3d printing: history and current techniques
TRANSCRIPT
3d printing: History and current techniques
And some playing around with Origami
What is 3d printing?
• Using a general-purpose machine to create a physical object, where the design of the structure is provided to the machine at build-time.
• Usually, the object is created additively, in a layer-by-layer process.
• Compare to "CNC" (computerized numerical control) which usually refers to a subtractive process like carving, routing, turning or cutting.
Why do we care about 3d printing?• Personalization and customization
• you can make a single copy of a thing, which is prohibitive with traditional manufacturing
• Complexity
• you can make objects with complicated internal structures, which is difficult with traditional manufacturing
Why do we care about 3d printing?• Rapid prototyping
• Can make a physical instance of a design, and quickly tell if it's the right size and shape for a job
• Can iteratively refine a design based on real-world performance
• Modelling for traditional manufacturing
• Build a complex shape, and use it as a mold for a more traditional material process like metalwork
Why do we care about 3d printing?• NRE (Non-recurring engineering) costs
• eg: $100,000 to set up a production line, each copy after than costs $0 (and a few seconds of time)
• (idealized, for a small simple part)
• 3d-printing a copy costs $5 (and a half hour of time)
• Once you are making more than 20,000 copies, traditional manufacturing is cheaper.
• Traditional manufacturing is also far higher quality and far faster.
$400k NRE versus 3d printing
$0.00
$2.50
$5.00
$7.50
$10.00
Units (thousands)10 20 30 40 50 60 70 80 90 100
cost/unit (traditional)cost/unit (3d print)
How did we make things before 3d printing?• Carve the part out of wood or plaster
• Also, carve the internal structure of the part separately
• Cast a series of molds of stronger materials until you have a steel form for the inside, and a separate steel form for the outside
• Pour molten plastic (metal, whatever), and let cool
• eject the part from the mold
• Alternatives: cornstarch molds for food gels like gummies
What are the limits of 3d printing• a 3d printed part is not as good as a manufactured part.
• more fragile, lower resolution, more expensive and takes longer to produce
• 3d printing requires specialized equipment and materials
• a 3d printed part requires a 3d design file
• expert knowledge required to produce a design
• but, designs can be shared and modified
• Consumer 3d printing is limited to thermoplastics, and ~10cm3 build area
3d printing and social change• NRE means it’s only feasible to make a thing if you can sell tens of
thousands of them, or if you can charge a lot for them
• commodity versus luxury; walmart versus bespoke
• 3d printing means things can exist that are both inexpensive and non-commodity
• 3d printing has limits, so how does this extend to other things?
Fab Lab• 10 machines to build anything
• 3d printing is one of them
• laser cutters arguably have higher utility and usability
• Circuit miller is arguably more important for making high tech things
• Price is prohibitive, but dropping
3d printing controversies• Guns or other restricted things
• 3d printer means anyone can make anything whether or not the government likes it
• as long as it’s made of plastic and the size of a loaf of bread
• 3d printed guns are not very good guns, and people make bombs out of pots and pipes
3d printing controversies• Printing Bioproducts
• Printing custom pills with exact dosages
• Printing organs for transplant
• Printing biotoxins and chemical weapons
3d printing controversies• Information Ownership
• Many corporations are identifiable by their physical products
• Coke bottles, toys associated with movies, nike shoes
• Design patents prevent consumer confusion by disallowing one company from manufacturing a product with similar or the same “trade dressing”
3d printing controversies
• Economics, industry
• What happens to the world economy when people can print whatever they need at home?
Different kinds of 3d printing• Selective Laser Sintering (SLS)
• Fused Deposition Modelling (FDM) or Fused Filament Fabrication (FFF)
• Stereolithography (SLA)
• Powerbed gluejet printing (3d printing proper)
➡ laser-melted nylon power
➡ melted thermoplastic filament
➡ Photo-cured acrylic resin
➡ metal power and glue, later annealed with copper
most consumer printers
Know your material• FDM/FFF printing can use a few different thermoplastic materials
• Acrylonitrile butadiene styrene (ABS) : Strong, food-safe, lego plastic; awesome.
• Polylactic acid (PLA): biodegradable; derived from corn, tapioca or other plants. more brittle, higher melting temperature, harder to work with, not as strong. more properly called a polyester.
• Specialized thermoplastic materials: ninjaflex, conductive plastic, chocolate etc.
• All have specific properties that will influence your ring
Know your printer
• Each printer is different, and fail in different ways
• Know your printer and maker custom supports and modifications
• eg mouse ears
• Fit tolerances for connecting parts and external parts
SLS$1,000,000
Consumer SLA$100, or $3500
Consumer FDM$500-$5000
Model Replication• To replicate a physical model on a 3d printer, there are two ways
• 3d scanning
• Model Measurement
• (third way: find someone online who’s already made one)
• Many commercial products and maker plans
• Microsoft kinect, makerbot digitizer, etc
3d scanning
3d scanning
• 3d scanner is expensive
• (but getting cheaper)
• Many layers of postprocessing required
• (but getting easier)
Model Measurement• Use the right tools
• Calliper, protractor etc
• be precise
• Model as you Measure
• Aim for easy replication
• think construction process
• Find inspiration from existing models
3d modelling software• Tinkercad
• Blender
• Sketchup
• Zbrush
• Meshmixer, Meshlab, Netfabb
3d modelling in sketchup1. Set template to “3d printing: millimetres”
2. Install STL export extension
1. click on the ruby box (install extensions)
2. double-click “Sketchup STL”
3. click “download”
Scale
• Consider the smallest discernible element your printer can generate
• Simplify your model to match characteristics of the printer
• Don’t try to print (or even model) anything smaller than 2 mm
• Use the right tool for the job: metal pins and screws are better at providing mechanical structure than 3d printed plastic
Edges, planes and points• Building an object that looks nice in sketchup is easy
• Building an object that prints well is hard
• Edges can’t just look close, they must meet exactly.
• Objects must be water-tight and right-side out
• the printer will try to do what you tell it to do. If you say print an inside-out box, it will try. and fail.
Boxesright side out inside out
Making a box• Draw a rectangle
• type in numbers to provide an exact size, in mm
• Extrude the rectangle into a box with push/pull
• NOTE: points, edges, and planes are all separate and can be manipulated
Sketchup Tools• Line; Arc; Rectangle; Push/pull; Offset; Move; Rotate; Scale;
• Also: follow me; constrain to axis
• Xray mode can be useful for finding problems with internal structure
• sketchup will try to help you
• midpoint, parallel to edge, on edge
Rotate
• rotate a plane or edge
• everything selected is rotated
• Everything else is fit as best as possible
OK
Bad
Move
• rotate a plane, edge, or point
• everything selected is moved
• Everything else is fit as best as possible
OK
Bad
DEMO: origami boxin 10 minutes of modelling
Wall Width
• A box will be printed solid (filled in with infill specifications)
• A frame can be built so it will not be filled in. Choose wall widths for appropriate strength
Support• FDM printers layer melted plastic
on each previous layer
• Some things are impossible
• Aim for, at most, 45 degree overhang, 2.5 cm bridge
• otherwise, add your own removable support, or tell the software to calculate support
Print Orientation
• Consider the way in which your model will be printed
• You may choose to separate your model into more than one piece, to make support-less printing possible
not as good good
Model Segmentation
3d modelling for origami
• Flat surfaces, simple folds
• look at “low-poly” (low-polygon count) models for inspiration
Aside: foldable 3d prints and CNC• Special modelling techniques:
flexible and bendable joints, hinges etc
• flexible materials: ninjaflex
• Thermoformable / hydroformable materials (also called 4d printing: 3d plus time)