Hi sneather,

> There is still some weird line data in the new piece I arrived at, but the surface itself looks perfect,
> and if it looks that way once it gets into C4D, then that problem is solved!

If the boundary has got gaps in it like it did here sometimes you may also need to draw in some additional curves and also include those when doing the trimming, in order to make a better formed boundary, check out above for how that looks.


> P.S. I forgot. One other question. The scale tat which these products are importing is tiny. When I
> receive the same kinds of product CAD from one of their affiliates who use ProE, the files seem to
> import accurately at 1:1 in MOI. The NX guys are using inches, but would that account for such a
> massive discrepancy?

Hmmm, I don't really know what would cause this, other than if they're actually modeling things at a tiny scale in NX to start with. If they are doing that it could also explain some of the trim curve problems as well because gaps like the one shown here can sort of be treated as ok (and not refined further or calculated to higher accuracy or things like that) if they're at a very small size.


> Is there something which I should be doing in MOI to counteract that?

Well, you can scale the model, either click on the size line in the properties panel in the upper-right area of the window, or use the Transform > Scale command to scale things up.

But if model data itself happens to be tiny then it will come into MoI tiny initially as well.

You might try testing the STEP file with other programs too, to see if the tiny size is indeed just how the file is set up or whether there is something going on with MoI in particular.

It's hard for me to know for sure what's going on with that without being able to look at the actual STEP file.

- Michael

Thanks, Michael T.
Great info. I'm Mac based, so my choices for CAD help are rather limited, to say the least. I just checked on CAD Exchanger, per your suggestion, and there is some form of a Mac OS Beta. But I need a license to try it, so I email them that request. So, until then, I'm stuck with getting either the STEP or the IGES files.

Although, do you have any other suggestions regarding little tips or tricks for setting up the files in NX, to help avoid some of these issues down the line? Or is it just inevitable, because the way the STEP files are processed and opened inside MOI, as Michael G. stated?

Thanks.

Hi sneather also just a heads up - since we've posted a few messages at the same time here it may have been easy to miss some of them above.

- Michael

Michael G.
The import scaling is odd. I'll talk to the NX CAD guy again, to see what else he can think of. But like I said, these guys are doing real manufacturing, so somehow things are working out in their pipeline. I could see it being directly on their end, if they were hobbyists, or just doing conceptual work. But I'm a little stuck (being on Mac OS). MOI is my only app for importing STEP, before exporting .OBJ for Cinema. I also have a Rhino Mac Beta, but it specifically does not handle importing STEP files. Which is a real bummer, to say the least.

Hi sneather, you could also try ViaCAD for importing the STEP file, I'm pretty sure they have a Mac version. If things behave pretty differently between MoI and ViaCAD for the import then that could mean something needs to be tuned up in MoI. If they behave the same then it's pretty likely to be just how the file is set up.

Is the 3DM file you posted one that is at the import scale that you're talking about or did you scale that up already?

- Michael

Yes. I forgot about ViaCAD. I'll look into that.

The example file I posted is unaltered in scale. Because I get random changed and updated pieces from my clients, it's crucial that I maintain a consistent set of standards throughout. So if I can avoid having to scale their work up, then it's all the better. That just adds some variables, and as you pointed out, the tiny size can have an impact on how the edges (and gaps) are seen by MOI upon import.

I need to check on the option to send you the original STEP file. Unfortunately, I have certain agreements with the clients, so it may not be possible. I hope you understand.

By the way. I'm still using MOI v2.52. I suppose there would have been no way for you to know.
Should I definitely be trying the V3 Beta? Might that help with what we're talking about right now...?

I installed a trial version of ViaCAD Pro Mac, and the original STEP file imports with no obvious geometry defects. So, it does seem to appear that MOI might be having a little harder time with certain STEP files.
However, it did take substantially longer to import into ViaCAD than MOI. But that's not really critical.

The hyper-small scaling issue seems to persist, however. I tried performing a bevel on an edge, and found that I needed to use incredibly small (.001) radii for it to take. Just like what happens in MOI. So, it seems to be an issue on the NX designer's end.

Hi sneather,

> By the way. I'm still using MOI v2.52. I suppose there would have been no way for you to know.
> Should I definitely be trying the V3 Beta? Might that help with what we're talking about right now...?

I would generally recommend using the v3 beta to just have the latest stuff. There have been some updates to the STEP import library since v2.52 so it is possible that it could behave better.

It's generally best to run with the v3 beta primarily though.

- Michael

Hi sneather,

> I installed a trial version of ViaCAD Pro Mac, and the original STEP file imports with no obvious
> geometry defects. So, it does seem to appear that MOI might be having a little harder time
> with certain STEP files.

Also I think in ViaCAD there are some options for "healing" the file which tries to automatically modify problematic geometry, it could be possible that is actually repairing the problem. That's probably also why it's taking a while for it to process it. It's pretty hard to know for sure without more detailed examination of the STEP file.

ViaCAD also comes in a less expensive version that's just $99: http://www.punchcad.com/p-9-viacad-2d3d-v8.aspx which I'm pretty sure also includes STEP import - it can be a pretty useful tool to add into the mix.


> I need to check on the option to send you the original STEP file. Unfortunately, I have certain
> agreements with the clients, so it may not be possible. I hope you understand.

Certainly, I understand, and please don't do anything to jeopardize the relationship with your clients. Sometimes it can be hard for me to give very much specific additional feedback about file translation issues when the actual files involved can't be shared though.

Also if you need to keep something private you can send it to me through e-mail at moi@moi3d.com instead of posting it here on the forum.

- Michael

Hi sneather,

> The example file I posted is unaltered in scale.

Ok, but the example file you posted does not seem to be so exceptionally tiny in scale though... the whole piece is about 4 inches in size across, isn't that probably the actual size of the physical object that they're producing?

They've got some pretty small little individual features as part of that model but the overall full object scale does not seem to be so tiny there... ?

- Michael

Good. I'll get going with the V3 beta. I assume that it won't affect my reliable v2.52, right?

With ViaCAD, I did enable the STEP import option to "Stitch Surfaces Into Solid". Perhaps that helped with the dodgy geometry?

And thanks for the email address. I'll see about getting you and intact STEP file for your evaluation purposes.

The import scale is a weird one. I had no idea that it was that size in MOI, and that ~4inches is right in the ballpark. Now things are even more confusing.
My reason for assuming the scales are off, is because I have a set of reliable numbers I use (for instance) for adding small bevels to certain hard edges on the products. I do enough of these products were I can count on those numbers to look right. Normally, I would use something like .1 or .25. Now, that has always worked with the ProE STEP exports I get, and they are the same products as the ones I am also now receiving from NX. But with the NX STEP file, I had to back WAY off to .001 to approximate the same edge profile.
So, I don't know what to do to figure this out.

Hi sneather,

> I assume that it won't affect my reliable v2.52, right?

Yeah it should not have any effect on v2.52 .


> With ViaCAD, I did enable the STEP import option to "Stitch Surfaces Into Solid".
> Perhaps that helped with the dodgy geometry?

Hmmm, probably that particular setting doesn't control that. Some other programs based on the same library that ViaCAD uses have options for turning on or off "healing" of the imported geometry. I thought ViaCAD might too but I see it doesn't. Maybe ViaCAD just has that permanently turned on.


> But with the NX STEP file, I had to back WAY off to .001 to approximate
> the same edge profile.
> So, I don't know what to do to figure this out.

I guess I'd need to know more about which specific edge you're trying to bevel in each case to be able to give you more information about this one... Are you sure you're not trying to bevel an edge that is just longer and on the outside of the object in one case but then doing one that is much smaller on some little portion of one of the inside details in the second case?

- Michael

"""""""The import scale is a weird one. I had no idea that it was that size in MOI, and that ~4inches is right in the ballpark. Now things are even more confusing."""""""""""""

You might assume that the NX step file is being written as "MM" instead of inches.

Hi sneather,

I've been using NX (unigraphics) professionally for the past 11 years and MoI at home since V1, if you like PM me, we could organise for me to have a look at the file in question, confidentiality assured of course, I can run a few checks in NX to check the geometry to see if it's a modelling problem or a translation problem and maybe work out a solution or work around.

Cheers
Danny

Thanks BurrMan. Do you know whether there is a separate units option in the STEP export process from NX?
Again, I trust the designer when he says that they work in inches, inside NX. So maybe it's an export-related issue?

Thank you, DannyT. That's quite generous of you.

As of yesterday, I'm on a crash course, trying to learn the basics of ViaCAD Pro for Mac. It was recommended that I might try that, in order to see whether it might be able to process the STEP file better. And it does. No geometry issues, and it even seems to have slightly better structure, too. I have no idea why it would be that much different from MOI, but it seems to be so far.

I also installed the V3 MOI Beta. Michael G - that DID seem to fix most of the bad geometry. There is still one odd spot, where the surface has a hole. But it's much better than what happens when I bring it in with V2.52.

I have a suspicion, that I might just need to use both MOI and ViaCAD in my model prep pipeline. I'm becoming extremely comfortable with working in MOI (and I LOVE this fantastic help forum - simply nothing else like this!) so I might try processing the STEP files in ViaCAD, and then doing the rest of my work in MOI. Plus, ViaCAD seems to be lacking any control over the final .OBJ output (which is crucial) and both MOI and Rhino have fantastic mesh generators.

Hey sneather,
"""""""""""Do you know whether there is a separate units option in the STEP export process from NX?
Again, I trust the designer when he says that they work in inches, inside NX. So maybe it's an export-related issue?""""""""""

I dont think so, but NX is a higher end modeler and has several different ways it handles units. The only real way to track it down would be to get the nx file to someone like Danny, who could then review it's particular setup. There should be no problen with working directly from NX to MoI.

I would be certain the model looks good in NX. NX using the parasolids kernel, will have several different means to construct geometry in "difficult" areas. Like the area where you are showing a problem, looks like one of those areas where the filleter crashes into and goes beyond itself (this would fail with MoI's filleter), but generates a result. The translation of that area just isnt going through the 2 translators, nx's export and moi's import, as intended.

My suggestion would be to ask the designer to provide you with a few of the formats that MoI handles when sending the models over. Package up a STEP, IGES and a SAT. Then, you can find the one that imports the parts as intended. You will find that different models (areas of difficult surface generation) will come through in different formats. Try an iges, the most generic surface translator.

<<<<The import scale is a weird one. I had no idea that it was that size in MOI, and that ~4inches is right in the ballpark. Now things are even more confusing.
My reason for assuming the scales are off, is because I have a set of reliable numbers I use (for instance) for adding small bevels to certain hard edges on the products. I do enough of these products were I can count on those numbers to look right. Normally, I would use something like .1 or .25. Now, that has always worked with the ProE STEP exports I get, and they are the same products as the ones I am also now receiving from NX. But with the NX STEP file, I had to back WAY off to .001 to approximate the same edge profile.
So, I don't know what to do to figure this out.>>>>

 

Sounds like your Pro-E files were in MM and your new files from NX are in inches. A .25 fillet on a 4" part is rather large. A .25 fillet on a 102 mm part sounds like what you were doing. I don't think any weird scaling is going on with any of your files. Measure some of your old files. A .001 fillet is very close to a 1/4 of a mm.

I get quite a few files from Pro-e, solidworks, inventor etc. and all of them usually need a few things touched up. Things like the corners of fillets bad trims etc I don't think there is a perfect solution. Nothing a few rail sweeps wont fix. I would ask for .step and .iges files and you should have your bases covered.

P.S. I have played with via cad a few times and it would crash a bunch of larger CAD files. I my opinion MOI is much better. Every once in a while I use a open source program called free cad. I seems to have a very robust .iges and .stp importer and may be worth a try on some troublesome files.


-Shane