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A Problem with a 3D Model Can Cause a Failed Print
Two of the most common issues with 3D models that are giving you problems to print, no matter if you designed them or somebody else did, are the presence of Non-Manifold Edges and Flipped Triangles. There are of course some more issues that may be present as well, but I’ll be talking about these two as they are the most common cause that may result in you 3D print looking not as it was supposed to be.

Non-Manifold Edges are parts of the model that have holes in them or unwanted faces, often this is referred to as the 3D model not being water tight as if you pour water in something with holes it will just get out.

Flipped Triangles are parts of the object geometry that is facing the wrong way, it is normal for connected triangles to be facing the same direction, however often when you design a 3D object you may end up with triangles that are facing different directions.

As a means of demonstration I’ll be using two cubes drawn with SketchUp (go back to Part 4 of the series to learn more about that software) and in these two I have intentionally created issues, so that you can easily see the problem and how it may affect your 3D print. The cube on the left is with a flipped triangle on the side and a surface on the top and the cube on the right is not watertight (has some holes on one of the sides). Notice how SketchUp uses different colors for the two triangles on the side, this is a hint for the user that there might be something wrong as they seem to be pointing at different directions. The large holes, intentionally left big, are clearly visible as well, though imagine if you have many of these and they are very small or the flipped triangles are small and you need to zoom in a lot to notice the color difference.

Depending on the 3D printing software you use the standard 3D model preview might or might not show any problems, often flipped triangles are not being shown in the default preview and as I said holes in the models might be too small to notice. When you generate the Print Preview however and the software actually slices the 3D model to a layer by layer structure you can see weird things happening to your models such as strange deformations or missing parts. This happens as while the slicer is working the problematic geometry actually confuses the software and it just gives weird results. Of course depending on the object and the issue sometimes even with a non-water tight model you can still get a good print without problems.

When you see that something is wrong the best thing to do is go back to the 3D modeling software and try to find the problem in your 3D model, then fix it and open it again in the 3D printer software. In case you noticed a flipped triangle somewhere it is very easy to fix it in SketchUp for example, just select the problematic face, right click with the mouse and choose Reverse Faces. If you found a hole somewhere you can just add some extra geometry to fill it in and make the 3D model solid again. Of course at times finding these issues can be a problem, especially if you have problems that are not easily visible from the outside of the 3D model.

Some 3D printer software like the Simplify3D slicer I talked about in the previous part of the series has additional tools for detecting problematic geometry in the 3D model that may be helpful in figuring out what is wrong. It even has some automated tools to help you try and fix the problem without having to edit the actual 3D model, though these may not work very well or as intended some of the time. There are also alternatives available for different software and even online services that offer to fix common issues in 3D models without you having to actually edit the 3D model.

Automatic Repair of Problematic 3D Models
Since there are quite a few options for automatic fixing of problems with 3D models that need to be repaired in order to be 3D printable I will not be covering them all. However I want to point your attention to a free online service for 3D model repair that in my experience has been giving some of the best results in successful repair of various issues after quite a lot of testing of different tools and methods. The service is being ran by a company called Trinckle that apart from offering to freely repair your models also provides 3D printing services, though you can just download the fixed model and print it yourself. So you might want to give it a try before going into manual fixing mode trying to figure out where the problems in the 3D model might be and how to fix them yourself, especially if you are new to the whole 3D printing and 3D modeling thing.

Sanding and Painting 3D Printed Models
One of the “problems” of the consumer 3D printers is the fact that when you get a 3D print ready you can usually see the lines that build up the object (these are the printing layers), though that is not actually a problem, but just the way these devices work. The higher the resolution you print with, the thinner the layers are and the visual quality is better, but that is achieved with more time needed for the printing. There are ways however that you can improve further the final quality of a 3D print with some additional post-processing work after it is made by the 3D printer. This is achieved by using sanding paper to take away some of the outer surface of the model and/or by using paint to fill in some of the gaps between the layers and make them less distinguishable.

The sanding process does require some effort and time and is not always applicable as some objects have way to complex form and many small details, making it very hard to sand by hand (a rotary tool with a fine tip could also be used at low RPM). Furthermore the sanding process requires you to use sandpaper with different grit size, starting from a rougher lower number and going in a few steps to a much finer higher number. This way you essentially start by taking more material from the object smoothing the differences between layers and then moving to a finer grit to actually smooth out and polish the surface. You may need a little practice for this to get the hang of things, but the final results could be well worth it.

The alternative option is to use paint to cover a sanded on non-sanded 3D printed object, it is a good idea to use paint that can provide thicker layers such as spray cans of paint for objects that are not going to be sanded as it covers better and gives better results. If you have sanded the object you may as well go with a thinner paint cover such as the one achieved with an airbrush for example as you already have a pretty smooth surface. Furthermore, depending on the paint used you can get either a matte or glossy look, this can be further strengthened if you decide to apply some clear coating on top of the paint. You can get creative here and the results can be quite nice with some paint. Using paint also gives you the option to overcome some of the limitations in terms of colors that the filament you use has. You can of course use some acrylic paint to hand paint a figure that you have 3 printed for example, that way you will get a better looking “full color”-like print from a 3D printer that can work with single color filaments only.

Other Ways to Improve Visual Quality
The commonly used 3D printer filaments such as ABS and PLA have a hidden weakness, they can very easily be dissolved by some strong chemicals, but you can use that fact to your advantage. Some people are using the vapors of strong chemicals such as Acetone and THF to actually smooth the outer surface of 3D prints as these are essentially melting the outer perimeter of the layers and are giving them nicer and smoother look and feel. A word of serious warning here, these chemicals can be dangerous to your health and should you decide to use them you should be very careful not to get them on a bare part of your body or to inhale any of the fumes from them. Because of the possible danger to your health these methods are not that popular as for example using sandpaper or painting your 3D printed object.

Anyway, if you want to try, then you should go for Acetone for ABS plastic as it melts it and creates a smoother and glossy looking surface. As alternative to Acetone you might try smoothing ABS 3D printed objects with the use of Methyl ethyl ketone (MEK) with good results. Have in mind that Acetone and MEK are not suitable for PLA 3D prints like with ABS ones, so do not try them for smoothing PLA 3D prints. For PLA plastic smoothing you need to go for Tetrahydrofuran (THF) instead. Another dangerous solvent that needs to be extra carefully handled and also very flammable like the other two chemicals also mentioned already!

Another, much more safer alternative that could be used for smoothing of all kinds of 3D printed objects is the Smooth-On XTC-3D coating.

Protective coating for smoothing and finishing 3D printed parts that does not melt plastic. XTC 3D fills in 3D print striations and creates a smooth, high gloss finish. The need to post finish is almost eliminated. XTC 3D can be applied to both SLA and SLS prints. It works with PLA, ABS, Laywoo, Powder Printed Parts and other rigid media such as EPS, EPDM and urethane foam as well as wood, plaster, fabric, cardboard and paper.

I have tried this solution where you mix two components and then apply a thin coat of the material over the 3D printed object, then wait for it to cure and you get pretty good results. So it works pretty good, though you may need some getting used to working with the coating in order to be able to achieve consistently satisfying smoothing of different objects.

In the end you have multiple different variants for additionally improving the look and feel of your 3D printed parts, it is up to you to choose what works for you should you even need to do this extra work at all.

Connectivity Options for your 3D Printer
Depending on the model of the 3D printer you got you may have multiple options to print on the device, either connected to a computer and being controlled from it or working standalone from a 3D file you send to the device in some way. Usually the higher the price of the device, the more options you have available to choose from. What you should have in mind is that different connectivity options may require specific things and may not always be the best choice for your needs.

Starting from the lowest end, in terms of price, consumer 3D Printers you usually get only the option to connect the device to a computer and control it from the 3D printing software. There is no standalone mode available, so while working you will always need to have a computer connected to it. Not a wise idea to use a laptop that you may be taking away with you, the best choice would be a desktop computer or small and compact one that does need a lot of processing power. Using a direct USB cable connection should also give you the opportunity to monitor and control the device manually from the printing software at any point (only if the software supports it). This functionality might be useful especially with DIY setups where monitoring the printer operating parameters can help you find possible issues and things that you might be able to work on to improve.

The mid-range consumer 3D printers do get some extras, apart from the USB cable connection, they usually also come with either a flash card reader or a separate USB port for USB flash drives. This allows you to have the printer operate independently, not needing to be connected to a computer all the time or at all as you can load the models with a flash card or a drive directly to the device itself. This functionality can be quite convenient at times and I often prefer to print this way instead with a cable connection. This way I also know I have one more backup of my 3D models on an external drive, though it is always best to have an additional backup of your work on a separate device than your computer and/or the flash memory you may be using with a 3D printer (flash cards and USB drives do break as well, especially when you use them more often).

Some of the higher-end consumer 3D printers may also come with cable LAN or even WiFi option for connectivity to the device, this can be especially useful if you are getting a device for multiple users like in an office, not as much at home though. The availability of network connectivity may also come with another useful feature and that is a camera that can show you while the printer is working, so you can monitor the 3D printing process even remotely for example. In the previous articles I have mentioned already that it is not a good idea to leave a 3D printer unattended while working, but if you have a monitoring camera you might feel safer as long as you don’t forget to check the video feed from time to time.

It is a good idea to check what connectivity options will the device you have or even better are planning to get as having more than just the USB cable connection can be useful. So just don’t overlook that part of the 3D printer specifications.

The Typical 3D Printing Workflow

Normally the 3D printing process goes in a few steps like:

1. You create a 3D model or fine one to 3D print
2. You open the 3D model in the 3D printer software (slicer)
3. You check if everything looks good in the initial visualization
4. You set the printing parameters and generate a Preview of what the printed result should look like
5. You inspect for possible issues in the Preview as often you may find here some not seen on the initial view of the 3D model
6. If everything is looking fine you send the data to the 3D printer to start printing
7. You wait for the device to finish the print process and remove the finished physical object
8. At this point you may do some postprocessing work to make the printed object look better

So far in the series of articles about 3D Printing I have covered most of the steps in the workflow you normally follow, though for some I’m going to be talking in the upcoming parts of the articles. Especially important are the steps where you need to inspect the print preview for possible issues and if there are any to get back and correct them by editing the 3D model you want to print. Another very important thing can be the post processing step where you for example sand and paint or threat the surface of the 3D printed object with different things in order to improve the quality and finished look of your prints. These two will be the topic of the next part of the series, so stay tuned.

Now, if you are 3D printing something for personal use the above steps may be enough for you. However once you actually get a 3D printer and start using it you may want to offer 3D printing as a service, even without turning that into a business. You can register on 3D Hubs and start offering your 3D printing services to other users that may want to try and get something 3D printed without actually having to buy a 3D printer yet. You will find a great community and may even get to know other 3D printer owners around you, the service is connecting people all around the world, so no matter where you live you might find somebody else with passion about 3D printers close to you.

Alternatively, for people that actually make their own 3D designs, there are services where you can upload your designs and start selling them to people that may want to buy the finished 3D printed product. This is another good opportunity to extend your 3D printing hobby to something more than 3D printing at home things for yourself. Examples of such services are Shapeways and i.Materialise, though there are others as well. What is even better with these services is that you can also make something yourself in the form of a 3D model, test print it on your 3D printer at home and get it professionally 3D printed on a high-end machine with better quality and a wide range of materials that you cannot use on your consumer 3D printer. An example of this would be to design some jewelry, test print it on your device and actually start selling your own products that will be 3D printed from metal, including precious metals as well.

So as you can see getting a 3D printer with the idea of trying it out and playing around at home or in the office can just be the first step to many opportunities, you just need to be willing to take the jump into the unknown. Making the first step and continuing to learn and improve your skills as you go can really turn into an exciting journey into new technologies and new opportunities…

Alternative 3D Printer Software (Slicer)
The 3D printer software you get with your device or the so called Slicer (the software that turns 3D models of objects into a layer by layer data fed to the 3D printer) is usually great for you to get started. It might be even fine for users that don’t want to play around and experiment with different printing materials or upgrade and modify their printer, but as you continue to learn and try different things you will most likely start to see flaws and lack of useful features in what you have available.

I know as it has happened with me soon after I got my first 3D printer – the MakerBot Replicator 2. The software that ships with the printer – MakerBot Desktop, was nice and user friendly, so I was quick to learn to use it and that is a great thing for a newbie into 3D printing. However I started noticing things that could actually be better such as the speed of slicing more complex 3D models (it took forever) or getting more control over the printing parameters besides the really basic stuff. Now, have in mind that this was probably more than 2 years ago, so meanwhile these have been a lot of improvements and the latest version is faster and offers some more advanced parameters of the printing process to be tweaked.

Back in time, about 2 years ago I started looking for alternative 3D printing software to the default one for my 3D printer and I have found one that a lot of people were recommending. It was a commercial program called Simplify3D that other users of the Replicator 2 and other devices were recommending as being much better and offering a lot of extra useful features for more advanced users. I was a bit skeptical at first, especially considering the price tag of the software and it not having a trial version, though I still risked it and bought a license. Two years later and I’m still mostly using the Simplify3D software instead of any other official 3D printing software and am really happy that I made the decision to get a license back then. It has really saved me a lot of trouble and failed prints, especially when using more exotic filaments or I have to print larger and more complex 3D models. So I definitely recommend the Simplify3D software as an upgrade over the stock 3D printer software as long as your device is compatible with it.

For the 3D Printer Compatibility List of the Simplify3D software…

There are a couple of things that I like the most about this alternative slicer. First it has a really fast 3D model slicer engine that turns a virtual 3D model into a layer by layer information for the 3D printer. Back when I first got it was multiple times faster than the MakerBot Desktop slicer, so it really saved me a lot of time just for being significantly faster. Now it may not be that much faster, but it probably still has one of the fastest slicing engines out there and that essentially save you time, time otherwise spent waiting for the software to do its job. When preparing a 3D model for printing you may want to try playing around with different printing settings and that means that you need to generate the Preview multiple times to check how the options you tweaked may affect the final result. So even saving you a couple of seconds for each preview can make a big difference and normally you get more time saved. Furthermore the 3D model preview and Print Preview of this software do look better and more useful than what the standard software for the Replicator still provides you with. In the 3D printing series of articles I have actually shared a number of screenshots from both the Replicator 2 Desktop software as well as the Simplify3D software.

Another very useful feature I like is the flexibility of the support structure generation that is available in the Simplify3D software. You have some control over the automatic process of generation of support structures (I have described in detail what these are and what they are used for in an earlier post of the series). What is much more important and useful here however is the ability to actually manually add or remove support material and that is huge advantage and I mean really huge. The automatic generation process not always does great and you may need to apply some extra structures or remove some of the added ones, but in most standard 3D printer software products you just don’t have the option to do that. So if you want to use support material you can only rely on the automatically generated one, or not use support structures at all, but with Simplify3D you have the much needed additional control.

Other useful feature is the one that can help you identify potential problems in the 3D model you want to 3D print, the software even has some built in tools that can sometimes help you automatically resolve potential problems. These features do work decently, though they are not the best I’ve seen and there are other automated tools that may help you better, though at least you can know that there is a potential problem that may result in issues with quality or even unsuccessful print. These features need some more work, but even at the moment they can be useful as again a lot of the standard 3D printing software does not even offer such functionality. I’ll be talking abut these potential issues with the 3D models additionally and in more details in the future, so you might want to read about them as well in the next post from the series.

There are other useful extras also available such as much and I really mean much more control over the printing parameters and the ability to tweak just about everything you want such as printing speeds, use different infill patterns and settings, change layer or extruder settings if you are using a custom printing nozzle for example (with larger or smaller hole), much finer control over the support structures, rafts and some other useful structures that can be printed to help you get better results, operating temperatures of the printing head(s) and the heated build plate (if available), even add custom code that the printer can execute if you want to. So again, I do recommend that you check the Simplify3D software and consider getting it if your device is supported, it is really useful and will improve your experience and capabilities when using your 3D printer.

What is a 3D Scanner

A 3D Scanner is a device that is used to analyze and measure the physical characteristics such as shape and color of a real world object, based on the information collected using different techniques it can then reconstructs a digital 3D model of the physical object that was scanned.

For 3D scanning something you essentially use a specialized piece of hardware, either hand-held or stationary, to recreate a digital copy of a real object that you can then later on 3D print thus turning it back into a real physical thing. There are many different techniques employed by 3D scanners in order to get the required data for the shape of an object. Some 3D scanners do provide only a 3D model of the shape of the scanned object, while others might also include additional data such as the actual colors in the form of a texture as well. Do note that 3D scanners are not used only for 3D printing, they are helpful in many areas where you might want to digitize a real world object and make a realistically looking 3D model such as in movies for example.

Normal consumers usually don’t have access to 3D printers that can print in full color (these are much more expensive), but instead mostly use a single color filament, so a 3D scanner that provides color information as well is not very needed. What is very attractive in the idea for a 3D scanner to new 3D printer users is the fact that such a device would be able to essentially “clone” real world things and then 3D print copies as much as they want. The reality however is harsher and things are not always as easy as they may seem, or as 3D scanner manufacturers may want you to believe.

Many believe that using a 3D scanner is easier way to make a 3D model of something real and then quickly just 3D print it than having to design the model themselves. I have already talked about the need for some, even basic 3D modeling skills, for properly taking advantage of the capabilities of a 3D Printer at home. Even if you don’t have these yet, you can start learning and quickly get up to speed with a simpler program like SketchUp. A 3D scanner may save you some time, especially in getting a 3D model of more complex structures, however you will most likely still have to do some additional work to get a good result before actually being able to 3D print something useful or looking a lot like the original that you have scanned.

Affordable Consumer 3D Scanners
Just like a regular newbie when I got my first MakerBot Replicator 2 3D printer and was making my first steps into the world of 3D printing I also got interested in 3D scanners. Obviously the first thing I did was to go to the website of the company that made my 3D printer and look if they are also offering 3D scanners. They of course did offer the MakerBot Digitizer, though at that time I thought that it was a bit too expensive, right after purchasing the 3D printer. The prices of 3D printers two years ago were higher and there weren’t that many options available as there are today, the same goes for 3D scanners. I see that the MakerBot Digitizer Desktop 3D Scanner is still available for sale at a reduced price, currently $799 USD.

Though in the end I did not purchase that one, mostly because of the higher price and the fact that was limited in functionality… it only offers you a small table for scanning small object. I wanted to go for something that would allow me to scan larger things, so I went for a handheld scanner instead – the Cubify Sense, now 3D Systems Sense. This model seemed like the better choice at that time for me and was available at a better price, so not a bad model for trying out the technology without investing too much into it, right? It ended up being a good choice in the end as it allowed me to try 3D scanning first hand without paying too much and then just getting not very happy by the results I got. Frankly said, I did not research a lot about 3D scanners, unlike for 3D printers, before actually going for a device, so I was a bit unprepared what to expect. That is why you should manage your expectations better and just know that you are most likely not going to get much in terms of details and quality from a consumer grade 3D scanner.

When I’m talking about a consumer grade 3D scanner I mean devices that are not intended for professional use and are pretty much with a price range up to about $1000 or maybe not more than $2000 USD. These devices are simply not going to be able to provide you with very good resolution and thus the detail level will suffer, their software is also probably not as advanced as with the many professional solutions available for higher-end 3D scanners, so that means you will need to spend more time cleaning and refining the 3D model data that you will get after the scan is over. Even repeating the scanning process is often required in order for you to try to get better results than the first try you did. In the end when you finally get to the 3D printing part and the resolution of the printing does also take away some of the detail you might not be very happy with the final result.

Surely the consumer 3D scanners are fun and nice to play with, you just have to know that you should not expect too much from them. You will not be getting 1:1 copies of the things you scan, although the general shape will be there, the finer details most likely won’t be scanned properly. Of course you can always go through the extra step in refining the more basic 3D model you get from a scan with the help of a serious 3D modeling tool to add the missing detail or even enhance so of the not so good results you achieved with the scanning process. That however would require an extensive knowledge of 3D modeling techniques and thus is not something that most normal users will know how to do. So the thing you are probably going to do is to rely on the tools for cleaning up a bit and enhancing the results from the scan that software you got with the device will allow you to use.

Professional and Expensive 3D Scanners
If you want to take a look at what a high-end professional 3D scanners is capable of and how much it costs to get good results you can check Artec – one of the leaders in professional hand-held 3D scanners. They most basic model starts at about 10000 USD/EUR price level and the more precise and feature rich models can go up a multiple times. Artec is the company that a while ago actually did a 3D scan of President Obama using their 3D scanners, so you might be interested in reading about it if you have missed it.

Of course there are other companies producing high-end 3D scanners for professional use that are able to deliver good results in terms of higher quality and level of detail, the common thing about them is that they are all pretty expensive. This makes the entry barrier for a regular consumer unreasonably high, so what is left for us is a not so good consumer model that is actually affordable or not to go for a 3D scanner at all in this stage. Unlike the 3D printers market where the last few years we have seen a lot of development in the consumer segment, 3D scanners have still yet to live their consumer revolution moment.

One of the reasons that high-end 3D scanners are expensive, besides the business-only orientation and limited number of products made and sold, is also related to copyright infringement. Being able to precisely scan a real world object and then replicate it with very high accuracy is scaring big names in the business, just like I’m sure the consumer 3D printer boom a few years ago also did. The truth is that there are already many alternative ways to get even better accuracy in copying and replicating something, so there is nothing going to stop you if that is your original goal…

So Should You Get a 3D Scanner Now or Wait
Time to answer the big question now: should you get a 3D scanner or not to go along with your 3D printer? Unfortunately there is not a definitive answer like a yes or no. If you are going for a consumer 3D scanner make sure you don’t spend too much and don’t have too high expectations for the quality and level of details. If you are going for a professional model then you are most likely going to need it for work, like if you have a 3D printing business and want to provide a 3D scanning services to customers for example and thus the high cost may be justified.

As a regular user getting starting in the world of 3D printing it will be much better to focus on learning how to 3D model things, a skill that will be useful not only for making things to 3D print. A 3D scanner may seem like a shortcut, but with an affordable consumer level device you will quickly change your mind on its usability for replicating physical objects. Especially when talking about more complex things or ones with a lot of fine details, you might be able to design these from scratch with much better accuracy and quality than having them scanned. That of course will require some time learning and improving your 3D modeling skills, but that is one thing that you simply need to do at one point if you are seriously interested in 3D printing anyway.

Important tip: Do a proper research of the model of a 3D scanner that you might want to get – read user opinions and reviews, try the scanner software if available for free download before buying the device, download some 3D models scanned with it (preferably made be users and not official by the company making the device) and try 3D printing them. Regardless if you have selected an affordable consumer 3D scanner or a professional level solution, do your research before and not after you buy it!

If you want to explore a bit more about what kind of quality you can get from a professional high-end 3D scanner you can visit the link below. Artec does provide some 3D scans made with their products and they are also available in STL format, so you can open them with your 3D printing software and even print them if you wish. Just don’t forget that this is what you can expect to get with a professional level 3D scanner and not a consumer grade one!

To Explore and Download Some 3D models with Professional 3D Scanner (STL files)…

Alternatively you might want to check what a consumer grade 3D scanner like the MakerBot Digitizer I have mentioned earlier can do, there are a lot of user made scans available on Thingiverse that you can check and download in STL format and open with your 3D printing software as well or also print on your 3D printer.

3D scans made with MakerBot Digitizer made by users and available for download…


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