Posts Tagged ‘3D printing

Do You Need to Get Better Quality or Have Faster 3D Printing Speed
3D printing is often a process where you may need to choose if you either need something printed fast or with higher quality. The larger the object you want to 3D print and the higher the quality you want, the more time it will take for the 3D printer to finish the job. Larger maximum quality prints can easily take from a few hours to even a day, though most of the time you will most likely be printing smaller objects and with not so high quality, so that they will need from a couple of minutes to an hour or two.

In-house 3D printing is often also used for the so called process “rapid prototyping” as it allows a product design to be printed in relatively short time, and then have it inspected and maybe tested. If there are some corrections required they can be done to the model and then have a new print with the applied change and so on. With a 3D printer available at your disposal corrections can be made and applied much faster than having to send the 3D model somewhere to be made physically and sent back to you.

Because rapid prototyping (as the name implies) and because it actually makes for a much faster prototyping of something with help of a 3D printer, while you are designing it, than it would take otherwise, some people believe that 3D printers are very fast. Yes, they can be fast for small objects, but still printing larger and more complex designs with higher quality does take quite a lot of time. So be prepared to wait and it is not a wise idea to just leave your 3D printer unattended while it is printing something for hours, especially when you are just starting. When you get more experience and you are sure there should be no potential problems you might be more confident, though still it is wise not to leave the printer do something while there is nobody around for long periods of time.

There are three general levels of detail when talking about the most common FDM/FFF consumer 3D printers, these depend on the thickness of the layers that will be used to build the physical object from the 3D model you have. These are with a thickness of 0.1mm, 0.2mm and 0.3mm (other values might also be available) and the thicker each layer is, the faster the 3D print will be ready as you will need less layers of thermoplastic material to make it. However the thinker the layer height you use, the lower the resolution and the detail level of the final object will be. As I’ve already told you – faster speed or higher quality, you can’t have both at the same time.

To get an idea on how the final 3D printed object will look like with the settings you have chosen in the 3D printing software (the slicer) you can just hit the Preview button and the program will try to estimate how long it will take to print it as well as will provide you with good estimate how the resulting object will look like. The numbers you get are a rough estimate of course, thought they are usually close to the actual ones, so you can use them as a pretty accurate reference. If you need something printed faster, you can just change the settings and Preview again to see if your changes were enough to speed up the process. Even though the resolution is pretty much the most influential parameter that can result in faster or slower printing time, other parameters such as the use of raft or support material as well as the infill percentage can also affect the time needed.

Different 3D printer software may give you different previews of how the 3D printed object will look like, but these usually don’t look as good as the final object will, mostly because you often zoom while in Preview mode. They can still be useful for inspecting how the resulting physical model should look like and if there might be some issues printing it as the preview very closely represents how and where the printing head of the device will move to create the 3D print.

This is the step where you can also find if there are some potential issues with the 3D model you have, it has some problems such as non-manifold edges or flipped surfaces these will cause problems in the print preview even though everything might seem fine on the initial 3D model preview in the software. I’ll be talking about the issues in the 3D models you use as a source for 3D printing an object in some of the next part of the series as well as provide some useful tips on how to avoid and fix these.

A useful tip for new users in getting to know what their 3D printer is capable of is to choose a relatively simple 3D model of something and print three copies from it, each with a different layer height or resolution/quality. This will give you a very good idea on what to expect from the device when used with different layer height both in terms of quality and in terms of time required for the print. Again the finer the resolution, the more time it takes as the 3D Printer needs to lay double or triple the number of layers it would usually need for the lowest level. Higher resolution makes for better print quality as the lines of each layer are thinner and not as noticeable as when using thicker layers.

When you learn what to expect from your device in terms of printing quality and speed with different settings after you use it for a bit, then it will be easier to select the right level of detail you may need. For the moment however going for the medium level is usually a good starting point for novice users as you get a good balance between speed and quality. Though often you might need to use a lower quality initially just to get more things printed in less time as you are experimenting with different things learning about your 3D printer, this is also fine.

How to Define or Change the Strength of a 3D Printed Object
If you remember in one of the earlier posts of the series I have explained the basic parameters you set for the printing of the model, one of these is the so called Number of Shells, or Outline/Perimeter Shells or just Shells or something along the lines. So I’ll just quote myself on that first and then continue to actually show you what it actually means and how you can control the process.

Number of Shells represents the number of outer shells or walls that you are going to have on a 3D printed object before the inside part starts. The outer shells are fully solid while the inside part can be solid or semi-hollow based on the Infill percentage you have set. Normally the default value of 2 or 3 should be enough and you won’t have to change it.

Here you can see a print preview of an example object that is set to print with 10 Number of Shells. This is pretty much pointless and way too overkill, but just as an example on how this setting affects the actual object that you are going to get 3D printed. As you can see there are 10 solid layers on the outside wall of the object and after them starts the infill material structure that is semi solid. This way you are going to get a very thick wall making the 3D printed object very strong and tough on the outside.

This is a bit overkill as using just two or three layers as an outside wall should be enough in pretty much most of the cases. If you go for a thicker outside wall you are going to use more filament material and the printing time required will be increased, so you should do that only when you really need much stronger outside walls. The infill structure inside should be more than enough to provide additional strength and help with the support of the top layers instead of having a hollow insides of the object.

How Much Filament to Use When 3D Printing Something
There are multiple factors in play that ultimately decide how much material is needed for the priming of a 3D model and you have control over these with the settings you can change for the printing process itself. Normally the larger the 3D print is going to be, the more material will need to be used, but that may not always be the case. The main factor that can influence that is the Infill parameter, again going to quote myself here.

Infill is a percentage value that represents how solid a 3D printed model should be. Going for 100% means that the inside of the 3D printed object will be completely solid, going for 20% for example will result in having a semi-hollow structure inside that will be reinforced with hexagonal or square patterns. Most 3D prints are just fine with between 10% and 20% percent infill as it is enough to provide good strength while also reducing the needed material and the extra print time that a fully solid insides will require.

The Infill material or the internal structure of a 3D printed object has two main roles – to provide additional structural strength and to act as an inside support material. Because of these two important roles you cannot just go with a hollow insides of a model, or to be more precise you should not do it unless for a specific reason. You can remove all of the infill material by just setting a 0% Infill or if you want completely solid model inside you can just go for 100%. Either of the two extremes is rarely used as they can cause some issues, or it will take too much time and extra material, so most of the time you will be just fine with a small percentage of infill like 10% to 20%.

On the comparison image above we have a Preview of how the same simple object will look inside if printed with just 10% or with 50%. Using just 10% should still be able to provide decent additional strength while still acting as a decent support material for the upper layers and it would take just about 16 minutes (at maximum quality) to print with about 3.7 grams of material used. Using 50% is already going a bit overkill, unless you really need it, and will require 21 minutes for printing (5 more) as well as more than double the amount of filament with about 7.7 grams needed. It is up to you do change the Infill setting as you like or need, just don’t go too high or too low without a reasons and most of the time you will be just fine with the recommended small range for that parameter.

How to Calculate the Filament Cost of a 3D Print
Ok, so you have just 3D printed something cool, but how much in materials did it cost you? You can easily do the calculation of the cost for the material used thanks to the 3D printing software telling you an estimate on how much filament it will need when in the Preview mode (you probably noticed that on one of the above images). Again it might not be 100% accurate, but should be very close to the actual amount used. For better accuracy you can just measure the weight of the 3D printed object yourself using digital scales for example. You would also need to know the cost of the filament material you have used for the print, so it is a good idea to remember how much you paid and what was the weight of the spool you bought. Below you can see an example calculation:

Price of 1 kg spool of filament – 30 USD or EUR
1 kg = 1000 grams, so 1 gram costs 0.03 cents
Filament used for the 3D print 7 grams
Total cost in filament 7 grams times 0.03 cents equals 21 cents cost

Of course this is a simple calculation of the cost of the filament you need for a specific 3D print, smaller things are actually quite cheap to print, though larger builds may end up much more expensive. For the total cost of the print you need to also take into account the electricity used for the time it took printing and also the amortization cost of the 3D printer itself. To the total cost will be a bit higher than what you have spent for the filament along, but again it will not be that much especially for smaller 3D prints that do not require a lot of time to print and don’t use a lot of filament.

Since you already know how to calculate the cost of the filament needed for a 3D print before you actually even started printing the 3d model you have prepared and you know how to vary the amount of the filament needed via the different printing parameters you should be able to also influence the final cost. This is important if you actually want to start a small business for printing some 3D stuff for example, or just to properly manage your cost and plan when to stock on more filament spools.

Before I go on with explanation of Raft and Support and why and how you can or need to use them I’ll have to go for a sample 3D model meant for 3D printing that has the right design for my specific needs. As going only with some short text explanation might be hard if you are novice to 3D printing, so instead I’m going to show you how and when you can take advantage of these feature as well as why they can be helpful if you are having trouble 3D printing some things.

The good example I’ll be using is a new 3D model of a 3D printable espresso coffee cup you see on the image above. A Word of Caution: It is not a wise idea to 3D print models such as cups for hot drinks from thermoplastic materials and then use them to hold something with a high temperature such as tea, coffee, or even water!

What is Raft and How to Use it
The use or not of Raft is one of the basic 3D printing options that you have available as I already explained in the previous Blog post from the 3D printing series of articles I’m working on.

Raft is a special additional base that is being 3D printed below your actual 3D model. It is being generated automatically for you if you activate the feature. You may need to use it if your 3D model has a very small base and is having issues sticking to the build plate for example. It could also help with larger 3D prints where one of the edges of a larger base of the model starts peeling off the build plate, you would of course need to restart the print.

I bet that as a novice user you don’t see any potential problem in 3D printing this espresso coffee cup on your new 3D printer, but as you gain some actual experience printing things you will start to notice these just by taking a quick look at the 3D model. It is not necessary that you might have issues printing the 3D cup, but there is the potential for issues on some 3D printers. I’m saying on some 3D printers and talking mostly about FDM/FFM-based devices, because these ate the most commonly used devices by home users. On a high-end business class 3D printer that may use other materials such as ceramics or metal you are much less likely to have a problem because of the different way of doing things there.

So back to the potential problem that the use of Raft may resolve with this 3D printable coffee cup used as an example. The base of the cup has very little contact surface with the build plate of the printer. If the first layer of the print does not stick very well to the printing base you might experience unsuccessful print soon after the model starts to get printed. This can happen as the print head moving around and building layer by layer can apply some pressure on some of the sides of the model and cause it to detach from the build plate if it is not sticking well. This may never happen of course and the 3D model may still finish printing without an issue even with the small contact area it has with the build plate.

By activating the Raft option in the 3D printing settings what you will be getting is the 3D model you want printed to rise by a few millimeters and some automatically generated structure will be added below it. That structure is the so called Raft that will expand the contact surface with the build plate (base) between the 3D printer and the 3D model you are printing. Don’t worry, the extra material added at the bottom of the cup is not that much and it is easier to remove from the base and from the 3D printed cup or whatever model you are using.

The side effect when using an additional Raft is that the base of the cup may not be as even and flat as it would be if it is directly attached to the build plate without the additional Raft. This you can still easily fix with some sanding of the base of the 3D model, but it does require additional attention. Of course this may vary from printer to printer and from model to model that you print, so it is not an always needed additional step to perform.

Another issue that using a Raft may help you with is when you are printing a larger 3D object and one of the edges starts detaching from the build plate as the model is being printed. You can still get the model to finish printing if it has a larger contact surface to the base of the 3D printer, but it will be slightly deformed at the problematic edge. Activating a Raft is such a case can be helpful, though may not always resolve the issue as it may be caused by a serious problem with the leveling of the build plate. That however is another different issue that I’ll be discussing about at a later time and not in this post.

What is Support and How to Use it
So let us get to the other thing that I need to explain with example, the use of Support and why you need it when talking about consumer grade 3D printers. But first let us remember the explanation from the previous Blog post:

Support is additional structure that also gets automatically generated and added to your 3d model in areas that need some additional material to assist in properly printing them. There is no way a 3D printer can print a part of a 3D model that just hangs in the air and has nothing to hold it to the base of the printing surface, this is where the additional support material comes to help and resolve the issue by allowing you to print the model. After the print is ready you can just remove the extra support material that was used.

So time for another look at the 3D model of the cup in the 3D printing software, in this case the software is MakerBot Desktop used by the 3D printers from MakerBot like the Replicator 2 that I’m using. Reading the description above and looking at the model you should quickly realize that the cup handle is mostly there in thin air with no connection to the build plate. This means that when the 3D printer reaches the lowest part of the handle it will just start to extrude material in thin air and the 3D print will essentially fail with an incomplete cup. That is if you don’t add Support material to assist in connecting the parts that hang in thin air to the base of the 3D printing surface or other parts of the 3D model.

If you activate the use of Support then the slicer (printer software) should calculate automatically where it needs to add them and will apply them where needed – you will see them added in the preview window before starting to print. The software for 3D printers is usually pretty smart and does a good job at adding Support material when needed, but sometimes it may fail to do its job properly and unfortunately not all slicers also come with the option for the user to add manually additional support structures or to remove existing ones.

As you can see on the above image the slicer for the Replicator 2 3D printer did a pretty good job on adding Support for the handle, only as much as really required. It also has added some support material to other areas of the 3D coffee cup – some at the base and some even on the steemit logo on the side. Some of these areas could do just fine even without support material, but the handle of the cup cannot simply be properly printed on an FDM/FFF 3D printer without the use of Support material. Unfortunately the MakerBot Desktop software is one of these slicers that does not yet have an option to allow the manual addition or removal of support structures, so you are stuck with what the automated algorithm does.

When is Support material usually a must have for proper printing? The answer of that question is a bit harder as you will learn yourself as you gain experience printing different things. As already mentioned in the case of the cup handle it is a must have, but some of the other parts where Support structures were added may just do fine even without the extra material. They could either print just fine or with some tiny defects that should not affect much the general appearance and usability, there are some simple rules that can be helpful however.

The use of Support structures is a must when you have elements of an object that are horizontal and/or point at a downward angle like in the case of the cup handle without them having contact with the base (they need to be printed in thin air and there is no way that will happen). If something is horizontal and in thin air, but is just a few millimeters short like the steemit logo on the cup you might up getting lucky even without support structures and getting either a good print or slightly not so good at the bottom.

If you have a part of the 3D model that is at steeper angle, not pointing down, but up instead like the upper half of the cup handle next to the main body of the cup you should be able to do fine without support material in most cases. If the angle is upward, but just a few degrees from the horizontal level you might be lucky without Support structures if it is just a few millimeters long, but if it is longer it will still require Support material.

Why You Need Both Raft and Support for the Example Cup
If you want to have a successful 3D print of the coffee cup that I have used as an example for this Blog post about 3D printing you will have to use both Raft and Support. I hope that by this moment you have understood what exactly each of these two functions does and when and why you need to use it. If you still have some doubts, don’t worry, you will quickly get the hang of it when you print some 3D models successfully with and without Raft and Support structures and when you get some failed prints and you analyze what went wrong.

Now for the coffee cup and why you need to use both for a successful print. Normally the cup might have been just fine for 3D printing without Raft if it did not require the use of Support material for the handle. When you activate the generation of Support material the base of the cup gets some extra contact surface to the build plate thanks to the extra support structures added. However the support for the handle is very thin and as a result there might be issues with it sticking to the build plate and remaining stuck to it as the printer goes up layer by layer building up the cup. The potential issues that can be caused by the small contact surface of the support material can be avoided with the addition of a Raft. So in the end you will need both Raft and Support activated to get a good and successful print of the 3D model of the coffee cup, don’t worry, you should be able to easily remove the extra material added by the two additional options.

3dprintmeetup-virtual-3d-printing-expo

3DPrintMeetUp is a virtual expo that will be held entirely online on 04-05 May, 2015. It is open and free for anyone interested in 3D printing and you “can be there” regardless of your actual location. The 3DPrintMeetUp uses the ExpoLike platform for virtual expositions that was already used for a virtual Crypto Currency expo last year as well as some other targeted online events. The event will feature a series of lectures from leading 3D printing professionals, an expo hall where attendees can find information about available products, view demonstrations, ask questions, and receive answers from company representatives, and various opportunities to network with members of the 3D printing community. There is already a short preliminary agenda available, though more things should be added to it as the event date approaches. We are going to be taking a look at the online event in May as it should interesting to check out, so you might want to give it a try as well.

For more information about the 3DPrintMeetUp Virtual 3D Printing Expo…


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