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top layers not printing / joining

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Hello, Im new to 3d printing and am hoping people can offer some advice on how to improve. Im printing jewellery using a copper PLA blend filament on the ultimaker 2. I have also used a Brass PLA filament. The result is ok, but the top layers are not complete in parts, and the infill does not meet the walls so you send up seeing gaps.

Any suggestions to improve greatly appreciated!


Heres a picture and my settings are below:



Rhino3d export settings:

Tolerance: 0.001

Max distance, edge to surface: 0.001

Min initial Quads: 16

Everything else:0


Cura settings:

Nozzle dia:0.4

Layer height:0.2

Initial layer height:0.4

Line width: 0.4

Wall Thickness:0.8

wall line count:2

Top layer thickness:0.2

Top layers:4

Bottom layer thickness: 0.8

Top bottom pattern: lines

Ignore small Z gaps

Infill density:50%

Infill wipe distance: 0.1

Infill layer thickness:0.1

Infill before walls

speed 30mm/s

outer wall speed 15mm/s

inner wall speed 30mm/s

top/bottom speed 15

Travel speed 150

cooling fans on, min layer time 5sec

union overlapping volumes

material brass PLA at 210 degrees

Also tried copper PLA at 210 degrees


Edited by Guest

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I would cut this part small and just print wing tips with a few hexagons as a test piece and do lots of tests.

Brassfill is difficult to print - it has so much brass in it that it doesn't stick to itself as well as typical PLA.

First thing I would change is to get all your speeds the same. Having an outer wall speed different than inner is asking for trouble. They will have different pressure in the nozzle and it takes a few second to switch to the new pressure causing over and underextrusion and those gaps in your top layer.

higher flow sounds great. Keeping printing speed under 30mm/sec will help. And keep travel speed fast like 250mm/sec. Having more top layers will help also. You might not need much fan since you don't seem to have any overhangs or bridging. Not sure. Fans can also help top layer bridging over infill. So I suppose make sure fan is at 100% by the time you get to the lowest hexagon top - meaning whichever top of a hexagon is lowest - you want fan at 100% by the time the nozzle gets to that Z height.

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I second gr5's suggestion for a larger nozzle, as well. I use a .6 for brassfill, woodfill, and lots of other exotics. It seems the quicker you can get them out the nozzle, the better luck you have. The thicker layers bridge better a lot of times, as well.

What retraction setting are you running? I like to retract hard and fast, but sometimes have to back it down when I'm printing exotics, I would think 4.0-4.5mm at 40mm/s.

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