LulzBot TAZ 6 prints failing

Recently I have had problems where my prints have been failing. I was using PC+PBT initially, but switched to PLA for reliability reasons. Also tried cleaning the build plate and the nozzle. Latest failure looks like this. How should I resolve this problem?

It looks like the base layers are sticking to the build plate… but upper layers are separating and warping.

What is your your print temperature, layer height, and fan speed?

I’m thinking you may need to increase the “Wall Thickness” (or “Wall Line Count” … either can be used to achieve the same goal). It’s common to see this at 1mm (with a 0.5mm nozzle that’s a count of 2 walls) … you could increase that to 2 or 2.5mm (which would get your 4 or 5 laps).

Also there’s an option called “Alternate Extra Wall”. This causes every other layer to get one extra wall. The idea being that the “infill” gets tucked between (sandwiched) the walls for a better bond between walls and infill.

If the part cooling fan is running on high speed then this can result in cooling the filament before it really has a chance to adhere to the layer below.

If the layer height is too higher, then the layers above will barely make contact with the layer below … you get no “squish” so the bond is weak. Commonly the layer heigh is 50% of the nozzle width. So .25mm layers with a .5mm nozzle. When printing “high speed” you can set it to 70% (.35mm layers with a .5mm nozzle) … but if you get to say 80% (.4mm layers with a .5mm nozzle) the bond between layers isn’t as strong.

You can also check your E-steps. Under-extrusion could also be responsible for this sort of thing.

PLA is pretty “low warp” … so while I can completely understand why PC or ABS would be problematic, I’m a little surprised to see this happen with PLA if you’re getting good 100% flow and using good temps and layer heights.