Emphasizing Important Information in a Technical Description
Review Chapters 2 and 3 then study Dr. Juneja’s email. For each of the five points he makes, identify a passage in the original draft that could be improved as he describes. Revise each of the five passages according to his suggestions. For example, the first point in his email refers to the title of the draft. Revise the title to reflect his suggestion.
Once you’ve completed your assignment, write a reflection about your work using the prompt below.
Return to one of the sources you consulted as you further researched 3D printing. Examine how effectively this source emphasizes important information. Explain the ways in which this source follows or strays from the principles of emphasis and coherence covered in the chapter. In presenting information about 3D printing, did any of your sources inspire ideas about how you might improve the organization and development of your own draft? How so?
A 3D printer is a device that enables you to create a three-dimensional object by creating it layer by layer. A layer is a thin cross-section of the object you are building. Each layer is attached seamlessly to the layer beneath it until the whole object is built. Even though there are different kinds of 3D printers, they all work the same way in that you need to begin with a computer-aided design (CAD) file, which provides the blueprint that the 3D printer uses to create the object. You can either create this CAD file using special 3D modeling software, or you can scan an actual object and create the CAD file that way. Then the software in the 3D printer “slices” the design into really thin horizontal layers, like a meat slicer does to a thick ham at the supermarket. There can be hundreds of these slices, or even thousands. Then the 3D printer “reads” the exact specifications of each slice and transforms the material into the exact specifications of the slice. The materials can be plastic, gold, other materials—even chocolate!
When a sculptor carves a statue, he is using what is called a subtractive process. This means he starts with a big block of stone or marble or wood and cuts away material until what is left looks like the thing he is carving, such as a bear. The industrial versions of this are cutting, milling, and machining. When a 3D printer is used, it is using an additive process. This means that the person starts with nothing, then adds layer after layer (using the instructions from the software) to build up the object you are creating.
If you don’t own a 3D printer, you can still use one. There are several companies that let you upload your CAD file and they will “print” the object for you and send it back to you.
At Nike, they use 3D printing to “print” prototypes of new shoe designs using materials very much like the ones that will make it into the sneakers. If they don’t like the way the prototype turns out, they can change the design in the software and print a new prototype. This way, they save thousands of dollars and many weeks of time. Other companies use 3D printing not to make prototypes but actual objects, such as jewelry and some kinds of clothing, that people buy. There is a company called RepRap which sells 3D printer kits that let you assemble your own 3D printer for around $1,000. (One day, you might be able to buy a kit, assemble the 3D printer, then have it create more 3D printers!) Google has some freeware for creating CAD files so you don’t even have to buy expensive commercial-grade software. One technology used in 3D printing is called stereolithography (SLA). The way it works is that a beam of UV light is concentrated on a vat of photopolymer resin, making it soft. When a bead of that resin is drawn out of the vat it hardens in the light, creating the slice. Another technology used is called Fused Deposition Modeling (FDM). FDM uses extrusion, pushing a beam of melted thermoplastics into a layer, then adding another layer. FDM is used in such products as LEGOs that are made of ABS plastic or biodegradable polymer. Another method is called Selective Laser Sintering (SLS). SLS is like SLA but instead of using liquid in a vat it uses powders such as glass, nylon, ceramics, or metals. The powder is fused (the technical term is “sintered”).
3D printing is now used in medicine, where researchers are starting to create human tissue and, eventually, entire organs. Pharmaceutical companies are also using it, as are architects who are creating 3D models of buildings without having to make them out of cardboard or other materials. Artists were among the first people to see the potential for 3D printing, turning CAD files into unique, beautiful objects out of all kinds of plastics and metals. Archaeologists are creating 3D models of priceless fossils for use in schools and museums. There is even a 3D replica of King Tut’s tomb!
Document 3.2: Dr. Juneja’s E-mail
Let’s concentrate for the moment on this general description of 3D printing. We’ll leave the discussion of our class project for later.
The central challenge you will face in revising this draft is that it’s hard to read. It doesn’t hang together. Let me pose a few questions for you to consider:
· It has a title, but the title is too broad. What is it about 3D printing that you plan to discuss?
· This piece is going to go on the Web. People prefer short chunks of information, not long paragraphs, when they read online. Can you break up the text into smaller paragraphs? Add clear topic sentences?
· Could you group the information by topic? One part is about the different technologies, one part is about how industry is already using it, etc. Add headings to announce each topic? Keep in mind that our readers are not necessarily engineers, and many of them have never heard of 3D printing.
· Some of the paragraphs wander from one idea to another. One paragraph = one idea. Use topic sentences. Transitions within the paragraph. Use lists where appropriate.
· Some of the information is unclear to me. How are medical researchers creating tissue? Readers don’t need a lot of details, but nothing you say in the description explains how you get from resins and ABS to human tissue.
Let me see another draft, please. Do any research you need to fill in the holes. Keep it to 1,000 words. But most of all, work on the structure.