by Jochen Hanselmann | Jun.22, 2012

The first month using my Ultimaker caused excitement as well as some frustrations. In this article I'd like to share some of my experiences and some insights I gained from this first phase.

I admit that I was not prepared for all the caveats and challenges which exist to run a DIY consumer 3D Printer. I had assembled the Ultimaker together with others at an assembly workshop at the FabLab Lucerne, Switzerland, and was really keen on running my new printer at home. As many others, I was fascinated about all the possibilities. Most reports in the media also talk mainly about the bright future but not about the still early days of DIY / consumer 3D printing. It is not - yet - plug & play. However, there are already assembled consumer 3D printers as 3D System's Cube or the Up! from Delta Micro Factory Corporation. They promise a much more easy and out-of-the-box user-experience. I am wondering how this will work for John Doe eventually. Let's wait for more reports by users of these machines.

Very soon I realized that the quality of the 3D printed objects depends very much of a lot of influencing factors which needs to harmonize with each other. To get good results you need to gain an understanding and fine-tune each:

 

  • Software (various tools, parameters as layer height, infill, upskin, downskin,...)
  • 3D model (minimum wall thickness, overhanging angles,...)
  • Printing material (PLA, ABS, depending on color, diameter, provider)
  • Mechanics of the printer (axis adjustment, belt tension, print bed leveling,..)
  • Printing speed
How to understand all these dependencies? Most helpful for me was reading all the various posts of other, more experienced people on the Internet and just by experimenting with various settings. For each print I noted the settings and documented the results. Eventually, you need to set various parameters for each new print. Constant quality can be expected if you print a model with good quality and then just print the same model with the same settings again. Up to now I have only used PLA and sliced / printed with ReplicatorG, Netfabb Engine for Ultimaker and Cura (new, not yet enough). I've got already very good results printing with 0.12 mm layer height. Every second or third print job fails. I am confident to reduce this failure rate with more experiences. From my perspective and as experienced so far the following points are important to get good print results:
  • Adjusting the Z-limit switch:

To avoid damage to the printer and to have a good starting point for your 3D prints the height of the print bed needs to be well adjusted. The optimal height is reached when the extrusion head almost touches the print bed (less than 0.5mm) when the Z-limit switch is triggered. After a few prints I check this by turning the Z-axis leadingscrew manually (printer turned off) until the Z-trigger is reached. Then I tighten or unscrew the 4 screws of the print bed until I can move a sheet of paper between the extrusion head and the print bed. For me this is much easier than moving the Z-limit switch itself.

  • Stickiness of the first layers on the blue tape:

As soon as the print starts (printing the outline or object) I manually turn the Z-axis leadscrew to ensure that the extrusion head almost touches the print bed (closer is better). This is essential that the first layers will stick to the blue tape. Don't worry, you can turn the Z-leadscrew by hand without damaging the mechanics. In addition, there should be no cooling for the first (few) layers. Most software does this automatically. Worth to check if your object does not stick to the print bed.

  • Check the extrusion mechanism (filament feed):

Before starting a print job or changing the material I check the filament feed mechanism. Ensure that the hobbed bolt / knurled wheel is not filled with material particles. You can clean it with an old tooth brush or a small metal brush. To check optimal feed, set the recommended or planned extrusion temperature (e.g. via ReplicatorG). Then turn the big extrusion gear manually. If the filament flows smoothly and without too much force out of the extrusion head the setting is good. If the filament slips you need to tighten the pressure regulation bolt at the extrusion mechanism. From my perspective the extruder mechanism is the most delicate part of the printer. My prints failed either far too less material was fed or the hobbed bolt grinded completely into the material. Recently, Ultimaker had a quality issue with too tight bowden tubes which caused the filament to stock. The Ultimaker support exchanged the bowden tube without charge after complaining (btw, good support, thanks a lot).

  • Temperature PLA: My findings so far:
    • The temperature should be reduced the thinner the printed layers are.
    • Printing with higher speed usually affords and allows higher temperature (+10-20 degrees C). This ensures a consistent material flow. On the other hand the extrusion rate could be increased (recommended to me but not tried yet).
    • Example: half-translucent PLA from Ultimaking, recommended temperature: 220 C:
      • Some problems occurred when I printed an object with high infill and thin layers. The PLA "warped" at some parts, i.e. the material expanded more than expected and over the printed layer. This caused a very bad surface and the extrusion head slammed over these too high parts of the print. After decreasing the temperature to 200/205 C and the speed the problem disappeared.
      • My settings now: 0.35 mm layer: Temp. 215-225 C. (usually Netfabb prints with 225 C at this setting) 0.15 and 0.12 mm: Temp. 210-220 C. (usually Netfabb prints with 230 C at this setting). As mentioned above, in some cases reducing it even more is meaningful.
    • To find the best temperature for each material manually you can heat the extrusion head up to e.g. 180 C. Then turn the big gear by hand. If you can turn it without much effort, filament comes out of the nozzle, and the feed-mechanism does not skip steps, then this might be a good starting point to print slow and with thin layers. If not, increase the temperature in steps of 5 C and try again.

I hope that my experiences will help other beginners. Continuously, and after each print I learn more. I will update this blog post frequently with new insights.

Best sources for me are: the Ultimaker Troubleshooting Site, the very supportive user community with tons of comments and reports in various blogs (e.g. by Florian Horsch or DFRobot) and forums Ultimaker Google Group or Ultimaker Forum.

Happy printing!


Image credit: Jochen Hanselmann

 

Posted in 3D Printers

 

 

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Brian wrote at 1/21/2014 5:24:50 PM:

Apparently you received all of the parts for your kit. Congratulations! Dealing with Ultimaker to obtain an omitted Bowden Tube has pretty well soured me on the company and I'd heartily recommend that new 3D printers go for a full-assembled printer from a different manufacturer.



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