first couple of layers

Hi,

Here is a video of my first couple of layers.
It's a TAZ3, setting are medium ABS

To abbreviate, there is a:
1. blotch on the closest corner, which keeps following up from the start to the next couple of layers.
2. a grinding sound near the end of video (53-54s), that seems like the tip of the extruder is crushing the previous layer. That happens on the north longer perimeter side

I've tried to implement lowering of temperature in the bed, right after the first layer (from 100 C to 80C), in case it happens because they are not cooling fast enough and possibly remaining expanded (?!)
Any help is appreciated
Thanks

And the video:
youtube video

Firstly, the perimeters appear to be printing very fast. I would slow that down a bit in the slicer. Does the grinding/blobbing occur on every print? Or is it just this slice or every slice? The first layer seemed to be sliced a little wierd with no perimeter around the inside box. The grinding sounds like you have too much current going to the motors so you can crank that down a tad until it is more quiet. The motors should make little to no noise, more of a musical sound.

Well everything sorts itself after first couple of layers. The grinding is only on that north perimeter side, and it's deffinitely from extruder touching the previous layer. Would mabe Z lift on the extruder solve it? Generaly why would the nozzle be touching the previous layer? Because of dye-swell?

Could the blobs on the corners of first layers and brims be because of no acceleration on the first layer?
In slic3r i cannot find jerk x,y .. there is only acceleration for perimeters, infill, first layer etc..

I looks like you are printing either too thick of a first layer or your z is too low. I had similar problems on a Prusa i2. If you have pretty good bed adhesion you don't need that first layer so squished. I found that getting a good first layer is probibly the most important and frustrating thing. If you are getting 'grinding' only, or more so, on one side your bed is not level. Do the paper trick with the hot end at 200C and get your bed as level as you can.

On my Mendel90 z0 has the tip of the extruder at 200C just touching the bed. I now get perfect first layers. Just make sure your slicer knows what's up. I get inconsistant results from Slic3r so I switched to Cura.


PS: I found out the Prusa had a bad Z endstop so natrually I took it apart and built a Mendel90 out of it.