← IGCSE Computer Science Paper 1

3D printer

An output device that builds a solid object from a digital 3D design file by adding material, such as melted plastic, one thin layer at a time.

Part of: IGCSE Computer Science 0478 — 3.2 Input and Output Devices — Module 28

Understanding 3D printer in IGCSE Computer Science Paper 1

What it does: A file such as design.stl holds the digital 3D design that the 3D printer reads and turns into layers to print. Resin is one material a 3D printer can use, alongside plastic and metal, to build the object layer by layer. It takes data from the computer and produces a solid object, so it is an output device. Prototypes are a common use of 3D printers because a test model can be made quickly and cheaply. 3D printers can make prosthetics and other parts that are custom made to fit the patient. Scanning a heartbeat is a sensor job. 3D printers use additive printing: each thin layer is added on top of the last until the whole object is built.

Common mistakes: A 3D printer is additive: it adds material one layer at a time. The line should be ADD_MATERIAL(layer), not REMOVE_MATERIAL. A 3D printer needs a digital 3D design file as its input, such as an STL file. A JPG is only a flat 2D image. It should be gear.stl.

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This module's key terms are also in a printable crossword (Modules 273–282) and word search (Modules 262–282).

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Learning
Duo
How does a 3D printer build an object?
It cuts the shape out of a solid blockIt adds material one thin layer at a time
Matches
A 3D printer prints by cutting a solid block of material away until the shape is left
↓
A 3D printer is additive: it adds material one thin layer at a time. It does not cut material away from a block.
Applying
Meanings
Term
3D printer
Meaning
An output device that builds a solid object from a digital 3D design file by adding material, such as melted plastic, one thin layer at a time.
Practice
design ← "bracket.stl"
Testing
Gaps
designFile
Check Answer
Spots
3WHILE layer <= total_layers
4 REMOVE_MATERIAL(layer)

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Quick Questions

1. How does a 3D printer build an object?
A. It adds material one thin layer at a time ✓
B. It cuts the shape out of a solid block
A 3D printer is additive: it builds the object up layer by layer, rather than carving material away.
2. Which one does a 3D printer need as its input?
A. A digital 3D design file ✓
B. A paper drawing fed through a slot
The printer follows a digital 3D design, usually made in CAD software or created with a 3D scanner.
3. A 3D printer is classed as which type of device?
A. Input device
B. Output device ✓
It takes data from the computer and produces a solid object, so it is an output device.
4. Which material can a 3D printer use?
A. Only ink and paper
B. Plastic, resin or metal ✓
3D printers can build with melted plastic, resin and metal. Ink and paper are used by inkjet and laser printers.
5. A company wants to test a new phone case design cheaply before mass production. What should it make with a 3D printer?
A. A prototype ✓
B. A barcode
Prototypes are a common use of 3D printers because a test model can be made quickly and cheaply.

Match the Pairs

3D printer → An output device that builds a solid object from a digital 3D design by adding material, such as melted plastic, one layer at a time
additive printing → Building an object by adding thin layers of material on top of each other, rather than cutting material away
A 3D printer needs a digital design file as its input before it can print a solid object → design.stl
A 3D printer can use different materials, such as plastic, resin or metal, to make a solid object → material = "resin"
A 3D printer prints by cutting a solid block of material away until the shape is left → A 3D printer is additive: it adds material one thin layer at a time. It does not cut material away from a block.
A 3D printer is an input device because it takes in a design from the computer → A 3D printer is an output device because it produces a physical object. The design file is the input.

Key Term

3D printer
An output device that builds a solid object from a digital 3D design file by adding material, such as melted plastic, one thin layer at a time.

Fill in the Blanks

1. INPUT designFile OUTPUT solidObject
Hint: Type the keyword that shows the digital 3D design is data going into the printer.
2. FOR layer ← 1 TO totalLayers printer.addMaterial(layer) ENDFOR
Hint: Type the keyword that starts a loop repeating once for every layer.
3. layers ← height / layerHeight OUTPUT layers
Hint: Type the arithmetic operator that works out how many thin layers fit in the object's height.
4. DECLARE material : STRING material ← "plastic"
Hint: Type the data type used to store the name of a material as text.
5. IF designLoaded = TRUE THEN printer.start() ENDIF
Hint: Type the Boolean value that means the design file is ready, so printing can start.

Spot the Error

Question 1
A design <- LOAD("cup.stl")
B layer <- 1
C WHILE layer <= total_layers
D REMOVE_MATERIAL(layer)
E layer <- layer + 1
F ENDWHILE
Line D — A 3D printer is additive: it adds material one layer at a time. The line should be ADD_MATERIAL(layer), not REMOVE_MATERIAL.
Question 2
A design <- LOAD("gear.jpg")
B material <- "resin"
C PRINT(design, material)
Line A — A 3D printer needs a digital 3D design file as its input, such as an STL file. A JPG is only a flat 2D image. It should be gear.stl.
Question 3
A thickness <- 0.2
B layers <- 60 * thickness
C OUTPUT layers
Line B — The number of layers is the object height divided by the layer thickness. It should be 60 / thickness, not multiplied.
Question 4
A IF use = "implant" THEN
B material <- "metal"
C ELSE
D material <- "ink"
E ENDIF
Line D — 3D printers build objects from solid materials such as plastic, resin or metal. Ink is used by inkjet printers, so the line should be material <- "plastic".
Question 5
A FOR layer <- 1 TO 100
B MOVE nozzle TO position
C EXTRUDE cold_plastic
D NEXT layer
Line C — The plastic must be melted so it can flow out of the nozzle and fuse to the layer below. It should be EXTRUDE melted_plastic.

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