[Fermé] First Layer inconsistency  

RE: First Layer inconsistency

• A dirty PEI print surface. Even if you don't think this is the cause, it's always a good idea to make sure your PEI surface is clean before trying any other fixes. Take it to the kitchen sink and give it a good dunk with Dawn (original formula, no vinegar or hand softener variants) dishwashing soap or your local equivalent (e.g. Fairy in UK). Use a clean paper towel to clean it off, and another to dry it. Avoid using any sponge or cloth that has been in contact with grease. Above all else, avoid touching the PEI print surface. Once it's good and clean, you should be able to use 91%+ isopropyl alcohol between prints, 100% acetone when that fails (smooth PEI only, don't use on textured -- can't make out which you have), and another dunk when acetone fails. Worst-case, use a 3M 7445 ScotchBrite pad or equivalent on smooth PEI to give it a very light buff, but only infrequently.
• If you have not already done so, try using Jeff Jordan's "Life Adjust" procedure for calibrating your Live-Z setting. It is much easier to use and understand than the on-board routine. In general, start high (less negative) and work lower (more negative) in large increments (e.g. 0.1mm) until the filament starts to stick on its own. When it's right, you should be able to gently rub it without it coming loose. Then start lowering (more negative) the level until there are no gaps between layers. When you've got your Live-Z setting adjusted properly, you should be able to gently rub the extruded lines without dislodging them. 

RE: First Layer inconsistency

Posted by: bobstro

This is a common problem that can be caused or aggravated by two factors that need to work together well for successful prints. The direct cause of that rippling is that your Live-Z adjustment is too close (too negative) to the bed, causing adjacent lines to crowd and eventually buckle, causing that pattern. Here's mama's tried and true copypasta recipe to get you going...

 

PLA should lay down cleanly on the PEI print surface and hold throughout the print without surface distortion. Many users end up with a Live-Z adjustment that's too close to the bed when they try to compensate for poor adhesion by reducing (making more negative) the Live-Z gap between nozzle and the print surface. Even if you're dubious that these are the cause of your problems, they're 2 fundamental troubleshooting steps that you need to complete to rule out the basics:

 

• A dirty PEI print surface. Even if you don't think this is the cause, it's always a good idea to make sure your PEI surface is clean before trying any other fixes. Take it to the kitchen sink and give it a good dunk with Dawn (original formula, no vinegar or hand softener variants) dishwashing soap or your local equivalent (e.g. Fairy in UK). Use a clean paper towel to clean it off, and another to dry it. Avoid using any sponge or cloth that has been in contact with grease. Above all else, avoid touching the PEI print surface. Once it's good and clean, you should be able to use 91%+ isopropyl alcohol between prints, 100% acetone when that fails (smooth PEI only, don't use on textured -- can't make out which you have), and another dunk when acetone fails. Worst-case, use a 3M 7445 ScotchBrite pad or equivalent on smooth PEI to give it a very light buff, but only infrequently.
• If you have not already done so, try using Jeff Jordan's "Life Adjust" procedure for calibrating your Live-Z setting. It is much easier to use and understand than the on-board routine. In general, start high (less negative) and work lower (more negative) in large increments (e.g. 0.1mm) until the filament starts to stick on its own. When it's right, you should be able to gently rub it without it coming loose. Then start lowering (more negative) the level until there are no gaps between layers. When you've got your Live-Z setting adjusted properly, you should be able to gently rub the extruded lines without dislodging them. 

And above all else, avoid touching the PEI print surface.

 

Try those 2 steps. If you're uncertain of the Live-Z results, post pics here of the 75x75 print bottom and you'll get quick help. 

In the future, a good dunk with Dawn will restore both sides of your to like-new condition and is always a good thing to try when you encounter 1st layer problems. 

 

If you want more detail, I've consolidated my notes on Prusa PEI adhesion, bed cleaning, and Live-Z calibration. I've done a brain dump on nozzle sizes as well.

 

Hi bobstro, 

Thank you very much for replying!
I did what you provided, including washing print sheet, wipe with IPA 99.99 and printing with 75x75 Live-Z setting. 

Here's what I got.

Still having some weird inconsistency issue

RE: First Layer inconsistency

As Bob said, but also in the realm of possible is bed flatness and mesh level.  Make sure you are using the 7x7 level method, and try with and without magnet correction, use whichever provide best full surface correction.

RE: First Layer inconsistency

Hi Tim,

Thank you for the suggestion! Really appreciated!

However, do you know where can I select 7x7 mesh bed leveling setting? and also magnet correction?

RE: First Layer inconsistency

I found it. 
It's in settings!

RE: First Layer inconsistency

You can also enforce it in your printer settings startup gcode:

G80 N7 R5; mesh bed leveling