Inconsistent z-adjust and blobs building up  

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llangley27
(@llangley27)
New Member

So I'm having a very frustrating issue right now concerning my prints.  I've had my printer for about a week and a half now and it seemed as if the settings in PrusaSlicer were locked in as well as my Z-adjust.  Recently, I started having the hotend leave little blocks and strings when hoping around which build up upon concurrent layers to where the print eventually fails.  Even more recently, the details on the prints are not coming out smooth at all, even though my Z-adjust seemed to be locked in.  

 

This is the picture of my Z-adjust using life adjust Z.  In this test I did not change the Z-adjust at all, but you can see a significant difference between the first half of the print and the last.  The first half of the print seems great while the second half has gaps and is noticeably thinner in structure.  

 

 

I don't know if this is related, but this issue seems to especially affects supports and infill which are noticeably weaker and are very susceptible to the blob buildup issue that I mentioned before.  Where I once had really solid detail on objects also now looks like a mess.

 

I've tried hotend temp changes both hotter and colder (currently running 225/55 first layer and 193/55 all others - using Hatchbox white PLA), adjusted Z-adjust up and down, played with the contact z-distance, pattern, and pattern spacing, and have turned on only retract when crossing perimeters. I've even played with the extrusion width and fan settings.

 

For the record, I'm also cleaning very thoroughly with 91% isopropyl alcohol and not using my fingers.  The first layer for the most part seems to stick ok.  I'm also hearing a slight crinkling sound at times when the filament is being printed.  Using 7x7 mesh bed leveling.

 

Anyone have any ideas what I'm doing wrong and what could cause the z-adjust to be inconsistent?

This topic was modified 5 months ago by llangley27
Posted : 07/06/2020 8:25 am
llangley27
(@llangley27)
New Member

Tried to run print benchy just now from the included code and couldn't even make it though the first layer.  This is what came out.  Could the extruder be jammed possibly?

 

Posted : 07/06/2020 8:37 am
tetious
(@tetious)
New Member

I've a couple ideas for you:

1. Did you change filament rolls/brands between your initial success and current state? I've had what appeared as z-level problems like that turn out to be inconsistent filament diameter. If the diameter is oscillating, it can manifest as under and then over-extrusion. It can even cause some problems with extruder noise if it is really bad, as the filament can bind up in the PTFE tube (or the space directly between the gear and tube).

2. Are you storing your filament in a humid room? The popping you mentioned (if it is coming from the hot-end) could be moisture.

This post was modified 5 months ago by tetious
Posted : 07/06/2020 1:15 pm
llangley27
(@llangley27)
New Member

Hi tetious,

 

Thanks for responding.  I was using the Prusa PLA initially after first setting up the printer and had a couple of successful prints.  It then started leaving little strings upon retraction which started to build up, similar to the problem I'm having with the hatchbox white.  I switched to the matchbox white and had a few successful prints, although the minor stringing/blobs on retraction still persisted.  Problem is, it's gotten worse to where I can't even complete a print now or put down a consistent life adjust Z.  See the picture below, which is another print for life adjust Z I just did.  The print on the left is the print I did yesterday and the print on the right is the one just completed.  As you can see, they pretty much identical for when the prints start failing and when the issues start.  Both start off fine and then begin to have issues about half way through.  There is no modification to the gcode for life adjust z in these prints either.

 

The humidity in the room isn't an issue.  Everything is room temp indoors and I live in an area where humidity isn't a factor.

Posted : 08/06/2020 12:35 am
h.waibel
(@h-waibel)
Estimable Member

Hi there,

just a few random thoughts thrown into the discussion:

1. wash the sheet, I know it sounds stupid, but it is in fact a simple solution for a lot of problems that seem to get worse over time. Even though you're careful there is always some grease build up over time and IPA unfortunately helps spreading the oils around the sheet quite nicely.

2. from the images it looks like your heatbed might be somewhat warped. Check it with a level/blade tool. If it is warped there are a few how to's on the web explaining a process that involves tightening and loosening the screws that hold the heatbed down.

3. random thought, did you build the kit or did you get the assembled unit? If you built it the Y-axis extrusions could be warped and thus also warping the heatbed. Again a level might be your helper there.

4. your z could still be a bit on the high side from the look of your benchy attempt. I can strongly recommend the https://forum.prusaprinters.org/forum/original-prusa-i3-mk3s-mk3-assembly-and-first-prints-troubleshooting/life-adjust-z-my-way/ thread. A lot of very experienced people are monitoring that thread and you normally get help there rather quick.

 

hth

Hansjoerg

Posted : 08/06/2020 7:11 am
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