Monday, April 25, 2016

Build a Vacuum Former

I finally built a vacuum former. I've been looking at builds for years, and I started talking about this build three years ago, but finally it happened.

If I ever build another one, this post lists everything I need and the tricks I learned along the way. To buy a vacuum former like this, I would have spent over $5,000. I spent a LOT less.

Originally I was going to rely on an oven and a shop vac, but once I started sketching I decided to build my final vacuum former instead of a starter, though I am considering building a small toaster oven based former for small parts.
This is an all in one unit. The heaters are mounted at the top, a lift arm raises the plastic frame and holds it in place while it heats. The lift arms lower the frames onto the platen/object and I flip a switch to activate the vacuum, sucking the plastic onto the object.

The trickiest part of the build was coordination. Figuring out the steel to wood connections wasn't bad, but plumbing was a puzzle as I had to get the equipment first and then figure out what I needed and if it existed. Creating the oven was challenging as well since I was using differently sized heating elements and had to wire it up without tripping the circuit breaker. While I could have bought a pre-fabricated heat setup, that would have cost a few hundred dollars instead of the $20 I spent. This runs on a 20 amp breaker, 120 volts.

  • (1) 3/4" Plywood sheet 4'-0"x8'-0" for (1) 18x24 perforated platen, 18x24 platen base, 22x28 stand base, (2)17.5"x2.6" shelving, 18x24 heater box, etc (Note: A 16x22 bed would allow a standard 18x24 'For Sale' sign to fit into the frame.)
  • (4) 8'-0" Oak 2x4s for framing- legs and shelf bracing
  • (2) Rigid Casters
  • (2) Swiveling & locking casters 
  • #8 x 3" bugle head drywall screws for 2x4 to 2x4 connections
  • #6 x 2" bugle head drywall screws for plywood to 2x4 framing connections
  • (16) #12 x 1" hex head bolts for casters. Be careful not to overtighten..
  • (1) 1/2" Concrete board 3'-0"x5'-0" for the heater box
  • 1-1/4" Zinc coated screws for the concrete board
  • (4) (2) Toaster Ovens. I bought them from Goodwill. They were $5.00 each. Look for the ones that have (4) heating elements. I've seen them have between (2) and (4). My 20 amp circuit breaker could only support (2) units with (6) total elements.
  • (4) 3/8" 1-1/2" Hex Bolts at vertical to horizontal steel connection
  • (4) 3/8" 2-1/2" Hex Bolts at vertical bottom table connection
  • (4) 3/8" 3" Hex Bolts at vertical top table connection
  • (12) 3/8" Nuts
  • (20) 3/8" Washers
  • (2) 3/8" 1-1/2" Hex Bolts for tank mounting
  • (1) #10-32 cap screw 2" for pump mounting
  • Fire stop caulk for the concrete board joints and holes for wire
  • Contact cement to attach the aluminum plate to the plywood platen. I re-glued it with Gorilla Glue.
  • (2) 5" long 1/4" hex bolts for base of lift arm
  • (6) 1.5" long 1/4 bolts for lift arm joint
  • (2) 3" long 1/4" hex bolts lift arm to frame
  • (2) 2" long 1/4" hex bolts to prevent the frame from rotating. These do not attach to the lift arm, but to the steel slider. 
  • (4) Nylon spacers for 1/4" bolts for lift arm connections
  • (4) pieces of steel for lift arm to lift arm connection. I used 1/16"x3"x3" steel.
  • (2) pieces of steel for the frame bracket  I used .25"x3"x3" steel.
  • (2) 1"x1"x 32" longer wood lift arm. Doing this again, I'd use steel tube.
  • (2) 1"x1"x18" shorter wood lift arm. Doing this again, I'd use steel tube.
  • (12) 1.5"x1.5" Aluminum angle for the heater brackets
  • (4) 1.5" long 1/4 bolts & nuts that connect the metal plate lift bracket to the wood lift arm
  • (4) #12 x 1" hex head bolts for the closet flange
  • Paint - I used a gloss gray base, satin white mid-coat, and a green color coat
  • Round Aluminum Duct- For the control panel. Round aluminum duct is cheaper than flat sheet metal. While it's thinner, it's $3 instead of $30

Steel Supplies:
I bought steel from a local welding shop. You can check, their prices are fair and shipping isn't bad if you can't find a local source.
  • (1) 1/2" 16 gauge expanded aluminum 16"x22" sheet
  • (2) 1/2" 16 gauge expanded aluminum 16"x3" strips
  • (1) 16 gauge aluminum plate 19.5”x25.5” (I sized this to wrap around the edges of the plywood.
  • (4) 33” 1"x.125" steel square tube for vertical heater support
  • (2) 19” 1"x.125" steel square tube for horizontal heater support
  • (2) 10” 1"x.125" steel square tube sliders
  • (4) 18” long 1”x1"x.125" steel angle forthe frame
  • (4) 25" long 1”x1"x.125" steel angle for the frame
  • Doing this again, I would make the lift arms steel tube. 

Plumbing Supplies: 
Galvanized fittings are cheaper than brass, but barbed fittings only come in brass.
Some of these components I got at a big box store, some I could only find at a hardware store.
I used a 1/2" check valve because I could only find the 3/8" size for an industrial application which was very expensive.
What I should have done is delete 1/4" coupling, delete  3/8" hose barb 1/4" fitting and instead used a 1/4" to 1/2" fitting to connect the pump to the check valve. Doing this again, I would have added a nipple on each of the 3/4" ball valve and done 90* fittings on each end, with a 90* fitting and nipple at the closet flange. This would have resulted in straight stretches of vinyl hose and shorter runs.

Electrical Supplies: 
  • (2) Toggle switches - 20 amp, single pole single throw
  • Safety cover switch for the oven switch (because it looks cool) and distinguishes the two switches.
  • (2) junction box
  • (6) 3/8" twin screw cable clamp
  • duplex receptacle 
  • 1/2" EMT conduit
  • 1/2" EMT strap
  • Black 14 gauge solid wire
  • White  14 gauge solid wire 
  • (1) 3 prong cord. I salvaged mine from a computer power cord.
  • Wire Nuts. I used sizes for (2) 14 gauge wires and (3) 14 gauge wires. 
    • Measuring tape & pencil to mark lengths, attachment locations, etc
    • Circular Saw/Table Saw to cut the plywood and 2x4s
    • Punch to mark drill holes
    • Drill/drill press for pre-drilling holes and attachments
    • Sanding block to smooth any rough edges from cuts
    • Clamps to secure wood (lots of clamps)
    • Rubber mallet to adjust clamped wood
    • Round file in case any drilled bolt holes need enlargement 
    • Flat file for metal edges
    • Jig saw with metal cutting blade
    • Socket wrench with 3/8" and 1/4" sockets for the bolts
    • Adjustable wrench for plumbing fittings 
    • Screwdriver 
    • Solder iron for heater connections
    • Test light to confirm you've wired everything correctly
    • $70  for wood and associated screws
    • $16 for casters
    • $160 for all steel
    • $100 for plumbing fittings
    • $10 on toaster ovens
    • Concrete board was leftovers as were the associated screws, though it would run $15
    • $30 Air tank
    • $130 Vacuum pump  
    • Welding - I have a friend that welds, so this didn't cost me anything. Done professionally, I would estimate $120-180
    • $8 Aluminum angle
    • $30 Electrical
    • $15 Paint
    • TOTAL: $569. That isn't bad considering you'd spend five thousand buying one outright. Forgoing steel would only save an additional $100.
    The table base is wood 2x4s and plywood. The verticals are 2x4s and the shelves are 2x4s for bracing with a plywood top. I split a 2x4 and used that to brace the top. I split the 2x4 for the top bracing as I knew I would be adding controls and gauges and needed the height.

    While 2x4s aren't always square and straight, they are always cheaper than steel. To square up the shelves and top, once the 2x4's were attached to each other, I screwed in one corner of the plywood to the 2x4, and then clamped the 2x4s to align them with the plywood. The clamps help pull the 2x4's in line with the plywood edges. Then I screwed the plywood to the 2x4's while clamped.

    I would clamp whatever piece I was attaching to mark holes for drilling. I added a 6" apron around the top, reason one is for my controls and release valve and two, it looks better and matched the height of the heater box.

    All holes are pre-drilled to avoid potential splitting. I used 3" screws when attaching through a 2x4 and 2" screws when attaching through plywood. The table was 36" high from top to bottom before casters. The casters add about 4" which is a perfect height.

    I added a shelf above the base for the tank and pump, which created storage on the bottom. I don't know what I'll store, probably scarp plastic, but space is always welcome.
    The tank is attached through the plywood with hex head bolts. I drilled a hole in the leg supports for the tank.
    For the pump, I removed one of the bolts mounting it to the plate and replaced it with a 2" long #10-32 cap screw that runs through the plywood.

    The vertical heater supports are steel for rigidity and straightness. A steel tube slider will run in between the supports to lift and lower the clamping frames.

    I drilled the holes in steel with a drill press. I clamped the steel to the table and used the holes in the steel as a guide for the holes drilled in the wood. This ensures the holes are straight. Make sure you have enough space for the slider. It should should slide easily but not wiggle. I'll probably wax the tracks when I'm done so it slides smoothly.

    To help coordinate the location for the vertical supports, I applied a horizontal clamp for the bottom of the tubes to rest on, this makes clamping it to the table much easier than  trying to hold it still vertically and horizontally. Hex head bolts secure the verticals to the table.

    If any of your holes are off, a round file will help enlarge the hole.

    I had to shim the steel to ensure the tubes were straight and level. This will help the heater box fit well.

    A 3/4" hole was drilled through the top of the base.   A 3/4" closet flange was screwed from the bottom. During finishing I will caulk between the flange and plywood.

    The platen is 3/4" plywood sandwiching 1/4" tall, 3/4" thick plywood. A 3/4" hole is drilled through the bottom. The expanded metal was screwed into the base to stop it from moving around. The bottom of the platen was attached to the top of the base from the bottom side with 1" wood screws. The overall size is 18"x24".

    The angle iron frames have an inside size of 18"x24". If I did this again I would make it 16"x22". That way a standard large "For Sale" sign would fit in the bracket as the signs are 18"x24".

    I used contact cement to attach the aluminum plate to the platen top. I later had to re-glue it with Gorilla glue. Before attaching, the board needs to be 1/8" less long and less wide than the bottom of the platen to account for the aluminum plate thickness. I wrapped the edges of the aluminum down 90* at the edges. If I build this again, I won't wrap the aluminum edges, while I like the look it was an added headache that isn't functional. Or if I do it again, I will account for the thickness of the aluminum first! It looked really good the first time I bent the edges down. When I had to bend them up and recut the platen to fit the frames, it got a little beat up looking. Upon regluing, I took a small nail to ensure all of the openings were clear of glue or debris.
    I marked 1/16" holes at 1" on center, accounting for the 1/4" spacer around the perimeter. The spacer needs to be relatively small as it takes up air space. and the tank only holds so much. The larger this air space, the less effective the tank is at removing air.

    I hammered the aluminum down on the sides with a rubber mallet.You want to bend the whole edge down evenly a little bit at a time.

    The heater box is plywood, fastened the same way as the base with bugle head drywall screws.

    To attach the horizontal support, I placed a piece of steel tube between the supports and attached a horizontal clamp. This made clamping the horizontal supports much easier. Due to clearance, I drilled a 5/8" hole on the inside of the horizontal supports so the bolt heads wouldn't protrude  as the concrete board rests directly against the steel.

    The bolts of the horizontal supports intersect the outside plywood trim to hold the heater box in place. I also added bolts that insert from the bottom of the heater supports as I wanted a solid connection from steel to box.

    I used concrete board as an insulator for the heater box. The concrete board was cut to fit the box and then screwed to the wood. I used fire caulk at all joints and seams. I attached the concrete board to the heater box with zinc coated screws I already had.

    I salvaged heating elements from the toaster ovens. Cut the connections and then use a belt sander to clean it up. You could use a grinder, but you may accidentally grind right through the steel connectors.

    I took the heating elements salvaged from the toasters ovens and began arranging them. You want the elements to be evenly spaced throughout. This is a bit tricky when dealing with multiple heating elements of various sizes.  A heating kit would be easier, but is much more expensive.

    I spaced my elements at roughly 3.5" on center and 3.5" from the perimeter of the box. While I originally was going to have (11) heating elements. My 20 amp breaker couldn't support it. I have (6) elements. I was going to craft brackets for the elements from metal leftover from the microwave, but decided to use aluminum angle for a better looking and stronger finished product.

    I drilled holes in the aluminum brackets to hold the ceramic posts. The aluminum was trimmed to 1.5" lengths. and screwed to the concrete board.

    Lift handle
    I have a 10" piece of steel tube that will slide between the vertical supports on each side. I had thought about facing it with nylon, but that proved too expensive. A bolt goes through the lift handle, tube, and into a bracket welded to my angle iron frames. The lift handle is wood, as is the cross bar. I used scrap steel to create the hinge to connect the two arms using 1/4" bolts and nuts. Scrap steel screwed to the lift arms with 1" wood screws acts as the bracket to the frames.The wood screws were later replaced with through bolts.

    The long lift arm is 32" long. The shorter is 18".  One end of the shorter arm was rounded, so that it could rotate. I glued a stop on the bottom side of the lift arm. This allows the lift arms to lock into place and hold the frame near the heater without falling back down.
    A nylon spacer is between where the lift arm attaches to the base so the lift arm clears the bolts and vertical steel tubes.

    The lift handle attaches to the angle iron frames. If I had to build this again, I would consider attaching 1" steel tube  to the bottom of the frame. It would make the attachment to the lift arm a little cleaner. I welded on a piece of steel to the frame. One bolt connects to the lift arms, the other bolt attaches to the slider to prevent the frame from rotating during use.

    Plumbing was determined as I went along. The fitting on the air tank is 1/2" female. The fitting on the vacuum pump is 1/4" male. I used 3/4" inner diameter tubing to the platen and 3/8" inner diameter tubing to the vacuum pump.

    A 1/2" nipple connects the air tank to a 1/2" ball valve. Another 1/2" nipple connects the ball valve to the  3/4" to 1/2" reducer tee.
    One end of the reducer tee is a 3/4" thread 3/4" barb fitting. This side uses 3/4" vinyl tubing to connect to the 3/4" ball valve with 3/4" thread 3/4" barb fittings and the galvanized closet flange with a 3/4" barb fitting.
    The other side of the tee has a 3/4" to 1/2" coupling and a 1/2" thread 3/8" barb fitting. This connects to a 3/8" threaded tee and 3/8" thread 3/8" barb fittings. One end of the tee goes to a 1/2" check valve with 1/2" thread 3/8" barb fittings and a 1/4" thread 3/8" barb fitting and 1/4" coupling to the pump.
    The other end goes to the vacuum gauge with a 1/4" thread 3/8" barb fitting and 1/4" coupling to the gauge.
    All threads were wrapped three to four times with plumbing/teflon tape. The tape helps seal and ensures connections attach smoothly. The tape should always be wrapped in the direction of the threads, and you want to start on the second thread.
    Conduit clamps sized to 1" hold the ball valve in place on the control panel.The wood had to be recessed so the handle could clear the front. I also had to recess the wood at the switches.

    Doing this again, the 3/4" barbs would screw into a 3/4" 90* angle. This would create straight runs of the vinyl tubing and shorten it by quite a bit. 

    Wiring this rig is an area I'm not as familiar with. While I assume there has to be a more efficient way, this is what I came up with based on trial and error and tripping the circuit breaker.

    I salvaged a three-prong cord from an old computer monitor. This will plug the vacuum former into a wall outlet. I want this to be plug and play.

    In the base, the power cord feeds to the junction box. From this junction box, one set of wires runs to the duplex receptacle for the vacuum pump, the other runs to the junction box on the oven. An inline toggle switch is attached for the receptacle and the oven. I used a test light to confirm the switches were installed correctly. Testing the electrical at each step, narrows the possibilities if having problems later. I confirmed the pump worked, then confirmed I was getting power to the oven junction box before connecting the heaters.

    My heater box is built with a gap where the vertical supports extend up. This gap is where I have a junction box mounted. I have a piece of conduit running along the top so that the wiring can access both sides of the box and remain hidden from view. Conduit runs from the oven down to the base adjacent to the vertical support.

    I revised the number of elements from (11) to (6) based on what would NOT trip the breaker.

    Some elements heat up to full temperature wired in series, some need to be wired alone. Trial and error will determine. I looped the wire on the elements to test the setup before soldering.  (2) groups of (2) elements are wired in series and (2) elements are wired straight.

     If they elements don't glow red/orange, they aren't up to temperature.

    All wiring connections were wire capped and taped.

    I didn't have a good way to test for even heating as I didn't have access to and didn't want to buy a thermal camera. In the test run, even before respacing the elements, it seemed to heat fairly well.

    I couldn't leave it plain. I wanted a cool finish or theme, though I wasn't sure what. I wanted something robotic or military based. This step is completely unnecessary, but the joy is priceless.
    Even if you don't want to theme it, I recommend painting or staining it just to protect the wood.

    I disassembled everything.

    I painted all wood gloss gray. This will mimic a steel finish. I then sprayed everything with a satin white. The white will look like a prime coat. My color coat is a green. I wanted something more military green, but I had this on hand.

    After spraying the white, I rubbed it off on edges, corners, and anywhere I wanted the 'steel' to be revealed.

    Then I applied mustard where the green paint will 'flake' off to reveal the prime coat and steel. This is going to be areas that wear more like edges. I also used salt, which gives a pitted finish. I had never tried salt before, and wish I had used more of it. Wet the salt slightly so it sticks better.
    Then you can spray the green. Once it's dries, wipe off the mustard and salt to reveal the 'steel' and prime coat. You can go back over the green with acetone or mineral spirits to remove green or create wear places. Be careful that you don't remove too much paint.
    I used the round aluminum duct to create a panel for the front. I removed the curve from the duct by running it over the edge of a 2x4.

    Once weathering is complete reassemble the unit. I was going to use black enamel and rubbed it on then off, to accentuate crevices and recesses. It adds a nice layer of grime and use to the unit. When that's complete, clear coat everything to protect the finish.

    I added weather stripping where the frames meet the table.

    First Use
    With this project finally done, the big question is, does it work. It does!
    It's a bit trial and error. First I evacuated the air tank with the pump. I turned the heaters on and let them get hot as I clamped the plastic in the frames. Once the heaters were hot I raised the frames.

    I have a small leak in the vacuum lines. I plugged the pump in a separate outlet on a separate circuit since I know I can't run the pump and heaters simultaneously.

    Once the plastic started drooping, I switched off the heaters, lowered the frames and opened the valve. My plastic stretched too far underneath one item that was suspended off the table and broke the seal, so I know I can get a tighter pull.
    If the seal didn't break, I would have closed the ball valve on the tank and switched on the vacuum pump to remove any additional air. This step might be unnecessary. I need to do a few more pulls to perfect it.
    My second pull turned out much better. Gaps and holes less than 1/4" won't pop a hole in the plastic. For concave shapes like sunken eyes in masks, drill a hole so the air can be evacuated. For good edge definition, raise an object off the table by an 1/8".
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