3D Printers Reading Answer

Ever wished you could find a pair of shoes to match your outfit? Fancy a pizza but don’t want to go out or wait for your delivery service to arrive? Simple. All you need is a 3D home printer. Whilst admittedly not yet mainstream technology, it is only a matter of time until the 3D printer becomes as much a part of the domestic furniture as the statutory TV or the washing machine. Currently, however, the technology remains firmly in the province of geeks and gadget lovers.

The design of the 3D home printer is nevertheless refreshingly simple. Its components are relatively few, and could theoretically be assembled by anyone with a rudimentary knowledge of mechanics and technological know-how. The 3 main elements of the printer are a metal framework which contains the mechanical part of the printer, a printer control board and a PC. The PC is connected via USB to the printer control board, which in turn is connected to the framework of the printer and attached to the side of the latter. A plastic filament of around 3mm in diameter feeds into the printer from an external source, connecting to the extruder motor inside the printer. During printing, the controlled movement of the extruder motor ensures the correct volume of plastic is used. The extruder motor in turn is connected to a heated extruder or ‘hot end’ that heats the plastic filament during printing. As the heated plastic emerges or is ‘extruded’ to use the correct terminology, it cools and is arranged in layers to create a solid 3D model.

In order to move the extruder about in 3D space, there are 3 axes, each controlled by motors. The X-axis motor, located in a midway position on the metal framework of the printer, moves the extruder left and right, using a pulley. The two Z-axis motors, which are located on either side of the heated printing bed, move the entire X-axis up and down via two threaded rods. The heated bed of the printer, which lies directly underneath the hot end of the extruder, is moved back and forth beneath the extruder by the Y-axis motor located underneath the heated bed. The bed is

heated to around 70 degrees Celsius to ensure the newly laid plastic does not warp as it cools. Overall control of the printer is effected by the printer control board and the PC which contains the programme of the model that is being printed.

Once assembled, in theory it should be possible to print a 3D version of virtually anything. However, comparatively easy as it is to assemble, would-be DIY gadget enthusiasts should be warned that the printer has major technical limitations. The finished product will always have banding and surface detail remaining as evidence of how the model was laid down. In addition, operators of the printer have to be extremely careful not to knock it whilst the machine is in the process of printing, since this will end up in model distortion. Extreme care also has to be taken in the choice of plastic filament which will ultimately create the structure of the model. Some types of plastic may warp if the temperature is not controlled properly when the melted plastic leaves the nozzle, and later, when it is cooling on the bed. Obviously the 3D model will be the same colour as the plastic filament forming it, but colour limitations can easily be overcome by painting afterwards for a multicolour finish. Another problem is that the plastic structures have to be supported as they are laid down on the heated bed or they will distort or fall away as the plastic cools.

It is virtually certain, however, that such issues will be overcome in the future. The innumerable advantages of 3D printers far outweigh any disadvantages and justify time and resources spent on such technology. Firstly, the product can be produced on the spot within a very short time frame, thereby reducing time and cost of manufacturing by traditional means. Secondly, printing objects on a 3D printer removes the need for storage space of items since whatever is required is printed as and when necessary. Finally, despite expensive set-up costs, in the long run, 3D

printing works out far cheaper than normal manufacturing processes since there is no longer a need for labour costs

1 Z-axis motor

2 hot end of extruder

3 extruder motor

4 plastic filament

5 X-axis motor

The Pros and Cons of 3D Printers

Cons

The finished product is far from perfect, exhibiting 6 …………………. in addition to banding. In order to 7 …………………. desired, extreme care has to be taken in selecting the plastic filaments to be used. It is also necessary for plastic structures 8 …………………. during the printing process to avoid distorting the printed model.

Pros

Only every 9 ………………… is required to produce 3D models. 3D products are also much cheaper to make than using normal manufacturing processes and need no storage space. In theory 10 ………………… of 3D printers to create virtually anything from pizza to fighter planes is astounding.

Whilst 3D printing is far from becoming 11…………………, so far experiments with the new technology have been promising. Although 3D models have yet to produce anything as 12 ………………… as fighter planes, the foundation for such a technology is in place. For the moment, however, the realisation of such projects remains in the 13 ………………… future.

Reading Answers

1 Answer: D

Question type: Diagram Labelling

Answer location: Paragraph 3, line 3 – line 4

Answer explanation: The selected lines says that “The two Z-axis motors, which are located on either side of the heated printing bed, move the entire X-axis up and down via two threaded rods.” This tells us that as shown in the diagram, the two Z-axis motors, labelled as D are placed on either side of the heated printing bed. Hence, the answer is D.

2 Answer: E

Question type: Diagram Labelling

Answer location: Paragraph 3, line 5 – line 6

Answer explanation: In the quoted lines of Paragraph 3, it is said that “The heated bed of the printer, which lies directly underneath the hot end of the extruder…” This highlights the fact that the portion labelled as E is the hot end of the extruder which is placed above the heated bed of the printer as shown in the diagram. Hence the answer is E.

3 Answer: G

Question type: Diagram Labelling

Answer location: Paragraph 2, line 9 – line 10

Answer explanation: In the quoted lines of the second paragraph, it is said that “The extruder motor in turn is connected to a heated extruder or ‘hot end’ that heats the plastic filament during printing.” These lines point out that the extruder motor is attached to the hot end or heated extruder and is labelled as G in the diagram. Hence the answer is G.

4 Answer: F

Question type: Diagram Labelling

Answer location: Paragraph 2, line 6- line 7

Answer explanation: In the specified line of Paragraph 2, it is stated that “A plastic filament of around 3mm in diameter feeds into the printer from an external source, connecting to the extruder motor inside the printer.”. In other words, the portion marked as F is the plastic filament which is attached to an external source and connects to the extruder motor as depicted in the picture. Hence, the answer is F.

5 Answer: B

Question type: Diagram Labelling

Answer location: Paragraph 3, line 2- line 3

Answer explanation: In the specified line of Paragraph 3, it is stated that “The X-axis motor, located in a midway position on the metal framework of the printer, moves the extruder left and right, using a pulley.”. In other words, the portion marked as B is the X-axis motor which is placed in a middle position in the framework of the printer. Hence, the answer is B.

6 Answer: surface details

Question type: Summary Completion

Answer location: Paragraph 4, line 3- line 4

Answer explanation: The mentioned line of Paragraph 4 says that “The finished product will always have banding and surface detail remaining as evidence of how the model was laid down.” As it is clear that the finished product is exhibiting surface details in addition to banding and is far from perfect, the answer is ‘surface details’.

7 Answer: create the structure

Question type: Summary Completion

Answer location: Paragraph 4, line 6 – line 7

Answer explanation: The specified lines state that “Extreme care also has to be taken in the choice of plastic filament which will ultimately create the structure of the model.” So, it is clear that in order to create the desired structure, extreme care has to be taken in selecting the plastic filaments to be used. Hence the answer is ‘create the structure’.

8 Answer: to be supported

Question type: Summary Completion

Answer location: Paragraph 4, line 11 – line 12

Answer explanation: The lines from Paragraph 4 says that “…the plastic structures have to be supported as they are laid down on the heated bed or they will distort or fall away as the plastic cools.” It states that it is also necessary for plastic structures to be supported during the printing process to avoid distorting the printed model. Hence the answer is ‘to be supported’.

9 Answer: short time frame

Question type: Summary Completion

Answer location: Paragraph 5, line 3- line 4

Answer explanation: The lines from Paragraph 5 says that “Firstly, the product can be produced on the spot within a very short time frame, thereby reducing time and cost of manufacturing by traditional means.” It states that a short time frame is required to produce 3D models, which is the product. Hence the answer is ‘short time frame’.

10 Answer: the potential

Question type: Summary Completion

Answer location: Paragraph 4, line 1

Answer explanation: The provided lines says that “Once assembled, in theory it should be possible to print a 3D version of virtually anything.”. As it is clear from the statement that in theory the potential of 3D printers to create virtually anything from pizza to fighter planes is astounding. Hence, the answer is ‘the potential’.

11 Answer: mainstream technology

Question type: Summary Completion

Answer location: Paragraph 1, line 3 – line 4

Answer explanation: The given lines say that “Whilst admittedly not yet mainstream technology, it is only a matter of time until the 3D printer becomes as much a part of the domestic furniture as the statutory TV or the washing machine.” This statement points out that while 3D printing is far from becoming mainstream technology yet, experiments with the new technology have been promising and will soon become a part of every household. Hence the answer is ‘mainstream technology’.

12 Answer: ambitious

Question type: Summary Completion

Answer location: Paragraph 4, line 1

Answer explanation: The provided lines says that “Once assembled, in theory it should be possible to print a 3D version of virtually anything.”. From the phrase ‘virtually anything’ it is quite clear that 3D models will, in the future, be used to create ambitious creations like fighter planes. Hence the answer is ‘ambitious’.

13 Answer: very distant

Question type: Summary Completion

Answer location: Paragraph 1, line 3 – line 5

Answer explanation: The following lines from Paragraph 1 says that “Whilst admittedly not yet mainstream technology, it is only a matter of time until the 3D printer becomes as much a part of the domestic furniture as the statutory TV or the washing machine. Currently, however, the technology remains firmly in the province of geeks and gadget lovers.” From this reference, we can conclude that for the moment, the technology lies in the hands of limited people and the realisation of such projects remains in the very distant future. Hence the answer is ‘very distant’.