Auto-Closing of Topics, and Converting WRL to STEP


#1

What is up with auto-closing topics after only 30 days??? It’s insane. I would like to comment on this topic from @MacSimski:

but it was closed a week ago even though the OP was at the end of March 2018. So instead, I have to make a new post on the same topic, cluttering the forum and making it much more difficult for people to find consolidated information in future searches.

@Rene_Poschl says that no one should ever need to do this conversion because the wrl format is a mesh approximation rather than a parametric model and therefore in his eyes useless.

@maui says that no one will ever need to do this conversion because there is a new library of STEP models for KiCad.

Both of these answers are unsatisfactory. There are many instances where an approximation from a mesh would be perfectly fine and useful, and there are also many instances where there is no step file for my component in the “Holy Grail” library but I do have a wrl of the part already, and I would prefer to convert my existing wrl to a step automatically rather than design it from scratch and “have not use a calipers all the time and introduce errors by hand” as the OP requested.

So if anyone has a useful answer to the OP’s question for a way to convert wrl to step rather than a statement that no one should ever need such a thing, that’d be awesome.


#2

If the approximation is good enough for you then use wrl. (wrl is for nice pictures, step is for precise valid MCAD models.)

I don’t really understand the point you want to make. Kicad still supports wrl so no need to got down the route of step for your personal libs.
We over at the official libs however have higher standards.


And a clarification: It is simply not possible to convert a wrl file to a valid step file.
Maybe an analogy will help to understand this:
You can not convert a video with 144p into a valid 1080p video.
You can save it as a 1080p video but it will still look like a mess of pixels. The information to get a 1080p video simply does not exist in the 144p video and no matter what you do you will not get it back.


So if you have a circular hole in your part, in a step file it is stored as the mathematical representation of a cylinder. It can be used by an MCAD tool as a object for attaching constrains.
If you have a wrl file then the cylindrical hole is not a cylinder any more. It is a extruded polygon. The MCAD tool will not be able to use this as a source for constrains.


#3

I don’t understand why you want to do this.

Thanks to @Rene_Poschl I now understand the differences between the two files.

I once purchased a Blu-Ray movie that I already had in DVD. When watching the movie it really did not seem to have the quality of a good true Blu-Ray disc. After a little closer reading of the back of the box I noticed the new disc used the same codec as the original DVD, only the sample rate on the new release was a little bit higher.

My question then, “If you know it is of lower quality, why do you want to name it as a higher quality one?” Why would you not want to keep the label of what it is actually what it is?

A Blu-Ray player will play DVDs. If KiCad continues to support the .wrl file then that seems like an okay solution to me.


#4

As of today, there is a year old thread that was resurrected. And, it seems to be on-topic and related.

I did not think bringing back old dead threads back to life was a problem for this forum; but there most likely is a good reason for this change.


#5

Might also just be a change in the default settings of the software used behind this forum.


#6

@Rene_Poschl

AAAAARRRRGGGHH !!!

AAAAARRRRGGGHH !!!

Do you have any idea how many of my custom library items I’m going to have to fix now that I understand the difference?

…sigh …it’s going to take hours…


#7

It’s for illustration, and for checking fit of the PCBA into an enclosure. I don’t care if holes are polygonal approximations, in fact in some cases I don’t even care if holes are shown - a reasonably accurate outline of the part would work (although of course it’s much better if it has some detail).

I’m not highly familiar with the wrl format, but if it’s a mesh like STL then you are wrong about not being able to convert it to a usable step file for many purposes. I have utilities that convert STL to STEP and the results are fine. We’re not talking Minecraft pixelation here, we’re talking about a mesh of tens or hundreds of thousands of triangles.

This has little to do with “quality”, it has to do with the fact that (AFAIK) KiCad cannot export a 3D step model of a complete PCBA unless all the components have step models. Maybe it can export a vrml model of the complete PCBA, but this is useless for integration with other CAD tools, so the question would still be the same - I need to convert vrml to step, whether at the component level or PCBA level. I would prefer to do it at the component level because there are many step models in the new KiCad library, so why should I waste all those “high-quality” ones - I do want to change over to STEP 100%, but a convenient tool to help with the conversion of those parts for which I don’t already have a STEP file would be nice.

Specific case: I have a board all done (before v5 was practical for me), vrml models complete. Looks beautiful in the 3D viewer. Customer says “we need a step model so the enclosure designers can check fit”. Now that KiCad 5 is close to release, I think maybe I can finally do this without resorting to workarounds or modeling the PCB from scratch in a mechanical CAD app (as I’ve done in the past). I install the new STEP model library, but find that I’m missing models for maybe 6 - 12 of my parts, and it happens that the manufacturers of these parts do not offer step models. So if there is a program that will convert them, it will save me some hours of modeling them myself. I can’t believe this scenario is so strange that I have to explain it.


#8

If it is fine for you go for it.


#9

Not being totally sure I belive freecad can do the conversion, perhaps using the mesh - > solid.
Perhaps using “refine shape” can remove some of the unneeded geometry.

Can you please elaborate on which models you are missing in step?


#10

I am using V5rc2 nightly, I forget the date, but I can check if you want.

It successfully used the .wrl image files assigned to many footprints to export the complete PCBA in Step format.


#11

I think that needs step models with the same name as the wrl model in the same folder.


#12

This is correct. I deleted the wings and step models from the folder, and the export noted the errors. When viewed in FreeCad those items were in fact missing from the export.

Well, I have learned a lot; and it’s starting to make my brain hurt!


#13

The one that spawned this topic is the SDS-50 DIN-5 connector from CUI. The older KiCad libraries miraculously had a wrl for it, but the STEP has not made it into the new library AFAIK. Not that it would be a huge job to model this part myself, but in anticipation of other similar instances, I thought I’d ask if there’s a converter out there.


#14

But I don’t have a wrl-to-STEP converter, so I can’t go for it, lol :smile:


#15

you can save a wrl file as a stl file using blender. Both are triangulated approximations of a shape so this conversion always works.


#16

Haven’t checked too much on the license but they supply a step models from their website, that could potentially be used. I know this is not the question but I thought it perhaps could be usable
https://www.cui.com/product/resource/3dmodel/sds-50j

Also I have added the series on my scripting todo list :slight_smile:

Have you tried with Freecad? :slight_smile:


#17

Just letting you know that I noticed your comment and we have started an internal discussion with the currently ~8 people who guard this forum (anyone with the ‘Regular’ badge) to see what we are going to do about it.
Will keep you posted once there is some sort of conclusion.


#18

from your and your customer needs you cannot rely on an approximation of your models as you could obtain from a wrl to step conversion… particularly when you want this conversion on connectors, and use those to check your enclosure fit, you need something very precise to measure what you need in enclosure design… may be you can offer a wrl to step approximation, but your customer’s 3d designers would complain…

this is very unusual … most of manufacturers offer a STEP model of their connectors…

https://www.google.com/search?q=SDS-50+DIN-5
https://www.digikey.com/product-detail/en/cui-inc/SDS-50J/CP-2350-ND/97033
https://www.cui.com/product/resource/digikey3dmodel/sds-50j
from there you can get your STEP mechanical model…


and even if you cannot find through the manufacturer, you normally can get it at 3dcontent central or at grabcad on line libraries

that is saving you a lot of time doing a double job… a bad conversion without fitting your customer needs and later on a good search for a reliable source of mechanical parts…


#19

Not necessarily true; I’ve done a number of successful projects using STL models. Not the most professional way, but it can work.

Of course I know that, but “most” <> “all”.

Thanks for that! Last time I checked this part on the CUI website they had only 2D drawings.

Yes, I am aware of and use those repositories, but again, “normally” <> “all the time”.


#20

Thanks, Joan. I really think it’s a bad idea. Topics and discussions can be useful many months or even years later. I think the forum already gives a warning when bumping an “old” topic.