Setting up an Ultimaker 2, learning 3D printing basics and printing visor frames.
I had seen a DesignSpark tweet about using 3D printers to help produce masks and contribute to the effort to ensure that NHS staff and others had the necessary Personal Protective Equipment (PPE). The article linked in the tweet detailed how The National 3D Printing Society has partnered with Medical Supply Drive UK, to help co-ordinate the production and distribution of key PPE to the frontline medical staff, and how they were looking for people to help with the printing of this equipment.
Despite sitting next to a 3D printer most days at work, I had never actually used one, but I thought it would be good to get up-to-speed and try and do something useful while I am in lockdown!
Our printer is the Ultimaker 2, which is a number of years old and has seen quite a bit of use, but luckily a former colleague had given it a thorough service not too long ago. As I am working from home, my first task was to retrieve the printer and the rolls of filament from work. Then, as it had not been used for a while and the journey may have upset it, I thought it best to reset and re-calibrate it. To do this I needed to perform a Factory Reset.
The Ultimaker 2 has a fairly easy menu system which is navigated via a wheel/button combination, so it was easy enough to find the Factory Reset in the Advanced section of the Maintenance menu.
The instructions on the screen then walk you through the calibration process which is needed to get the glass “build plate” level and just the right distance from the nozzle that extrudes the molten plastic. If the distance between the nozzle and build plate is too wide, the material does not stick properly to the glass plate. On the other hand, if the nozzle is too close to the build plate it can block the nozzle.
Once the calibration was completed I was eager to try my first print, but first I needed to install the Cura software to produce the files that the printer uses. I have two computers at home that I am using for work at the moment; at this stage, I was using a laptop running Ubuntu with 4GB of RAM and since version 4 of the software states 8 GB as a minimum, I thought it best to install version 3. The easiest way to do this was through Ubuntu’s SoftwareCenter.
Later on, I revived an old Windows laptop that I had, which boasted a 17-inch screen and 8GB of RAM, so at this stage, I then downloaded and installed version 4 of Cura from the Ultimaker website.
Version 3 worked fine, but some of the extra settings available in version 4 to fine-tune the print quality came in handy.
My First 3D Prints
I found the file for printing a 20mm cube that Stuart had used for his article linked above and decided that would be a good first print. The printer already had some filament installed, so I navigated to the print menu, selected the file for the cube and pressed go.
The results were not good!
The print filament can degrade a lot over time as it absorbs moisture from the atmosphere and I hoped that was the trouble here. I had another roll of filament in a sealed bag, with one of those little packs of desiccant, so I swapped the existing stuff for that, following the instructions for changing filament.
My next print was much more successful.
The build plate of our printer had some blue tape added to it to help the print stick; there is a danger that the hot plastic curls up away from the plate as it cools and the tape was to help prevent this. It had obviously been on the plate for some time and partially came away when I removed my printed cube.
I decided to remove the tape completely and try the method that Ultimaker suggests: applying a layer of Pritt stick paper glue to the plate. I found that the only way I could get an even layer — as the glue is quite lumpy — was to apply it and then remove most of it with a damp cloth and then leaving the resulting thin, smooth layer to dry for 10 minutes or so.
Having a good sticky layer on the plate means you can do away with the “skirt” on your print that is there to aid adhesion. This speeds up printing and means you do not have to clean up your print once it is complete. You can remove the skirt from the print job by un-ticking the “Adhesion” box in Cura.
As the tape I removed was thicker than the glue I replaced it with, I re-calibrated the printer before continuing.
Printing the visor frames
The whole point of me doing this was to print some visor frames and contribute towards The National 3D Printing Society’s campaign. This is being co-ordinated through a Slack channel and so I went and signed up. Here I found links to all the files I needed to download and loads of discussion on how to get that right balance between quality and print speed.
My first attempt still had the skirt for adhesion to the build plate and my layer of glue was a bit lumpy.
I followed some of the advice on the Slack channel and tried setting the in-fill to zero, this reduced the print time to less than an hour and the results were not too bad, but could be a bit “stringy”. I needed to get a print that I was happy with, and that would be of consistent quality before submitting it via the Slack channel to be approved before I could go into full production.
I also saw that some people were printing stacks so the printer could be left printing 5 or more masks at a time. The first time I tried this I did it without "Support" enabled in Cura as it was suggested this was not needed as the necessary supports were included in the design. The support option in Cura’s automatically adds supports for parts of a print that would otherwise be “floating”. Anyway, I just ended up with a bunch of masks fused together, so I next tried it again, this time with Cura support enabled and got the same result! So I am back to printing one mask at a time.
I also tried nesting the prints but the build plate is not quite big enough.
Settings obviously vary from printer to printer, but for anyone else using an Ultimaker 2, this is what I am using and my resulting prints have been approved:
- 4mm nozzle
- Layer height: 0.2mm
- Wall thickness: 0.8mm
- Wall line count: 2
- Top / bottom count: 0.8
- Top thickness: 0.8
- Top layers: 4
- Bottom thickness: 0.8
- Bottom Layers: 4
- Print speed: 60 mm/s
- Infill density: 99%
- Infill pattern: concentric
- Build Plate adhesion: turned off
The visor frames need to be printed using either PLA or PETG, I am using PLA.
It has been great getting to grips with 3D printing and feeling that I am contributing something worthwhile in the battle against the virus. The printer is working away and the organisers are arranging for the mask frames to be picked up, and then shipped in batches of 150 to be sterilised and have the visors fitted. They are still looking for contributors and so if you have a 3d printer take a look at the original DesignSpark article and the Slack channel and join in!