Wednesday, April 19, 2017

Monday, April 17, 2017

A Three-Dimensional Look at 3D Printing Processes

By Russell Miles


A spaceship model that I created using our Makerbot Replicator FDM printer.


If you've been following the Hack Shack blog for a while, you've probably read a lot about 3D printers. Along with the basics of 3D modeling, we have talked about 3D printed food and 3D printed prosthetics. However, we haven't gone into detail about how our own 3D printer works.

All 3D printers have a few things in common. Nearly all of them use files from Computer Assisted Design (CAD) programs as blueprints to create objects. Most 3D printers build objects piece by piece, either in layers or in small sections. Aside from these few similarities, 3D printers can be vastly different from each other. Let's take a look a few of the most common 3D printing processes and the steps they take to create a finished product.


Fused Deposition Modeling (FDM)

The MakerBot Replicator, which can be seen in the ORHS Hack Shack (image source).
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Fused Deposition Modeling, the most common type of 3D printing, is used in the Hack Shack's MakerBot Replicator. FDM printers use heated plastic to construct objects one layer at a time. An extruder moves horizontally to put the melted plastic in place, and a flat printing bed moves downward as each layer is completed. Picture a tube of frosting moving back and forth, drawing multi-layered designs on a cake. Because these printers build objects vertically, plastic supports are sometimes added to the model. These can be removed after the print.

FDM printers are solid all-around printers because of their fast build times and their ability to print using production-grade plastic. These printers won't break the bank, with some available for a few hundred dollars. Check out this video for a closer look.


Selective Laser Sintering (SLS)

A product of SLS printing before the removal of excess powder (image source).

Unlike FDM printers, Selective Laser Sintering printers don't leave behind support structures or noticeable layer lines. This makes the process ideal for complex parts. A guided laser beam is shot into a bed of powdered material, causing the powder to fuse into a solid object. After one layer of the object is complete, more powder is added to the top. The end products of SLS printing have smooth, uniform surfaces, and can be made of hard nylon, glass, or even metal.

Also unlike FDM printers, SLS printers are very expensive. Most SLS machines cost tens of thousands of dollars, restricting them to industrial use. However, some websites allow you to order SLS-printed parts online. Watch this video explaining the process, or this video in which designers use SLS to print a wearable plastic dress.

Stereolithography (SLA)

Statue produced using stereolithography (image source).

This 3D printing process is the affordable cousin of SLS. While SLS uses powdered material, SLA uses liquid resin that hardens when it comes into contact with a guided laser. Because the resin is not as sturdy as the powder used in SLS, support structures are needed. After the resin is hardened, the supports are removed using a chemical bath. Some SLA materials need to be placed in an ultraviolet oven to harden. This video describes the process more clearly.

One advantage of SLA is the laser's ability to craft finer details than the extruder of an FDM printer can produce. However, while the strong plastic of FDM printers can be used for final products, SLA is typically only used for prototypes or molds. Desktop SLA printers are smaller than most FDM printers, and cost a few thousand dollars.

Other Processes

Product of Laminated Object Manufacturing (image source).

Many printing methods have smaller subcategories. Digital Light Processing (DLP) is similar to stereolithography, but it uses light that is focused using tiny micro-mirrors. Selective Laser Melting (SLM) printers use the SLS process to melt and solidify metal powder, while Electronic Beam Melting (EBM) uses a beam of electrons instead of a laser. Laminated Object Manufacturing (LOM) uses layered plastic sheets to create objects.

Which 3D Printing Process is Right for You?

A 3D bust of Star Wars' Yoda (image source).


If you want to explore 3D modeling as a hobby, you can't go wrong with FDM. The affordability of FDM printers make them ideal for hobbyists, and they can be used to create model figurines or end-use products. You can read our post about painting scale models made with FDM here.

If you want to use 3D printing to create intricate pieces of art, you may want to consider an SLA printer. These are slightly more expensive than FDM printers, but the extra precision may be worth the higher price tag. Keep in mind that SLA-printed objects are not as durable as FDM-printed ones.

If you want to use a 3D printer for manufacturing, SLS is your best bet. These printers can create objects out of multiple materials, and their durability and precision are unmatched. However, for the average person who doesn't need a printer more expensive than their car, it is better to order SLS-printed models online.
Whether you are looking to start 3D printing, or you just want to learn more about this revolutionary technology, I hope this post was helpful. Keep following for more information on 3D modeling and printing technology.


Sunday, April 16, 2017

Science fiction, or just Dubai?

By Tom Jeffrey


When the Chinese Tech Firm EHang plans to bring drone taxis to the skies of Dubai, we have to wonder.  

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Conceived in the bustling city street of Guangzhou, China in 2014, EHang set out with the goal to “Let Humankind Fly Freely Like A Bird”.  After receiving crowdfunding later that year for their successful GHOST DRONE 1.0, EHang became a leader in smart drone technology, producing top of the line consumer drones.  Having set up offices in both California, U.S.A. and Dusseldorf, Germany, the company has grown into an international frontrunner.  Their most ambitious project, pictured above, is unlike any product that has ever come before it.  Their concept is to totally revolutionize city travel by eliminating the four wheeled, two ton, space consuming taxi car and replace it with your very own personal drone taxi.  
EHang recently signed a contract with the government in Dubai to bring a fleet of these drone taxis to the city's affluent, high tech business community.  They expect these machines to become quite popular, as conventional car travel on the road can be expensive, in both time, and money.  
Though undoubtedly high tech, the premise behind such a product is quite simple.  After having perfected the commercially conventional sized drones, capable of carrying a video camera, they simply seek to enlarge the design and make it comfortable for human habitation.  Prominent on all EHang designs are the signature “over-under” propeller design, which work to minimize instability caused by rotational torque from the motor.  A series of lithium ion batteries carry the craft for a total of 30 minutes flight time, enough for several trips within a city, such as Dubai.  
Just as conventional drones are controlled from the ground, each taxi will be controlled by computer software, and overseen by a group of specialists on the ground.  
Testing has been going on consistently for the past two years, and reports are highly successful.  EHang recently did a public demo in Las Vegas, Nevada, to showcase the new technology.  
This highlights a trend towards automation that has been increasingly prevalent in past decades.  While many industries, like automobiles, may be slow to transfer over to self-driving methods, completely new industries, like air taxies, are being born into it.  People do not have the preconception that they should be able to drive the flying machine themselves as we do with four wheeled automobiles.  People are used to having others take the wheel on airplanes, so the continuation of such a trend should be of no issue.  Many people are still worried about the safety of such a craft, however.  
This also signals the advancement of lightweight, high capacity batteries that will allow for greater proliferation of electric vehicles in the future.  


Saturday, March 11, 2017

AutoHotkey: Reprogramming Your Keyboard



By Russell Miles

As technology becomes increasingly customizable, the traditional computer keyboard remains surprisingly restrictive. Keys cannot be easily rearranged, and useful functions are often hidden behind long strings of keys that are difficult to remember. However, this can all be changed with AutoHotkey: a free and easy-to-learn software that allows you to reprogram your computer keyboard in any way imaginable.
Getting Started

After downloading AutoHotkey, the easiest way to create a new script is to right-click on your desktop. Mouse over the "New" menu and select "AutoHotkey Script."


Right-click your new file to select "Edit script" and you are ready to go!



A finished script can be activated by double-clicking it on the desktop, or right-clicking and selecting "Run script." When you are done using your script, navigate to the taskbar to find the green "H," right-click, and select "exit."


Here are just a few things that you can accomplish using this program:



1) Experiment with new keyboard layouts.

Everyone is familiar with the classic QWERTY keyboard, but some people believe that other keyboard layouts are faster or more efficient. Autohotkey allows you to make changes as simple as switching two keys, or as complicated as rearranging your entire keyboard.

To create a new hotkey, enter the key you want to replace followed by two colons (::). After the colons, enter the key's new function. Here is a script that replaces the "Q" key with the "A" key:
Simple, right? Now you can proceed to make any changes you want. This script replaces the QWERTY layout with one that puts all keys in alphabetical order.


Once you have rearranged your keyboard, save your script through the "File" menu just as you would with a Word document. Remember that you have to activate your script to get it to work.



2) Manipulate the mouse.

Placing mouse functions on other keys can make your laptop more comfortable to use during long Internet-surfing sessions. The "WheelUp," WheelDown," "WheelLeft," and "WheelRight" functions allow you to scroll up, down, left and right. "LButton" and "RButton" refer to the mouse buttons. This script allows you to scroll up and down, as well as left- and right-click, with the top four buttons of the keyboard.


You can also experiment with MouseMove, MouseClickDrag, and several other functions for more advanced mouse operations.



3) Replace misspelled words using Hotstrings.

Sometimes, the spell-check in Microsoft Word or Google Docs just doesn't cut it. It's annoying to drag your mouse back to fix a squiggly red line after every typo. By using hotstrings, you can replace a string of keys with other functions. Instead of the single pair of colons following hotkeys, hotstrings are surrounded by two pairs of colons.


While this script is running, "omw" will be replaced with with "on my way." Capitalization is preserved, so "Omw" will give you "On my way" instead. Now you can add a personalized version of your smartphone's autocorrect to your computer.

I used my own autocorrect script while writing this post. With hotstrings, you'll never have to deal with these annoying typos again!



4) Activate a string of keys using a single command.

Here's where things can get really interesting. The "Send" functions allow you to program a hotkey to input a long series of keys. Try out this script that programs the "0" key to type a message:


Most keys can be activated in this way, but some require special codes. If you want to use this
function to press other keys like "Shift," "Alt," "Enter," or "Ctrl," you will have to put them in brackets.


This script holds down and releases the "Alt" and "F4" keys to replicate Alt+F4, a function that closes your current program. If you don't want to give up one of your keys to perform this function, you can create a function of your own.


Now, pressing Alt+X will function exactly the same as Alt+F4. The exclamation point is a code for "Alt" when used in a hotkey. Check the links at the end of this post for other codes.



5) Use custom functions to run programs.

If you want to go beyond the limits of Ctrl+C, Ctrl-V, Alt+Tab, and all the other familiar keyboard functions, you can use AutoHotkey to make your own. The "Run" function allows you to set hotkeys to run a variety of files.


Simply type "run," after a hotkey, then enter the name of a file on your computer. This script sets Alt+T to run Task Manager, Alt+C to run the Calculator app, Alt+N to run the Notepad, Alt+M to run Windows Media Player, Alt+G to run Google, and Alt+S to run the Snipping Tool. Notice that a select few websites, including Google, can be opened using the Run function. Alt+S helped me quickly capture screenshots of my scripts for this post.

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These are just a few of the things you can accomplish with AutoHotkey, but the possibilities are endless. AutoHotkey's online database is extremely useful, as it has pages for every function. If you are interested in experimenting with AutoHotkey, read the useful tutorials here and here for more information.

Happy Hotkeying!

5 Easy Steps to Painting Your 3D Printed Model


By Tom Jeffrey

16935791_1217084228408902_1060952381_o.jpg 3D Printing opens up a whole new world of potential for scale modelers.  No longer do we have to wait around for some company to create a model of a vehicle for us to buy.  We can dream, design, and print our very own, bringing a whole new meaning to Revell of Germany’s slogan, “I Made That!”
For this project, I will be using a model of an Armored Personnel Carrier that I designed using 123D Design and inspiration from the Fallout game Series.  

The list of required tools may look to be quite extensive, but in reality, is quite simple.  If you are interested in modeling, a collection of paints, brushes, and glues can be gathered over time as you need them.  When used sparingly (as you will learn is a virtue in modeling), they can last for many projects.  

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  • Your choice of hobby knives
  • Your choice of small-detail paint brushes.  These do not have to be fancy, just small!
  • Paint thinner.  This can help with thinning the paint if you so choose, for added effect (more on this later), or simply cleaning brushes.  A good multi-use supply.  
  • Your choice of model paints.  There are many brands, from the commonly found Testors to brands like Tamiya and Humbrol.  Generally speaking, cheaper paint has a shorter shelf life, and will produce less satisfactory results.  But remember, a little goes a long way!
  • A toothpick to stir those paints.  Shaking the paint is okay, but can cause issues like drying the cap shut and degrading the paint.  
  • A tissue or other painting rag.  You can wipe up excess paint, wipe off brushes, etc. A generally good item
  • Spray on primer
  • Super Glue or plastic modeling glue.  I find that super glue dries much faster and can be sanded just as easily as traditional model glue.  It is all up to personal preference.  
  • Masking tape
  • Sand Paper
  • Modeling clay.  Used to patch up mistakes in the print
  • Trash Bags. (Not Pictured) This is used for covering up surfaces that you do not want to get paint.
  • Model Stand.This is used to suspend your model in the air and make it easier to spray paint.  Optional, depending on the project.  
  • Proper Work Environment. (Definitely not pictured!)  Wherever you paint needs to be well ventilated.  This is mandatory.  These materials are not the non-toxic craft paints we all grew up with.  If breathed in in large volumes or daresay ingested, serious harm can be done.  Modeling is a fine hobby, but not without it’s risks.  However, if we take the proper precautions, there is nothing to worry about!

Step 1:Initial Printing and Setup

The first essential part of finishing your plastic model is to make sure that it is worth finishing to begin with.  Proper precautions need to be taken to ensure that the print is the right size for your display.  If it is too big or small, it will look awkward, and in either event, valuable material will have been wasted.  
Print in as fine detail as possible, to maximize the appearance of small pieces.  Also, make the judgment for what percentage infill you want for your model.  If printing say, a helicopter, it may be wise to increase the infill so as to increase the strength of thinner pieces that may come under stress later on.  
In summary, it is always worth it to take the extra time to make sure that what you are printing is actually what you want.  That is the key with model making: Take your time.  You will be surprised with the results you can get!

Step 2 : Post-Print Assessment of the Model

Using the blade of your choice (my preference is a thin, well sharpened blade with a medium length handle), scrape away the structural supports and “flash” on the model that can’t be gently broken off with your fingers.  Smaller pieces can even be slowly filed down, even with a regular nail file.  

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This is also the time to repair any imperfections in the print with the modeler's clay.  This synthetic clay will not dry out, crack, and shrink over time, maintaining your desired appearance indefinitely.   Within my experience, if you only expect to handle your model lightly, and the patches are small enough, nothing more needs to be done to the clay.  It can be sanded, painted, and sanded again, and hold up quite well.  An optional step is to paint over the clay several layers of white glue, and then sand it all flush.
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Step 3: Sanding

This is a relatively straightforward step.  Even if the print was set to fine detail, there are likely to be small lines that can be seen all over.  Lightly sand away at the plastic, being sure not to erase any small detail.  Sand as you see fit.
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This is a far more simple alternative to the popular Acetone Vapor Bath, which is both considerably more effective and dangerous.  I will cover how to best use this method on ABS plastic in a future post.  

Step 4: Priming

In order to prime your model, set up your painting station either outside, or in a well ventilated room.  My own personal preference is inside the garage, with the door open.  Wash your model with hot soapy water to remove dust and oils.  
Set up your trash bags around wherever you expect to paint.  A floor covering and one wall covering is sufficient.  Place your model on your stand.  For this model, I used a miniscule amount of modeling clay to attach the model to the top of the stick.  This allows for maximum coverage.  I can simply turn the stand around to get at different sides of the model.
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Specific to this model, I will be putting a communications antenna onto the back before I paint.  This is because the small hole that the wire goes into is likely to get filled with paint.  
Tips for painting: Go in long, thin coats.  Start spraying off to the side of the model, and quickly run the spray along the model.  In order to get the best finish, with no drips, try very thin layers.  In my experience, two layers creates a satisfactory base layer that does not eliminate detail.  
Optional: If you are planning on “weathering” your model, which means to put artificial wear and tear on the finish, try substituting your last layer of primer with a silver coat.  Later, you can scrape off the finish paint in select areas to get that worn paint look.  


Step 5: Finish Painting Your Model

This is by far my favorite part of the process, besides the initial design process itself!  This is where your creativity can really shine.  
I recommend by first setting up your painting station.  Again, set up in a well ventilated area that you do not mind getting dirty and or irreparably harmed (in this case, painted).  Do not paint on hardwood surfaces!  
Second, sand away any excess buildups of your priming coat.  This can be done after a lengthy drying period.  Within my experience, I like to let the model sit overnight.  
For this model, I will do a base coat of olive drab green, but will also touch up with black, mud, and rust, along with scraping away paint to reveal the silver underneath.  
I recommend using as little paint as possible.  Again, go for thin coats.  You can always put more paint on, but it can be hard to take paint off in a uniform fashion.  Detail on these models is very small, and it can be easy to cover it up with too much paint.
Finish off your model with a quick spray of clear coat and you’re good to go!
  
Optional: Dilute your paints using a small amount of paint thinner.  This can be used to “wash” over the base coat.  This can be used to effectively make your piece look rusty or dirty.  In reality, the possibilities are endless.  

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One coat of olive green paint


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Two coats of olive green paint


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Black details


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Use a hobby knife to scrape off paint, revealing the silver coat beneath.  Try along edges or raised portions, for example.  Go for small details as opposed to large scrapes, as I accidentally did here.  


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Mix light brown and red to make a spectrum of rust colors.  Dot this where you see fit, if you desire a worn look.  



The last step is to let your model dry well, (24+ hours), and then give it a sealing clear coat to protect the paint.  

Supplemental links for further reading and tips: