Pressure advance in slic3r

Hello everyone,
I am new to this forum.
I am using Duplicator 4,which has sailfish firmware, slic3r for slicing and flexible filament.
can someone please help me as,
1)how to calibrate the pressure advance value?
2)how the E value is calculated in slic3r?
3)whether the pressure advance influences the print quality?

Thank you.

I'm not sure slic3r does pressure advance, it does do volumetric extrusion, look this up in slic3r manual.

If you have got pressure advance then here's how I tune it, you can print a circular object with a thin wall, one perimeter thick (don't use vase mode as you want it to start and stop extruding on each layer).

Watch it print, if you get a bit of overextrusion at the start of the layer (and under extrusion at the end of the layer) you need less pressure advance. And obviously you need more if it's the other way around. It will change if you use filament with more or less elasticity, more so with long bowden tubes.

Setting it in a slicer is a huge ballache as you'd have to stop print and reslice and print again. If you have duet/rrf you can change pressure advance in firmware on the fly.

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Simon Khoury

Co-founder of [www.precisionpiezo.co.uk] Accurate, repeatable, versatile Z-Probes
Published:Inventions

Hi,
Thanks for your response.I tried a sample print with your advice and i can get the notable changes in my print.
But, when I sliced my model with slic3r, the Gcode which it generates doesn't have any line with code M572 D0 S0.1 which actually does the pressure advance ,as I inferred from the Reprap forum.
Instead it shows a G1 E0.05587 F3600.000 as the pressure advance.I have also enclosed the screen shot of my Gcode here.I am very confused with this thing.Please help me with it.

Thank you.

I think you'll need to ask in a sailfish specific forum how it handles pressure advance. But it should be firmware based.

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Simon Khoury

Co-founder of [www.precisionpiezo.co.uk] Accurate, repeatable, versatile Z-Probes
Published:Inventions

It looks to me that the pressure advance done by that slicer is crude. It's just extruding a little extra filament at the start of a move, to create extra filament pressure. In reality, the pressure buildup should be done linearly during the acceleration phase.

The other aspect of pressure advance is that the pressure needs to be reduced linearly during the deceleration at the end of an extruding move. The "coast to end" feature provided by some slicers is a poor substitute for this, but better than nothing. Maybe slic3r also stops extrusion early when you enable it's "pressure advance" feature. If so then it should be apparent in the gcode.

At high printing speeds or with high amounts of pressure advance, it is often necessary to reverse the extruder motion and start retracting filament before the end of the move. RepRapFirmware has done this for nearly two and a half years, but AFAIK no other firmware does this properly yet (someone please correct me if that's no longer the case). A good demonstration of this can be seen in this video: [youtu.be].

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].