First layer varies all over the print build plate  

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Eugene Gershtein
(@euggersh)
New Member

I've spent weeks trying to get a good first layer on my textured sheet.  I've been printing a pattern of nine squares to cover all areas of the sheet, and I can get some dialed in but the rest are a mixture of too high and too low.  I've even tried using the bed level compensation, and that's gotten me a bit closer, but since the bed level compensation only lets me work with four points, it's impossible to dial everything in.  (For example, I can have the rear and the right perfect, but the rear right corner will be too high or too low, so there are no compensation values that can bring everything together).

The problem is the same on both sides of the sheet, after washing multiple times with dish soap and cleaning with 99.9% isopropyl alcohol.  I don't know if it's relevant, but I measured the thickness of the sheet all around its perimeter and it seems to have a wide range from 658µm to 690µm.  This seems to me like it could be responsible for the problems I'm seeing, but I also don't know if that sort of variance is normal for these sheets and there's something else going on.

I was optimistic about Prusa support helping me, but the guy I chatted kept insisting that I just need to wash the sheet with dish soap and clean it with alcohol (which, again, I've done multiple times).  He also said that the thickness variation is because of the texture, which doesn't actually make any sense because the jaws on my micrometer are much larger than the detail of the texture.

So, I'm really hoping that someone out there can help me turn this device into something other than an expensive paperweight.  Thanks!

Posted : 26/04/2020 7:36 am
Peter M
(@peter-m-3)
Prominent Member

Disable bed compensation.

Clean bed with only dish soap 2 times with hot water. Use no alcohol.(first layer will stick better)

Activate 7x7 mesh bed leveling in the settings of the printer.

Let the printer get hot, pla and petg and abs have different temperatures(and bed will change), after it is hot do a z-calibration.

Then do a first layer calibration, how to ,this needs to be 100%(filament will stick better).

Make a picture so we can see at the forum. Most users need to go lower!!!!!

Pei and powder coated steel plate have different thickness!!!!!

If everything works, I do clean bed with dish soap, a few prints i use alcohol, the dish soap again.

Small objects and a big flat objects, I always do dish soap, this needs to stick very good.

 

Posted : 26/04/2020 11:02 am
Eugene Gershtein
(@euggersh)
New Member

I've done this both immediately after the soap-and-water wash and after soap-and-water wash plus alcohol.  The behaviour is the same.  I've done with with and without bed level compensatoin.  I've donw this with both 7x7 and 3x3 mesh bed leveling.  All of the Z calibration has been done at the correct temperatures.  I've spent weeks on this and done all of the suggested procedures and more.  The results are the same.

Small objects often print successfully because they use less of the bed and so there's much less variation in the first layer.  I can't print any large objects.

I've been printing a 9x9 grid of squares to cover all parts of the print bed.  When some squares are perfect, others are all scraped up from the nozzle being too close, and others are discrete lines becasue the nozzle is too far.  This isn't an adhesion problem.  It's a Z problem.

Posted : 26/04/2020 4:11 pm
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