Tough PLA poor results on Ultimaker S5

[someone 0]

Hello,

 

I am having issues printing a 5mm diameter cylindrical part with tough PLA black on an Ultimaker S5. The base of the print is squished, and the diameter of the cylinder decreases with each additional layer, until stabilizing after +/- 20 layers. I am using the default recommended settings with 0.2mm layer height, a skirt and no support generated. I can see several sources of this behavior: print speed too fast (defaults to 50mm/s with recommended settings) compared to temperature (defaults to 215°C). The fan doesn't seem to run as fast as when printing generic PLA. The skirt looks okay to me.

 

Note that:

- The machine has been calibrated on all axes.

- This problem only happens on small prints of this kind. Larger prints are okay because (I'm guessing) in any given point, the filament has time to cool down before the extruder places another layer above it. 

 

Any idea what causes this behavior, and how I could get away with printing these kind of structures ? I know 5mm is small but I would expect a much better print result from the default settings of a 6000€ machine 🙂

 

Thanks in advance for your help !

 

Edited December 31, 2018 by someone

[Smithy 1,141]

Try to set the minimum layer time to something higher, maybe 10sec and print slower. 

A 5mm part is really small and as you said, the previous layers could not cool down enough.

 

It can also help if you print 2 or 3 parts at once.