Changing Layer Heights Affects Extrusion Widths

I tried to reset my experience today and did some basic testing of circles with a fairly standard setting of extrusion 0.45 and layerheight 0.2.
I tested my calibration with axis and cubes : spot-on.
I tested Nopheads polycircles 1- 10.5mm circles with Slic3R and KS: spot-on.
With Slic3R I made a similar test with circles (non poly) 1- 10mm : all circles were 0.3-0.4mm too small diameter :-(
With Kisslicer I made a similar test with circles (non poly) 1- 10mm : all circles were 0.3-0.4mm too small diameter:-(
i made some larger circles 80-100mm sliced with Slic3R/Kissslicer, they all were app the same 0.4-0.5 mm too small :-(

0.3-0.5 mm is close to 1 extrusion width...
What is going on here, is my machine weird?
Are all slicers weird?
Are all machines weird?
Is the firmware weird?

if that is not the case all circles should be made app 1 extrusion width larger at design, but that of course is only a rule if you are using the same machine and same plastic at the same temperature and extruded with the same speed as me... and think like me..
Or should we just accept that this is one of the limits with plastic extruder technology?

Edited 1 time(s). Last edit at 12/08/2013 04:05PM by justcurious.

Your finding are strange considering Nophead only uses Skeinforge because his tests of Slic3r and Kisslicer all had the holes turn out too small. I would assume he uses his polyhole rule for all of his work so I can't see his finding being a result of to high of poly count. But again you used lower layers and narrower extrusion then he would. Could you try both Nopheads and your poly hole test with Slic3r using the default settings (layer height and automatic extrusion width)? Maybe try Kisslicer too with the settings generated by Slic3r? I would like to see if you can confirm that the layer height and width effects the accuracy.

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My quota has been emptied for today.
.
I used this one for the polyholes and had no problems to fit but do not know the settings of Nophead. http://www.thingiverse.com/thing:6118
i do not have patience to also find out of Skeinforge, 2 slicers are enough for me :-(
I never use the automatic setting of extrusion width with Slic3r, like you I do not trust the calcualtions from this.
i think your experience with lower layer heights is the way to go, but some answers are still to be found with this. I have not succeded to get the good results you made with the last testobject, but verified that Slic3R still have some errors to fix.
I do not find the extrusion width is very critical but do not find the time to make extensive tests for this, but varying slightly nearby nozzle width does not show any better results for me.