Opening a 3D Hub
After hosting the event "Love in 3D" together with 3D Hubs on Valentines day at our new office in Rotterdam, we decided that it might be nice to integrate a bit more into the local 3D printing community. So, we've decided to open up ourselves as the Perpetual Hub on the 3D Hubs network.
To sign up as a hub you first make a test print of 3D Hubs' mascotte: Marvin. Of course, our Marvin had to be printed from recycled plastic cups. Because of the experimental nature of the printing material, it took a few tries before Marvin was printed properly. Every design requires a little tweaking, and even more so when we print with recycled plastics.
Printing with Polystyrene (cups)
PS (polystyrene) is not often used in 3D-printers. Plastic filament for 3D-printers is engineered to have certain properties that make it suitable for FDM (fused deposition modelling). Plastic cups are produced in a different ways (i.e. blowmolding) so the plastic has different properties.
Actually, every type of mass-produced plastic product has probably been made with a dedicated compound. This is the trouble with re-applying waste plastics for different purposes. But it's not insurmountable!
PS cools down faster then PLA or ABS which prevents proper interlayer adhesion. By adjusting the gcode to extrude comparatively more material we mitigated this problem. We used a 0.8mm nozzle, made the layers 0.3mm thick and turned off the fan.
Also, because PS behaves "gummy" (a higher viscosity?) when extruded, the nozzle tends to tear away any layers that aren't properly adhered to the latter and the path of the layer is lost. This can be seen happening on Marvin's head in the first prints. The effect does not occur when printing an overhanging structure (Marvin's bottom) because the material is then pulled outwards.
To prevent this effect on Marvin's head, the shell thickness of the print has been made 3x the nozzle size. Another option would have been to reduce the layer thickness but this would negate the fact that we're trying to extrude more material to improve layer adhesion. Also, we were printing carefully at 30% of 20mm/s the print would take a very long time.
Next: 3D Hubs meetup
The 18th of April on a Friday afternoon (with drinks) we'll be hosting another party: a Rotterdam 3D Hubs community meetup. Since last time was also a success, our office is so conveniently located and has ample space to welcome in people (and we just like throwing parties). It will be an opportunity for all the makers of Rotterdam to get to know each other and find out what's keeping everyone busy.