an old copy of NX-2 just for you. This just details the technique that I mentioned worked in NX-3. The -8mm offset gives the same geometry as John achieved.

I also think that John's reasoning and explanation about why the direct modelling technique didn't work in the first place was probably as good as you're going to get on the subject. However try as I may from NX-2 up to NX-5 I cannot having deleted the blends then re-apply them and then use direct modelling to move, offset or replace the face by -8mm. Not that you really need to just that it would have been proof on the concept that the B-Surface blends were the culprit.

Cheers

Hudson

 

[DESUG]

Dear Mr. Baker

I have downloaded the files, since this is one the of the issues I have to deal very frequently (change models from Catia V4/V5).

Can you please post how did you manage to remove the "blends" in NX6.

I did try it, but no success.

Win 64 Bit, NX6 MP0.1

 

[hudson888]

If you have a look at how it was done in my last post that method works for NX-2 through NX-5. So I'm pretty sure it will work in NX-6 as well.

Cheers

Hudson

 

[uwam2ie]

direct modeling is a cool tool,
synchro- Tec. does the same way ( but no history).
The problem John pointed out above is to resolve the problem with b- surface. Is there a common workaround to resolve those problems? There is in the direct modeling a advantage in replace face to simplify the surface works fine on b- surface inside NX ( b-surface to plain or ruled / cyl/ surface conversation). Often direct modeling doesn't work when there is an geometric problem outside the area is to modify. In the old edit face -> delete face there was an option to create a new face, where is it in nx5.05 which direct modeling function does cover this?

 

[cowski]

John & Hudson,
Thanks to both of you for your helpful answers. I had not even thought to check for a B-surface. We are looking to move to NX6 soon, as we increasingly work with translated geometry. One of the 2 major hurdles is now behind us (upgrading hardware) now only if IT could figure out the new plotting software (are there any detailed documents on this that I could pass along?).

 

[Xwheelguy]

cowski,

If you can access GTAC, there should be a Plotting Quick Start Guide available for download under NX3, 4, or 5...can't recall which one.

That guide was very helpful to me when trying to initially setup the SDI plotting the first time I used it. The SDI Print Admin is quite a bit different from the old PQMGR but once you get a grasp of the overall scope of things, it shouldn't be too difficult to figure out what to do and how to do it.

There are some predefined printers and printer "models" included with the SDI software. I typically just copy those and rename and reconfigure to what we want.

Tim Flater
Senior Designer
Enkei America, Inc.

http://www.enkei.com

Some people are like slinkies....they don't really have a purpose, but they still bring a smile to your face when you push them down the stairs.

 

[Xwheelguy]

cowski,

I forgot to mention that the Plotting Quick Start Guide can be found under the Documentation link on GTAC....NX3 was the version, but will also apply for NX4, 5 and 6 for the most part.

Tim Flater
Senior Designer
Enkei America, Inc.

http://www.enkei.com

Some people are like slinkies....they don't really have a purpose, but they still bring a smile to your face when you push them down the stairs.

 

[JohnRBaker]

I used the Delete Face operation that is part of the new Synchronous Technology tools in NX 6 to delete the 'blends'.

As for the b-surface issues, we are working on enhancements for the Synchronous Technology tools for future releases which will provide more support for editing complex free-form models in manors similar to what can be done now with more 'conventional' solid models.

John R. Baker, P.E.
Product 'Evangelist'
NX Design
Siemens PLM Software Inc.
Cypress, CA

http://www.siemens.com/plm

http://www.plmworld.org/museum/

To an Engineer, the glass is twice as big as it needs to be.

 

[DESUG]

I am sorry, but I have tried all the possibilities that I could imagine (NX6) and it dose not work.

Is it possible to have a detailed description of the workflow used to do the job in NX6?

 

[NXMold]

I used to do a lot of work on imported and fully blended parts, using software that shall go nameless. I had one command similar to replace face, but it would only work with sharp corners. I could replace the blend faces with a neighboring flat surface, but that wouldnt work if multiple blends met at a corner.

My work around was to 'block out' the trouble areas by adding or removing from the solid, then replace my 'block out' faces with part geometry. This tecnique is pretty reliable, it works on this part, the tough part is identifying what to block out and accepting the odd and cluttered model tree.

I have attached a couple pictures of my process

NX 5.0.3.2 MoldWizard

 

[hudson888]

NXMold,

I'm a bit perplexed with this as I was able to use the old replace face in NX-2 through NX-5 achieve a similar result, I went on to use a simplify body to finally get rid of all the blends using direct modelling. Which is to say just using the method that was requested. The file is attached above to an earlier post.

I understand your method adds technique where in some cases you will need to model away an offending piece of geometry. That can be a useful way to handle such problems. It is worth considering if all else fails.

On this occasion however I think you're better to lose the 1mm edge blend entirely, as you still need to resolve how to put the blends back ON in your example.

Cheers

Hudson

 

[NXMold]

I see, I hadn't tried the magic combination with replace face.

I agree that removing ALL the blends is desireabe.

NX 5.0.3.2 MoldWizard