Why Bridge? Can I turn off Bridge
I have run the MK3 for years, still have one at home. At work I have the MK4 with Input Shaping. Have PrusaSlicer 2.9.1 at work but this issue has been across multiple versions of the slicer. I've noticed the bridging, specifically on the MK4 but I think on the MK3 as well. For most models it seems harmless. I've read this forum and some have referred to it as a support. Most of the time it is built into the infill and would never be seen on the final print. However, I often times use a modifier to set bottom/top solid layers to zero so the final print shows the infill pattern.
So up through layer 8, the infill prints without bridging. On layer 9, the bridge infill fills in a portion of the part that is exposed at the end of the print. On layer 10, the infill returns to infill without bridge infill. This part of the model is 13 layers thick. I scaled Z to make this part 60 layers thick and it bridges on layer 56, so four layers before the top floor. This suggests that the bridge is the first attempt to form the solid top layer, with three layers of solid infill before the top solid infill layer. It does not explain why PrusaSlicer wants to show bridging in an area where top and bottom layers are set to zero. I do not want to show the bridging on the final print.
I've played with various print settings. I reduced the fill density thinking that it wouldn't need to bridge shorter lengths, but the slicer forces the bridge on the outside perimeter of the infill pattern.
Ideally we could turn off bridging manually. Ideally bridges would not extend out into areas with not top or bottom layers. I feel like this is so simple, yet I have not found a real solution in my playing around or research. I am missing something very simple? I need to eliminate the exposed bridge layer.
Best Answer by Neophyl:
Simple answer is no. You are correct on your theory that this is being added as a supporting layer for the top layers (its Bridge Infill, not traditional normal bridging). As such it extends out to the next anchor point for the infill.
Personally I would class this as a bug. As its really there for the top layers and your modifier doesn't have top layers in that area. I can also see why it does it as its not actually part of the top layers. Its in that grey area between and I think its been overlooked when they were coding it.
The only thing I think you can do is change your modifier so it also has a different number of perimeters too (like zero). That will add perimeters matching the normal set amount around the modifier area and give that bridge infill a boundary to attach to which will stop it encroaching into the infill you want to be visible.
RE: Why Bridge? Can I turn off Bridge
RE: Why Bridge? Can I turn off Bridge
This is a physical example I found from last year. The exposed bridge makes the part less attractive.
RE: Why Bridge? Can I turn off Bridge
Simple answer is no. You are correct on your theory that this is being added as a supporting layer for the top layers (its Bridge Infill, not traditional normal bridging). As such it extends out to the next anchor point for the infill.
Personally I would class this as a bug. As its really there for the top layers and your modifier doesn't have top layers in that area. I can also see why it does it as its not actually part of the top layers. Its in that grey area between and I think its been overlooked when they were coding it.
The only thing I think you can do is change your modifier so it also has a different number of perimeters too (like zero). That will add perimeters matching the normal set amount around the modifier area and give that bridge infill a boundary to attach to which will stop it encroaching into the infill you want to be visible.