Strange adhesion problem  

RE: Strange adhesion problem

Try washing with dish soap and water.

regards Joan

RE: Strange adhesion problem

If that does not work, recheck your live Z.  

RE: Strange adhesion problem

Posted by: @yeshead

Is there a way to clean the surface of the smooth PEI (is light sanding a possiblity?)

Sanding is never required, nor is it a good idea. 

I did once use a rubbing compound to remove scratches made by getting the nozzle too close, but I can't even recommend that.  If PLA isn't sticking, an acetone scrub can help to remove oxides that do build up; followed with a drop of dish soap and hot water to wash away what the acetone lifts.  And I never follow soap and water with alcohol. I do use alcohol, but again, I follow that with soap and hot water.

RE: Strange adhesion problem

Sanding should be a last resort - right up there with acetone.  

RE: Strange adhesion problem

Sanding should be a last resort - right up there with acetone.  

RE: Strange adhesion problem

Hello All,

I tried wash it with soap and hot water.

It helped a little bit but not as expected. There was still some warping.

The Z-calibration is good and has nothing to do with it because it only happens on one side of the PEI sheet (the other side prints all right)  and only on a certain spot (range).

So, I must have damaged the surface but I can't see anything.

On one side I can print everything all right, the other side I don't use anymore.

So the only solution looks like buy another one.

RE: Strange adhesion problem

@yeshead

If one side is no longer sticking, 
try washing it again, using hot water and dishsoap, but this time, use the scotchbright side of a kitchen sponge, you have nothing to lose and may regain use of that side... 
regards Joan

RE: Strange adhesion problem

@yeshead

You do not need to buy another necessarily.  As Joan said, give it a good scrubbing

RE: Strange adhesion problem

@yeshead

I would not make that assumption myself.  I have found there is no such thing as a good Z calibration.  It's a myth.  Changing colors of filament or brand can change what the first layer Z height needs to be.  If you have simply printed a calibration pattern - good for you.  But that is the "get it close to ready" step, not the end all.  Are you familiar with the live-z menu choice?  It is there to dial in the first layer at any time.  

Calibration patterns are subjective - and they are not one-and done.  A change in humidity could require a Z adjustment.  As I mentioned, different colors need different Z very often, and each type (brand or material) can require adjustment.

Stop beating your head against the wall and do a live Z calibration while your second side prints.  Learn what a good first layer squish looks like - I wear maginfiers to check it.  Watch it as whatever the thing is you are printing that is having problems - be ready to make sure the whole skirt and the whole first layer look good.

And turn on 7x7 bed mesh leveling.

RE: Strange adhesion problem

@joantabb

When PLA stops sticking to any of my print sheets, it goes immediately to the sink. Period.  After a scrub with a paper towel and a few drops of detergent, I rinse is the hottest water I can get from my tap (130f+), and let it run for a few minutes. Then I dry and place the sheet on the rpinter and I am back in business; it works 100% of the time, every time.

And not to start a "this is best war" with Joan --- lol -- paper towel fibers (aka wood) are actually more abrasive than the blue non-scratch Scotch-Brite material. So I stick with paper towels rather than risk accidentally using my regular dish sponge. Why? Because I have picked up my disk sponge instead of that new sponge I had taken out of the bag ... and getting the butter scum off the sheet was a real task.

RE: Strange adhesion problem

@tim-2

That is why I use the "Green" Sponges from Scotch - More abrasive and still not scratch.

RE: Strange adhesion problem

@cwbullet

I haven't been able to find any definitive source (like 3M) that says the green and blue scratchless sponges are any different. Can you point me at one?

RE: Strange adhesion problem

Here's 3M's specs: the only difference is blue is non-scratch - both are heavy duty... lol.

Blue:

Green

RE: Strange adhesion problem

Posted by: @tim-2

@cwbullet

I haven't been able to find any definitive source (like 3M) that says the green and blue scratchless sponges are any different. Can you point me at one?

Assuming the pads a genuine Scotch-Brite, they color code the pads:

I've seen several notes that the green kitchen pads are equivalent to their 6448. The woodworking and automotive groups have a lot of details on these pads. Not authoritative but:

SCOTCHBRITE GRIT CHART (courtesy of Charlest) back to top
3M Scotch Brite Nylon Pads:
7445 - White pad, called Light Duty Cleansing - (1000) 1200-1500 grit
7448 - Light Grey, called Ultra Fine Hand - (600-800) 800 grit.
6448 - Green (?), called Light Duty Hand Pad - (600) 600 grit
7447 - Maroon pad, called General Purpose Hand - (320-400) 320 grit
6444 - Brown pad, called Extra Duty Hand - (280-320) 240 grit
7446 - Dark Grey pad, called Blending Pad (180-220) 150 grit
7440 - Tan pad, called Heavy Duty Hand Pad - (120-150) 60(?)
Green Scotch Brite is available EVERYWHERE. It's 600 grit.
Blue Scotch-Brite is considered to be about 1000 grit.
(The value inside the parentheses is directly from 3M.)
3M Chart

RE: Strange adhesion problem

@bobstro

Bob,

I meant the "Greener" sponges.  

https://www.amazon.com/Scotch-Brite-Greener-Non-Scratch-Plant-Based-6-Sponges/dp/B00JEQG4X8/ref=sr_1_9?dchild=1&keywords=green+scotch+sponges&qid=1621219952&sr=8-9

They might not be rougher, but I found they work better and last longer for me.  That and I can keep them straight from the ones I use for dishes.