How to edit stl files

There are millions of free stl files on the web for 3D printing. There are many times when I would like to start with an existing stl and modify it in some way. I haven't found a way to do that with the tools I have.

Available tools:

Windows 10
Sketchup
Designspark mechanical (this is great BTW)
Freecad
OpenScad

I am open to using other tools that are free or inexpensive.

... some edits can be done with Meshmixer - [meshmixer.com]

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I often find its quicker to design the part from scratch rather then to faff with stl files..... That said, Sketchup can handle .stl files with an addon and if I ever want to edit them I just use that. Fusion360 can also do it, but its annoying and a bit hidden away.

Edited 1 time(s). Last edit at 07/17/2017 02:27PM by Origamib.

I often edit STL files and use a polygon editor for this, in my case Cinema 4D. Depending on the mesh it can be either super easy or nearly impossible.
My workflow in general is to convert the triangulated mess STL produces to N-Gons and then clean up the mesh by hand. After that it is usually not a big deal to make changes, provided you are proficient with polygonal modeling. CAD applications of any flavor are usually useless at this task. You might try blender as a free polygon editor.

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This is what I do:

-Open STL file with Netfabb basic, repair if needed, Move 'to origin' and save.
-Import it with Openscad. Something like:
translate ([0,0,0]) import(file="File.stl");
-You can operate with the STL same as any other figure (union(), difference(), rotate(), ...)

Don't work with all STL you can find, but with a lot of them.

I use MeshMixer for mesh-type edits, and OnShape.com for CAD-type edits,

FreeCAD can sometimes be useful for converting an STL to a .STP or other CAD-importable type:
1. Analyse & Repair Mesh; sometimes it's actually better to skip this step.
2. Convert the Mesh to a Shape. (Mesh menu)
3. Refine Shape (Part menu)
4. Convert Shape to a Solid (Part menu)
5. Export Solid in .STP format (File menu)

Where FreeCAD fails, for CAD stuff, I "trace" the STL with OnShape.com to reverse-engineer it. Generate planes based on mesh points. Create line segments between points on the mesh to create edges. Generate circles and arcs using 3-point location. For more complex shapes, generate splines. Extrude cross-sections to a vertex on the mesh. As others have said, often it's quicker to just design a new item from scratch.

The good thing about OnShape.com (apart from that it's free) is that it encourages sharing of designs (if you use it for free you are forced to make your design public), so that people don't have to mess around with your STLs.

fusion 360 if anyone uses it turn of capture history then convert mesh to brep then goto the patch panel and use the merge function, it may not merge all triangles but give you planes too work with, or trace it in fusion 360

Edited 1 time(s). Last edit at 07/17/2017 06:39PM by chris33.

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For me the easiest way to edit STL files was tinkercad online.

It allowed me to do stl editing without learning CAD.

However I have Graduated to Fusion 360 Free, thou you will need to take several online tutorials for learning the basics.

Edited 1 time(s). Last edit at 07/17/2017 06:42PM by Roberts_Clif.

STL is not really a format that can be edited nicely in my opinion. Making an STL mesh of an object that is already an STL is going to give more chance of errors that can result in bad prints.

For me I find it quicker to model the part myself and make the changes as needed. Importing the STL is a good way to get the dimension.

depending on what level of customisation you are talking about I also often use Tinkercad to modify STL's [www.tinkercad.com]

Edited 1 time(s). Last edit at 07/20/2017 03:19AM by briangilbert.