during the 3D printing process

 

A step in the STL generation known as "repair" fixes such problems in the original model.^[54][55] Generally STLs that have been produced from a model obtained through 3D scanning often have more of these errors ^[56] as 3D scanning is often achieved by point to point acquisition/mapping. 3D reconstruction often includes errors.^[57]

Once completed, the STL file needs to be processed by a piece of software called a "slicer", which converts the model into a series of thin layers and produces a G-code file containing instructions tailored to a specific type of 3D printer (FDM printers).^[58] This G-code file can then be printed with 3D printing client software (which loads the G-code, and uses it to instruct the 3D printer during the 3D printing process).

Printer resolution describes layer thickness and X–Y resolution in dots per inch (dpi) or micrometers (μm). Typical layer thickness is around 100 μm (250 DPI), although some machines can print layers as thin as 16 μm (1,600 DPI).^[59] X–Y resolution is comparable to that of laser printers. The particles (3D dots) are around 50 to 100 μm (510 to 250 DPI) in diameter.^{[citation needed]} For that printer resolution, specifying a mesh resolution of 0.01–0.03 mm and a chord length ≤ 0.016 mm generates an optimal STL output file for a given model input file.^[60] Specifying higher resolution results in larger files without increase in print quality.

3:31 Timelapse of an 80-minute video of an object being made out of PLA using molten polymer deposition

Construction of a model with contemporary methods can take anywhere from several hours to several days, depending on the method used and the size and complexity of the model. Additive systems can typically reduce this time to a few hours, although it varies widely depending on the type of machine used and the size and number of models being produced simultaneously.

Finishing

Though the printer-produced resolution is sufficient for many applications, greater accuracy can be achieved by printing a slightly oversized version of the desired object in standard resolution and then removing material using a higher-resolution subtractive process.^[61]

The layered structure of all additive manufacturing processes leads inevitably to a stair-stepping effect on part surfaces which are curved or tilted in respect to the building platform. The effects strongly depend on the orientation of a part surface inside the building process.^[62]

Some printable polymers such as ABS, allow the surface finish to be smoothed and improved using chemical vapor processes^[63] based on acetone or similar solvents.

Some additive manufacturing techniques are capable of using multiple materials in the course of constructing parts. These techniques are able to print in multiple colors and color combinations simultaneously, and would not necessarily require painting.

Some printing techniques require internal supports to be built for overhanging features during construction. These supports must be mechanically removed or dissolved upon completion of the print.

All of the commercialized metal 3D printers involve cutting the metal component off the metal substrate after deposition. A new process for the GMAW 3D printing allows for substrate surface modifications to remove aluminum^[64] or steel.^[65]

Materials

Detail of the Stoofbrug [nl] in Amsterdam, the world's first 3D-printed metal bridge^[66]

Traditionally, 3D printing focused on polymers for printing, due to the ease of manufacturing of manufacturing and handling polymeric materials. However, the method has rapidly evolved to not only print various polymers^[67] but also metals^[68][69] and ceramics,^[70] making 3D printing a versatile option for manufacturing. Layer-by-layer fabrication of three-dimensional physical models is a modern concept that "stems from the ever-growing CAD industry, more specifically the solid modeling side of CAD. Before solid modeling was introduced in the late 1980s, three-dimensional models were created with wire frames and surfaces."^[71] but in all cases the layers of materials are controlled by the printer and the material properties. The three-dimensional material layer is controlled by deposition rate as set by the printer operator and stored in a computer file. The earliest printed patented material was a Hot melt type ink for printing patterns using a heated metal alloy. See 1970s history above.

Charles Hull filed the first patent on August 8, 1984, to use a UV-cured acrylic resin using a UV masked light source at UVP Corp to build a simple model. The SLA-1 was the first SL product announced by 3D Systems at Autofact Exposition, Detroit, November 1978 in Detroit. The SLA-1 Beta shipped in Jan 1988 to Baxter Healthcare, Pratt and Whitney, General Motors and AMP. The first production SLA-1 shipped to Precision Castparts in April 1988. The UV resin material changed over quickly to an epoxy-based material resin. In both cases, SLA-1 models needed UV oven curing after being rinsed in a solvent cleaner to remove uncured boundary resin. A Post Cure Apparatus (PCA) was sold with all systems. The early resin printers required a blade to move fresh resin over the model on each layer. The layer thickness was 0.006 inches and the HeCd Laser model of the SLA-1 was 12 watts and swept across the surface at 30 in per second. UVP was acquired by 3D Systems in Jan 1990.^[72]

A review in the history shows a number of materials (resins, plastic powder, plastic filament and hot-melt plastic ink) were used in the 1980s for patents in the rapid prototyping field. Masked lamp UV-cured resin was also introduced by Cubital's Itzchak Pomerantz in the Soldier 5600, Carl Deckard's (DTM) laser sintered thermoplastic powders, and adhesive-laser cut paper (LOM) stacked to form objects by Michael Feygin before 3D Systems made its first announcement. Scott Crump was also working with extruded "melted" plastic filament modeling (FDM) and Drop deposition had been patented by William E Masters a week after Charles Hull's patent in 1984, but he had to discover Thermoplastic Inkjets introduced by Visual Impact Corporation 3D printer in 1992 using inkjets from Howtek, Inc., before he formed BPM to bring out his own 3D printer product in 1994.^[72]

3 D Printing General principles

 

General principles

Modeling

Main article: 3D modeling

CAD model used for 3D printing

3D models can be generated from 2D pictures taken at a 3D photo booth.

3D printable models may be created with a computer-aided design (CAD) package, via a 3D scanner, or by a plain digital camera and photogrammetry software. 3D printed models created with CAD result in relatively fewer errors than other methods. Errors in 3D printable models can be identified and corrected before printing.^[48] The manual modeling process of preparing geometric data for 3D computer graphics is similar to plastic arts such as sculpting. 3D scanning is a process of collecting digital data on the shape and appearance of a real object, creating a digital model based on it.

CAD models can be saved in the stereolithography file format (STL), a de facto CAD file format for additive manufacturing that stores data based on triangulations of the surface of CAD models. STL is not tailored for additive manufacturing because it generates large file sizes of topology optimized parts and lattice structures due to the large number of surfaces involved. A newer CAD file format, the Additive Manufacturing File format (AMF) was introduced in 2011 to solve this problem. It stores information using curved triangulations.^[49]

Printing

Before printing a 3D model from an STL file, it must first be examined for errors. Most CAD applications produce errors in output STL files,^[50][51] of the following types:

1. holes
2. faces normals
3. self-intersections
4. noise shells
5. manifold errors^[52]
6. overhang issues ^[53]

Teacher Builds Better Balance for Fun in Retirement

Many people think of retirement as a period in life full of baking cookies, swinging on the porch, and golfing. But for many retirees, that routine might sound like a nice vacation for a little while but becomes tedious on a daily basis.

Karen J. was one of those retirees. She didn't want to settle quietly into her hobbies after she retired from teaching. The desire to fill up some of her time and satisfy her quest for continual learning took her back to the classroom part-time.

However, it didn't take long for her to realize a traditional teaching role in a classroom was no longer an ideal fit for her retirement years. "Being inside the school working with a very limited and tight schedule, I decided I wanted more flexibility," Karen says.

Seeking a Better Work-Life Balance in Retirement

Karen also needed a job that provided more consistent income to add to her savings and boost her hobby fund. "Not getting a salary when schools are closed, on holidays, during vacation weeks, or over the entire summer was a bit stressful!"

But Karen found that it was challenging to find a part-time job that matched her professional skills and experience on her own, which led her to FlexJobs.

Discovering New Options

Through FlexJobs, Karen was able to land not one but two part-time, flexible positions with TutorMe and Littera Education. And together, they fit her needs perfectly. Now, Karen is busy "enjoying more of life by having time for other pursuits, piano, crafts, church activities, or simply being with friends."

"I enjoy being at home because it is quiet. I can take breaks when needed, schedule work, and not feel rushed to get from one place to another by a certain time. Now, I can leave for appointments or just have additional time for my hobbies."

Beyond balancing her time, Karen enjoys staying relevant and learning new skills that align with her lifelong career. "These roles give me additional training since I am a lifelong learner and still would like to help students achieve success."

Advice to Anyone Considering a FlexJobs Membership

Like many retirees, Karen noted that it's a balancing act to fight against age bias and other stereotypes about retirees. She suggests that other retirees update their resumes strategically with a focus on communicating both their experience and desire to keep working.

And even though budgets can be tight in retirement, Karen thinks the paid membership is well worth it. She says, "Try it for three months and keep looking! FlexJobs has a LOT of jobs."

Create Your Own Retirement Rules

There is no standard blueprint for retirement anymore. As Karen discovered, you can create your work-life balance rules.

If you're ready to explore your flexible work options, FlexJobs can help. We post jobs daily in over 50 career categories, and we have an entire team of real people dedicated to verifying those jobs to ensure that our members only see legitimate opportunities. Take the tour and discover all of the ways FlexJobs can support you!

Balance and a Rewarding Career Using FlexJobs

For many, the United States Census Bureau study about commuting comes as no surprise. The Bureau's report shares that the average time spent commuting back and forth to work has grown to almost 30 minutes each way. And for most professionals who work in an office setting, giving up five hours of life each week for a commute is pretty standard.

But Sara S. struggled with a lengthy commute combined with long, draining hours. She realized that something had to change. Her work life was taking a toll on her family and personal commitments and pushing her to professional burnout. It was time to take back control of her life.

Committing to Pursuing Balance

Recognizing that she needed a change, Sara looked for remote roles independently. It was only a short time before she realized she was spending more time sourcing legitimate positions than she was applying for and following up on them.

"I had been looking for a remote position for a few months and wasted so much time and energy on fake job leads." Even with the many awareness campaigns, job seekers like Sara are often overwhelmed with the number of scams targeting job seekers. Fortunately, she found FlexJobs, and her job search became streamlined and productive.

Building a Rewarding Career

Sara knew that her next role needed to do more than create balance. She was also determined that it would be a quality position aligned with her career goals. "I didn't want to step backward in my career or be stuck in a position with no growth opportunities."

Fortunately, Sara remained focused on her goals and found a perfect fit in a fully remote role with UnitedHealth Group. Now, Sara can be more present for her family without having to put her career to the side. "I found an organization I can grow with, professionally and personally."

Thriving Throughout All Areas

If you ask Sara how working remotely has affected her life, she'll tell you she's enjoying building better balance in the larger, more apparent areas of her life. "I have more time for the things that are important to me—my kids, my education goals, and my health," she says.

But like most professionals new to remote work, Sara discovered that work flexibility has also enhanced her life in other areas. "I am saving on gas and auto expenses, eating healthier, and I can wear activewear to work, so I go for a jog or do Pilates on my breaks!"

Advocating for Work Flexibility

Now that Sara is thriving in a meaningful role supporting her work-life balance, she has become an advocate for others to make effective changes in their lives. "I have recommended FlexJobs to so many people. It was well worth purchasing the membership."

Her guidance to others looking for more work freedom? Your job search is much more than tailoring a resume and hitting "submit." Sara says, "Don't forget about the value of networking," also stating that, "A flawless resume is useless if no one ever reads it."

Create Your Own Success Story

We hear from job seekers like Sara every day, sharing the enormous impact that flexible work has made on their lives.

If you're ready to build a better work-life balance, take the tour and discover all of the resources that FlexJobs offers to support you in your job search.

Support international audiences

 To optimize your site for audiences in several countries or language regions, you’ll need to optimize your content and your technical setup. Let’s start with the content aspects of international SEO.

Doing targeted keyword research and writing fresh content for each audience is crucial. Take items of clothing, for example. An American vest is an entirely different garment from a British vest, a Dutch vest, a French vest, or a Spanish vest… you get the point. We don’t recommend using automated translations. Invest time and resources in proper research and translations to optimize your keywords and copy.

Another important aspect of international SEO is picking the proper domain structure. Generally, a different ccTLD (e.g., www.yoast.de) for every variation is only a good option for huge companies with big budgets. In most cases, subdirectories (e.g., www.yoast.com/de) are the way to go.

Search engines want to display the correct language version of your site to each visitor, whatever country they’re from. To help them, you need to implement hreflang. hreflang is code that tells the search engines what language variations of a page are available and helps prevent duplicate content problems. It’s quite a complex piece of code, but our hreflang guide helps you along the way — or you can take our Multilingual SEO training. This course is part of our Yoast SEO academy that’s free with a Yoast SEO Premium subscription.

2.7. Add Schema.org structured data

Structured data is kind of like a dictionary for search engines. By describing your content in code, you can instantly clarify that particular piece of content. Plus, you can tell who wrote it, who published it, and when on what site. Also, if this article featured recipe, FAQ, or how-to content, you could let search engines know about this. This way, search engines get a better understanding of your site. They can use this to help your site get rich results.

Structured data is essential for WordPress SEO. It used to be hard to add structured data to your site, but we set out to make it easy with structured data in Yoast SEO. Today, we generate the code search engines need to automatically make sense of your site and its connections. You only need to make a couple of choices in Yoast SEO > Site Representation. Select Person if your site is a personal site or Organization if it is a business or professional site. Don’t forget to pick or upload the correct logo or avatar.

That’s not all: you can also quickly build specific types of content pages with our structured data blocks. These blocks work in the block editor, and at the moment, we have two types: FAQs and how-tos. These blocks help you visually build the content while generating valid structured data in the background. Plus, the Schema controls allow you to specify what type of page the one you’re working on. So, you can quickly add structured data to your contact page by picking that specific type.

Pick Person or Organization to get Yoast SEO to generate the correct structured data automatically

What is duplicate content?

 Duplicate content issues arise when search engines encounter multiple URLs with the same or very similar content. As a result, search engines don’t know which URLs to rank higher, resulting in lower rankings.  

In the previous section, we’ve already addressed keyword cannibalization caused by writing about the same topic too often. But most of the time, the root of duplicate content is technical and can happen without you even noticing. For instance, some content management systems add session IDs or parameters for tracking URLs. Or, you might have indexed www and non-www versions of a particular page. Accordingly, you’ll have multiple URLs showing the same content.

Besides the technical reasons, your articles can get scraped or copied by other parties. So, there are many causes for duplicate content, as you can read in this extensive article on duplicate content.

If you want to find out if your site suffers from duplicate content, you can use these duplicate content tools to check your site for issues.

2.5.2. Solutions for duplicate content

How you should solve your duplicate content issue depends on the cause of the problem. In general, there are three ways to go about this — in order of preference:

• Whenever possible, avoid creating duplicate content. If your system creates session IDs in the URL, try to turn that off.
• Can’t avoid creating them? Redirect those URLs with a 301 to the original version.
• Need to keep a duplicate article? Make sure to add a canonical link to the original version in the <head> section of the duplicate article. It will show search engines what the original version of the article is to pass the link juice on to the original version. In the next section, you’ll find out how easy this is with Yoast SEO.

If you want to learn how to solve specific duplicate content issues, check out Joost’s ultimate guide on causes and solutions for duplicate content.

2.5.3. Set a canonical link with Yoast SEO

With Yoast SEO, adding a canonical link to a post or page is easy. No need for a developer! Go to the Advanced tab in the Yoast SEO meta box below your post or page or the sidebar of the block editor. There, you’ll find the Canonical URL field where you can enter the URL of the original article — the one you want to point search engines to:  

Fill in your canonical URL in the advanced section of the Yoast SEO metabox or sidebar

Yoast SEO will set a self-referencing canonical for you if you don’t set a canonical. This means that the article will point to itself. Learn why self-referencing canonicals are beneficial for SEO.

Maintain your content quality

 

Keep your content fresh and up to date

As Google strives to show its users the best and most up-to-date information, you should keep track of your content and revise it regularly because you don’t want to show your website visitors outdated, redundant or incorrect information.

This is easier said than done if you publish regularly and have hundreds or thousands of blog posts. That’s why we’d advise focusing on two specific areas for content maintenance: updating cornerstone content and preventing keyword cannibalization.

2.4.2. Update your cornerstone content

Some pages on your site are more important than others. The most valuable content of your site is called cornerstone content. We’ve written extensively about cornerstone articles and how they can improve your rankings.

In short, these posts or pages:

• contain essential information for your audience;
• are complete, up-to-date, and well-written;
• show authority;
• get the most links from related posts within your site;
• rank higher than your other articles on the same topic;
• get the most organic traffic to your site.

Always prioritize your cornerstone content when you doubt where to start updating your site’s content. Your business relies on them, and they should never go stale!

2.4.3. No outdated cornerstones with Yoast SEO

Yoast SEO makes it a little easier to keep your cornerstones up to date. You can mark a post as a cornerstone article if you use Yoast SEO on your site. In doing so, these articles will undergo a more rigorous SEO analysis. In addition, they’ll appear in a separate list in your post overview, which makes it easy to browse through them and check if they’re still up to scratch.

Keeping track of them is even easier if you’re on Yoast SEO Premium. The Stale cornerstone content filter only shows your cornerstone articles that haven’t been updated in the last six months. You’ll find this filter in your post overview. If it doesn’t show any posts, you’re good, and if there are one or more posts in it, make sure you check and update them!

Yoast SEO Premium keeps track of your cornerstone content and warns when they go stale

2.4.4. Keyword cannibalization

Keyword cannibalization means you’re eating away your rankings by creating too many articles for the same or similar keywords. For example, if you have a dozen articles on the same topic, search engines don’t know which one they should rank highest. As a result, you’ll compete with your articles for a high position in the search engines.

If you frequently publish, as we do at Yoast, you’re bound to run into keyword cannibalization issues someday. That’s why we’ve created a framework for dealing with keyword cannibalism. In short, you’ll have to:

• Find out for which keywords it’s happening;
• Analyze which content performs best for those keywords;
• Keep the best-performing posts;
• Decide if you should merge the other posts into the better-performing one;
• Or delete and redirect them.

Check out this detailed guide on how to fix keyword cannibilization issues on your site to learn how to go about this.