Editing Imported STL

[timesenemy]

I imported an STL that was sent to me. I want to remove a box shape protruding out. The STL opens fine. I go into the Part Design view, then try using the Subtractive Primitive (Box) feature, but FreeCAD 0.18 responds with:



"In order to use PartDesign you need an active Body object in the document. Please make one active (double click) or create one." The second paragraph in the "No active Body" error states, "If you have a legacy document with PartDesign objects without Body, use the migrate function in PartDesign to put them into a Body."

I saw this https://forum.freecadweb.org/viewtopic.php?t=21741, but the provided answer is too vague.

Creating a new Body, then dragging the imported STL object into the Body shows an arrow icon (looks like a shortcut icon), but does not appear to do anything once the object is dropped, or the mouse button is released. The same No active Body error appears after trying this.

How do I add an imported STL object into the/a Body, so I can then use tools like Subtractive Primitive?

[bejant]

Hi timesenemy, and welcome! The Part Design WB only works with solids, and your .stl is a mesh. Instead, after doing File > New and Importing your .stl, change to the Part WB (not Part Design) and from the pull-down menu choose Part > Create shape from mesh. From here you can change your mesh to a solid.

Going only by your description, I'd avoid the Part Design Wb altogether if all you want to do is remove a simple box shape from the model. You can change to the Shetcher WB and create a Sketch of the cross-section of the shape you'd like to use to remove the box shape. Then go back to the Part WB and Extrude your Sketch. From there you can do a Boolean Difference to subtract you Extrude from the solid.

Or instead of Sketching a shape and Extruding it, you can stay in the Part WB, create a Cube, change the size to suit your needs, move it into place, and subtract itt from your solid.

If you need more help, post back - and it might help to include your model.

[bejant]

How do I add an imported STL object into the/a Body,

If you want to use Part Design:
First create a Solid from your .stl.
Go to Part Design and create a Body.
From the history tree, drag and drop your Solid into Body.
A new copy of your Solid, named BaseFeature, will be created inside the Body.
You can work with the new BaseFeature in Part Design.

[HarryGeier]

You can also watch some of my videos based on that workflow for 0.17 or 0.18

[chrisb]

Part->Defeaturing may be worth a try as well.

[wmayer]

Instead, after doing File > New and Importing your .stl, change to the Part WB (not Part Design) and from the pull-down menu choose Part > Create shape from mesh.

Depending on the kind of mesh data you have it's not always the best to convert it into a shape because this usually creates a very heavy B-REP model often causing difficulties for further processing.

So, the alternative is to create a sketch, extrude it and then go back to Mesh design and convert the solid into a mesh. Then you can use the boolean cut operation of the Mesh design workbench.

[timesenemy]

Hi timesenemy, and welcome! The Part Design WB only works with solids, and your .stl is a mesh. Instead, after doing File > New and Importing your .stl, change to the Part WB (not Part Design) and from the pull-down menu choose Part > Create shape from mesh. From here you can change your mesh to a solid.

Going only by your description, I'd avoid the Part Design Wb altogether if all you want to do is remove a simple box shape from the model. You can change to the Shetcher WB and create a Sketch of the cross-section of the shape you'd like to use to remove the box shape. Then go back to the Part WB and Extrude your Sketch. From there you can do a Boolean Difference to subtract you Extrude from the solid.

Or instead of Sketching a shape and Extruding it, you can stay in the Part WB, create a Cube, change the size to suit your needs, move it into place, and subtract itt from your solid.

If you need more help, post back - and it might help to include your model.

bejant, and all who replied, thank you for your responses!

bejant, as I was reading your response, I realized it was a mesh, not a solid! Rookie mistake ... but i am a newbie at this so it is fitting. Also, I used your advice, using the Part WB and extruding a sketch to remove the box shape, and it worked perfectly! Again, thank you!

[timesenemy]

How do I add an imported STL object into the/a Body,

If you want to use Part Design:
First create a Solid from your .stl.
Go to Part Design and create a Body.
From the history tree, drag and drop your Solid into Body.
A new copy of your Solid, named BaseFeature, will be created inside the Body.
You can work with the new BaseFeature in Part Design.

bejant, I may try this later, just to get more familiar with FreeCad. Thank you!

[bejant]

Depending on the kind of mesh data you have it's not always the best to convert it into a shape

Thanks Werner, I'll have to remember that!

bejant, and all who replied, thank you for your responses!

bejant, as I was reading your response, I realized it was a mesh, not a solid! Rookie mistake

You're welcome, and as you can see, I'm still learning too!