Perimeter width and extruder steps

Hi

I have recently finished building a Prusa Mendel i2, and I'm having some issues in various areas. Firstly the perimeter and extruder steps are not behaving as expected. I am using 3mm filament and 0.5mm nozzle.

I have calibrated the extruder steps per mm by measuring the plastic being fed in using digital calipers and I'm happy these are reasonably accurate. For reference I get a value of 844 (Marlin firmware) using a Gregs extruder.

When I print the 0.5mm single wall cube test object, I measure a thickness of 0.6mm instead. The perimeter width test object also does not fit together. Reducing the extrusion multiplier in slic3r gives me exactly 0.5mm walls and the perimeter test now fits perfectly. However, the top surfaces on my objects now have gaps in them. I suspect the nozzle size is slightly larger than 0.5mm, or am I doing this all wrong?

I get really nice top layers with my slicing software (Slic3R) set to extrude top solid infill at 75% width. It fills all the gaps and provides a finer pattern.

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-David

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Ah! Thanks I'll try that setting out.

Am I correct in reducing the extruder multiplier to improve the perimeter thickness accuracy? Or is this just masking another issue?

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X3T
Ah! Thanks I'll try that setting out.

Am I correct in reducing the extruder multiplier to improve the perimeter thickness accuracy? Or is this just masking another issue?

Yes that is the correct way.

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gforce1

Quote
X3T
Ah! Thanks I'll try that setting out.

Am I correct in reducing the extruder multiplier to improve the perimeter thickness accuracy? Or is this just masking another issue?

Yes that is the correct way.

Awesome thanks.

I have also tried the top infill at 75% and noticed a massive increase in the top layer quality! Although I am still getting gaps between perimeters where there is no infill.