Weird print behaviour

I just finished upgrading my Ender 3 with an original E3DV6 hot end, fang fan, metal extruder, PEI bed. It prints better than ever except a weird issue in the front, mostly on the right. It seems as if the plastic is dribbled on top of the bottom layer, causing pinholes below. Subsequent layers are fine and no trace of the defect is seen on top layer. It also aways happens in the same areas.

Any ideas?

Edited 1 time(s). Last edit at 08/14/2018 02:49PM by Modmike.

looks like an improperly levelled bed. Are you sure that your PEI bed isn't warped?

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MBot3D Printer
MakerBot clone Kit from Amazon
Added heated bed.

Leadscrew self-built printer (in progress)
Duet Wifi, Precision Piezo parts

Yes and yes. I have auto level also. The issue is that as I was watching it print, it seemed like the head went up and dribbled plastic. Any chance it's an adhesion issue?

Edited 2 time(s). Last edit at 08/14/2018 02:53PM by Modmike.

If the head is going up, it's either a problem with the auto-level (Mesh? 3 point? What method are you using?) or it's a problem with your printer's action being warped.

If it's doing something weird that happens in just that location, it's under-extruding.

Is there anything that might be impeding the movement of your filament/extruder? Is this direct-drive or bowden?

If it's bowden, is the front right the most distant (or closest) point to the extruder? Is there any strain on the tube connecting them?

If it's direct drive, is there any strain or restriction on the filament to that point? Where is the filament mounted, is that most/least distant from the spool?

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MBot3D Printer
MakerBot clone Kit from Amazon
Added heated bed.

Leadscrew self-built printer (in progress)
Duet Wifi, Precision Piezo parts

You were right the first time. I ran out, bought a piece of glass cut to fit the bed, laminated the PEI sheet to the glass using a piece of 3M 468, disabled auto level, reinstalled Z switch and it looks like it is working.

Thanks!

Just for the record:
What type of bed does the Ender3 have? A MK2b PCB heater or MK3 aluminum heat spreader style? Or something else, that doesn't seem to work without glass?

The Ender 3 has an aluminum bed that is known to warp. I suspect mine has more issues than that.

It worked fine for a while but the moment I added PEI, I had printing issues. Since I added the glass under the PEI, everything is better. I did have auto level on it but I ended up having to re-level for every print because the bed is so unstable.

If your bed "wobbles" when you touch it then the wheels under the bed need tightening. The bed should ONLY move on Y axis.

Before I fixed this problem on my Ender 3 I had a lot of horizontal shifts and ridges especially on prints with flat vertical surfaces (like the side of a cube).

After ensuring the bed was secure and not shifting or wobbling these problems dissapeared.