Bridging logic issues

I need to bridge at a considerably slower speed than the rest of the print otherwise the extruded filament tends to break up over the gap, and I therefore set the bridging speed accordingly. This was always a big advantage of Slic3r over Cura for me, because Cura does not have a bridging feature, forcing me to slow the entire print if there was any bridging.

Previous versions of Slic3r used to slow down a perimeter to that speed when the perimeter passed over a gap (bridge). With the latest release version, the perimeter is printed at full speed across gaps (which causes me problems) and only the infill bridging is slowed down. In addition the first solid top layer now infills at bridging speed (which I guess makes sense as it is bridging over the infill, but unnecessary except with very low infill densities). It would therefore seem that the change was a deliberate decision rather than a bug. Could anyone explain the logic behind the first change? If the infill requires a different speed, surely the perimeter will also always require it?

I also have noticed that Slic3r usually bridges between the sides with the shortest distance, but sometimes not. If I have walls 3mm apart and 100mm long to bridge, clearly they should be bridged by running back and forth over the 3mm gap instead of over the 100mm gap - but Slic3r does not always do that - I'm not sure if that was always a case or a recent "feature".

Dave

Hi Dave, I do also have some problems with bridges. For me it seems like the printhead is running back and forth when trying to make the bridge without bounding to the borders leaving all to fall down.
I see folks who make great bridges but Its a mystery to me how they do. Anybody?


RS - Ormerod with Ormerod-0.5 settings

Well, sorry to say I have given up Slic3r for the present. Each release has different major bugs, and the last time I wasted time and filament was the final straw. So I forked out the cash for a commercial product that seems to do everything that Slic3r can do (and far more besides), but without the bugs. It was fairly major money, but well worth it in increased productivity and less frustration!

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ThorsenRune
Hi Dave, I do also have some problems with bridges. For me it seems like the printhead is running back and forth when trying to make the bridge without bounding to the borders leaving all to fall down.
I see folks who make great bridges but Its a mystery to me how they do. Anybody?

I have exactly the same problem with slic3r...

@dmould can you say which commercial product you have switched to? Thanks.

I made some film with a webcam to illustrate the fact but cant upload them so its just 3 images for those interrested.
This is slicer 1.2, I found that slicer 0.98 doesnt recognize the bridge so it just ignore the setting but it works better. Im using [gcode.ws]. It really helped me a lot
Anyone knows which slicer is the first to recognize bridges?
Cheers
Rune

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oscahie

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ThorsenRune
Hi Dave, I do also have some problems with bridges. For me it seems like the printhead is running back and forth when trying to make the bridge without bounding to the borders leaving all to fall down.
I see folks who make great bridges but Its a mystery to me how they do. Anybody?

I have exactly the same problem with slic3r...

@dmould can you say which commercial product you have switched to? Thanks.

I now use Simplify3D

Dave

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ThorsenRune
Hi Dave, I do also have some problems with bridges. For me it seems like the printhead is running back and forth when trying to make the bridge without bounding to the borders leaving all to fall down.
I see folks who make great bridges but Its a mystery to me how they do. Anybody?

Hi,
I have the same problem, when the nozzle terminate a bridge and touche the other side, a fast move is immediately done and the plastic does not attach where it need to. It seems tu occurs only for the bridged perimeters, for the infill it looks better because there is no fast move between the different bridges.

First, I enabled "only retract when crossing perimeter" because I think it was the problem, but it already occurs...

Futhermore, the bridges are attached only by one thickness on the both side, it will be better if the bridges exceeds a bit more when possible.

Here you can find pics, movie, gcode and stl if it helps you to fix the problem:
[lkiefer.org]