Notifications
Clear all

Unable to determine what's causing this issue  

Page 1 / 2
  RSS
Aaron C
(@aaron-c-2)
Active Member
Unable to determine what's causing this issue

After a disastrous print a few months ago destroyed several parts of my MK3, I purchased and reassembled the printer with the new parts.

However, while a calibration cube print seems to be OK, my print attempt for an STL file I've purchased and sliced using the latest PrusaSlicer fails miserably after the first layer. I'm using Prusa filament (the older stuff, not Prusament) and everything is set to the standard settings. I've done a complete calibration wizard setup on the 3d printer as well. The extruder gears seem aligned correctly and the tension on the extruder also seems correct (followed Prusa's video guides for that).

But, I'm at a loss. It seems like it's "scraping" away the print. A PINDA probe self-test following the documentation seems to be fine as well. 

Your help and suggestions are much appreciated. I bought this originally pre-assembled.

 

Posted : 02/09/2019 9:04 pm
--
 --
(@)
Illustrious Member
RE: Unable to determine what's causing this issue

It looks like your layer height is too high.  What are your slice parameters and nozzle size?

It also would not hurt to see the part preview after slicing.

This post was modified 2 years ago by --
Posted : 03/09/2019 4:16 am
Aaron C
(@aaron-c-2)
Active Member
Topic starter answered:
RE: Unable to determine what's causing this issue

Standard .4mm nozzle (purchased from Prusa)

I'm using the standard 0.20mm SPEED MK3 print settings from Prusa Slicer 2.0.0 (PrusaSlicer-2.0.0+win64-201905201652).

Layer Height/First layer height: 0.2mm

I've exported the full config and attached it. 

 

 

 

 

config

Posted : 03/09/2019 12:21 pm
tj
 tj
(@tj-2)
Trusted Member
RE: Unable to determine what's causing this issue

i'm guessing on some kind of height problem, possibly dependent on where on the plate the object is printed.

if you print a test cube in a different area on the bed, can you make it fail too by just moving it?
for example closer to each of the 4 corners or sides.

perhaps the nozzle is closer or higher on one side than the other, maybe redo z calibration on the printer? and also first layer calibration plus testing it at different areas of the print bed

i don't know if 7x7 mesh bed leveling is on by default or not but might be worth making sure it is.

Posted : 03/09/2019 4:53 pm
--
 --
(@)
Illustrious Member
RE: Unable to determine what's causing this issue

Not sure why infill is set so fast: 0.20 mm SPEED maybe.

infill_speed = 200

But it looks like layers aren't sticking together.  Temps all look good, so maybe it's a flow limitation.  Try the 0.20 quality setting since it slows things down enough.  Alternatively, you can keep the 0.20 SPEED profile and try setting the volumetric limit from 15 to 10 mm3/s. 

Another quick test is to use TUNE to slow print speed down at least 50%.  But I recommend reslicing with changes above.

Posted : 03/09/2019 5:42 pm
tj
 tj
(@tj-2)
Trusted Member
RE: Unable to determine what's causing this issue

max volumetric speed is controlled from filament settings and for PLA the default is 15mm3/s and i believe that overrides the settings done under print settings.

the default profile settings for the most part work just fine for me on my printer so i don't think it is a settings problem (but changing max volumetric speed from 15 to 11.5 i think is a good idea for PLA but that's a different story)

 

my bet is that this is some kind of mechanical or calibration issue.
try one of the pre-sliced gcode files like the benchy to rule out the slicer or its settings as a problem

Posted : 03/09/2019 7:16 pm
--
 --
(@)
Illustrious Member
RE: Unable to determine what's causing this issue

Plicer uses the lowest of the two settings (at least it is supposed to).   You can see the extrusion rate change during acceleration, hence VF is a likely reason for the problem.  Not 100%, like most print issues, but #1 candidate.

Tor - some of your suggestions have been a bit far afield of what the symptoms show.  For example this case, layer height is NOT an issue, so why tell someone it is?  In another post you're telling someone to fix things that aren't a problem when adhesion is obviously the primary issue.  And while defaults work most of the time, they do not work all of the time. Especially with some of the matte looking Prusa filaments and print speed.

And Arron - just to be sure: the 0.4mm nozzle is the same that shipped with the printer, and you haven't changed nozzles recently?

 

 

 

Posted : 03/09/2019 8:13 pm
Aaron C
(@aaron-c-2)
Active Member
Topic starter answered:
RE: Unable to determine what's causing this issue

The nozzle was an exact replacement (same 0.4mm nozzle as was originally shipped). 

What's "VF"?

I'll try the quality setting with a standard Prusa model if you think that will help. 

Posted : 03/09/2019 8:21 pm
tj
 tj
(@tj-2)
Trusted Member
RE: Unable to determine what's causing this issue
Posted by: Tim

Tor - some of your suggestions have been a bit far afield of what the symptoms show.  For example this case, layer height is NOT an issue, so why tell someone it is?  In another post you're telling someone to fix things that aren't a problem when adhesion is obviously the primary issue.  And while defaults work most of the time, they do not work all of the time. Especially with some of the matte looking Prusa filaments and print speed.

ok fine, i was just trying to help out but if it is not wanted then i'll stop, i got better things to do.

Posted : 03/09/2019 9:25 pm
Aaron C
(@aaron-c-2)
Active Member
Topic starter answered:
RE: Unable to determine what's causing this issue

I tried to print the Benchy boat and it became unstuck for some reason about half-way through (this was using the quality setting):  

 

 

Posted : 04/09/2019 1:13 am
JoanTabb
(@joantabb)
Moderator
RE: Unable to determine what's causing this issue

Hi Aaron,

what does the bottom of the Benchy look like?

regards Joan

I try to make safe suggestions,You should understand the context and ensure you are happy that they are safe before attempting to apply my suggestions, what you do, is YOUR responsibility. Location Halifax UK...
Posted : 04/09/2019 1:28 am
Aaron C
(@aaron-c-2)
Active Member
Topic starter answered:
RE: Unable to determine what's causing this issue

Here's the bottom of the print as requested.

 

Posted : 04/09/2019 2:12 am
JoanTabb
(@joantabb)
Moderator
RE: Unable to determine what's causing this issue

Hi Aaron,

it's difficult to see in the picture, but your first layer looks a bit uneven... 
how do you do live adjustment for Z level?

are you using 7x7 bed levelling (set in the LCD Menu, under Mesh Bed Levelling, I think!)

do you use the LCD first layer calibration tool?  

have you tried https://forum.prusaprinters.org/forum/original-prusa-i3-mk3s-mk3-assembly-and-first-prints-troubleshooting/life-adjust-z-my-way/

there are three versions of the test patch, in a zip file at the bottom of the first post!

regards Joan

I try to make safe suggestions,You should understand the context and ensure you are happy that they are safe before attempting to apply my suggestions, what you do, is YOUR responsibility. Location Halifax UK...
Posted : 04/09/2019 2:22 am
--
 --
(@)
Illustrious Member
RE: Unable to determine what's causing this issue

The primary cause of a part breaking loose off the bed  is contamination of the bed.  PLA sticks to clean PEI like masking tape. It should take some effort to remove a part.  The most common contaminant is finger prints - and alcohol doesn't do a great job removing those oils.

Hot Water wash: often, as needed  (and is helpful after any of the following methods)
            (not recommended for daily use on Powder Coated sheets, but some find it necessary)

  • Handle the bed only by the edges.
  • Wash the bed in hot water, use a fresh paper towel as a wash cloth, with a few drops of plain dish soap (Dawn, unscented, no anti-bacterial, etc.).
  • Rinse well in hot water - if you have very soft water, rinse a bit longer. Water should bead and sheet off.
  • Dry the bed with a fresh paper towel.
  • Handle the bed only by the edges.
  • Place bed on printer.

Alcohol wash: every few prints as needed

  • Gloves recommended.
  • Once in a while, an alcohol rinse is helpful to remove PLA residue. It does not remove finger oils well.
  • Pour a 5 cm puddle of 91%+ alcohol in the middle of the bed, with clean or gloved hands use a fresh paper towel to scrub the bed. Wipe up all the alcohol.

Acetone wash: infrequent as needed
            (Not recommended for USE on Powder Coated sheets, but some find it necessary)

  • Pour a 2 cm puddle of acetone on the bed, scrub it around with a fresh paper towel. It will evaporate fast as you clean. This step removes PEI oxides that form over time and with heat, and improves PLA adhesion to a like new state.

Streak test: when contamination is suspected

  • With a fresh piece of paper towel, and very clean fingers, dampen the towel with 91%+ alcohol, and wipe the bed side to side moving back to front, like you're painting it with alcohol. The alcohol should be thin enough on the towel it quickly evaporates from the bed. If you see any streaks, the bed is dirty and needs a wash.
This post was modified 2 years ago by --
Posted : 04/09/2019 2:34 am
Aaron C
(@aaron-c-2)
Active Member
Topic starter answered:
RE: Unable to determine what's causing this issue

Thanks!

I did not have mesh bed leveling set to 7x7 -- it was set to the default 3x3. I'll change that.

I've cleaned the bed using the water and alcohol wash frequently.

I'll do a few trials of that mesh bed gcode file you suggested I try Joan. (I do wish there was a nice summary somewhere with good pics as the 28 pages of discussion make it a bit hard to sort through).

 

Posted : 04/09/2019 12:57 pm
--
 --
(@)
Illustrious Member
RE: Unable to determine what's causing this issue

Alcohol does not clean the bed unless you wear gloves and use gallons.  Here's an image of a bed cleaned exceptionally well with alcohol: 

One pass with soap and water fixed it.  I never use alcohol now except to remove PLA residue. Then I use soap and water to wash off what the alcohol leaves behind.

 

Posted : 04/09/2019 7:34 pm
--
 --
(@)
Illustrious Member
RE: Unable to determine what's causing this issue

My cal procedure is simple:  Print a circle, watch as the pattern fills, adjust to ensure the strips weld together.  The end sheet should be a solid piece of plastic, no strands within the sheet, and it should pull off the bed with a force about like masking tape. 

Cal Circles

This sample is pretty close to perfect - a few very small gaps visible.

This post was modified 2 years ago by --
Posted : 04/09/2019 7:38 pm
Aaron C
(@aaron-c-2)
Active Member
Topic starter answered:
RE: Unable to determine what's causing this issue

I'll try your cal circle tonight and using soap/water. I had pretty good success I think this morning with the sample print suggestion Joan made. 

It stuck like you're describing and I think looked a lot like that. 

Then, I'll try the benchy boat again and then if that goes well, back to the original issue of the self-destructing print I was trying. I'm confident that the printer is getting better with all of your help. Thanks!

(I do wish Prusa provided more of this direct advice like not relying on the alcohol as much for effective cleaning).

 

Posted : 04/09/2019 8:39 pm
--
 --
(@)
Illustrious Member
RE: Unable to determine what's causing this issue

Prusa has private reasons for choosing alcohol only cleaning and for saying their bearings come "oiled and ready for use."   Two of my pet peeves. 

Soap and water can rust the sheets. Sure, but that isn't a reason to say only use alcohol. Instead, tell people that the sheets need to be dried at temp after a soap and water wash. Problem solved. 

As for grease, unless custom ordered, all bearing manufacturers say they ship with a special rust prevention oil not intended for lubrication; that new bearings need to be cleaned and packed with suitable grease before use.  Sure, some bearings shipped prepacked with grease - but not Prusa's.  When I installed my Prusa bearings, they had machining debris and grit in them - they had not been cleaned or lubricated - and they lasted a couple months.  Its also a fact oil doesn't adhere well to the top and side rows of bearings - it works to the bottom where it pools.  Grease doesn't pool - and why manufacturers spec grease over oil.

ps: there are bearings designed for oil baths, they have holes for oil to flow, and they do not have grease seals.

 

Posted : 04/09/2019 10:20 pm
Aaron C
(@aaron-c-2)
Active Member
Topic starter answered:
RE: Unable to determine what's causing this issue

Here are the results.

The circle at 100mm seemed to go pretty well. It's got a bit of a rough feel though on top. It was very consistent throughout the disc shape and the bottom was very smooth. It holds together very well and stuck to the printing surface like somewhat sticky tape.

The boat however was not as successful. 

It stuck till nearly the end and then popped free. I just happened to be watching it, but honestly don't know what caused it specifically. Pop! And then, it was moving around the surface. 🙁

These were printed with the default .20mm QUALITY MK3 settings. 

I've got the 7x7 turned on. 


Posted : 05/09/2019 12:40 pm
Page 1 / 2
Share: