.STL to .STEP (or other common CAD format)  

...mostly because there isn't a good way of doing it - yes, it *can* be done, but not efficiently or easily.  .STL is not a CAD file format, it just describes the surfaces, it does not preserve the underlying structures that give rise to those surfaces.  Always preserve the original CAD file for later re-use.

Cheerio,

RE:

An STL is very different from a STEP body and much "Body" type of information is lost from the 3D cad to the STL creation. There is no way to put it all back.. Sometimes it is easier just to remake the part, if you are reasonably familiar with Fusion. There is a way to turn mesh STL files into Fusion 360 solid bodies. It involves creating face groups, combining them and then doing a convert (from the Mesh menus), but you get all the triangles from the STL mesh. It is too bad more people won't provide a STEP file that can be modified easily. Depending on what you are doing, you can make simple mods to STLs in Fusion.. but because of all the triangles there is also a big resource overhead and Fusion can choke on complex/large STL bodies. I always will provide a STEP file when asked for any model I publish. Sometimes in Fusion I'll import the STL/mesh and rebuild the body overtop of it, using the mesh just for measurement accuracy.

Posted by: @largriff

Is there a way to convert .STL files so that they can be edited in Fusion or Solidworks?  Fusion has the ability, if you subscribe, but the free version doesn’t.  Looking for a free or online converter.  Sorry if this has been asked before, but searching the forums wasn’t fruitful.

RE: .STL to .STEP (or other common CAD format)

.stl is used as the least common denominator, it also has the least information.   

.stl is a triangle mesh.   .step is a full surface, hole, curve definition.    I have seen .stl converted to true triangular surfaces for CAD work, but it usually overloads the system since there are so many triangles.  The worst surface to handle in CAD is a triangular surface.  I know of companies that have spent millions and years trying to get a .stl to "proper cad" convertor and ultimately failed.   The best I have seen is using the .stl as a framework to recreate the surfaces.   Demos look good on simple parts, but medium to complex parts it may not have an advantage over recreating from a print. 

Many CAD systems are now importing .stl as .stl for limited manipulation.  On top end systems it tends to be a pricey option currently.

RE: .STL to .STEP (or other common CAD format)

I’ve used Fusion 360 to convert many .STLs successfully.  A few required some minor touchups.  In every case, it was easier than starting from scratch.  I just hate having to subscribe to what would otherwise be “free for personal use” just for that one feature, even though I’m still just using it for personal use.