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What are the Main 3D Printing Parameters
8 Sep2014
When you are doing a 3D print of a model there are multiple parameters that you have control of and these parameters of the printing process can affect things like quality, durability and speed of the printing process. So you should know what and how to change in order to get a stronger model or a faster print or actually a useable print if you are having trouble printing a 3D model.
Infill is a value usually represented in percentage that shows how much a solid model should bi filled in with material when printed. Normally, unless you want maximum strength, you would not need to go for maximum fill of a 3D model, especially if you also want to save on material costs, model weight and want to get the print faster. Going at up to about 20-30% percent Infill is usually more than enough for normal use, unless you want something specific like high fill percentage for optimal strength. When you are not using the maximum fill percentage a special pattern is used to create strong and durable inside support structure.
Number of Shells (Outline/Perimeter Shells) is a value that sets the number of outlines printed on each layer of your object, the more shells the stronger the printed object is, so setting a higher number of essentially shells make the printed part with denser outside walls. However you should be careful not to increase that number too much and the visual result may not be that nice. The default number of shells is usually 2 (one is too little) and you should normally not go to more than 5, though you are welcome to experiment. Instead of increasing the number of outside shells of the object you may want to increase the Infill percentage.
Layer Height is the main parameter that affects print quality as it sets the thickness of each layer that is being printed. The lower the number, the thinner each layer is, the better quality you get of your 3D prints. However decreasing the layer thickness also means more layers will be needed to be printed and the time required for the 3D printing may get significantly increased. Usually the preset quality level does change the layer height and you can expect something like Low/Fast layer thickness of 0.3mm, Normal/Medium of 0.2mm and High/Slow setting with layer height of 0.1mm.
Extruder Temperature is the temperature at which the extruder of the printer needs to be while printing. This right temperature depends on the material used, the standard value of 230 degrees Celsius is usually used for printing using PLA or ABS filament, however flexible filaments usually require lower extruder temperature. So check what are the recommended printing temperatures depending on the print material (filament) you are using for your specific prints. Sometimes you may need to tweak a bit the temperature depending on the model you are printing as the default recommended one may not be doing great, but this is rarely needed.
Printing Speed (Speed while Extruding) is the speed at which the printing head moves while extruding the filament to create the physical representation of the 3D model. Depending on the model and the filament you use you may need to lower the printing speed to be able to get good quality prints. Increasing the printing speed may help you get some prints a bit faster than usual, however too much increase of the speed may start to result in bad quality and failing to print 3D models.
Movement Speed (Speed while Traveling) is the speed that the printing head moves while not extruding filament, here the speed can be faster than while extruding and normally up to twice the speed while printing is Ok. Normally you should not need to modify the default values for the movement speed as the printer manufacturer probably already selected the best value.
There may be some other options available for the control of the 3D printing process, depending on the software you may be using for 3D printing, but these are the main ones you will probably see and need to probably modify. It is not recommended to play with setting that you are not aware of and especially how they affect the 3D printing process as there is even the possibility that you may damage your 3D printed if setting values that are not OK.
What are Rafts and Supports in 3D Printing
7 Sep2014
When you are 3D printing a more complex model you may need some extra help to get a good 3D print, the software for 3D printers usually has the options to automatically generate extra Rafts and Supports for the models if you choose to use them. But what are Rafts and Supports and when do you actually need them, this is something that you would probably ask if you are new to 3D printing. On the image above you can see a 3D model of a teapot that we may want to print, however the when you look at the handle and the spout of the teapot “hanging in the air” you may have trouble printing the model normally. So you need to use some kind of support structure that will start from the base and reach to the handle in order for the 3D printer to be able to extrude plastic on something and not in the air. This a case where you will need to select the 3D printer software to add Supports in order for the model to be printed properly, otherwise you may get a 3D print that is not so good-looking useful. After the Supports are printed along with the 3D model they can be easily removed from the model and it will look as it should be.
Automatically adding Supports to a 3D model however may not always work great, as you can see on the photo above showing a simulation on how the 3D printed model will look like. There is a support material added inside the handle, no under it however and not in front for the spout. The two small “pools” of material in the base are the Rafts, these are usually not needed for solid objects with larger base. Rafts are a helpful tool if you are printing a 3D model without a larger or solid base that can easily stick to the build plate of the 3D printer and the idea of the raft is to provide this contact surface in order for the model to stay stuck to the plate while it is being printed. Rafts may also help you prevent another problem while printing and that is the edges of the model to start warping upwards. The automatic calculation of Rafts is usually more precise than that of the Supports from the printing software, but when using both it is wise to take a look at the Toolpath Visualisation or what the simulation of what the 3D printed model will look like from the 3D printer software before starting the actual print. The preview usually gives a very good representation of what the final 3D printed model will look like and it can help a lot in spotting some problems that are not visible in the 3D model visualisation part of the software where everything usually looks great. When printing more complex 3D models it is always wise to get a look at the preview and even do some more detailed examination on layer by layer basis to be sure that everything will be printed as it should.
So Rafts and Supports are two useful options that may help you get better prints, even though these two extra functions may not always performs great. So it is a good idea to also look for a function in the software that will allow you to manually add or remove support structures to the model, so even if the automatic calculation does not work great you can fix it. Unfortunately not all 3D printer software do offer such support, for example the MakerBot MakerWare can only do automatic Supports calculations and there is no way for the user to control or modify them. As a result these functions may not always perform great as you can see with the example shown above. This is why it is a good idea to check for alternative software options that have support for your 3D printer, as the supplied by default software with your device may lack some useful options. Also do note that some 3D printing technologies such as Selective laser sintering (SLS) for example do not need support structures to be printed due to the way that the model is being printed.
When you get a new 3D printer using the most common FDM technology such as the MakerBot Replicator 2, one of the first things you will notice are the instructions on how to level the build plate. Doing a correct leveling adjustment of the build plate is one of the key factors in getting a good 3D print, as if the distance between the extruder’s nozzle and the build plate is not right you may have all kinds of trouble when trying to print. Most of the more affordable 3D printers that use thermoplastic material for printing do need manual build plate leveling adjustment from the user and the manufacturers of these have thought of various ways to make it easier for the users to do the calibration. There are also some newer more expensive printers that have automatic mode for leveling the build plate, but that may not always work great, although it may sound as a good idea to have as a feature. Normally you will level the build plate before the initial use, but you may also need to do some readjustments after printing several 3D models on the device – this depends on the 3D printer and what you are printing on it.
So what are the symptoms of the build plate not properly leveled up? There are two common ones, depending if the printing nozzle is too high from the build plate or if it is too close to the build plate. If the printing nozzle is positioned too high from the build plate the thing that you will observe while trying to print a 3D mode is that the extruded material will have a hard time sticking to the base. And if the first layer cannot stick to the build plate, then there is not chance for the printer to print a proper 3D model. The other problem that you might have is if the printing nozzle is positioned too close to the base, this will cause the extruded thermoplastic to stick to the nozzle instead to the built plate. If the build plate is properly leveled you should have no trouble with the printing of the first layer, it should stick well to the base and should look squashed and not round on top (a sign that the nozzle may be a bit higher than needed). So make sure that you have the build plate properly leveled up before starting to print, especially if you haven’t used the printer for a while.