How to create a flat solid surface on the underside of supported material
I have a PLA print that has a large horizontal surface that needs support. I have set up for a single interface layer which is PETG. I am expecting the support to be printed with the support extruder followed by the separation layer from it's extruder followed by the material that is being supported. What PrusaSlicer does is it generates another layer called 'overhang perimeter' which is a layer with tiny gaps between the individual strands of filament. It is not a nice, smooth, solid layer.
How can I change the density of that layer to eliminate the tiny gaps between strands of filaments? Alternatively, is there a setting to not generate that layer or is there a way to print that layer with the separation layer extruder so it can be peeled away?
Best Answer by jens:
I finally figured it out ..... I had to turn off 'detect bridging perimeters' under the 'layers and perimeters' heading.
BTW, there was no 'bridge' anywhere in this project. The bridging layer was sitting on a solid separation layer.
A picture of the resulting print illustrating the issue would be of more use as it's not clear why this is a problem.
In general, 'how to slice this' questions are easiest to answer when accompanied by a project file:
Save your project as a .3mf file
Files > Save Project as
Zip the .3mf and post it here. It will contain both your part and your settings for us to diagnose.
... and don't expect miracles from an algorithm - the slicer is good at calculating simple cases but for specific requirements it's often better to design custom supports in CAD.
Cheerio,
RE: How to create a flat solid surface on the underside of supported material
It would also be nice to know what hardware you plan to use for printing.
Mods for Core One: Core One HT 450 degrees, Comfortable display , Very fast print start and Reducing noises
Mods for Prusa XL: Very fast print start
RE: How to create a flat solid surface on the underside of supported material
A project file as the others have suggested would be the best bet as its hard to be certain from pictures. However from your pic that other layer which you are calling overhang perimeter IS the bottom layer of your object. So its not an 'extra' layer you can peel away. It is probably doing that because you have a setting called Extra Perimeters on Overhangs enabled. We can't be sure without your attached project which is why we ask for them.
The bottom flat surface is definitely an overhang so it fills it up with perimeters. Problem there is like concentric infill there's going to be small gaps that are smaller than the nozzle extrusion width. It wont use gap fill to fill in those like a bottom layer on the print bed as its an overhang. Without that setting it will do just normal perimeter amounts based on your settings and then fill in the layer with normal rectilinear infill.
RE:
I finally figured it out ..... I had to turn off 'detect bridging perimeters' under the 'layers and perimeters' heading.
BTW, there was no 'bridge' anywhere in this project. The bridging layer was sitting on a solid separation layer.
RE: How to create a flat solid surface on the underside of supported material
Turning off detect bridging perimeters makes it slice as if Extra Perimeters on Overhangs is OFF, you have turned off all bridges, including he ones that are internal over normal interior infill. By turning bridging off you have changed the way the algorithm works in many ways. Some of which may cause other unintended issues.
For example now your perimeters on that layer will print at normal layer speeds and not be slowed down for printing on top of your support interface layer. Depending on your printer and materials that may or may not work. Be very sure to check the various preview options to make sure its not doing something unexpected.
RE: How to create a flat solid surface on the underside of supported material
I will check for unintended side effects - thanks!