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prusa3d / PrusaSlicer

G-code generator for 3D printers (RepRap, Makerbot, Ultimaker etc.)
https://www.prusa3d.com/prusaslicer/
GNU Affero General Public License v3.0
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Smarter bridging #10925

Open Matszwe02 opened 1 year ago

Matszwe02 commented 1 year ago

Is your feature request related to a problem? Please describe.

When there's a hole and at some point it contracts to a smaller diameter, cura will brigde in one direction, causing half of the bridges (that ones that are not supported at both sides, so ecery line that ends at the smaller hole) to fall. PS already has a feature that can be used as a core for this bridging, it anhors "floating" top infill to the sparse infill (like it will seek for anhors to determine possible bridges supported from both sides). I don't know if that exact feature may be used for it, but it came to my mind.

It could also be used for bridges that aren't perfectly straight - bridge what can be bridged at first, then treat everything else as overhangs.

Describe the solution you'd like

The solution will be to bridge lines that can be bridged, than rotate 90 degree, bridge what can be bridged, rotate 45 degree, and so on - creating some shape like octagon. Then print the perimeter supported by these bridges.

Describe how it would work

image

Some 3d designs already force printing in a way that I'd like to be implemented, but it will work on multiple layers, instead of a single one image

Describe alternatives you've considered

sacrificial layers - they need to be included in 3d file (user has to take care of them), they need to be broken away, and the final result looks very close to my suggested attempt.

neophyl commented 1 year ago

Duplicate of https://github.com/prusa3d/PrusaSlicer/issues/9973

Tupson444 commented 1 year ago

It isn't exactly a duplicate, because Matszwe02 suggests doing the same thing but in a single layer, which may even be simpler to implement (just a guess, I have no idea).

Having bridging over multiple layers means a loss of thickness (e.g. 0.3mm layer height x3 = 0.9mm) which can result in weaker part if it is already very thin. Also, it can already be implemented by adjusting the model in CAD.

On the other hand, there is no workaround for this complex bridging that can be done in CAD. If someone has time, it would be good to make such a gcode manually and test it. If it proves that it works well, it would be the best solution for bridging around holes.

neophyl commented 1 year ago

Its a duplicate as his option b is identical, you even use pretty much the same example of the hole modelled in CAD that way with the 2 bridge passes to support the final hole.
I've modelled holes this way in CAD and it does work which is why people use it. Prusa themselves have used the same modelling on some of their holes in the past. No one is saying that as a design option it doesn't work, on the contrary.

Discussion of this general technique (a variant of it) goes as far back as issue https://github.com/prusa3d/PrusaSlicer/issues/127 you might want to read the developer response in that issue.

Matszwe02 commented 1 year ago

Its a duplicate as his option b is identical, you even use pretty much the same example of the hole modelled in CAD that way with the 2 bridge passes to support the final hole.
I've modelled holes this way in CAD and it does work which is why people use it. Prusa themselves have used the same modelling on some of their holes in the past. No one is saying that as a design option it doesn't work, on the contrary.

Discussion of this general technique (a variant of it) goes as far back as issue https://github.com/prusa3d/PrusaSlicer/issues/127 you might want to read the developer response in that issue.

I only show the desired shape, but the "option b" is just to show how that one layer will be printed. I think it's not a duplicate, because I have also a suggested work flow that checks the lines it can print and repeat with rotated fill direction and so on

Tupson444 commented 1 year ago

Its a duplicate as his option b is identical

If I understood the option B in #9973, it means printing several layers of bridging, each partially covering the hole edges, only at different angles so eventually (usually 3 layers are enough) it covers the whole hole edge. I know about this trick and I also use it all the time, even for some more complex hole shapes (I can do whatever I want in CAD), and it works great.

On the other hand, this issue suggests doing the same thing, BUT all in a single layer. This is something that cannot be achieved by CAD tricks. Also, I suspect that it might not work just as easily, because bridges would need to connect to other bridges without going on top of each other, that is why I said that it needs testing. There might be needed some tweaking of overlap, speed, order of lines, etc.

Matszwe02 commented 1 year ago

Its a duplicate as his option b is identical

If I understood the option B in #9973, it means printing several layers of bridging, each partially covering the hole edges, only at different angles so eventually (usually 3 layers are enough) it covers the whole hole edge. I know about this trick and I also use it all the time, even for some more complex hole shapes (I can do whatever I want in CAD), and it works great.

On the other hand, this issue suggests doing the same thing, BUT all in a single layer. This is something that cannot be achieved by CAD tricks. Also, I suspect that it might not work just as easily, because bridges would need to connect to other bridges without going on top of each other, that is why I said that it needs testing. There might be needed some tweaking of overlap, speed, order of lines, etc.

You're right, that's a tough process that needs to be tuned that every sagging or other bridging imperfections will have to be kept in mind.