Excess PLA on first layer - what am I doing wrong?

Hi all -
My Prusa Mendel i2 prints are steadily improving, thanks to all your advice - thank you!

I now have machined pulleys and GT2 belts (BIG improvement there), and have fully calibrated X, Y, Z and E.

Still have excess plastic on my layers though. Thought my E calibration was off, but that does not seem to be it.
Thought it was the fact that I was using 200% infill on the first layer... nope.
Some data:

0.5mm nozzle
0.3mm layer height (all layers)
0.5mm layer width (all layers)
150% first layer infill

Image attached of a simple rectangle, first layer. What am I missing here?
Thanks in advance!

Rob

Correction: My extrusion width (using Slic3r) was set to auto. I am running another print with 0.5mm explicit width and 0.3mm layer height. Pic uploaded soon.

One other thing - I am using 200C for the extruder on my first layer, and 180C on all others. In the interest of turning over all stones on this puzzle, I am lower the temp of the extruder at steps of 5C and retrying to see the results. Stay tuned.

Hi Rob,
I know you said you calibrated Z, but is it possible to be too low and as a result the plastic has no room and therefore goes sideways? So when it meets other plastic at the table it goes up and in the gets in the way of nozzle.

Demetris

You may have already done this but you have to calibrate z=0 when the machine is hot due to thermal expansion. If you calibrate z=0 on a cold machine, it will be too low on a hot machine.

@demetris -
That is exactly what I thought it was, and what it looks like - going sideways and overlapping/interfering with the neighbor lines of plastic. As many know, the reason for the squishing is to have good adhesion to the print bed. This is definitely a first-layer phenomenon.

@konwiddak -
That's an interesting question. I calibrate between runs, so the extruder is hot, but not 200C. I can try calibration on really cold extruder and see if this helps.

The puzzler here is that I don't want to have the extruder too high for the first layer - I have dealt with *many* bigger problems of plastic not sticking to the bed, So it looks like there is a sweet spot that needs to be achieved here - close enough to stick, but not too close as to cause excess squish of the plastic. So I may be going back to try to figure out my first problem again to solve my second one

I think the following made this situation quite a bit better:
1) Raise the Z=0 level a bit, not squashing the first layer so much, in combination with
2) Going a bit slower on the first layer (10% speed instead of 30% speed) to make sure the PLA takes to the bed without moving around.

So far results are promising! Less excess overlap.

Thanks all for the feedback!
Rob