Print quality issues, bubble looking effect after first few layers

Ericf1983

Hey everyone,
After some tinkering and trouble I've gotten Repetier firmware and host installed and working the printer. I have done a few prints and noticed the pieces have what looks like bubbling after the first 10-15 layers. I'm sure this is a setting that I'm just not aware of
The temp settings on this piece were 215 at the extruder and 90 for the bed, 80% infill. I've tried from 215-230 for the extruder and 90-110 for the bed though I don't think the bed temp has any effect
Material is ABS, I don't have and PLA to try yet
Suggestions are appreciated!

Thanks

Repetier

Sure temperature is right? 215 seems low for ABS and if you can not extrude continuously you might get such a picture. As a test you should push filament by hand through nozzle. That should be possible without too much force. Increasing temperature makes this easier and at some point easy enough to print continuously even with extruder. But do not go up too high, thats not good with abs. ABS types I know need 230-250°C depending on vendor.

Ericf1983

I'll turn the temp up and give that a shot
I also noticed last night that the Z axis motor was moving the bed up and down quite a bit while in the middle of printing each layer so I disabled auto levelling in the eeprom, that did help with a print I tried last night, I'll test with a hotter extruder tonight

Thanks

Repetier

Autoleveling needs z axis without backlash or it can in deed also get unwanted artefacts.

Ericf1983

I've increased the temp to 240 and disabled the auto bed level and am still having that happen.
Could it be related to feedrate and flowrate? It almost looks like it's depositing too much material. I watched while it printed and it appears the filament is coming out in spurts almost
Is there a best practice for adjusting or starting the feed and flow rates other than trial and error?
I have the flowrate set to 125 and feedrate @ 250

Thanks

RAyWB

startpoint is usually 100 for both settings. do the primary adjustment in slicer for printing speed and filament.
from my experience printing speed of 40mm/s was good starting point for ABS.
As far as i know you cannot print abs that fast as PLA, so thats why i suggest that printing speed.

Ericf1983

Awesome, I set the speeds slower and now I'm getting much better results. I have it set to 60 mm/s for both perimeters and infill, feed 120 and flow 70 and that seems to be working out well
So PLA can be printed faster thank ABS? I've yet to print with PLA but have a roll on order that should be here tomorrow. Should the feed and flow rates be closer to 250 and 125, respectively, as a starting point?

RAyWB

if your slicer is set ut correct both should be close to 100. and yes,from my eperience pla can be printed faster than abs.
abs doesn´t get that liquid as pla.But i´m not that experienced in printing.
having the need for feedrate at 120 and flow at 70 shows your slicer is not set up correct.
so 60mm/s at feed 120% results in 72mm/s which seems pretty high to me for ABS

Roko

You should make sure your extruder is calibrated so when you tell it to push 100mm it pushes 100mm. There are guides on the web for the correct procedure.

Ericf1983

Roko said:

You should make sure your extruder is calibrated so when you tell it to push 100mm it pushes 100mm. There are guides on the web for the correct procedure.

Good to know, I had no idea that needed to be done.
I just looked up instructions and will give that a try as well.

Thanks

Ericf1983

Well, thanks for all the suggestions.
I spent a few hours tonight tweaking the printer, after calibrating the extruder, leveling the bed a bit further and adjusting the per/mm settings in Slic3r I've gotten it to print good quality prints.

Thanks for the info!

Eric