12. Moulding and Casting

Assignment

• Group assignment:

  • Review the safety data sheets for each of your molding and casting materials
  • Make and compare test casts with each of them
  • Compare printing vs milling molds

• Individual assignment:

  • Design a mold around the process you'll be using, produce it with a smooth surface finish, and use it to cast parts.

Group assignment

Link to this week's group assignment

Casting a epoxy light bulb

Modeling

I modeled the bulb and the base mold in FreeCAD, the CAD file is here.

Path generation

Then use the Path workbench to genreate the tool path for cutting out the mold.

The cutting is done in two passes, first using a 4mm diameter endmill to remove large portion of the material and cut out the big features, then using a smaller 2mm endmill to finish the surface of the mold.

Set up the endmill that will be using in the FreeCAD Path job.

First pass I will use the 4mm endmill to do a 3D pocket operation, to remove large portion of the material.

Then I need to do a 3D Surface operation with a smaller 2mm endmill to produce a finer surface finish.

I'm using FreeCAD 0.21.2 when doing this assignment, and as the 3D surface FreeCAD documentation states, the 3D Surface is an experimental feature, so it needs some additional steps to enable the feature, for the version I'm using, I need to go to Tools > Edit parameters ... from the menu, and go to BaseApp > Preferences > Mod > Path and find the EnableAdvancedOCLFeatures parameter and set its value to true. Then restart FreeCAD.

Now the 3D Surface tool is available in the Path workbench.