After a week of almost constant printing I have come across a fair amount of errors that range from, making your print look ugly to turning your print into an unholy mess of melted plastic. As you can see from the picture they aren’t all winners. That was supposed to be Pikachu..
I’m going to run through some of the errors I’ve encountered as well as the advice I have received in fixing those errors.
Lifting occurs when the filament cools and releases its hold on the build plate. As the printer will continue to print the edges become thin and warped in the final result. On my first few builds this happened a lot until I found two possible solutions.
Start by using either hairspray or washable glue sticks on your print bed to help with adhesion. These are part of the basic tool kit I mentioned in my last article and are essential to creating quality prints. this should help the corners adhere to the print bed and stop unsightly curling.
The other way means using a little more filament to complete your builds. Using a raft has been the surest way to adhere your print to the bed and stop the lifting on the corners. The raft is a more solid print thickly and strongly pushed into the bed, while connecting to your print very loosely. Rafts are especially helpful for thin prints such as lids that can curl at the edges.
Tip: Use rafts early in your printing career to make sure all your prints come out well. I still use a lot of rafts in my delicate prints to make sure it goes smoothly.
Over extrusion occurs when too much filament is pushed out of the nozzle causing overlap and rippling. It seems to happen more at angles too small for supports but greater than around 30 degrees.
The simplest fix for this is to reduce the flow percentage of your extruder in your Slicer program. Cura and software like it have settings to allow you to reduce the flow until you have a comfortable level.
These three settings will determine how much filament passes through your extruder. The filament you buy may say it is 1.75 but using a set of Caliper will tell you the exact diameter. Your nozzle size is fixed by manufacturer so make sure you have the right size.
This is still an issue I am facing even now. I have tried different methods and each time I get a little better results but I still haven’t go the perfect Pikachu!
Very similar in appearance to over extrusion, this occurs when the filament is in a small area and doesn’t have a chance to cool sufficiently before the next layer is put on top. This is another problem that seems to occur at angles that are too shallow for supports.
The simplest way to reduce this problem is to reduce your print speed. Its very easy to fall in to the temptation of running your printer at a speed of around 50mm/s but your prints will be far rougher in appearance. Now that is fine if you a trying to rapid prototype and only need a rough model, but for more sophisticated models dropping your print speed down to 30mm/s or even 20mm/s will increase your quality exponentially.
If you have a little extra cash and your 3d printer allows the modification, an extruder fan will help cool your filament without destroying the structure of the model. My Maker Select comes with one as do some others and they are some of the first modifications recommended by experienced printers. You can even 3D print the duct to allow some control over the fans direction.
This problem also causes points to be a little less pointy than you may wish. As you can see as the filament fills a smaller and smaller hole it becomes uneven. The very best way I have found to fix this is to print two prints far away from each other on the bed. This allows each layer to cool down before the next layer is added. Obviously if you need two of something thats great, if not you will need to create a small cone the height of whatever model you actually want. This does mean using extra filament but if you are trying to get as accurate a model as possible, this is the best way.
Holes in Print Shell
This is perhaps the first, and easiest mistake to fix. These holes are caused by 2 or 3 basic numbers. Shell Thickness, Fill percentage and Top Thickness, all work together to create smooth finishes.
Shell thickness is the sides of you print and should be a multiple of your nozzle size. My nozzle is 0.4mm so a shell thickness of 0.8mm can also be read as twice as thick. Bottom.Top thickness is the same as Shell though I sometimes increase it to 1.2mm, or 3x, to insure a smooth outer layer.
Fill density is a figure I never thought about until I actually purchased my printer. I assumed all prints were made of solid plastic all the way through but this is not the case. The most any of my prints have been so far is 50% full. Cura, the software I use for slicing, creates a diamond lattice inside the print making them extremely tough even at 25% infill.
By increasing your Fill density you decrease the gap your top layer has to bridge and therefore reduce the risk of making holes in your model.
Tip: Fill density is a fine line and one you should play with all the time. For rapid prototyping use a low fill, as low as 15% and for high quality, high finish art pieces think about increasing this to create strength and beauty.
So there you are, after nearly 400 meters of filament and many failures I am slowing learning the pitfalls. Hopefully by reading this you can dodge some of the more basic ones and your first prints will be hassle free!