• Scam Alert. Members are reminded to NOT send money to buy anything. Don't buy things remote and have it shipped - go get it yourself, pay in person, and take your equipment with you. Scammers have burned people on this forum. Urgency, secrecy, excuses, selling for friend, newish members, FUD, are RED FLAGS. A video conference call is not adequate assurance. Face to face interactions are required. Please report suspicions to the forum admins. Stay Safe - anyone can get scammed.
  • Several Regions have held meetups already, but others are being planned or are evaluating the interest. The Ontario GTA West area meetup is planned for Saturday April 26th at Greasemonkeys shop in Aylmer Ontario. If you are interested and haven’t signed up yet, click here! Arbutus has also explored interest in a Fraser Valley meetup but it seems members either missed his thread or had other plans. Let him know if you are interested in a meetup later in the year by posting here! Slowpoke is trying to pull together an Ottawa area meetup later this summer. No date has been selected yet, so let him know if you are interested here! We are not aware of any other meetups being planned this year. If you are interested in doing something in your area, let everyone know and make it happen! Meetups are a great way to make new machining friends and get hands on help in your area. Don’t be shy, sign up and come, or plan your own meetup!

CAD Technical Foundations

Janger

(John)
Vendor
Premium Member
https://www.shapr3d.com/blog/what-is-cad-the-technological-foundations-of-cad-software

Good article on how CAD works under the hood, parametrics, file formats, & some best practices.

Quoting the article - see below info on file formats. I am going to try 3MF for my 3d printing instead of .STL files.

Common mesh formats​

Mesh data can be stored in multiple ways, which means you have a handful of options when it comes to mesh file formats.

STL (Stereolithography, Standard Triangle Language)​

One of the oldest formats. It’s a very simple file format that contains not much else besides a list of triangles. It is recommended to avoid using it whenever it’s possible, since it does not store unit information.

3MF (3D manufacturing format)​

The modern replacement of the STL format. Can contain unit, material, color and many other information that are necessary for manufacturing a part.

USDZ, GLTF​

These formats are very similar, both are optimized for visualization purposes as they store lighting and PBR material information. USDZ and GLTF are the standard formats for Augmented Reality as well. Most modern iOS (USDZ) and Android (GLTF) devices natively support these formats for viewing and for Augmented Reality.

OBJ, FBX, 3DS​

There is a long list of additional 3D mesh formats. These formats are primarily used by 3D graphics software, and they can be also used for interfacing between CAD systems and graphics software.

Pro workflow tips​

  • Be careful when you are working with imported mesh data, like STL or 3MF files. Meshes are great for being used as reference objects for reverse engineering, but are hard to edit in a CAD system.
  • It is strongly recommended to use 3MF instead of STL, as 3MF is a modern format that also contains units unlike STL.
  • Don't trust mesh to CAD converters unless you really know what you are doing. These converters either just transform the triangles one by one to faces, or try to approximate the CAD geometry. Neither will lead to accurate results, and most often simply remodeling the part will lead to higher quality results. Even when the conversion succeeds, it might introduce hidden issues that can cause inaccuracies and modeling errors later on.
 
https://www.shapr3d.com/blog/what-is-cad-the-technological-foundations-of-cad-software

Good article on how CAD works under the hood, parametrics, file formats, & some best practices.

Quoting the article - see below info on file formats. I am going to try 3MF for my 3d printing instead of .STL files.
I was using Fusion Mesh tools. I have a startup license which gives a few more options than the hobby license. I was easily able to convert a clean STL automatically into BREP. I choked on scan data. I would think that most things you download from thingiverse that are mechanical, are simple enough to do this type conversion. I am including an example.


In picture 1, I seperated the faces into groups. picture 2 same picture surfaces, picture 3 are surfaces that nee to be fixed to make it into a solid that can be altered easy. I estimate with these surfaces, it would take less than 1/2 hour to repair.
 

Attachments

  • Capture.JPG
    Capture.JPG
    40.8 KB · Views: 19
  • Capture1.webp
    Capture1.webp
    27.7 KB · Views: 15
  • Capture2.JPG
    Capture2.JPG
    56.6 KB · Views: 16
Back
Top