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)