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Mike Daneman
(@mike-daneman)
Estimable Member
Advice on first layer

Hi guys,

I would appreciate some advice on my first layer quality.  I notice that in regions that first layer is somewhat "fuzzy" and has small bumps in a few places.  This is mostly obvious when I print something with a very large first layer (like a storage box) and less so on smaller things. The 2nd & 3rd layers typically smooth things out to some degree, but the non-uniformity is still visible from the top on prints that have a fairly thin bottom. I would appreciate any expert advice on what you think the issue is.  Should I raise Z somewhat, should I reduce the temperature?  I'm printing with Hatchbox PLA at 220C/60C.  I apologize that the pictures are not in the best focus, but hopefully give you an good idea on what's going on. 

Thanks in advance for your help.

-Mike.

 

Posted : 03/09/2019 6:12 pm
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(@)
Illustrious Member
RE: Advice on first layer

This looks like a thick layer 1 - Live-Z could be raised a bit to help.  But...

This looks like a drive gear issue: filament is not being extruded evenly: either some teeth are full of debris or the gear isn't aligned with the filament path. Or even just poor QC in the filament diameter... but the change is fast enough it's hard to guess the cause. Could also be some weird resonance with the belt being too loose... again - really tough to tell.

And it MIGHT be underextrusion during fast infill ... but... 

This post was modified 2 years ago 3 times by --
Posted : 03/09/2019 8:18 pm
JoanTabb
(@joantabb)
Moderator
RE: Advice on first layer

Hi Mike, 

Are you using the 7x7 mesh bed levelling or the 3x3 standard mesh bed levelling?

7X7 makes life a lot easier for you!
If you look again at your pictures and click on them,  they should open out to larger pictures now... 

this is because I have clicked theLink to Media File option in the bottom right of the window

Your pictures are showing ripples like the ripples you get in the sand, as the tide goes out... that means that your Live Z setting is too close to the build plate (Too large a negative number)
re run the test piece but reduce the Live Z 20  at a time and watch the printout, when you stop getting ripples, you are about the right level,

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 : 03/09/2019 8:23 pm
Mike Daneman
(@mike-daneman)
Estimable Member
Topic starter answered:
RE: Advice on first layer

Joan,

Thanks a lot for your advice (on both the first layer setting and how to better embed images :).  I'm using the standard 3x3 leveling.  How do I change it to 7x7?  That sounds like a great idea!

I suspected it may have been a Z height issue.  However, I don't see it everywhere on my test piece, only in some regions (maybe again pointing to imperfect bed leveling).  That's probably why it's more visible on pieces with a large footprint.  I'll play with the Z and see how it comes out and, if I figure out how, try setting bed leveling to 7x7.

Posted : 03/09/2019 10:11 pm
Mike Daneman
(@mike-daneman)
Estimable Member
Topic starter answered:
RE: Advice on first layer

Tim,

Thanks for your advice as well.  I'm not sure if this helps to diagnose, by here is a more zoomed out image of the first layer (again apologize that it's not the best picture).  Upper-left seems pretty smooth, while bottom and bottom-right have ripples.  For this reason I don't think it's an extrusion issue as I would expect that to affect the entire layer.

Posted : 03/09/2019 10:19 pm
bobstro
(@bobstro)
Illustrious Member
RE: Advice on first layer
Posted by: joan.t

Your pictures are showing ripples like the ripples you get in the sand, as the tide goes out... 

Immediate flashback to the scene in the original Bladerunner movie. "Like tears in the rain..." I'm submitting this for the 3D printing "best poem or haiku" category this year. 

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 : 04/09/2019 1:40 am
CybrSage liked
BlazeR
(@blazer)
Active Member
RE: Advice on first layer

Hi mdaneman, 

I had a very similar issue where the first layer was not printing smooth and had waves-like surface. This was not happening on the entire surface though, and I could overcome the issue by releasing the extruder idler screw a little bit (just enough tension to extrude properly). I am assuming that if it's too tight will cause the issue. Now I am having more reliable first layers. I hope this could help a bit. Cheers!

Posted : 04/09/2019 10:11 pm
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(@)
Illustrious Member
RE: Advice on first layer

It's possible the PEI sheet has surface imperfections from manufacturing -- pressure rollers that apply the PEI sheet to the steel that aren't quite perfect -- a print then having highs and lows that show over extrusion at the peaks left by the roller.  Stranger things have happened.  

You could try the flip side of the sheet to see if the effect remains, or even rotate the steel sheet 180 for a test run to see if the pattern changes sides.

If they are sheet related, perhaps they'll smooth out over time and heat cycles.  

In the Settings menus, look for mesh calibration. You set 3x3 or 7x7 there, along with number of point samples (I use 5), and whether or not the code compensates for magnetic fields.  Try with field correction on and with with off: use the best result.

Posted : 04/09/2019 10:30 pm
JoanTabb
(@joantabb)
Moderator
RE: Advice on first layer

Hi Mike, 
there are a number of factors involved here...

1, use 7x7 mesh bed leveling,

2, sort the middle of the bed using LiveZ,

3, check the perimeter of the bed using the attached file and if problems exist, use 'Bed Level Correction' in the configuration menu... 

to adjust left, right, front, back edge, if a corner is bad, adjust the adjacent sides, unlike like live Z, you can adjust both positive and negative so if the right side is ripply, try changing the right setting more positive to raise the extruder, if the front is not squished enough, try moving the settings for the front edge more negative...

 

the attached file should print a large hollow square, using concentric infill, let it run a couple of laps, if you can see problems, stop the print and adjust the bed level correction values, then clear the build plate, and run the file again,

regards Joan

Attachment removed
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 10:46 pm
Mike Daneman
(@mike-daneman)
Estimable Member
Topic starter answered:
RE: Advice on first layer

Thanks for all the advice.  I already made some improvements and will play around with it more this weekend and report back.

Posted : 05/09/2019 4:45 pm
CybrSage liked
Mike Daneman
(@mike-daneman)
Estimable Member
Topic starter answered:
RE: Advice on first layer

Hi guys,

Sorry, it took me a bit long than I expect, but I wanted to report back on how I did with the bed leveling.  I have my leveling more or less perfect now.  The key things I change were:

1. Enabled 7x7 mesh bed leveling with 5 sample points.  This improved things but didn't make it perfect.

2. Lowered print temperature to 210C (was previously at 220C which was probably a bit high for my PLA).  This again made things better, but I was still getting some small humps on the lower-right of my bed.

3. Per Joan's advice, I went to "Bed Leveling Correction" menu and raised the nozzle by 30um on the right and 30um on the bottom.  After this the lower-right became pretty good, but I started getting some gaps between the lines in the upper-left.  I then lowered by global Z by 15um and now pretty much my entire bed looks good.

One more note is that I found that just printing a big filled-in square on the first layer showed my problem better than the rectangular pattern that Joan.  This one form thingiverse may work well also, although I haven't tried it: https://www.thingiverse.com/thing:2899815

Thanks to everyone for your advice and I hope my experience can help others.

Posted : 16/09/2019 5:35 pm
Nigel
(@nigel)
Honorable Member
RE: Advice on first layer

With the smooth PEI steel sheet, I calibrate, and then add a layer of uhu glu stic. No problems with first layer. Glu stic lasts for many prints. Every so often I wash the glu stic off. And start again. I always handle steel sheets on sides with fingertips. Saves a lot of faffle.

Nigel
Life is keeping interested and excited by knowledge and new things....
Posted : 21/09/2019 12:58 am
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