Odd z height behavior and globbing

[nU.metA]

Hey again, folks.

Are there any obvious reasons why my z-height would be dropping lower after every print? I'm really at a loss. I have gone through the calibration process several times, probably upwards of 50. I go through the process at least twice a week because everything seems to come unglued, figuratively speaking, after even smaller prints. The change i've noticed has been an actual drop in the z-height, so that it's physically lower to the point where it contacts the plate. Has anyone else experienced this after printing? And if so, is there anything we can do to combat this? In addition to this issue, we've been experiencing excessive globbing, which you can see in the pictures attached. You'll notice that it gets HORRIBLE around small detail parts and sections, like the teeth on the dino skull. I called seemecnc, and the guy thought that perhaps our retraction settings were jacked up. The current settings are set to the defaults (we are using slic3r):


nozzle diameter: .5 mm
length: 5.4 mm
lift z: .2 mm
speed: 100mm/s
extra length on restart: .1
minimum travel after retraction: 2

Do those look correct?

current print settings:

layer height: .1mm
first layer: .35mm
parameters: 3
solid layers top: 5 bottom: 3
infill density: .15

speeds are set to 30 mm/s, except for that first layer, which is 15, but i think we used 10 for the piece in the pictures.

Anyway, really appreciated the feedback last time, definitely hope for some more help like that again.

[nU.metA]

Just bumping for updates. I think that we have a belt issue or something similar. Has anyone else experienced changes in calbration mid print or at other random times? Let me know if there are any specifics you'd like to know and I'll do my best to accommodate. Would really like get moving with this thing! Thanks in advance.

[Polygonhell]

Most likely you are printing slightly too hot, you are probably over extruding slightly and you might need more cooling.

[nU.metA]

Most likely you are printing slightly too hot, you are probably over extruding slightly and you might need more cooling.

Thanks! So our multiplier is currently set to 1.0, would suggest we drop it down to .9 to see if that helps as well? is the z height varying after prints normal? I didn't realize we would have to recalibrate so much if that is the case.

[Polygonhell]

For extruder calibration I would recommend my "very informative" post here http://forum.seemecnc.com/viewtopic.php?f=54&t=1163

As to Z changing, no there should be no significant change between prints, I adjust mine when I change the hotend or the build plate and never at any other time.
To me it suggests you have a pulley or belt slipping issue, check the pulley set screws are tight on the stepper shafts, and check your belts on the inside about 1/3 to 1/2 way up for abnormal wear, if your head hits the build plate, the pulleys can destroy the belt teeth.

[nU.metA]

Thanks again for the input. I'll work on it a bit tonight when i get home from work. referring back to the guide, there is a section on how to tighten the idler pulley from the top. This is one of many parts that's extremely vague. He basically says to stick a screw driver in at the top pulley to move the belt, then tighten by it by hand. I have no clue what this is referring to, as nothing i can see can be tighten by hand at the top of the shaft. I can definitely see the tension on the belts being an issue, as they're not nearly as taut as suggested. They even look loose when pressed, which i'm sure can lead to some slippage as you said. As it is though, our screws up there cannot be tightened anymore with a screw driver, and definitely not by hand. Am i missing something here? I wouldn't rule that out at all.


We have adjusted

[nitewatchman]

Would suggest that you look at some of the adjusters for the top of the towers.

[Gr8Scott]

I had Z height issues for the longest time until I removed the belt pulley for each motor and made sure the flats I had ground were really deep and then put on fresh loctite on the pulley mount screws and fastened them tightly. Once that was complete, I have had no other Z-height issues since and I have made many prints since then.