Consistently Under-Extruding

[GoremanX 0]

Ender 5 Pro with a Duet 2 Maestro board, E3D Titan extruder driven by a 0.9 degree motor direct over a E3D Volcano hotend with a 0.6mm NozzleX configured for 3mm filament.

 

I used to run a BMG extruder with a 1.8 degree motor through a bowden tube into a Micro Swiss hotend with 0.4mm nozzle setup for 1.75mm filament. I had the extruder steps/mm set to 420, and that worked perfectly for months. Never had any extrusion issues. I could command 100mm of extrusion through the Duet web control interface, and that's exactly what I got every time. Prints came out perfect, or if they ever failed, it wasn't due to extrusion issues.

 

Now with the new setup, I went through calibration steps and came up with 840 steps/mm, which makes sense since I switched to an 0.9 degree motor. Once again, if I command 100mm of extrusion through the web interface, that's exactly what I get every time at any hotend temperature within 10c from the filament recommendation and at any extrusion speed from 1 to 4 mm/s.

 

But prints from Cura are coming out terrible. There's very obvious under-extrusion throughout. Gaps between lines, fragile infill, holes in the top skin, it's all miserable. If I increase filament flow by 20% through the web interface during a print, the issues mostly resolve themselves, though the top skin still doesn't look anywhere near as nice as it used to with my old setup. But +20% seems like a heck of a bandaid. I'd love to know why Cura isn't asking for more filament flow.

 

I've confirmed that I have the nozzle size set to 0.6mm, and the filament size for the extruder settings is at 2.85mm. The filament itself measures in at exactly 2.85mm and seems consistent. It's a good quality ABS (Polymaker Polylite ABS) and it's dry.

 

What would be appropriate steps to take to diagnose this issue?

Edited August 28, 2020 by GoremanX

[tinkergnome 927]

13 hours ago, GoremanX said:

What would be appropriate steps to take to diagnose this issue?

 

 I would (in unsorted order):

1. try a different slicer to rule out (or confirm) Cura settings as the cause
2. disable interpolation for the extruder - leave it untouched for all other axis (config.g M350)
   I had similar experiences with a 3mm DDG extruder, interpolation mode of the trinamic drivers results in a lot less torque of the motor (as far as i understand it) and that may well explain the underextrusion.
   It's working well with "M350 E32 I0".

[GoremanX 0]

2 hours ago, tinkergnome said:

 

 I would (in unsorted order):

1. try a different slicer to rule out (or confirm) Cura settings as the cause

Good call! Tried it in Slic3r. There's absolutely no under-extrusion when I print a file from there, and I'm not adding any extrusion in firmware. In fact, the top surface came out perfect, no issues whatsoever. I was even able to turn off some of the retraction and pressure advance hacks that I've been using to try to deal with this issue. Slic3r is giving me the kind of print quality with my current setup that Cura used to get me with my old setup. The reason I don't typically use Slic3r is that it doesn't have any enclosure temperature control, and I'm just much more familiar with the Cura workflow.

 

So now the question is, why is Cura causing so much under-extrusion with my current setup?

[burtoogle 516]

7 hours ago, GoremanX said:

So now the question is, why is Cura causing so much under-extrusion with my current setup?

 

 Could you please provide an example gcode file that exhibits this problem? Thanks.