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Adding a file header. - Nathanael Coyle - 2024-09-25

I’m new here, and I recently made 2 different parts in Inventor. I then converted them from .obj files to use in Part Designer, and set up their connection points. After exporting them as an LDraw file (.dat), I understand I should have a header in the file for submission to the part tracker.
What application do I use to add this header?
Also, I don’t need to add color information anywhere do I?

RE: Adding a file header. - Magnus Forsberg - 2024-09-25

Hej Nathanael, and welcome.

The rules for the header are here:

   

The best tools for making a correct header are DatHeader and LDPartEditor.
https://www.ldraw.org/downloads-2/third-party-software.html

Maybe you could upload you file here in the forum, so that we can see what you have?

RE: Adding a file header. - Nathanael Coyle - 2024-09-25

(2024-09-25, 15:34)Magnus Forsberg Wrote: Hej Nathanael, and welcome.

The rules for the header are here:



The best tools for making a correct header are DatHeader and LDPartEditor.
https://www.ldraw.org/downloads-2/third-party-software.html

Maybe you could upload you file here in the forum, so that we can see what you have?

Thanks Magnus I'll look at those.

Here are the two parts. I think the file-naming convention is correct?

RE: Adding a file header. - Chris Böhnke - 2024-09-25

Hello and welcome Smile 

Regarding the file header, I think it's also a good idea to look at some recently certified parts on the Parts Tracker as examples.

Here are few things you might consider:

  1. That is quite a large file, usually LDraw parts don't use that many polygons, it makes the file hard to handle.
  2. What program did you use to export the files to .dat? Most of your triangles seem to have 5 instead of 3 vertices specified, which LDraw Parts Editor lists as errors.
  3. This part should use conditional lines (https://www.ldraw.org/article/218.html#lt5). You can use the tool Edger2 (part of LDPE) to generate them easily, however a little manual adjustment is often required afterwards.
  4. The understud can be replaced with primitives, to save some lines of code

Your parts look very realistic, did you have any existing model file to work from?

RE: Adding a file header. - Nathanael Coyle - 2024-09-25

(2024-09-25, 16:58)Chris Böhnke Wrote: Hello and welcome Smile 

Regarding the file header, I think it's also a good idea to look at some recently certified parts on the Parts Tracker as examples.

Here are few things you might consider:

  1. That is quite a large file, usually LDraw parts don't use that many polygons, it makes the file hard to handle.
  2. What program did you use to export the files to .dat? Most of your triangles seem to have 5 instead of 3 vertices specified, which LDraw Parts Editor lists as errors.
  3. This part should use conditional lines (https://www.ldraw.org/article/218.html#lt5). You can use the tool Edger2 (part of LDPE) to generate them easily, however a little manual adjustment is often required afterwards.
  4. The understud can be replaced with primitives, to save some lines of code

Your parts look very realistic, did you have any existing model file to work from?
Thanks Chris.

Some background: I'm a mechanical engineer that's moved more toward controls, so my 3D modeling skills have been largely unused for the last 2 years. This has been an opportunity to bring them back online, improve them, as well as get experience in a CAD software similar to SolidWorks that I hadn't used before (Autodesk Inventor) for my own professional development. These parts are just a few that I am using in a reef MOC and didn't currently exist in Studio 2.0, so this was a great way to "kill two birds with one stone."

1 & 2. Without having used them, I don't know the intricacies or differences between the different programs under LDraw's umbrella, so forgive me if I misname them. I am assuming you are looking at the files within the LDraw/LCAD program? I don't have this/these installed, so I haven't seen this. But I'm assuming this is probably a side effect of designing in a graphical CAD vs the (as I understand it) text-based LDraw (or associated CADs), and the "mesh" detail will just intrinsically be more detailed? 
I used PartDesigner's built-in "Export as LDraw" tool to export the .obj file as a .dat file. This was my first time using PartDesigner, but there was some option
to "generate outlines" for the part with a slider for sensitivity. I just used the default sensitivity, and wasn't sure what this did. Would this contribute?

3 & 4. I haven't used these programs and prefer not having to spend more time picking them up too. Could there be an opportunity for someone to co-author and take care of that?

I have the models so that they are usable in Studio 2.0 to my own satisfaction, but figured even if these weren't perfect, I did want to contribute at least a  starting point for the community on these parts, rather than "cut the rope bridge behind me." Unless it's an easy fix from the issues being attributable to the beforementioned PartDesigner setting, I'm hoping that I can just add them "as is" to the part tracker after adding the correct header details.

No, the only models I had to work with was holding the parts in my hands and using a caliper for measurements Smile . I didn't actually search for any existing models, but again, this was in order to help my own learning and experience.

Hopefully my reply makes sense, I'm sure there are several things that I just don't know that I don't know.

RE: Adding a file header. - Chris Böhnke - 2024-09-29

If you want to go that route, you should be aware that LDraw is more or less just an approximation to the real part and sometimes omits a few details which actually only have a function for manufacturing the element.

Unfortunately it is hard to give exact rules what should be omitted and what must not, so best look at some parts in the database and compare them to their real counterpart. 3001.dat (the classic 2x4 brick) for example misses the cavities under it's stud, the inner ribs and the 'thin wall supports' (included to save material on the inside).

I would say that the fillets you included along the top edge of the seastar as well as those in between it's limbs have too small of a radius to be regarded. Others might disagree here though, so take it just as a suggestion.

I am not sure if there are possibilities to do this more easily, but from a quick test I was not able to 'lower the resolution' of your parts by common LDraw tools. Unfortunately I am not that familiar with Inventor, so - do you have any options that would allow you for less polygons when exporting to .obj? I typically use FreeCAD when designing parts from scratch. It's exports (although not always too reliable) have a far more 'LDraw-compatible' resolution.

Hope that helps a bit,
br Chris