Top layer blistering
Hi,
I updated to the latest firmware yesterday and also started using the latest Slic3r Prusa Edition 1.41.
My slicing settings are:
Print settings: 0.35mm FAST
Filament: Prusa PLA
Printer: Original Prusa i3 MK2
Fill density: 20%
Support: None
I made some smaller prints and they looked good but then when I started a big one (almost 13h) it failed after about 4h30min. The top layer of my enclosure (bottom in the enclosure) did not stick to the layer below. I think it may be because of the fan cooling it too fast but where can I adjust the fan speed on the "top" layer. And why are the layers below perfect? See picture of the problem
The gcode file can be found here:
https://www.digiactive.net/prusa_forum/enclosure_lower_0.35mm_PLA_MK2S.gcode
Best regards
Nicke
Re: Top layer blistering
I had that with that profile a long time ago (12-18 monthes). Then it is not related to the firmware nor slic3r release. My filament was of different material.
I don't know exactly what changings solve the issue the most.
First i would say 0.35mm is too high for a 0.40 nozzle. If i want to have nice print speed i go to 0.30mm layer and 0.6mm width.
It should be related to the infill, infill rate and number of top layers. You could go from cubic to rectilinear and increase the number of top layers (six?)
Supermerill ( https://github.com/supermerill/Slic3r/releases ) propose a nice feature in its slic3r version which is to increase the infill rate under top solid layers.
Re: Top layer blistering
I think someone did the math for Z steps and layers somewhere.
I have a Prusa,therefore I research.
Re: Top layer blistering
Yes, that's very likely the culprit. You want to keep layer heights below 80% of the nozzle opening diameter. Otherwise, you're printing round extrusions with very little of the squish that provides inter-layer adhesion. For 0.40mm you want layer heights below 0.32mm for best results. Lower is better (within reason). Turning down the fan a bit may help, but only so much. The layers have to stick together to start with.
[...] First i would say 0.35mm is too high for a 0.40 nozzle.
Re: Top layer blistering
OK, thanks for the comments, I'll try with 0.30 on the weekend...
Re: Top layer blistering
Once the peeling of the last layer was so easy and the layer under was nice enough that i accepted the part with the top layer removed. 😀
I now use around 35mm/s for the top speed.