First and foremost – sorry for not getting this out sooner. Its amazing how procrastination can set things back not the day you plan but a month…or two. SO – more to come soon. I promise. ok – on with vacuum forming.
Vacuum Former 7000x – So what’s a tool if it doesn’t have a cool name. Ok, maybe not cool but I really wanted to name it. It was better than the runner up which was the Sucker Former v2.0. Anyways…
I figured I have one of two options for forming the visor parts for my Daft Punk helmet – Either take the cast and plastic somewhere and pay for a professional services or build my own. Since I am a firm believer in that I can build anything I may need, I built my own. It was quite cheap too, only about 18$ for everything. If you go to Lowe’s or Home Depot, look for damaged goods, they will usually mark them down to half price for you. Especially if you only need a small part of lumber from a larger piece. All you have to do is ask!
First arms foremost – dimensions – I’m a huge fan of metric measurement system, it puts the F’ing standard system to shame. I made mine A3+ which comes out to 13×19. Upside to this is most of the standard sizes I have used in the past 5 years have been tabloid sized (11×17) and fit nicely with room to work with. Something to consider is make sure the size you choose also fits into your oven. its no good to make something that doesn’t fit and have to start over again with the build. There are, I’m sure a number of ways to building a variety of different housings to make this work. I chose what seemed to work best for me. 4 inches thick x 13 wide x 19 long. Measure twice cut once. Trust me it sounds way too obvious but i say it to myself all the time.
Each project varies in what type and size of plastic you may need to get. PETG is my plastic of choice and is a good standard for moldable vacuum forming. Thickness is something else to consider and varies per project, but make sure it’s thin enough. If you purchase locally, just inform the sales rep and they should know what to get. Living in seattle, my preference for plastics is Laird down in the Sodo district just off 6th. Not to undermine their services or their plastics, I do not shop at Tap Plastics, only because they get their stuff from Laird and charge a lot more since its cut down to manageable sizes. From Laird, you buy by the sheet Cut it down yourself and make sure you have extras.
1 x 2×4
1 small roll of Aluminum tape
20 to 24 2.5 inch deck screws (depends on how many to want to put in)
1/2 sheet of 1/4 inch thick ply wood
1 role weather stripping tape
Ruler at least 18 inches long
Pen or pencil
Drill with 1/16th bit, 1/4 bit, 2 inch hole bit
100 grit sand paper
The vacuum former requires to parts a top and a bottom. For the main body I cut the 2×4 to make up the side of the body. Before completely piecing together, I predrilled holes and counter sunk them so the heads of the screws wouldn’t stick out and damage any of the tape. I also sanded down all the edges that were cut to avoid splinter breaking the seal.
Once prep was completed I used 2.5 inch deck screws to screw it together and a touch of wood glue – not to hold in place but to reduce any airflow.
I purchase a damaged sheet of 1/4 oak plywood for half price and got it for about 4 bucks. I used the circular saw to cut this down to the 13×19 dimensions for the enclosed top and bottom. Again sanded down the edges since the saw will eat away at one side. Since I had bunch of screws already I used the same 2.5 to drill the top and bottom in place.
Some people use a predrilled plywood for the top but it’s more expensive and I would have had a lot left over. so I drew out a basic grid and drilled out the cross overs for the surface air holes. I guess technically you could get away with drilling only one larger hole in the center but I think that’s just lazy.
After all was pieced together and sanded down I applied aluminum tape along all the exposed edges that could allow air to seep through. This stuff works great. But for budget tight purposes other tapes work well too.
Be careful to not crease or fold the tape to avoid air leaking in. This is a vacuum, the tighter the seals the better the suckage. On the top edge of the main body I cut out strips of weather stripping for a nice clean seal. This also helps guide the top section to sit clean without leakage.
I tried to overlap the edges to again get the best seal.
In the side I cut out a hole large enough to fit my shop vac hose and lined it with scrap pieces of weather stripping to add grip and to increase a clean seal for a better vacuum. This completes the base.
For the top piece I used a 1×1 and cut it down to be slightly smaller than the main body. 18×12 giving me a 1/2 inch gap all the way around. That’s that.
With the wood when you are ready to form the plastic sheeting it needs to be stapled in place. Don’t be stingy with the staples either. The plastic will pull and leak air in if not stapled down completely.
In your kitchen preheat the temp to 350 or so. Get your base with your object you want molded ready with the vacuum in place to be turned on with ease. Once the oven has reached temp and is keeping its temp, place the frame into your oven. Haha baking instructions for plastic – ˚350 for approximately 39 seconds.
Once ready place the top section in the oven on some glassware or stilted off the rack or base. The plastic will stick to your oven and that end product is not good. I also had a major setback using a gas oven. It heats through the broiler and vents the heat through two smaller slits the bottom of the oven. This posed big problems since it focused the heat on the plastic and melted it almost immediately. I had to place aluminum foil on the bottom to help diffuse some of that heat. On top of that, its old and sometimes doesn’t like to work. My recommendation is to use an electric oven if you can (will heat from above the plastic which is ideal, even if the door is open you can still keep it close to the burner and it will heat it) and use one that isn’t cranky and old.
This part is difficult and may take multiple times to get it right. The plastic will start to droop or sag, let it, and let it sag for a short period of time before pulling it since it needs time to keep its warmth. If you pull it to early it will cool too quickly before you can put it on the vacuum. You kind of need to eyeball it. When its ready, pull it and place it on your base with your work in-between.
I recommend turning the vacuum on before you take the plastic out of the oven so you dont have to deal with it while trying to get the plastic in place before it cools too much. Having a friend help is also a good idea, something about extra hands is sometimes smart. At this point your plastic should, and I emphasize should, be warm enough to stretch around your work and the top frame should seal nicely to the base. With the Vacuum already on sucking air it should be molded and around your part.
If not – your plastic is either not warm enough or your not getting a clean seal on the base. A good way of checking your base seal is to test it before you put the top frame into the oven. If your plastic is not warm enough – well that should be obvious. If you have a nice clean seal and it molds correctly, let it sit for a minute BEFORE killing the vacuum, and cool so it keeps its shape.
After which it can then be pulled from the base. You may need to cut the mold out if your plastic is sucked into some undercuts. I had to, sometimes its a fight and the plastic wins.
Pull the new formed plastic from the frame and cut the scraps from the desired form. The staples should come out from the frame fairly easy; ready for another sheet.
Viola! You now have a vacuum former to duplicate everything you want. Well, almost everything.