Simplify3D User Forum

Whatever I try to print, z=0..5 mm is always trashed, but after that the print is really nice. It doesn't matter whether I'm printing something small or big. My printer is a CR-10S with BondTech direct drive extruder & hot end upgrade. I'm using Atomic Filament CARBON FIBER Extreme Black PETG, with layer height 0.14, full part cooling fan starting on second layer.

This example is a box that is 45x30x20 mm. Any ideas about where to start looking?

Thanks in advance!

Does this only seem to happen with this model or with other parts as well? Could you please post a Factory File so we can look into this more?

Here is the factory file. BTW, I looked at the gcode, and the extrusion rate in the bad zone is the same in as in the good zone. Strange problem!

I tried printing the same model with PLA and got the same result: I figured it had to be something mechanical. The machine is on a low table, so I got a mirror and looked under the hot end. Here's what the sock looked like: That blob of PETG & carbon fiber is about 5 mm tall. I pulled it off, and it prints like new again.

This reminds me of a problem I had with my MakerBot Rep 2 years ago. It was screwing up a print on only one side of a model because it had a blob on just that side of the nozzle. Anyway, I guess I need to get a little inspection mirror and keep it with the printer.