Introduction: Vacuum Former at Home
Like many makers, I have always wanted my own vacuum former. While I am at home in a shop, I don’t have a shop in my home. I wanted to find an easy way to make one that I could both make and use at home with just a few hand tools. This solution uses readily available materials and doesn’t require big power tools, so this is a good approach for those without the equipment or comfort level to build one of the many other options out there.
What You Need
- (2) wood artist trays or drawer organizers
- power drill
- drill bit(s)
- silicone sealant
- wood glue
- clamps or a bunch of heavy books
- round file
- adjustable aluminum window screen (at least as big as your wood trays)
- (8) metal screen corners
- hacksaw or X-Acto saw blade
- weatherstripping with adhesive backing (width to match frame of screen)
- (4) large binder clips
- small shop vacuum with hose
Helpful but not essential:
- White vinegar
- Paper towels
- Crowbar, claw hammer or sturdy flathead screwdriver
- Hole saw or forstner bit (diameter matching your vacuum hose)
- Small chisel
- Dremel with sanding drum
- Miter box
- Museum putty
- Thermoform plastic (ex: .03 styrene)
- Oven with broiler
- Oven-safe gloves or potholders
- Bricks or oven-safe ramekins
- Aluminum foil
- Talcum powder
Step 1: Make the Box Base
I had a couple of wood artist trays leftover from another project that seemed like a good way to make the box base without the use of a wood shop. Those with the tools and know-how to build a box from scratch may certainly do so and skip ahead to Make the Frame.
Step 2: Remove Sectional Dividers
Wooden organizer trays usually have sectional dividers. First, we need to remove those. Ideally, your trays have adjustable sections that you can just pull out. If they are glued in, place some vinegar-soaked paper towels at the glue joints and let sit overnight. The vinegar breaks down and loosens the wood glue. You may be able to pull the dividers free by hand. If not, use a crowbar, claw hammer or sturdy flathead screwdriver to carefully pry the pieces free. Reapply more vinegar if necessary. Plan ahead for this step as it may take some time for the vinegar to work its magic.
Step 3: Drill Holes
Draw a grid pattern on the bottom of one of the trays. The overall size of your grid should match the inside dimensions of your frame. I found that a grid spacing of 10 mm worked very well.
Plan ahead and figure out what size your frames will be. The final frame size should be the same size or smaller than your wood trays.
Drill holes at the intersection of each grid line. The holes should be fairly small; I used a 3/32 drill bit.
Step 4: Seal Inside
Apply silicone sealant to every joint inside the trays to make them airtight. Follow the instructions for your sealant and let dry as recommended.
Step 5: Glue Trays Together
Apply wood glue to the top edge on the trays and glue together. Clamp together for at least one hour. If you don’t have clamps, place some heavy books on the trays to give the glue joint the pressure it needs.
Step 6: Cut Out Hole for Vacuum
Measure the diameter of your hose on your shop vacuum. Mark the diameter at the center of one of the long sides of your box.
To cut out the hole, a hole saw or forstner bit matching the diameter you need is the easiest way. If you don’t have either of these on hand, you can drill a bunch of small holes around the edge of your marked circle to roughly cut it out. A small chisel may help to get your rough circle fully cut. Then use a round file or a dremel sanding drum to get a smooth circle.
Test fit your hose and continue filing/ sanding until you have a tight fit.
Step 7: Seal Outside
Apply silicone sealant on the outside of your box, where the two trays were glued together.
Step 8: Make the Frame
An adjustable screen is an easy off-the-shelf way to create two metal frames to hold your thermoform plastic sheets.
Step 9: Separate the Two Frames and Remove Mesh Screen
The frame I had used a simple plastic bracket to hold the two adjustable frames together. With minimal effort, you should be able to pop off those brackets to separate the two frames.
Pull out the stripping material that holds the screen in place. The mesh should come free quite easily.
Step 10: Cut to Size
Pull apart the frames. They should be held together with screen corners that just slide out.
Cut to length the aluminum frame pieces to fit on your box base. The final frame size should be the same size or smaller than your wood trays. Use a hacksaw or X-Acto saw blade to cut the aluminum. A miter box will help you hold the frame pieces and get a straight cut.
Put the frames back together. If the screen corners that came with it were plastic, replace them with metal screen corners.
Step 11: Apply Weatherstripping
Apply sponge rubber weatherstripping to one of the two frames. Make sure you have complete coverage to ensure an airtight seal.
Step 12: Use It!
Now for the really fun part.
Step 13: Set Up and Prep
1. Cut thermoform plastic:
I used .03 sheet styrene, which is readily available from most plastic suppliers. It is also easy to cut (scissors will even work) and is sandable. Cut your sheet to match the dimensions of your frames.
2. Prep oven:
Remove all but one rack from your oven. Line the bottom of your oven with foil. Wrap two bricks or ramekins with foil and place on oven rack. These will hold up your frame, which should be a few inches below the broiler. With the oven door fully open, line the inside of the door with foil and place your box on top.
3. Attach vacuum:
Set up your vacuum next to the oven within reach. Tightly place hose inside the hole in your box. For an extra tight seal, place a ring of museum putty around the edge of the hose.
4. Put material in frame:
Place your plastic sheet in between the frames. Hold the frame together with the binder clips. It is best to slide the clips underneath the weatherstripping. Place the frame in the oven on top of your bricks, making sure that plastic is free to sag and that the weatherstipping edge is facing down, away from the broiler.
5. Prepare part:
Place the part that you’re forming, on top of the box, in the center of your grid of holes. It is helpful to lightly dust your part with talcum powder to help release the plastic afterwards.
6. Prepare to form:
Get your gloves on or have potholders within reach. Make sure your vacuum power switch is within reach. Practice taking out the frame and quickly placing it, centered over your part. Turn on your vent hood and open any windows. The plastic will smoke a little.
A quick safety note: use only with adequate ventilation, wear a respirator, line your oven with foil, and clean your oven after you're finished. If you have concerns about heating plastic in your home/ oven, only proceed if you're comfortable with the risk. This is not intended for frequent use.
7. Heat material:
Turn on the broiler. If you can control the temperature on your broiler, I found that 380˚F worked well and reduced the amount of smoke and fumes from the plastic.
8. Heat until material sags:
From this point on, watch the plastic from below carefully as you’ll need to move quickly. What you see is the material starts to ripple from the heat. Then it will appear to level out again. Next it will start to sag. Turn on your vacuum and get ready with your gloves/ potholders. A general rule of thumb is to let your material sag to about ½ the height of the part you’re forming over.
Step 14: Final Form
When ready, grab the edges of the frame, carefully because it is hot. Do not touch the plastic at all. Quickly place the plastic, centered, over your part with the vacuum running and weatherstripping down on the box. If you’ve maintained an airtight seal, the hot plastic will immediately form over your part. Turn off the vacuum after a few seconds. Let the plastic and frame cool for another minute or two. Then you can remove the plastic from the frame and pop it off of your part.
Have fun and be safe! Note that this is a project best suited for those with some experience and not recommended for children.