A classis and useful workshop tip for scale modelers is making home-made vacuum formed plastic parts. For many, Vac-forming is an advanced modeling technique, and it is excellent for duplicating all sorts of scale accessories. These can include small panels, dashboards, fairings, engine cowlings, scale bombs and drop tanks. You can even make smaller items like scale goggles for your pilot figure as this article will show.
One of the best sources for information on vacuum forming is the book, “Do it Yourself Vacuum Forming for the Hobbyist” by Douglas E. Walsh. http://vacuum-forming.com/. It’s loaded with information if you want to really get into the process including making your own Vac-forming machine.
I have used several of the techniques mentioned in this book and have simplified the process to suit my own needs. So if you’re interested here’s how I made a set of 1/3-scale goggles for my Mini-me pilot figure.
Get the shape right
To make these goggles I first scanned a pair of vintage goggles and imported the image into my CAD program. I then traced the image to produce a working drawing that I then reduced to 1/3-scale. Using the drawing as a reference, I made a plug from some bass wood sheet material so I could then vacuum form the framework and lenses as one piece.
My Vac box is nothing fancy as you can see. I made a simple 12×16 inch wood box about 4 inches deep and topped it off with a sheet of 1/8-inch thick plexiglass. I drilled 3/32-inch holes on 1/2 inch centers and then screwed and sealed it to the top of the box. I use some stick-on foam weather stripping around the top to form a seal when the plastic sheet is placed on top of it. I also drilled a hole in the side of the box and added a plastic fitting that matches my vacuum cleaner nozzle. It works great when hooked up to a regular canister vacuum cleaner or a shop vac.
I place the plug on top of a small piece of window screen and mask off the top of the box with painter’s tape to minimize the vacuum area. I then place the box ready to go, next to the kitchen oven.
Next I taped thin clear plastic to 1/8 inch plywood to act as a carrier. Clear plastic sheets are readily available at most hobby shops and for small parts like this, I use 0.015-inch thick clear plastic. The opening in the carrier sheet is made so it will clear the plug by 1 to 1 1/2 inches all the way around.
Place the plastic and plywood carrier in the over as shown and heat at 350 degree F. until the plastic starts to sag through the opening in the plywood. It should droop of about 1 1/2 inches below the carrier.
Once the plastic is ready, switch on the vacuum and quickly move the plastic and plywood carrier onto the top of the plug, (plastic side down), and press down firmly. The vacuum will suck the plastic down over the plug and will start to cool off quickly. Should you find that the plastic does not form smoothly over the entire plug, you can drill a small 1/64-inch hole in the area needing more vacuum and try it again with a new piece of clear plastic.
Don’t force the plug out of the formed plastic. When the plastic has cooled enough, the plug should fall out easily on its own.
Here’s the formed lenses. The flash makes the plastic look a little foggy, but it is very smooth. Be sure to clean your plug completely of dust. You can also apply a thin coat of paste wax to seal and smooth the surface of a raw wood plug.
To make painting masks for the goggles, simply trace the outer edge of the plug with a soft pencil using some tape.
Here is the mask on the plug with the waste tape removed.
After adding the tape masks to the formed plastic lenses, burnish them down real good and spray on a couple mist coats of plastic primer. Then after the primer dries, mist on a light coat or two of silver paint. Be sure to mask the inside of the lenses to guard against over-spray.
Here are the finished goggle lenses and frames . You can use stick-on foam tape to form the skirt, but I decided to make mine from polymer clay.
Here my pilot bust with goggles added, I used clear setting Zap Formula 560 Canopy Glue, to attach the goggles. To make the goggles lay down against the rounded helmet skirt, I used a covering heat gun to gently soften the center of the goggles. Be sure to protect the lenses with your fingers while pressing the goggles in place.
These techniques can be used to make all sorts of parts from formed plastic. The sky’s the limit!
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