Top and Bottom Layer Gaps

[Brochel27]

Hi everyone, i have recently been working with a Builder Extreme 2000 printer. It is mainly used for large scale prints and has dimensions of 700 x 700 x 1700 mm. Currently i am trying to print an air intake for a bike which will be provided below. As you can notice from the pictures, the top and bottom layers don't quite seem to fuse together properly and make a solid part. I have been tweaking the settings and finally got a rather decent print but there is still stringing in some areas and the part won't make fully solid layers in certain areas leaving gaps. The nozzle being used is a 0.8mm nozzle and the filament is PLA. In this specific model, there is little infill because the walls are so small. Here are some of the settings i have that might be useful to know(Note: these current settings have provided the best print quality so far). Any assistance would be greatly appreciated!
-Extrusion Multiplier: 1.05 (default is 1.05)
-Extrusion Width: Auto(0.96mm)
-Retraction Distance: 5.00mm (default is 3)
-Extra Restart Distance: -0.2mm(default is 1)
-Retraction Speed: 900mm/min
-Primary Layer Height: 0.4mm
-Outline/Perimeter Shells: 2

[S3D-Jake]

You're printing rounded surfaces above supports. This is one of the more difficult types of geometry to support fully without resorting to a water soluble support material solution. The link below has some tips on how to increase your chances of success with these features.

https://www.simplify3d.com/support/prin ... -supports/

[Brochel27]

I have tried with the layer heights and around 3 for the vertical upper and lower seems to work best. I will try another print with the layer height decreased from 0.4mm to 0.3mm. The only issue is the print takes a very long time so no results show until a day later. Once this print is done i will provide an update. Thank you.

[Brochel27]

For more information, other settings are listed below:
-top solid layers: 5
-bottom solid layers: 5
-outline/perimeter shells: changed between 3 & 5
-horizontal offset from part: 0.7mm
-upper vertical separation layers: 3
-lower vertical separation layers: 3
-printing speed: 4200mm/min
-bridging extrusion multiplier: 110%
(the bridging is included because on every part printed there are a few lines that come off in the print)

[S3D-Jake]

-upper vertical separation layers: 3
-lower vertical separation layers: 3

I would set this to 1 for upper and lower unless you're having an extremely hard time removing supports from the finished print.

[zemlin]

Set your separation layers for 1 top and bottom. If support is hard to remove, increase your layer thickness. If build on top of support is messy, reduce your layer thickness.