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So you’ve followed the onscreen guide to set up your Ultimaker 2 and test printed an Ultimaker Robot, but how do you achieve the best quality from the machine? And what do you do if a print doesn’t turn out as desired. Below we will show you how the machine works, best practices and basic troubleshooting.

3 Steps to Print:

  1. 3D DIGITAL IMAGE: If you have a design of your own great. Cura accepts .STL/.OBJ/.AMF/.DAE files (also JPEG, more about that here). If not don’t despare visit YouMagine for a virtual world of user shared models available for free.
  2. Use Cura to slice (prepare) the model for 3D printing: Cura is free to anyone. Once installed you can load your 3D image into it and it will automatically start to process the file ready to 3D print. We advise using the quickprint settings when familiarizing yourself with the machine.
  3. Save GCode to SD card, insert into your Ultimaker and select the file to print.

How the Ultimaker 2 works:

There are different types of 3D printers and they are defined by the method of manufacturing models. The Ultimaker 2 is a Fused Filament Fabrication (FFF) 3D printer. In essence, this means that it’s method of manufacturing models is to feed a 2.85mm diameter reel of filament through a tube, heated up and laid down at the print head and cooled down by a pair of fans.

Best Practices:

Basic machine maintenance (Printer)

To start with, a well maintained machine produces the best results. The Ultimaker printers are quite low maintenance but here’s a few points that you might want to check, just in case:

  • A single drop of a low viscosity machine oil, such as sewing machine oil, on each axis will help things run smoothly.
  • Check that your rods are square
  • Keep your print bed clean from dust and oil. Coat the bed in a thin layer of glue of the same kind that you got with your printer, a glue stick for paper. To get a nice even layer you can use a damp cloth to spread the glue around after application and let it dry. You’ll be left with an almost invisible layer of glue.
  • Make sure your feeder bolt is clean.
  • Check that the set screws on your pulleys are tight.
  • Check your belts and make sure they’re not rubbing or are slack
  • Check that your bowden is held securely in place. If you tug on it gently it should not move either up or down

Feed your printer with good quality filament (Printer)

All filaments are not created equal. A cheap no name spool of plastic from China will, generally, not produce prints with as high quality as a high quality plastic from Colorfabb for example. That’s not to say that this is always true but more often than not the old saying “you get what you pay for” holds true for plastic as well.

We’re not saying this just to promote the product we sell, it’s simply just the way it is. If you’re just making things for pure function, go ahead and use the cheap stuff. But that’s not why you’re reading this page is it 🙂

Also remember to take good care of your filament. Store it in a dry, dust free and cool location. Storing your plastic in a damp basement where you’re doing woodwork is not exactly ideal. Different types plastics exhibit different levels of hygroscopy (water absorption). Storing your filament in an air tight container with some desiccant is not a bad idea.

 

Bed levelling (Printer)

A well levelled bed makes sure that your very first layer gets put down perfectly. Some people think that a badly levelled bed affects the entire print. In a way that’s true in that a poor bed level might cause warping on the lower layers or cause the print to detach from the bed. Barring those issues though, it is irrelevant once you get past the second to third layer. The reason is that the bed isn’t levelled to be level with the surface the printer is standing on, or even the frame of the printer. It is levelled so that the movement of the nozzle always stays parallel to the print surface. If you wanted to you could use the printer on its side or even upside down.

If you are having any issues getting the levelling correct watch this helpful video

What it does affect though is bed adhesion and the appearance of the bottom of your print. Perhaps the most important here is bed adhesion as it helps prevent warp.

If you want a perfectly smooth bottom surface with barely any signs of seems you have to be very very precise in your bed levelling and print with a thin initial layer. cura defaults to a 0.3mm first layer which is much more forgiving while still producing an excellent first layer. But, if you’re going for perfect you’ll want to decrease the first layer to 0.1mm and again, be extremely precise in your bed leveling.

Learn to love the “Layer view” (cura)

The layer view is accessed via the large button on the top right of cura. Clicking this button will give you a few different view options and of those the layer view is probably the most valuable.

Rather than printing models over and over to see how they turn out it’s much much faster to take a look in the layer view and see if things look reasonable. Note that it will take a little bit of time for cura to calculate the view completely (a progress meter is shown in the lower part of the window) and also that only a subsection around the currently selected layer is fully rendered. You change which layer to look at with the little scroll bar thing on the right hand side or by holding down “Ctrl” and using the up and down arrows on your keyboard.

The layer view will of course not tell you exactly what the finished print will look like, but it will give you a chance to see if you’ve made any obvious mistakes or if there were any issues with the slicing process. Imagine coming back to a finished 20 hour print and realise that you forgot to print a solid top… As an example the image on the left shows an issue where the holes have disappeared. This part of the guide uses layer view to check the fill pattern of a print.

Excerpts from “Getting better prints” by 3DVerkstan. A fantastic, in depth guide to the Ultimaker

Basic Troubleshooting:

First layer not sticking / Parts coming loose

By far the most common issue here is simply that you haven’t properly levelled your print bed (see above). It is very important that the bed is perfectly level in relation to the movement of the print head and that the starting distance from the nozzle is as close to perfect as possible. If the first layer starts just slightly too high the plastic will not be squished into the print bed properly and will therefore not stick and stay in place. You might also find that the parts are detaching before the print is completed.

When you first started your machine you were guided through a bed levelling wizard, you can re-start this at any time. Start the wizard with Maintenance -> Buildplate. Internally the firmware expects the bed to be 0.1mm from the nozzle tip at the end of the wizard. It just so happens that a sheet of standard 80gr printer paper is usually of this thickness and can be used as a crude feeler gauge. You want the paper to be able to slide in under the nozzle but you should feel a bit of drag/scraping on the paper. As you get more confident you might find that it’s easier to simply look along the glass and visually set the correct height. You want the nozzle to be very close to touching its own reflection without actually touching.

You might have to re-do this procedure a couple of times to get it right, it’ll get easier with time and luckily the Ultimaker2 build platform is very stable and rarely needs to be re-calibrated.

You can also adjust the levelling on the fly as the printer is laying down the first layer. Simply use the thumbscrews underneath the platform.

Leaning prints / Shifted layers

Leaning:

A leaning print is usually caused by friction causing the print head to move a shorter distance than expected. Make sure that the short belts that connect the stepper motors to the axes do not rub up against the main body of the printer. Similarly make sure that the pulleys on the stepper motors that the belts ride over are not touching the side of the printer. If they are you must move the pulley closer to the stepper motor.

It is difficult to reach the set screws that secure the pulley to the motor and you will therefore have to remove the white cover plates that the motors sit behind. These panels are held in place with a single screw on the side of the machine if you have a slightly older printer. On the newer ones there are two screws, one on the back and one on the side. Remove the screw and then lift the covers off by tilting the cover slightly towards the front and them lifting them out. The only thing holding them in place is a small metal tab at the bottom of the cover that sticks down into the bottom of the printer.

Now you will be able to reach the set screws of the pulleys. If you can’t reach the screws easily simply move the head around so that they rotate into view. Undo the screw a turn or so and then push the pulley closer to the stepper motor. The pulley should be as close as possible without touching the stepper motor. Don’t forget to re-tighten the screws when you are done and make sure they are very tight so that the pulleys cannot slip.

Shifted layers:

If the printer suddenly shifts the layers it is most likely that one or more pulleys are not secured properly to the axis/axes. To confirm that this is the case you can use a black marker and put marks on the pulleys and a matching mark on the axes. After printing a test print and seeing a layer shift you can then inspect your marks and see which pulley(s) have moved. It is likely that the pulley(s) that need tightening are those connected to the short belts. Tighten the set screws that hold the pulleys in place very tightly, probably a bit tighter than you expect. The small allen key that came with your printer will flex as you tighten the screws. Don’t forget to check the pullies that are attached directly to the motor shaft, you can read about those in the section above.

Try to move the head around manually with the power turned off. The head should move around quite easily and there should be similar resistance in both  the X and Y direction. If the head is moving stiffly it is probably a good idea to give the rods a drop of light machine oil each (such as sewing machine oil).

Another cause for stiff movement can be misalignment of the rods so that they are not perfectly square. Check this by moving the head to the left/right side of the machine and checking that the distance between the sliding blocks and the pulleys are equal on both sides and then repeat for the front/back of the printer. If you notice that the axes aren’t square you can fix this by loosening the set screws on the two pulleys of one rod so that the sliding block on that side can move without affecting the opposing block. Nudge the block the needed amount and then re-tighten the set screws.

Under extrusion

In most cases under extrusion is caused by a blockage in the hot-end.  This problem is easily resolved by applying “The Atomic Method”

3DVerkstan’s detailed photo version

If you are having further issues read this very helpful under extrusion troubleshoot

Excerpts from “A visual Ultimaker troubleshooting guide” by our friends 3DVerkstan.

Becoming an Expert:

Huge thanks to 3DVerkstan for their awesome guides to the Ultimaker 2, if you want to refine your expertise it take patience, practise and people to learn from.  3DVerkstan‘s two guides are essential reading if you want to understand your Ultimaker 2 inside out.

The Ultimaker Forum has thousands of active members and is a great place to join a world wide 3D printing network.

If you want a more direct helpful hand with your Ultimaker 2 please contact us with your name, details of contact and a description of your issue (including photo’s or video’s). 🙂

Article by Daniel Abram

In The Classroom

This is a professional development resource to allow you to learn some of the more common potential technical issues you may encounter with the Ultimaker 2, with tips and links to further support resources for how to solve these problems in order to more effectively support 3D Printing in the classroom. This is not a general classroom resource, however it may be useful at the stage when students are working independently to print their own designs.

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