Chocolate Batarang

Hi, this is Ed from Other Machine Co.

Perhaps you're obsessed with Batman. Or maybe, like me, you have a kid who loves the cartoons. Either way, what better way to show your love than to make chocolate Batarangs to both play with and eat.

Step 1: Tools and Materials

Tools

  • Othermill
  • Flat End mill, 1/8"
  • Ball End mill, 1/16"

    Materials

  • Machining wax, 3" x 3" x .5"
  • Food Grade Liquid Silicone
  • Ghirardelli Chocolate Melting Wafers

    Software

  • Inkscape (free)
  • Otherplan (free)
  • Fusion 360 (free)

    Step 2: Get or Make a 2D Image

    Chocolate Batarang

    What we'll need to make the 3D shape is a 2D shape for the outline of the Batarang. This 2D shape will need to be a vector file in a SVG format. If you're handy with Illustrator or Inkscape, you can create your own and export a SVG file of the result.

    If not, you can still create your own SVG file with the help of Google Image Search and Inkscape.

  • Search Google Image Search for "bat clip art"
  • Your ideal image would be one that is black and white with no grays like the one above
  • Save the image to your computer
  • If this is an SVG file, you can skip to step 5

    The image above is from here.

    Step 3: Make an Outline in Inkscape

    Chocolate Batarang
  • Open up Inkscape
  • Choose File > Import (Ctrl + I)
  • Choose Path > Trace Bitmap (Shift + Alt + B)
  • Select "OK"
  • Close the Trace Bitmap window

    Step 4: Save a SVG File

    Chocolate Batarang

    It will look like nothing has happened, but really a new vector version has appeared on top of the original image.

  • Move the image down
  • Choose the Edit paths by nodes tool (F2)
  • Click on the image you just moved

    You will see lots of little squares around the image. These are the points for the paths that make up the image. You can start messing around with the points to tweak the image, and I highly recommend learning that skill if you don't already have it.

    Otherwise:

  • Go back to the Select and transform objects tool (F1)
  • Select the original image
  • Delete it

    You now have just the vector image. Save it to be able to use it in the next step.

    Step 5: Going into Fusion 360

    Chocolate Batarang
    Chocolate Batarang
    Chocolate Batarang
    Chocolate Batarang

    Now it's time to get into 3D!

    Fusion 360 is a pretty new product from Autodesk that came out in 2013. It's a cloud-based software that lets you design in 3D. It also has CAM software built in. That means that you can create toolpaths for a CNC machine like the Othermill. Which is really, really awesome.

    OK, so let's get back to the project at hand.

  • Choose Insert > Insert SVG
  • Choose a plane
  • Click on the small folder icon (see pic) to choose a file
  • Click "OK"
  • If you don't see the image it's probably big and off the screen so zoom out

    Step 6: Moving into 3D Shapes

    Chocolate Batarang
    Chocolate Batarang
    Chocolate Batarang

    The SVG is in a 3D space, but it is still a 2D shape. To make it 3D and give it volume, we need to pull it up a bit. Here's how:

  • Right-click on the bat shape.
  • Choose "Press Pull."
  • Pull it up a tiny amount. I'm using 1 mm.
  • The color is now gray to show that it's a solid shape.

    If you just want a solid version of a 2D shape without any extra shaping, you can drag the blue arrow to make the object even taller. Don't worry about the numbers for now, just focus on getting the right proportions. Then you can skip to step 9.

    Step 7: Copying and Moving Up

    Chocolate Batarang
    Chocolate Batarang
    Chocolate Batarang
    Chocolate Batarang

    To get a tapered effect for the top of the object, it's quick and easy to use a copied shape. Here's how to copy the object and move it up.

  • Open up the Bodies folder in the browser on the left
  • Right-click on "Body1" to open up the menu
  • Select "Copy"
  • Right-click on "Bodies"
  • Select "Paste"
  • Drag the arrow up or enter a value in the text box to move it up

    Step 8: Modify Top Object

    Chocolate Batarang
    Chocolate Batarang
    Chocolate Batarang
    Chocolate Batarang

    A quick and dirty way to get a quick bevel edge effect is to shrink the top object. The amount you can shrink it depends a lot on the design. For example, this design does not give much room at all, but it can still have a nice effect.

  • Move into the TOP view so you're looking straight down
  • Select Modify > Scale
  • Select the "no selection" text next to "Point" in the Scale Menu
  • Select a point on the shape that you want to be in the center of the scaling effect
  • Change Scale Type to Non-Uniform
  • Tweak the scaling numbers

    Step 9: Connect the Two Objects

    Chocolate Batarang
    Chocolate Batarang
    Chocolate Batarang

    Now that we have two variations on the same object, it's time to connect them. Luckily we have a great tool, Loft, that can merge them.

  • Move the view with the Orbit tool so you can see both shapes
  • Select Create > Loft
  • Select both objects
  • Select "OK" in the Loft Menu

    This creates a new object that joins the object on the bottom with the one on the top and creates a smooth transition between the two.

    Step 10: Resizing, Part 1

    Chocolate Batarang
    Chocolate Batarang

    Now that we're getting closer to the final shape, let's make sure that we're working in the right size. The width of the machining wax that we're using is 3 inches (76 mm). We'll also want about an 1/8" (~3 mm) margin around the positive part of the mold once we make it, so that gives us a max width of 2.75" or 70 mm.

    So what we need to know is just how wide the current object is.

  • Select Inspect
  • Click on leftmost point of object
  • Click on rightmost point of object
  • See what the distance is in the results panel

    I can see that the distance here is 687.35 mm. That's huge! It's easy enough to scale it down, however. All we need to do is divide the end size we want, 70 mm, by the current size, 687.35 mm to get the scale factor we need: 0.1018.

    Step 11: Resizing, Part 2

    Chocolate Batarang
    Chocolate Batarang

    Now that we know the scale factor, it's just a matter of applying it.

  • Select Modify > Scale
  • Select object
  • Enter "0.1018" for scale factor
  • Select "OK" in Scale menu

    And zoop! it shrinks down to a tiny object. Zoom in to see it up close.

    Step 12: Fine Tuning the Shape

    Chocolate Batarang

    Now that we have the object at the right width, let's tweak the thickness.

  • Select Modify > Scale
  • Select "Non-Uniform"
  • Change the settings for the axis that controls the thickness until it has the effect you want. Be sure to Orbit around the piece to see the effect from different angles
  • Select "OK" in the Scale menu

    Step 13: Check the Thickness

    Chocolate Batarang

    Now we'll use the Inspect tool to see how thick the object is.

  • Zoom in on the object
  • Select Inspect
  • Select a point on the top of the model
  • Select a second point on the bottom of the model that is directly below the first point
  • See the results in the Measure panel

    The results here are 1.28 mm. This would make a pretty thin piece of candy so we'll make it a little thicker in the next step.

    Step 14: Drop the Bottom

    Chocolate Batarang
    Chocolate Batarang
    Chocolate Batarang

    I'm pretty fond of chocolates that are 6 mm thick which means that we need another 4.72 mm in the object. To do that, we just flip the object over and pull on the bottom.

  • Orbit around object to see bottom side
  • Right-click on object and select Press Pull
  • Enter 4.72 mm in text field
  • Select "OK"

    And we now have our final object! Whoohoo!

    OK, relax for a minute, now get ready for the next bit.

    Step 15: Stepping into CAM

    Chocolate Batarang

    CAM is what we do to go from a 3D model to creating instructions to send to the Othermill. With the CAM fille, the Othermill will be able to mill our shapes out of a piece of wax.

    The first thing we need to do is determine the Setup. This covers the size of the material and the position of the model within.

  • Choose SETUP
  • Select the "Top corner 1" for Bounding Box Point

    Step 16: Set up the Size of Material

    Chocolate Batarang

    Copy the information in the image above. This is all for the material which is machining wax with the dimensions 76 mm x 76 mm x 12.6 mm.

    Offsetting from the top by 1 mm makes sure that the mill will finish the top of the material. If the model was at the very top, the surface quality of the wax would be the surface of the final piece.

    Step 17: Creating the Roughing Toolpath

    Chocolate Batarang
    Chocolate Batarang
    Chocolate Batarang
    Chocolate Batarang

    Toolpaths are often broken down into multiple steps. There's the roughing toolpath and the finishing toolpath. When we want to clear a lot of material quickly we'll use a larger end mill. Here that's the 1/8" flat end mill. This clears out the large majority of the material, but still leaves a little bit around the model for a smaller end mill to clear away with more detail. It's a lot like painting a room where you use a roller brush to do most of the work and a small brush for the edges.

    To create the roughing toolpath, I'm using the Adaptive Clearing option under 3D > Adaptive Clearing.

    Recreate the settings in the pictures above. The second picture is how you choose the tool. Fusion 360 has a ton of tools to choose from. Here's how to quickly refine the tool search.

  • Select "Select" next to Tool
  • Change Tool Type to "Flat End Mill"
  • Enter "1/8" in bottom left text field

    That narrows it down to just a few end mills. I selected the last option.

    Step 18: Creating the Finishing Toolpath

    Chocolate Batarang
    Chocolate Batarang
    Chocolate Batarang
    Chocolate Batarang

    Now we want to create a finishing path. The finishing path cleans up the details on the top of the object with a smaller end mill: the 1/16" ball end mill.

  • Select 3D > Contour
  • Add the 1/16" ball end mill
  • Copy rest of settings in pictures
  • Select "OK" at bottom of menu

    Step 19: Exporting Toolpaths

    Chocolate Batarang
    Chocolate Batarang

    For each toolpath, we want to export these as files that the Othermill can use. This is done with the Post Process technique.

  • Right-click on Adaptive Clearing
  • Select "Post Process"
  • Enter in information like in picture with the Othermill post processor selected
  • Save to a handy folder
  • Repeat the process for the Contour toolpath

    Step 20: Post Processor

    Fusion 360 will soon be updated to include the Othermill post processor, but until then, here's how to add it.

  • If Fusion 360 is open, save the file and close it.
  • In the Go menu in Finder, select Go to Folder (or hit Cmd+Shift+G).
  • Type or paste ~/Library/Application Support/Autodesk/webdeploy/production and hit Go.
  • In the folder that opens, you'll see one or more folders with long names that are random letters and numbers. Look through those folders until you see one that has the Fusion 360 application in it and also a Libraries folder.
  • In that Libraries folder, go to Applications/CAM360/Data/Posts.
  • Move Othermill_tinyg_m3x.cps (attached) into the Posts folder in the other Finder window.
  • Open Fusion 360 and the Othermill post processor will now be an option.
    Chocolate Batarang
    Othermill_tinyg_m3x.cps26 KB

    Step 21: Setting up the Othermill

    Chocolate Batarang

    Yes! We've made it to the milling stage!

  • Turn on the Othermill and connect it to your computer
  • Place the purple machining wax in the front left corner of the bed. I'm using the alignment jig, but this is not necessary.
  • Holding the wax, run a bead of hot glue around the bottom edges to keep it in place during milling.

    Step 22: Setting up the Job in Otherplan

    Chocolate Batarang
    Chocolate Batarang

    Now we're very close to being ready to go. To get the file set up in Otherplan:

  • Select "Setup Material"
  • Select "Machining Wax (Purple)"
  • Select Standard size
  • Select "Continue" and "OK"
  • Import roughing toolpath file
  • Add "1/8 in flat end mill" as the "Tool to Use"

    Step 23: Insert End Mill into the Collet

    Chocolate Batarang

    Place the 1/8" flat end mill into the collet, tighten it, and follow the instructions for setting the height.

    If you have not done any jobs with the Othermill before, then be sure to check out the Hello World Instructable for more detail about this step.

    Step 24: Mill the Wax

    Chocolate Batarang

    It's happening!

  • Select "Start Cutting"
  • Watch the Othermill to make sure the job is going correctly
  • Once the roughing pass is done, delete the file in Otherplan
  • Import the finishing toolpath
  • Insert the 1/16" ball end mill
  • Select "Start Cutting" to start the finishing pass

    And with that, your piece should be done. Vacuum it off to clean it up, and you're ready to make a mold.

    Step 25: Molding

    Chocolate Batarang
    Chocolate Batarang
    Chocolate Batarang
    Chocolate Batarang
    Chocolate Batarang

    Build a box around the wax to hold the mold in place. It doesn't have to be fancy, it just can't be made of material that is absorbent. The box I made here uses a popsicle stick and some torn up parts of a cardboard box. It's all held together with hot glue.

    Once the box around your wax is ready, mix up two equal parts of the Copyflex Liquid Silicone. Stir it until it's well-mixed, about 20 seconds or so. It should be a consistent color.

    Pour the silicone from 12 inches above the wax piece. This height allows the silicone to stretch out and release air that was mixed in during stirring. This is called a "stretch pour."

    Once the wax is covered, let it sit for four hours to cure.

    Step 26: Melt and Pour

    Chocolate Batarang
    Chocolate Batarang
    Chocolate Batarang

    Put the Ghirardelli Chocolate Melting Wafers into a glass or bowl and microwave it. Watch it carefully so that you only melt it just as much as you need. Stir it up and then pour it into the mold.

    The chocolates can set in about 20 minutes.

    Step 27: Eat!

    Chocolate Batarang

    You now have bat-shaped chocolates. Make as many as you want for Halloween or a superhero-themed birthday party.

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