Let me introduce ourselves
We are a group of Industrial Design Engineering students from Belgium. For our product engineering course we had to make a tool that can embed a pattern in a sheet of PMMA. After looking for the best method we came up with a home made thermoforming machine.
In this instructable we will show how we did it.
If you have any suggestions to improve our design or you have any questions
please let us know in comments bellow
Have fun building it !
Step 1: MATERIALS & TOOLS
- Brich Plywood 5mm
- Birch Plywood 8mm
- 4 x Aluminium rails (500mm)
- Heat unit ( one ceramic cooking plate or three quartz lamps)
- Adjustable resistance (2000 W)
- Wood glue
- Aluminum sheet (thickness 0.8mm)
- 18 x Neodymium magnets ( Ø5 x 5)
- Zip ties
- Rubber sealing
- Soldering iron
- Hot glue gun
- VACUUM BOX.pdf
- HEATING BOX_1.pdf
- HEATING BOX_2.pdf
- HEATING BOX_3 + VACUUM SUPPORT.pdf
- PLATE HOLDER.pdf
- INDUSTRIAL DESIGN CENTER LOGO.stl
- POSITION PART (ABS)
Step 2: PREPARATIONS FOR LASERCUTTING
After you have gathered all of your materials you will need to cut the plywood to the right size. The size of your plywood sheets is dictated by your lasercutter. If you have acces to a big one, great cut your sheets of plywood big and arrange the lasercut files accordingly. If you have acces to a smaller one, then you might need to cut more smaller sheets of plywood and arrange your files to fit that size. We cut our plywood on the big panel saw at school, but this could be done with just a circular saw. If you don't have acces to a saw that can handle big sheets, you can always ask your wood supplier to cut it to size for you. The lasercutter we had acces to can handle 600x450mm so that is the size we arranged everything on.
- If you want no splinters paste some papertape where the cut will be.
- To save material, time and money you need to make sure that as many parts are placed on one plate.
Step 3: LASECUTTING THE FILES
Our thermoforming machine exist almost solely out of lasercutted plywood, this was the easiest way to get everything square and accurate. Every lasercutter uses software to convert the vector files in to usable data for the lasercutter it self. If you have a lasercutter, you probably know how to use one. So If you know how to prepare your files for the cutting, go ahead and do that. If you don't have acces to a lasercutter yourself the easiest way to get them cut is to go to find a fablab in your neighbourhood that has a lasecutter. They will gladly help you with the preparation and cutting, this can be expensive though so keep that in mind. After each sheet that is cut, you take out the finished sheet and put the next one in. make sure to keep track of al the components.
After you lasercutted the files check the part are properly formed
You should verify that the parts can be used or not and if not they should be lasercut again.
Step 4: SUB ASSEMBLY
Our thermoforming machine exist out of three sub-assemblies
first the vacuumbox , second the heatingbox and last but not least the plate holder
Everything is made separately and then assembled together
Step 5: MAKE THE VACUUM BOX
- Place the groundplate on the table
- Assemble the side plates with wood glue
- Assemble the support structure
- Place the support structure in the box
- Close all corners with silicone to make it airtight
- Glue the suction plate on tot he box
- Glue the spacers on the sides of the box
THE VACUUM BOX IS READY !
There are 3 aspects that you have to consider
1. The hole for the vacuumcleaner has to have the right size. So the diametre of the hole depends on the diametre of the vacuumcleaner. The more it fits, the less suction their is lost.
2. The top plate of the box, or suction plate, has to be on the same height as the edge of the box. this ensures that you need less suction. From tests we know that, the higher the suction plate is situated above the edge the better vacuum you create.
3. The suction holes in the suction plate ensure the suction of the plate. Two very important facts about them that you need to know, are the diameter of the holes and the number of holes.
The diametre has to be as big as possible so that their is made an optimale suction on the plate. But the diametre may not be to big beacause otherwise the molden plastic will flow in the holes.
You have to make sure that the holes are distributed equaly and that their are as many as possible.
This has to be a firm structure and the air needs to go trough or in this case under the structure so that the suction is seperated over the whole surface.
Place a rubber seal on the edges. This ensures an optimum vacuum.
Step 6: MAKE THE HEATING BOX
- Place the top plate on the table
- Assemble the side plates with wood glue
- Assemble the inside plates with wood glue into the box
- Assemble the top plate with glue
Glue the small pieces to the box
- Cut aluminum plates to the proper dimensions so that the whole box is layered with aluminum. This ensures reflection of the heat and that the wood catches fire
- Screw the aluminium plates into the box
- Assemble the control box with wood glue
- Install the heating unit in the heatingbox (CAUTION !! do not do this if you know nothing about electricity because this can causes serious injuries)
Connect the cables with the adjustable resistance and fit the adjustable resitance into the control box
Connect the grounding cable to one of the aluminum plates
Mount the control box to the heating box with wood glue.
Place magnets into the holes at the bottom of heater box.
Glue them with with your hot glue gun. Make sure the magnets are well placed. If this is not the magnets will push the plate holder away from the heating box instead of attract them together.
THE HEATING BOX IS READY !
What is important?
- The aluminum L-profiles serve in the first place to mount the heating element in the box, but on the other hand they provide for an air layer. This air layer is an insulating layer between the heat-d-element and the box.
- Make sure that the electrical circuit has been tested in advance for assembly.
- The adjustable resistor which is brought into the circuit, assures that the heat is adjustable
- The height of the heating box must be optimized so that the heat is evenly distributed. if its to small then there will be heated locally and not evenly.
Step 7: MAKE THE PLATE HOLDER
The plate holders are designed to lay the sheet between it. The position parts ensure that the plate fit nicely into the plate holders. In order to clamp the plate between the holders we have chosen for strong magnets
1. Place the magnets in holes of the upper and lower holder. In the upper holder you need to place two magnets. Glue them with with your hot glue gun. Make sure the magnets are well placed. if this is not the magnets will push the plates away from each other instead of attract them together
2. Glue the position parts to the lower holder with your hot glue gun. Make sure the thickest part of the position pieces are glued to the holder
Step 8: ASSEMBLE ALL THE PARTS
First drill holes in the rails so you can assemble it with the the vacuumbox and the heatingbox. Make sure your drill is sharp
The only thing you need to do now is mount the four rails with screws on the vacuumbox and the heatingbox.
Why aluminum rails?
Because of the relation between weight and strength
It is important to have a minimum distance between the heatingbox and the vacuumbox . Otherwise, the plate would be heated and at the same time it be sucked in.
Plate holder and heating box
Because there are magnets in the plate holder and in the heating box, the plate holder adheres to the heating box
Step 9: PRINTING THE MOLD
Congratulations you have reached the last step ,this means that you have a working thermoforming machine, to make parts you will need a would though. We chose to print our mould because it gave us a lot of freedom what the pattern could be. If you choose to print your own mould we would like to give you some tips.
- Print in ABS or PC, these are both materials that can take more heat than your average PLA.
- Do not print a PLA mould, the radiation from the heating element will make the PLA soft and weak. After a couple of tries your mould will be unusable
- .Make sure to add draft angles to your part when you design it, this will help tremendously with the demoulding.
- Create a platform that your part sits on, this way you will be able to cut out the part you want, otherwise the pmma might not be pulled far enough.
- When deciding on how big to make your model, make sure to leave enough room for the PMMA to be sucked over the sides.
Step 10: WHAT CAN YOU DO WITH OUR PATTERN?
After you cut out the shape, you can mount a LED strip in it
Then you have your own DIY wall lamp !
Second Prize in the
Build a Tool Contest 2017
Josehf Murchison made it!