Hi, this is Ed from Other Machine Co. and I like sci-fi. Star Wars is great and all, but it's even better when combined with chocolate. Thus, the chocolate Millennium Falcon! Fly it around for a bit of a space battle before eating it up. Pew pew! Nom nom!
Step 1: Tools and Materials
Step 2: Make or Find a Model
With lots of people making things and sharing them online, I didn't have to model my own Millennium Falcon. I found this Millennium Falcon by Glitch on Thingiverse.
This model is broken up into three pieces to make it easier for 3D printing. You can download them all, but I'm only using the top two pieces since this will be a one-sided mold.
Step 3: Prepare the Model in MeshMixer
MeshMixer is a great, free tool for tweaking .stl files (standard tessellation language). It's perfect for what we need to do here, which is combine the two .stl files into one. Here's what I did:
- Insert the middle .stl file.
- Flip it over.
- Scale it up by 2x in the z-axis to make it thicker.
- Insert the top .stl file.
- Line up the two pieces.
Attached is the MeshMixer file so you can see what those results, as well as the exported .stl file, look like.
Step 4: Start on the Toolpaths
Now that there’s an .stl file that works as a piece of chocolate, we need to create toolpaths. Toolpaths are the instructions that tell the CNC machine how to move the end mill around in 3D space. These toolpaths depend on things like the type of material you’re cutting into, the spindle speed, and the smoothness of the finish that you want.
To create these toolpaths, I’m using MeshCAM (free for 15 days, $250 after). I'm going to be creating a roughing toolpath and a finishing toolpath. The roughing toolpath clears away most of the material and uses a larger end mill: a 1/8" flat end mill. The finishing toolpath uses a smaller end mill: a 1/16" ball end mill.
The first thing to do is load up the .stl file for the Millennium Falcon from the last step. The units for the file are in mm. Choose the 3-axis milling option.
Once the .stl file is in, it needs to be scaled down. I'm milling this out of a piece of wax that is 3"x3" or 76 mmx76 mm. Since I want to have a little space between the positive shape and the edge of the wax, I want a maximum dimension of 70 mm. Choose the scaling option and scale it all by 0.73.
Step 5: Set Up the Material for the Toolpaths
The model is now ready to go, so the material needs to be determined.
- Select the "Stock Size" button (the first item in the Toolpath section).
- Choose "Fit to Geometry."
- Turn off "Center Z."
- Add 1 mm to the top offset.
You're now ready to create toolpaths.
Step 6: Make the Toolpaths
Now that everything is sized up and placed, it's time to set the settings for the toolpaths.
- Select the "Create Toolpath" button (the last toolpath button).
- Match your settings to those in the picture above.
- Click "OK."
Step 7: Save Your Tooplaths
You'll see a list of checkboxes. This combines all of the toolpaths, including the roughing and the finishing. Since we're going to be using different end mills for these two processes, we'll need to save them as different files. This can be done by choosing which toolpaths get exported as your file.
- Turn off all finishing path checkboxes.
- Save the roughing path as "Basic GCode-Inch(*.nc)."
- Turn on the finishing path checkboxes and turn off the roughing path checkbox.
- Save the finishing path as "Basic GCode-Inch(*.nc)."
Step 8: Edit the G-code
Unfortunately, MeshCAM doesn't include instructions in the G-code to start the spindle at the beginning and stop it at the end. Lucky for us, we can use a basic text editor to fix it!
Add these two lines to the beginning of the file:
This starts the spindle (M3) and sets the speed to 12,000 rpm (S12000).
At the end of the file, add this line:
This stops the spindle.
Step 9: Prepare the Wax
Now that you have the G-code for the job, it's time to get started on the Othermill.
- Make sure the bed is clean of any debris.
- Place the machining wax on the front left corner of the bed.
- Holding the wax in place, run a bead of hot glue around the bottom edge of the wax to secure it to the machining bed.
Step 10: Set Up Otherplan
OK, now it's time to get started on Otherplan, the software for the Othermill.
- Select "Setup Material."
- Select "Machining Wax (Purple)" for the preset. If your wax has different dimensions, choose "Custom Size" and enter the dimensions into the text boxes.
- Select "Import Files."
- Select the roughing toolpath.
- Select the "1/8 in flat end mill" as your tool.
Step 11: Insert the End Mill
- Select "Set" next to Tool in the top-right of the screen.
- Put the 1/8" flat end mill into the collet and tighten it.
- Follow the instructions for setting the height of the end mill.
Step 12: Mill!
Now that everything is ready to go, select "Cut" and then "Yes" to get started. The Othermill will start spinning the end mill and go to work on the roughing toolpath. Be ready for lots of wax shavings.
Once the roughing is done, clear out the inside of the Othermill with a vacuum and get ready for the finishing toolpath. The process of setting up the tool and path is just like the roughing toolpath process.
- Delete the roughing toolpath.
- Import the finishing toolpath.
- Change from the 1/8" flat end mill to a 1/16" ball end mill.
- Select "Cut."
When that's done, your wax Millennium Falcon will be ready for some mold making.
Step 13: Make a Mold
Double check your wax positive to make sure that it's completely clean. Then check again.
OK, now time to make a mold. We're using Copyflex Liquid Silicone.
- Mix equal parts A and B to activate the silicone.
- Stir thoroughly until the silicone mixture is an even color.
- Brush a thin layer onto the wax positive.
- Pour onto the wax positive from 12" above your mold.
Note: Since this piece isn't that detailed, we skipped Step 3, but it would be needed for more ornate pieces. Pouring from 12" helps to reduce the amount of bubbles. The silicone stretches out as it falls and helps to get rid of the air that was mixed in when stirring. This is called a "stretch pour."
The Copyflex cures in about four hours. You now have a mold!
Note: The item being molded in the picture is not the Millennium Falcon.
Step 14: Melt and Pour the Chocolate
You'll want tempered chocolate for making the final pieces. You can easily make your own following one of many tutorials online, but we took a shortcut and used Ghirardelli Chocolate Melting Wafers.
Here's the process:
- Melt the wafers in the microwave.
- Pour the chocolate into the mold.
- Put the mold in the fridge.
The chocolates should set in about an hour.