As part of a cosplay project, I needed a plastic visor for a helmet. I reached out to my local library makerspace and my alma mater UD asking about their vacuum forming capabilities, and was told none of them had working machines. Cursory searches online showed it was more than possible to get serviceable results using homemade devices, so I made my own.
Content List
Premise
Before you build, you gotta learn how these work. The “vacuum” part of the tool is kinda a misnomer, “suction former” would be more accurate. But it’s a familiar misnomer at least, wrong in the way that vacuum cleaner should also be called a suction cleaner. Some research later and I had a working understanding of what I was trying to build.
At its core, the vacuum former is just a box whose lid has holes and some other wall has a port to connect a typical shop vac. Plastic is prepared by clamping it in a thermally stable frame and heating the assembly in an oven until the plastic sheet starts to sag. Then the frame assembly is removed from the oven and swiftly rammed over the buck on the activated box. The visor will be significantly smaller than the stock plastic sheet, so the pull need not be perfect all across the buck, just the top surfaces. Anything unneeded (called the flash in injection molding and other forming processes) can be trimmed away.
Several cosplay creators online have used homemade DIY vacuum formers. Luckily it would seem that grit may be enough to get one good visor in my timeframe. I learned that dyeing clear plastic a dark color after forming is a viable way to create a tinted visor, since I couldn’t find any tinted plastic sheets available online. Punished Props Academy’s videos on building a DIY former and tinting a formed pull were very helpful and are what I based my efforts on.
Design
My initial plan was to create the box mostly from MDF panels and only 3D print a port to connect the vacuum. Then I learned that MDF is porous enough that it needs a surface treatment to seal it, and that the addition of a baffle layer would help even out suction. I started to wonder why I couldn’t just print the whole thing. It took some doing to fit the large plates in the build volume of my Core One L, but after several hours I modeled up a concept. Because the parts are large, I didn’t want to risk not having something that worked, so I ended up making both.
Small Scale Fit Tests
Before dedicating days of print bandwidth, I printed several version of just the corner to test the fits of the parts. It was a good idea that helped me catch a few mistakes quickly.
Prototyping
Aluminum Clamp Frame
The frame for holding the heated plastic needs to be metal for thermal stability. The PETG sheets I ordered are 12″ x 12″, so I need a metal frame of that size to clamp the sheets tight. I got right angle aluminum stock from the hardware store along with some countersunk screws, a countersink bit, and flat corner braces for the frames. Things got a bit jank as I tried to use a hacksaw in my miter box, but several hours later I had a pair of appropriately sized aluminum frames.
MDF Version
With frames done, I returned my focus to the box made from MDF. I used my miter saw and circular saw to cut the large sheet down to the pieces I needed for a design to fit inside the frame. Because some of the 12″ x 12″ plastic sheet is clamped between the aluminum, the box actually needs to be around 10.5″ to a side at most, which I rounded down to 10″.
I sealed the inner faces of my MDF boards with polyurethane to reduce leaking through the faces.
With the boards sealed, I needed to drill a lot of holes in the platen. I went with a scale paper template taped to the board.
The suction port used a template, too. I placed it on the underside for symmetry with the platen lid.
With each face ready, I started assembling them together. My initial attempts to use wood glue didn’t work, so I designed some corner clamps that ended up adding too much to the size. So with clamps holding the proper shape, I taped it together as best I could.
MDF Forming
Now for the forming! I heated the oven to 380° based on very little at all, precariously balanced the frame on some upside-down loaf pans, and did a few pulls. Thanks a lot to my mom for being an extra set of hands, it’s tricky to move quickly while carrying the frame out of the oven. I can understand why professional products connect the heating and suction elements with rails…
These may look rough, but most of the plastic is cut away keeping only the top face. All the wrinkling by the base will be discarded, making these good enough for this project.
Printed Version
It was at this time that the last job for the printed version finished. It went together pretty well, and though I had a usable pull from the MDF version I did a pair using the printed box to see if it had a noticeable effect. I wasn’t able to notice any difference!
Dyeing
With my pulls formed, I moved to dyeing the plastic dark. I used iDye Poly black synthetic fabric dye and made three visor candidates with different exposure lengths.
Read the full project details at the Cosplay section of this site!