Experienced but new and odd issue

[RomeFallsAgain]

I have a unique issue that started recently that I haven't had before and the resolution eludes me so far.

For the sake of this issue, let's say I'm printing a rectangle that is 2 inches by 5 inches and 1/8 inch thick.

Here's a photo of the results.....


The area that's smudged on the part has a corresponding place on the print bed where there's material smeared and stuck to the print bed.
When I pull the part off the print bed, the material that should stay on the part seems to be smeared onto the print bed instead.
It almost looks like the print head is dipping down into the print randomly for some reason and smearing the layers below.
The belts are all tight, the motors secure, nothing I can find is loose, the print bed is leveled.
There are no bubbles or raised points on the print bed. It's glass with kapton tape overlay.

Here's one of the smears on the print bed....


Any ideas?

Thanks

[RomeFallsAgain]

Anyone?

[dkightley]

Crap on the bed!

PS That's an observation....not advice.

[RomeFallsAgain]

Are you suggesting I use Krapton Tape instead?

[dkightley]

Seriously....I think you have a rather dirty bed surface...and what you're getting is small areas sticking very hard to the bed...and when you lever the part off the bed, its ripping some of the material off the bottom of the part.

Clean any adhered material carefully off the bed and degrease it. And I would recommend trying a BuildTak (or similar) sheet on your bed instead of tape or gunk. I swear by one....not at one!

[RomeFallsAgain]

Thanks Doug.
The Kapton tape is new and I've been using Kapton tape like this for years with no issues.

Take an ultra high res close up, flash lit photo of your print bed and I'm sure it'll look even dirtier

This is definitely an issue somewhere else....just haven't been able to find it yet, but I will.

When I do I'll post the solution. Odd issue but then I do a LOT of printing.

[horst.w]

May be a bump of the printbed and / or the Kapton caused by heat expansion.

H.

[RomeFallsAgain]

May be a bump of the printbed and / or the Kapton caused by heat expansion.

H.

If that was the case, I should be able to simply preheat the bed and see it.