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Rough first bed suddenly?  

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Alpha
(@alpha)
Estimable Member
Rough first bed suddenly?

Hi all,

This has happened a couple of times, but whilst I usually fix through fiddling around, I've never quite put my finger on the cause.

I've just printed a 20cm by 15cm model 28 times - so the printer's been working flawlessly. Only printing in PLA.

I've then gone to print a different model and not the first layer is suddenly very rough.

Any ideas what causes this?  Can't tell if it's a new nozzle needed, I've redone first layer calibration and that's fine, used some cleaning filament.

Many thanks in advance

 

 

Posted : 13/10/2019 2:48 pm
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(@)
Illustrious Member
RE: Rough first bed suddenly?

Fingerprints on the bed cause this.  Soap and water wash will fix it.

Hot Water wash: often, as needed, and after any of the following
              (not recommended for daily use on Powder Coated sheets)

  • 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.
  • Dry the bed with a fresh paper towel.
  • Handle the bed only by the edges.
  • Place bed on printer.
Posted : 13/10/2019 9:16 pm
Alpha
(@alpha)
Estimable Member
Topic starter answered:
RE: Rough first bed suddenly?

Hi Tim,

Yes that was my first thought - so I gave it a clean as you describe (also tried turning over and spare pei).

So far:

- tried z recalibration

- re-ran whole setup wizard

- changed nozzle

- tried different filaments (eg Prusament)

Thinking I may need to strip down the whole extruder, I just don't really know what I'm looking for! 

Z calibration works fine except for corners I occasionally get the filament not sticking and peels up slightly.

I know all the symptoms point to the pei sheet, I just can't see why it'd affect all pei sheets suddenly having worked perfectly moments before!

My only thought is whether this could be something to do with inconsistent extrusion where the filament is getting stuck and gets pulled up - I know it's a stretch but I've very occasionally been hearing a click from the extruder which is often a tell tale sign of something awry.....

 

Any ideas welcome!

Posted : 13/10/2019 9:25 pm
Alpha
(@alpha)
Estimable Member
Topic starter answered:
RE: Rough first bed suddenly?

I've added a video of the standard z calibration which really clearly shows the effect - I've tried all sorts of z heights (ie bringing it back a bit) - it just seems to be really 'sticky' to the nozzle

https://vimeo.com/366294074

Any ideas?

Posted : 14/10/2019 5:29 pm
Alpha
(@alpha)
Estimable Member
Topic starter answered:
RE: Rough first bed suddenly?

Also done the rough extrusion check - 100mm extrusion command results in about 95mm of extrusion...so looks like a bit of underextrusion. Could this be related?

PS did a full acetone and wire wool treatment on the PEI sheet - this has definitely improved its adhesion, just still getting the stickiness and peeling at the end of the calibration test (ie where it's building up a solid sheet surface)

This post was modified 4 years ago by Alpha
Posted : 14/10/2019 5:57 pm
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(@)
Illustrious Member
RE: Rough first bed suddenly?

Try something simple: like one these cal circles.  The result should be a flat, solid layer of plastic.  If there are ridges in the extrusions, that would indicate Live-Z being too low.  If there are gaps between the extrusions, that would indicate Live-Z too high. 

Cal Circles

It's unlikely under extrusion is part of the problem.  But that will manifest elsewhere and should be dealt with later.

Next run, try listening closely to the sounds during extrusion.  If you hear any hissing or spitting sounds your filament isn't dry. The surface in your photo could be due to wet filament, though usually it takes very wet filament to do that, but worth checking.  You might try a fresh now spool to see if it perhaps works better.

 

This post was modified 4 years ago 2 times by --
Posted : 14/10/2019 6:02 pm
Alpha
(@alpha)
Estimable Member
Topic starter answered:
RE: Rough first bed suddenly?

Hi Tim agree - I've been using the calibration square (forget the fella who posted but brilliant post nonetheless) - essentially the same.

It generally gets about a fifth of the way through the calibration square with a smooth surface, then it starts to peel up/gloop up the nozzle etc.

Have tweaked z until you get that standard squish on the layer that you want - still relatively new (bought my MK3 last September) but it's been printing pretty much 50% of every hour since then, so pretty good sense of what it should look like.

Pretty certain it's not the filament as have tried three different ones including Prusament and a fresh out the bag one as you suggest.

Feeling daft..........!

Posted : 14/10/2019 6:28 pm
Alpha
(@alpha)
Estimable Member
Topic starter answered:
RE: Rough first bed suddenly?

Ok, getting somewhere slowly.

Something seems to be happening a certain way into prints.

As you can see this is starting from the bottom right as a calibration square (pretty spot on to start with) and then by the time it reaches halfway it's starting to degrade. Does this help at all?

Posted : 14/10/2019 8:56 pm
Alpha
(@alpha)
Estimable Member
Topic starter answered:
RE: Rough first bed suddenly?

Heh, ok Jo Prusa, where's the cameras? I'm on a candid camera show for 3d printing clearly.

These issues are just bizarre. Now I'm getting a relatively reliable lay down of print, but the lines are 'wobbly'??

Anyone seen this before?

Posted : 14/10/2019 9:44 pm
bobstro
(@bobstro)
Illustrious Member
RE: Rough first bed suddenly?

Raise your Live-Z (make it less negative). I'd go up 0.06mm or more. Better to be high and come in. You'll notice the lines evening out as you go higher.

My notes and disclaimers on 3D printing

and miscellaneous other tech projects
He is intelligent, but not experienced. His pattern indicates two dimensional thinking. -- Spock in Star Trek: The Wrath of Khan

Posted : 15/10/2019 12:04 am
cwbullet
(@cwbullet)
Member
RE: Rough first bed suddenly?
Posted by: @katie-o

Heh, ok Jo Prusa, where's the cameras? I'm on a candid camera show for 3d printing clearly.

These issues are just bizarre. Now I'm getting a relatively reliable lay down of print, but the lines are 'wobbly'??

Anyone seen this before?

That is waving or buckling.  As said above, you are too close to the bed.  

--------------------
Chuck H
3D Printer Review Blog

Posted : 15/10/2019 12:11 am
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(@)
Illustrious Member
RE: Rough first bed suddenly?

I'd take a look at the extruder gears.  Make sure it is firmly attached to the motor shaft, and the idler axle is centered in the two ears.  Then. inspect the filament drive teeth looking that they are clean and not filled with dust & debris.

It might be Live-Z set too low causing the pattern, but I'm not convinced.

Are you using 3x3 or 7x7 mesh leveling?  And have you set any mesh compensation (the Left/Right/Front/Back settings)?

 

Posted : 15/10/2019 12:45 am
Alpha
(@alpha)
Estimable Member
Topic starter answered:
RE: Rough first bed suddenly?

Hi Tim,

 

Interesting thought regarding the extruder gears - I'll have a look tonight. I recall there was a bit of brown dust there, so probably need an oil?I

I'm using 3x3 - have used octoprint's bed visualiser and actually a very flat bed. I could try 7x7 if you think worth testing?

 

 

This post was modified 4 years ago 2 times by Alpha
Posted : 15/10/2019 5:36 am
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(@)
Illustrious Member
RE: Rough first bed suddenly?

7x7 is easy, change one setting and you're done, and it generally provides a better layer one over 3x3. 

The Bondtech gears only need a light coat of grease on the large drive teeth, a little bit goes a long way. You don't want to over do it and have grease squishing over to the filament teeth.

 

Posted : 15/10/2019 11:00 am
Alpha
(@alpha)
Estimable Member
Topic starter answered:
RE: Rough first bed suddenly?

Yeah, know the 7x7 is easy, just like to understand what's changed....!

I've greased the larger teeth and 18 hours of printing later it's looking good again.

Think this must've been affecting the feed of filament.

I'll give it another few days and claim victory....! Thanks for help Tim and everyone!

Maybe I need a Mini as a backup....... 😉

This post was modified 4 years ago 2 times by Alpha
Posted : 15/10/2019 8:15 pm
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