holes in walls

[waspinator 0]

I'm printing on a UM3 using original CPE light grey filament using default fast (0.2mm) settings. This is a section of 30mm tall wall in a box with 2mm wide walls. 3/4 walls are almost perfect (just 2-3 holes), while the one in the picture is pretty bad. What causes these holes, and what settings should I change to fix this?

 

The filament was purchased less than 30 days ago from an authorized reseller.

[geert_2 558]

The PET I used (which I think is a sort of polyester, just like CPE?) has a tendency to accumulate on the nozzle while printing, and then this accumulation discolors into a thick light brown goo, which eventually sags and gets deposited on the print as big brown blobs.

 

Also, while traveling through space, the nozzle has a tendency to leak, and then upon arriving on the next wall, a blob is deposited on the side. Especially when printing fast, due to the nozzle-pressure not reducing immediately.

 

In my UM2, printing slow reduces the effect, but does not eliminate it.

 

I don't know if this is the cause of your phenomena, there could be other reasons, but maybe you could keep watching while printing a test piece? If it would be the above problems, you can easily see it happening.

 

[gr5 2,234]

I agree with geert_2 - printing slower will help these a lot.  There is something in cura that creates these but I don't quite understand how to fix them other then simply printing much slower.

 

Regarding the filament sticking to the nozzle - that should be improved if you buy ICE coated nozzles from 3dsolex (disclaimer - I sell ICE coated nozzles also).  3dsolex has these for S5/UM3/UM2 and more.  Pretty much all their nozzles are ICE coated now.  The coating is a mix of chemicals including some kind of teflon such that molten PLA (and I assume CPE/PET/nGen) doesn't stick to the nozzle.

[geert_2 558]

20 minutes ago, gr5 said:

I agree with geert_2 - printing slower will help these a lot.  There is something in cura that creates these but I don't quite understand how to fix them other then simply printing much slower.

 

Regarding the filament sticking to the nozzle - that should be improved if you buy ICE coated nozzles from 3dsolex (disclaimer - I sell ICE coated nozzles also).  3dsolex has these for S5/UM3/UM2 and more.  Pretty much all their nozzles are ICE coated now.  The coating is a mix of chemicals including some kind of teflon such that molten PLA (and I assume CPE/PET/nGen) doesn't stick to the nozzle.

Now that you say this, I remember: in the beginning I used to wipe the nozzle with a tissue wetted with silicon oil, and PTFE-oil: sometimes the first, sometimes the second. These sprays can be found in car shops. This also reduced accumulation. It seems that after some time the nozzle gets a coating of PTFE and/or silicone, and it gets less sticky. There is still some build-up of goo, but less. So, now I don't need to wipe them with oil anymore; I just clean them immediately after each print.