[FIXED] Bridging layer goes in wrong direction

[brian442]

That's the problem, Simplify3D prints perimeters first, and after printing them there are no more "foundations" left, they are "used" by the perimeter

It prints the exact number of perimeters that you ask it to. So if you tell the software to print 3 perimeters, of course it's going to follow that direction.

Like I said many times already, you can either set it to use only 1 perimeter on that layer or make sure your part has a sufficient foundation to support bridging.

[upsm]

That's the problem, Simplify3D prints perimeters first, and after printing them there are no more "foundations" left, they are "used" by the perimeter

It prints the exact number of perimeters that you ask it to. So if you tell the software to print 3 perimeters, of course it's going to follow that direction.

I also told it to bridge. Why is "perimeter" more important then "bridge" ? To me bridge is more important.

Why is this printed as perimeter when this was supposed to (and is in every slicer out there that knows what bridging is) printed as bridge?

bug.png (65.92 KiB) Viewed 7330 times

And this "correct orientation that you support" -> the "foundation" you talk about does not exist, it is printing completely in air

There is nothing under this "bridge", there's no any foundation, it's just touching the side of the perimeter that should not exist there in the first place

[curious aardvark]

whoever said to set the perimeters to 1 - thank you very very very much
I owe you a drink or two
I don't really understand why, but that works !!!
Waheyyyyy

This thing has been doing my head in for about a week. (as you probably gathered).

The wierd thing is that it prints everything exactly as it did with 3 perimeters, but It now bridges horizontally.

So is it that it can only bridge if it thinks there's infill to anchor to ?
And normal non infill perimeters are invisible to the bridging bot ?
because the wall is printed with two lines exactly as before. I'm using a 0.5mm nozzle that extrudes at 0.52. I can live the the extra 4 hundredths

Anyway guys, many, many thanks for trying to explain the mathematical 'illogic' to a strictly logical bloke.

Bloody good start to the week

[brian442]

Happy to help!

If you want to understand why, you can try changing the preview coloring to "feature type". Then try slicing your model with 3 perimeters like you had originally and look at the yellow bridging extrusions. If you look at the underside of those yellow lines, you can see that there's nothing below them, so that is pretty much guaranteed to be a bridge that will fail. For the bridge to work, you want to make sure those yellow lines will overlap with something from the layer below.

If you change the number of perimeters to 1, then slice and look at the underside again, you can see that those lines will overlap with the sidewalls of your vent model, so they are going to print much better.

So if you run into this in the future, it can help to look at the "feature type" coloring to make sure that your yellow lines will have some kind of overlap with the layer below.

[dkightley]

If the photo in this Twitter post re testing is of testing changes for the pending upgrade, I'm somewhat worried that the main issue being talked about here isn't even tested for, never mind being addressed:
https://twitter.com/Simplify3D/status/8 ... 1596450816

[wirlybird]

If you change the number of perimeters to 1, then slice and look at the underside again, you can see that those lines will overlap with the sidewalls of your vent model, so they are going to print much better.

When you say "change the number of perimeters to 1" are you meaning only for the layer where the bridging will need to be?

[dkightley]

When you say "change the number of perimeters to 1" are you meaning only for the layer where the bridging will need to be?

I think the answer will be "Yes".......which is no way right! We shouldn't have to fudge one feature to make another feature work correctly.

[wirlybird]

Completely agree! I have fought with this at times and it has made no sense. Sometimes turning the model has helped but not always.
Anyway, if it can help I am not opposed to adding a couple processes to get a better result but a real fix would be nice.

[upsm]

If the photo in this Twitter post re testing is of testing changes for the pending upgrade, I'm somewhat worried that the main issue being talked about here isn't even tested for, never mind being addressed:
https://twitter.com/Simplify3D/status/8 ... 1596450816

Definitely not, the images are of "standard" bridges where there's plenty of room for "extra inflation distance"... dunno what they are testing but it does not look like these corner cases where they have to decide to put bridging priority over perimeter priority.. anyhow I welcome any development and improvement no matter how small it is... I would just love if they start pushing those changes to us so that we can benefit from them ... a thousand small changes is imo better then one big every two years

[DarthRevan]

Ah - they've changed the forum - never used to allow images. - Ah still doesn't.
why can't we upload images directly to the forum ?


These bridging algorithms are just plain bloody stupid.

rotating model makes no difference, making the duct longer makes no difference.
I even put a central wall in the duct to encourage s3d to bridge the really short gaps.



But no matter what i do - it simply refuses to do anything even remotely sensible and does this every time. Even on the machines with cooling ducts in place, they can't bridge a gap this long. This is bloody ridiculous.


I'm now forced to go and wrestle with cura. Actually before I do that I'm going to reinstall a version 2 of s3d and see if that will do the job better.
I'm sure I never used to have these issues.
Could be wrong.
Yep - I was wrong. Bridging algorithms have always been bloody awful.
2.2.2 does exactly the same thing.

Even if this duct was installed - there is no way it could bridge that long a gap. This should be an easy print - even without a print area cooling fan.
It just needs to bridge a 3mm gap. But instead chooses a 50mm gap.
I'm not being unrealistic here, Algorithm looks at gap: compares length by width - chooses shortest path to bridge.
Surely that's what it SHOULD do ?

And i really don't like cura. But needs must when the expensive software turns out to be bloody awful at bridging.

Can you share this model? I'd like to see if my printer has these same bridging issues.