This is a pretty standard design. I have a wooden frame to hold the material to be vacuum formed, and a wooden box with holes on the top to act as the vacuum forming bed. It was cheap to build and works really well.
Step 1: Design and Supplies
A base board would have a hole in it for a household vacuum hose. A small frame would be built in the center of that measuring 11in x 11in. It would be glued to the base and then later sealed with caulk. A square section of pegboard would be glued to the top of that frame and act as the bed for the vacuum former. Separately, two frames made of MDF would sandwich the material to be vacuum formed and those would be held together with bolts. Some sort of rubber tape would run around the perimeter of the frame to form a vacuum seal. This frame with the material in it would go into the oven to heat the plastic and then be placed over the bed to form the part.
I bought the following parts from Home Depot for this project:
- 1x2-8ft Strip: $0.98
- White Peg Board Panel: $8.45
- 3/8"-16 Wingnut (3 bags): $3.54
- Hex Bolt, 3/8x2-1/2 (8x): $2.96
- Foam Tape: $5.67
- 1/2" 2'x4' MDF Project Panel: $9.73
- 1x4-8ft Common Board: $4.12
- 3/4 PVC Pipe: $1.23
- 3/4 90º PVC Elbow: ~$1
You'll need basic wood working tools for this one: a miter saw, circular saw, and a power drill. Wood glue is a must and caulking is optional but recommended. I found a Dremel was just fine to do the job of cutting the center out of the frames, but any method you prefer will work too. You may also want some type of square to make sure those corners are 90 degrees.
Step 2: Cut the Wood
- 1x2 Strip cut into 4 pieces with 45º miter joints on either side, 11in on the longest side
- Pegboard cut to an 11inx11in panel
- MDF cut into 3 18inx18in sheets, one will be used for the base, the other two for the frames
Step 3: Assemble the Base
I used a large square with inch markings on it help both center the frame and the make sure it was square. Once satisfied with the placement, glue the 2x1 frame pieces in place and allow the glue to dry. While drying the center hole can be drilled. Since I was using PVC pipe I found a hole saw of that size and used it to cut the hole. At this point caulking can be applied to fill any gaps that may cause air leaks.
Once any caulking is dried, place glue all the around the 1x2 frame. A continuous line of glue will help prevent any unwanted air gaps as caulking around the pegboard would be difficult. Finally, place the pegboard on the frame and allow the glue to dry.
Step 4: Cut the Two Frames
Step 5: Add Final Touches
The first modification was to add the plumbing. I coated the short piece of PVC pipe with adhesive/caulking and placed it in the hole on the bottom of the base. I then put another piece of PVC pipe that went to the outside of the base so I could easily connect the vacuum.
Next I added some legs to raise the platform a little bit and clear the PVC pipe. These are just scrap wood I had that I glued to the base board.
Lastly, I put some foam rubber weather stripping around the perimeter of the 1x2 frame for some extra sealing.
Step 6: Using the Vacuum Former
I sourced my ABS plastic from Widget Works Unlimited. I found that they had very reasonable prices on material meant for vacuum forming. There's also a video on their product page that will show you essentially the same thing that I will here.
First, sandwich the material to be formed between the two MDF frames. I found it easiest to loosen all the nuts but only remove two bolts on the same side and slide the material in. Tight down all the nuts. Place the base somewhere close to the oven and connect your vacuum. Any vacuum will do. Place your mold on top of the peg board. Heat your oven and then load the entire frame assembly into your oven.
Ok, I know what you're thinking: "I'm not going to put that in my oven, it'll get ruined!" And believe me my parents weren't thrilled about it at first either, but as long as you keep the temperature set to the forming point of the material and use materials that don't tend to outgas at low temperatures you should be fine.
For the ABS I used, the forming temperature was 325-350F, I went with 340F. After a few minutes (depending on the thickness) you'll see the material start to sag in the frame. That's how you'll know it's ready to be formed. Turn on the vacuum and quickly move the frame assembly from the oven to the vacuum table and slide it down over the part. Be sure to use oven mits, it'll be hot! The vacuum should suck the material close to the mold and the pegboard. Wait about 30 seconds or until your material hardens and then remove the vacuum.
If you're part didn't quite form right you may not have heated the material long enough or your part may be too tall for the material to stretch around. It took me a couple of tried to get it right. Also, depending on the intricacies of your mold you may need to prep it a certain way. A quick web search should return all the information you should need. I'm not an expert and my only experience is making simple parts.