Introduction: CNC Milled Military Helmets (or Bert & Ernie Helmets)
I created these 3d helmets in Maya for the military uniforms of the soldier apes I have used in my animations (sample above from "good enough for the people"). Once I made them, people mentioned that the gold helmet looked like Bert and the silver one, Ernie, from Sesame Street. Not my intention but I can see that.
To create them as physical objects, I sliced the 3d models in Autodesk 123D Make and CNC milled the pieces on 1/2" foam that was stacked and covered with fiberglass. The LED lights run off of 9 volt batteries.
The steps for this project will hopefully help you through working with your own model but I did include the files for these.
3D model, saved as .stl
files and sandpaper and dust mask
2 small lightbulbs
5 styrofoam cones
Blue and Pink ink
7 LED lights: 2 LED lights for the gold helmet, 5 LEDs for the silver one.
three 9 volt batteries and cases with power switches
wire, solder and soldering iron
OPTIONAL, fiberglass and Aqua resin. Or you can cover the foam in plaster or white glue
Step 1: Prepare 3D Models
Bring your model down to one single mesh and export it as a .stl file. For the silver helmet, I knocked out 5 circles with cylinder Booleans for the cones. With the gold helmet, I knocked out a hole on each side with cylinder Booleans for the lightbulbs.
Step 2: Slicing in AutoDesk123D Make
Settings for AutoDesk123D Make:
Select "Import" in the top left corner to import the .stl file. I kept the Object Size measurements in millimeters, but make sure that they match your 3D model file. You may have to change the numbers to match the original.
The foam pieces I used were Super TUFF R from Home Depot, 48" x 36", and 0.5" inch thickness, so I set up a custom size in the top left menu for the layout. When you select custom you can input the layout size and material thickness in the bottom center menu that pops up. When you have the settings in place, select the "Page" icon next to "Get Plans" on the bottom left of the menu. In the center bottom, select "EPS", then "Export" and name the file. You can also hit "Print" so you have a hard copy map if you do not change this layout. I opened the exported file in Illustrator and rearranged the pieces to save on material and then printed that new layout as my map.
I kept the numbers but did not select those as cut paths in MasterCam. Use the hard copy map of the pieces to label the numbers with blue tape on the foam so it easier to assemble.
Step 3: Cutting and Building the Pieces
Leave the silver and blue covering on the foam for cutting. It will keep it flat and help reduce some of the foam debris.
In your CNC software (I used MasterCam for a Techno CNC), select only the shape outlines as the cut lines. For the thickness setting, I brought it down to 0.48" which was more accurate for the Super TUFF R foam. I used a standard 1/4" bit.
Remember to label the pieces with their numbers according to your map after they are cut but before you move them from the CNC bed.
Once they are all cut, remove both coverings (blue plastic and silver sheet) so foam is glued to foam. Glue the stacked pieces together with white glue. When they are dry, give it a day, use a file to shave off the edges. Then you can sand it with medium sandpaper. Make sure to wear a particle mask.
If you are not covering it with fiberglass, then sand it more with finer sandpaper. I left the inside rough, with the steps. You can fill in any gaps with plaster and paint the entire helmet with white glue to seal it. The glue can be thinned with 25% water.
Fiberglass: If you decide to use fiberglass, I cut small pieces of lightweight fiberglass (6" x 6") and applied them all with Aqua Resin.
When the surface is sufficiently smoothed out, paint it with acrylic paint (gold and silver in this case).
Step 4: Making the Details for the Lights
The silver helmet has 5 styrofoam cones, each with one white LED light. The center cone is 10", middle 2 cones 8" and the outside cone are 6". Add an extra inch to each measurement and then file the cones to the width of the holes. File the bottom inch inward to slip into the holes. Then use a long 1/4" drill bit to hollow out the cone up to about a third of the height. A small file will also help clear the material.
To maintain translucency, I painted the cones with diluted colored inks, a couple of coats. Then coat them with clear acrylic or thinned white glue to keep them from breaking.
Insert each cone into the appropriate hole, securing them with glue and plaster or Aqua resin to close the seal.
Carefully cut off the very bottom of the 2 light bulbs with a fine saw bit on a Dremel. Wear goggles and gloves to avoid any glass fragments. Remove the light filament. Roll 2" wide heavy paper into a tube that fits around the base of the bulb.Secure it with glue. Insert the tube and bulb into the 2 holes on the earpieces on each side of the helmet.
Step 5: Adding the LED Lights
For both helmets, glue in a little shelf with a piece of the extra foam to hold the battery packs. The white LED lights in both helmets are powered by 9 volt batteries.
The 5 LED lights inside each cone use two 9 volt batteries, one chain of 3 lights and another of 2 lights.
2 LED lights, 1 inside each light bulb.