Cura Low Extrusion At The Start Of Perimeters?

Hi all,

I'm printing with BQ PLA at 200 degrees using Cura 3.0.2 on an Ender 3.
Cura is set to 3 top and bottom layers and 2 perimeters, (Inner Perimeter first, Outer Perimeter and then Infill) Flow rate is 103%.

Small parts and retraction tests print great, but larger parts have 10-20mm of weak under-extrusion at the start of each perimeter.
This was the retraction test I used -
[www.thingiverse.com]

The Ender 3 uses a standard bowden setup which is about 200mm long, I think my retraction settings are still standard.
Retraction Distance - 5mm
Retract Speed - 40mm/s
Prime Speed - 40mm/s
Retraction Extra Prime Amount - 0mm cubed

Any ideas how I can increase the flow at perimeter starts on large parts without causing over-extrusion on small parts?

The newer cura slicer versions have 2 retraction options.
make sure you have 'retraction at layer change' enabled

I will check that out. Thanks

Cura is up to version 3.4.1 now.

Are you using a volcano heater block with a large nozzle?

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Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]

Thanks for the suggestion Obewan,

The Retraction At Layer Change option was disabled as default, I have set this active now and very slightly increased the flow rate to 104%.
I have just finished re-printing the parts, but unfortunately the tweaks have had little to no effect.

Hi Digital Dentist,

I thought I was a few versions behind but I didn't really want to risk having any incompatibility issues, are you aware of any problems others have had upgrading to the latest versions of Cura? Also have the Cura team added any cool new features between 3.0.2 and 3.4.1?

Nope, I don't have a volcano hot end or an oversized nozzle. I'm just using the standard Creality hot-end and extruder with the 0.4mm nozzle, but I have added capricorn tubing and bowden clips. The extruder has been moved and re-orientated to gain a little Z height and stop the fillament from fouling on the lead-screw, but its basically in the same position as standard.

The Cura web site has all the details on the improvements and bug fixes.

Turn on and use the retraction extra prime amount. Start with a small value- you're retracting 5 mm so unretract an extra 0.5 mm to start and adjust up or down from there.

There's a plugin called "scalable extra prime" that uses an extra prime value that is proportional to the travel distance for each retract, travel, unretract sequence.

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Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]