If you’ve ever had to manufacture a really complex, organic shape, you may have wanted to split the model along a parting line for machining. Well, this can be a very tough job without a very powerful tool, plus a little guidance. Luckily, we are talking about Rapidform here, so “check” on the powerful tool. As for the guidance, here’s a tutorial that one of our favorite customers has used repeatedly to split some of the most difficult meshes out there.

By the way, this tutorial was written with the simplified RapidWorks interface in mind. That said, all the instructions here also apply to Rapidform XOR, but the commands may be in a different place than we describe here. Anyway, without further ado, here is our guide to trimming complex meshes…

Parting Lines 101:

How to Get Those Pesky Meshes to Trim

1. Run the Healing Wizard to get rid of all defects in the mesh. Optionally, run it a second time to
iron out any remaining defects.

2. Perform a Global Remesh, keeping the default settings. Check the box “Make clean and
manifold solid mesh” if the mesh encloses a volume (i.e. is not just a surface shell).

3. Accept the edits to the mesh at this point.

4. Create/edit a parting line as a 3D Mesh Sketch. Make sure the curve is a closed loop (indicated
by a red dot where the start and end points join together).

5. Rebuild the parting line with a very tight tolerance. Optionally, split the curve into several
smaller pieces and then rebuild all of them with a tighter tolerance. See the two pictures below:

6. Copy the mesh and paste it at the bottom of the Feature Tree. Edit this new copied mesh.

7. Try to trim the mesh using the “By Curve” method, and choose “Rearrange Poly-Vertices” at the
bottom of the command tool.

8. If this doesn’t work, or you get a message like the one below, you need to tighten the tolerance
on the parting line curve even more. Exit out of mesh-editing mode, then edit the 3D Mesh
Sketch of the parting line.

9. Select the whole parting line (i.e. all the segments that make up the closed loop). It’s time to try
some edits that will help the trim run smoothly:

– a. If you did not split the curve before, do so now by choosing the Split command with the
“Pick Points” option and clicking on several points around the curve.

– b. Double-check that the curve is closed by identifying a red point somewhere on the
curve.

– c. In the “Rebuild” tab at the top of the screen, make the allowable deviation (of the curve
from the mesh) smaller by a factor of 10. You should notice that the number of control
points increases drastically to meet the stricter tolerance.

Accept the changes to this 3D Mesh Sketch.

10. Edit the copied mesh again. Trimming should now work for you. If not, repeat steps 9 and 10
until it does trim well.

Choose both the inner and outer portions as “remaining regions,” and accept the command.

11. Choose the “Flood Fill” selection tool at the bottom left of the screen (i.e. the paint bucket).
Hide all meshes besides the one you are editing, and then click on one side of the active mesh.

When you have selected one half of the trimmed mesh using the Fill tool, hit Crl+C or select
Edit.Copy. Now accept the changes to the mesh and hit Ctrl+V or select Edit.Paste outside of
any mode to paste a new mesh into the Feature Tree. This new mesh is made up of only those
polyfaces that were selected before, so it is one half of our desired result.

12. Edit the complete, trimmed mesh once again. Choose the Flood Fill selection filter, and use it to
select the other half of the trimmed/split mesh. Copy this portion just as you did in step 12
above, then exit out of the mesh editing mode. Outside of any particular editing mode, paste
the selected polyfaces as a 2nd (or 3rd) new mesh in the Feature Tree. You now have both pieces
split along the same curve and saved as individual meshes. Save the RapidWorks project, export
your split meshes and continue with your overall workflow! Here is a shot of the final result:

Happy mold making!