beej

tolerances on File conversions

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I"m wondering if anyone has had any luck using tolerances to help with importing solid models.  we always have problems with solid models that come in from Japan. They always convert in as surfaces or open sheet bodies and the edges are all over the place  keeping them from knitting together as a closed solid.    There are too many layers of insulation between me and the people generating these solids to get any help from Japan.

just wondering if there are tricks to help myself, that I'm missing.

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It's always best if you can to have the native CAD format...

Years back there was a chart that showed the parasolid format was +98% correct on translation and that was the highest....step 214 was +96% all other formats fell lower down on the %

If data integrity is crucial, native is the way to go, even if that means investing in the plug-in to allow to open.

 

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Agree get the Native and a good CAD Software that can work with them. Spaceclaim does an excellent job at working with just about any format. You have to Pay for the Catia add-on, but it will read them very well.

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6 minutes ago, JParis said:

It's always best if you can to have the native CAD format...

Years back there was a chart that showed the parasolid format was +98% correct on translation and that was the highest....step 214 was +96% all other formats fell lower down on the %

If data integrity is crucial, native is the way to go, even if that means investing in the plug-in to allow to open.

 

that's a good point. I'm not sure what the native format even is.  it's not easy to get that kind of information the American purchasing agents who don't seem to know a lot about their Japanese counterparts.

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30 minutes ago, beej said:

just wondering if there are tricks to help myself

Spaceclaim…  it's model repair utility can sometimes do amazing things

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6 minutes ago, gcode said:

Spaceclaim…  it's model repair utility can sometimes do amazing things

thanks for the ideas, guys.  I never heard of Spaceclaim, I'll look into that.  and also try to find out the native format of these files.

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9 minutes ago, beej said:

I never heard of Spaceclaim

check your pm's

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1 hour ago, JParis said:

It's always best if you can to have the native CAD format...

Years back there was a chart that showed the parasolid format was +98% correct on translation and that was the highest....step 214 was +96% all other formats fell lower down on the %

If data integrity is crucial, native is the way to go, even if that means investing in the plug-in to allow to open.

 

THAT surprises me.

I never realised conversions were less than 99.9999% accurate!

Everyday is a school day!

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1 minute ago, Newbeeee™ said:

THAT surprises me.

I never realised conversions were less than 99.9999% accurate!

Everyday is a school day!

There's a reason that it (iges format) referred to as "I guess"  I guess it's close enough

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1 minute ago, JParis said:

There's a reason that it (iges format) referred to as "I guess"  I guess it's close enough

Oh yes, fully understand the Iguess untrimmed surface chit, but I hadn't touched that format for 20 years!

Parasolid and Step were my friends of choice, but the potential inaccuracy has gobsmacked me!

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beej sent me a file and I attempted tp repair it in SpaceClaim

between SpaceClaim and SolidWorks Import Diagnosis, I was able to turn it into a watertight solid

but the model is no longer accurate. Those are some nasty models beej has to work with

You'd think it wouldn't be a problem in this day and age

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Just now, gcode said:

beej sent me a file and I attempted tp repair it in SpaceClaim

between SpaceClaim and SolidWorks Import Diagnosis, I was able to turn it into a watertight solid

but the model is no longer accurate. Those are some nasty models beej has top work with

You'd think it wouldn't be a problem in this day and age

What format did you receive it in?

I have seen Catia models bounced between several formats end up ugly as sh!t at the receiving end

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2 minutes ago, JParis said:

What format did you receive it in?

I have seen Catia models bounced between several formats end up ugly as sh!t at the receiving end

I think that is what is going on.  It gets converted several times before it gets to us.  But I'm betting the original file was Catia, which has been a conversion problem for as long as I can remember.  We always gitter done.  but it adds a lot of time.

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10 minutes ago, JParis said:

What format did you receive it in?

step and parasolid.  if you open up the step file in Notepad, you can see it was created in NX. the parasolid file was created in Solidworks,  But I do not think either are the native files.  When I researched the Manufacturer, I saw that they use Catia and that there was also an article about them creating their own cad software.

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3 minutes ago, beej said:

I think that is what is going on.  It gets converted several times before it gets to us.  But I'm betting the original file was Catia, which has been a conversion problem for as long as I can remember.  We always gitter done.  but it adds a lot of time.

If is the for any of the Tier ones that fly aircraft and proper DPD/MBD process have not been followed and there is ever an audit then it could lead to some major issues. Part of the correct MBD process is a model integrity check. If that is not being done and followed from Japan then they are in violation of Boeing D6-51991 if it is for them. Other Tier ones have similar integrity checks. A lot of the newer MBD files I have seen are in 3D PDF with a Step 242 File saved in the PDF you extract.

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15 minutes ago, gcode said:

beej sent me a file and I attempted tp repair it in SpaceClaim

between SpaceClaim and SolidWorks Import Diagnosis, I was able to turn it into a watertight solid

but the model is no longer accurate. Those are some nasty models beej has top work with

You'd think it wouldn't be a problem in this day and age

thanks for trying, Tom.

1 minute ago, crazy^millman said:

If is the for any of the Tier ones that fly aircraft and proper DPD/MBD process have not been followed and there is ever an audit then it could lead to some major issues. Part of the correct MBD process is a model integrity check. If that is not being done and followed from Japan then they are in violation of Boeing D6-51991 if it is for them. Other Tier ones have similar integrity checks. A lot of the newer MBD files I have seen are in 3D PDF with a Step 242 File saved in the PDF you extract.

its automotive. I didn't really want to give the maker, because I'd hate to complain about an otherwise GREAT customer.

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I think the default "Export Tolerance" for Catia is 0.1mm.

This means your model faces/edges can "float" by up to 0.00394", and often results in models that are not watertight.

That "loose" of a tolerance really helps if you are working on designing something large, like a ship(boat) or plane. It is a terrible default value for exporting models, but you'd have to communicate this issue back to your customer's engineering department.

If you can get them to change the value, I'd suggest 0.002mm Export Tolerance. That would get you under 0.0001" for face/edge gaps.

I worked for a company years ago that bought a full Catia Design License, for the sole purpose of being able to open the native ".CatPart" files, which allowed us to then set our own export tolerances. Moreover, we could check for "poor design practices" in the native model itself, and fix the issues before performing the export function. This saved me easily several "weeks of effort" over the year, from problems that I would have had to re-model or fix myself inside Mastercam.

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there is serious problems with the understanding or lack of model base these days.

our engineer sent me an stl file to program to, i asked for another format stp or iges. he sends me an iges with note that solidworks gave him errors bringing in the stl file. of course the iges file contained nothing. i asked for the native. oh thats a catia file he said. well just so happens that is the company standard and i have a seat. DUH.   

so this file was converted out of catia to stl then attempted  conversion through solid works to iges.   I am very confused of the thought path of even attempting that.

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This is really a case of GIGO Buffers effecting the model inside Mastercam.

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Now, what is GIGO? Just a bit of humor as there are, of course, no such thing as GIGO Buffers in Mastercam. GIGO is simply an apt acronym for this situation.

 

Garbage In = Garbage Out

 

In your case, you could open up the "Import Tolerances" to 0.020", and Mastercam could likely cobble together a "water-tight solid", but the model that Mastercam generates would not match the same "face and edge locations" as the original model.

Again, garbage in equals garbage out.

In your case, you'll obtain the best results by manipulating the upstream data, to give you a quality model to work with.

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41 minutes ago, Colin Gilchrist said:

If you can get them to change the value, I'd suggest 0.002mm Export Tolerance. That would get you under 0.0001" for face/edge gaps. 

 

it would be easier for me to talk to Abe Lincoln. if something is going to change it will have to be on my end.

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Just now, beej said:

it would be easier for me to talk to Abe Lincoln.

Then your best bet, would be for your company to invest in a Catia Design license. That's going to be the easiest route to take. (Although also potentially very expensive.)

Otherwise, rebuilding the model might be your best option, or using a 3rd Party tool like SpaceClaim.

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Just now, Colin Gilchrist said:

Then your best bet, would be for your company to invest in a Catia Design license. That's going to be the easiest route to take. (Although also potentially very expensive.)

Otherwise, rebuilding the model might be your best option, or using a 3rd Party tool like SpaceClaim.

Why not just loosen the tolerances on solid from surfaces and call it a day?

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1 minute ago, Colin Gilchrist said:

Then your best bet, would be for your company to invest in a Catia Design license. That's going to be the easiest route to take. (Although also potentially very expensive.)

Otherwise, rebuilding the model might be your best option, or using a 3rd Party tool like SpaceClaim.

I appreciate your input Colin.  it will help me with other customers to know that about Catia's tolerance defaults.

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2 hours ago, crazy^millman said:

Agree get the Native and a good CAD Software that can work with them. Spaceclaim does an excellent job at working with just about any format. You have to Pay for the Catia add-on, but it will read them very well.

You mean moldplus? Or the other one?

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Just now, byte said:

Why not just loosen the tolerances on solid from surfaces and call it a day?

It really depends on what is the "authority" for making the part. Is the "model" the standard to which the part should be made, or is it a drawing with tolerances?

The export issue doesn't just effect the "closure of the face edges", but the actual position in 3D space as well. I've seen walls that were "off" by 0.002-0.004", when simply opening up the stitching tolerances. This isn't to say that the "create a solid from surfaces" function is causing the issue. That isn't the problem at all. It is the "quality of the import geometry" that is really going to effect the outcome.

1 minute ago, byte said:

You mean moldplus? Or the other one?

My preference was for the Moldplus Catia Translator, but the translator that is available from Mastercam directly has also been improved recently, so take that with a grain of salt.

I'm not aware of any comparisons between the two translators, to tell us definitively which is the better translator option, so my preference is purely anecdotal.

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