Terrible bridge over support. Bridge not extending fully from perimeter to perimeter.  

RE: Terrible bridge over support. Bridge not extending fully from perimeter to perimeter.

I don't know if I would call that a bad print.  You gave it a very hard problem - put down filament and perimeters over nothing but an air gap.  It will never be smooth when you do that and the first layer is going to be rough.  The threads there are not sticking together to make a layer.  That looks like a challenged design.

If you want it to be a little better (layer integrity wise) tell the support to be at the .1 distance instead of the detachable .2 distance.  It will give you a better transition layer density than what you see here.

If it were me though, I would be trying to find a different way to print that part.  Redesign it to have a snap off element perhaps (model the fill instead of having the slicer do it) - if you get the snap-off part about .1 mm away (barely touching - still can see 'light' thru the gap in the modeler. it might print better.  Or turn it over on the bed so you don't need support.

RE: Terrible bridge over support. Bridge not extending fully from perimeter to perimeter.

Posted by: @hooch

[...] I have issue with bridges. On the image here (image link) you can see the underside of my part. This bridge was printed over support (default support settings). Why this bridge is not connecting fully to perimeter? I used default support settings but added supports under bridges to try to fix this issue. This whole briged area was supported.

Unfortunately, supports are one area that PrusaSlicer still lags a bit behind the competition in. The results are usable but not particularly good looking compared to normal top or bottom surfaces. Any print atop removable supports is going to have issues since you don't have the squish between layers to get good adhesion. You can try to reduce the need for supports:

1. Reorient the part to reduce the need for supports.
2. If you are designing the part, include built-in sacrificial support.
3. Cut the part so it can print without supports and assemble after printing.

PrusaSlicer uses a solution inherited from Slic3r that lays down a bridge layer underneath the supported layer that doesn't pull off easily and tends to look sloppy even if the actual support pulls away cleanly. I've found that ideaMaker does a cleaner job with supports. Here's a quick comparison print I did recently. It's an elevated 50mm square X 0.2mm thick:

Left-to-right, top-to-bottom, those are results from ideaMaker, Simplify 3D, PrusaSlicer and Cura. 

I've read that Prusa is working on supports, and I expect PrusaSlicer will excel with that feature very soon. In the meantime, experiment to see what gives you the best solution.

RE: Terrible bridge over support. Bridge not extending fully from perimeter to perimeter.

@bobstro

Hey, I know this thread is a bit old but I just installed IdeaMaker. Can you share your printer profile? I have an MK3S

RE: Terrible bridge over support. Bridge not extending fully from perimeter to perimeter.

Posted by: @jluvs2ride

@bobstro

Hey, I know this thread is a bit old but I just installed IdeaMaker. Can you share your printer profile? I have an MK3S

I have a basic profile here. 

It's a bit old but should work to get you started.