Bridge tuning help

[desert valley]

Hey,

Been trying to get bridging dialed in and really struggling and not sure if it's a setting that's enabled on the profile or just me being inexperienced but below is the set of test prints with the speed and flow that I was using for them. The entire bottom row were at 1.0 flow.

Any help would be amazing as it's the last thing I really need to tune in now.

Info:

• Bambu P1S with 0.4mm hardened nozzle
• Overture Matte PLA in Light Grey
• Model is here: https://www.printables.com/model/1424606-bft-bridge-foundation-test
• Print profile is my usual one with the modifications detailed in the model description

[lunar kiln]

looks like the 0.85 at 10m/s gives you a good result

https://discord.com/channels/1137181739773603922/1402876760336629831

[desert valley]

This is a better set of photos of that one specifically

[desert valley]

I'll give that a read thank you

[desert valley]

This was .81 and 10mm/s and I think the cleanest I've ever gotten. Curious on your thoughts

There's some stringing but not super fussed about that

[lunar kiln]

That looks like a great result compared to where you started, thanks for giving it a go , I wanted to create a test just for the foundation layer of bridging at realistic bridging distances

[lunar kiln]

What filament is it ?

Is that still the Matt pla?

Setting are different for everyone but that looks good, so when you print a bridge on a normal print look out for big speed changes at the bridge junction if you PA setti gs are out you can get detachments

[nocturne island]

Wow! That looks incredible! I have never gotten mine that good.

[lunar kiln]

I don't think I got mine the good either 😁

But I was using HT filaments

I'm going to have to try some Matt pla now😉

[desert valley]

Overture Matte PLA in their Light Grey

[desert valley]

Thank you for making the model its been very helpful!

[desert valley]

You should see the pile of test ones I have 🤣

Ended up making each plate have 5 or so of them and just tweaked the object settings on each so I could see a range of speeds / flow ratios

[desert valley]

Thats good to know thank you I am going to do the adaptive PA tuning next so hopefully that will catch any issues

Not sure if the adaptive PA will work well with my Bambu P1S printer but we shall see

[lunar kiln]

im not sure how the PS1 handles the PA settings

[desert valley]

This was the last one I ran off

Iirc I went with .021

[lunar kiln]

0.02 ... i have found that this calibration test is a good starting point but for printing parts the PA value may still need tweaking

[desert valley]

What do you recommend for PA calibration?

[lunar kiln]

i use the tower , i find this more realistic, will be interesting to see if it gives you the same answer

[desert valley]

I'll run one off after the currnet plate is done and see what I get from it, I always used the pattern as it was much easier to read for my novice brain

[lunar kiln]

the tower gives you visual which is nice

[desert valley]

Fair enough, assuming you use the default settings?

[lunar kiln]

yes there ia always that, i sometimes just print a 3 wall cube no top layers or infill and change the PA setting as its printing so i can see the effect

[desert valley]

It's running off now so will see when its done in 20 mins or so

[lunar kiln]

now you can see the effect on the print

you have to mease from the bottom of the print to the place which looks the best

[desert valley]

To my eye at least it was around 10.48mm which worked out to a PA of 0.02096

[lunar kiln]

so very close to the value you got before

[desert valley]

Yes just under what I got from the pattern

I might experiment a bit with both styles to get better at reading them and see which I prefer

[lunar kiln]

try not to over tune on calibration parts, try printing a real part to get a feel of the results

[desert valley]

I've been using the kitchen sink as my "check" print and have a shameful collection of them

[nocturne island]

Can you provide the project 3MF on how you got this print? I would like to take a look at your settings. There is a discussion happening over on GitHub about how to get better bridging. Some users (including a YouTuber) got the same effect you did, are claiming their way should probably become the new standard and are requesting some pretty major changes to Orca, but I think they went about it in a MUCH more complicated and unnecessary way.

[desert valley]

Let me dig out the file

The 3mf if anyone wants it

[nocturne island]

FYI, here is the link to that conversation and request in case you want to get involved in it:
https://github.com/SoftFever/OrcaSlicer/issues/11209

[desert valley]

Will give it a read

[tepid marsh]

I have also attempted to calibrate bridges for the last few days. Found this GitHub PR which builds on the last issue. https://github.com/SoftFever/OrcaSlicer/pull/11255

So far I have gotten the best results on my MK3S+ with a Flow of 1.85 (going down this current path I should be somewhere between 1.8 and 1.85 with further tuning), thick bridges disabled and a Speed of 10mm/s

This causes overextrusion on supported bridges

When printing bridges as an isolated feature without surroundings, the normal bridges look just okay (don't have a pic rn but not happy with the quality). The perimeters of my Bridges are displayed as overhang walls are in very bad quality when printed as test pieces with only a bridge. increasing speeds in test pieces up to 50mm have resulted in better perimeters with worse quality and separation on hte bridge infill

Copying over my question from #🐋│orca-chat since it will get burried and might be relevant

@nocturne island with outer layers being printed as overhang walls, are there signifficant differences to how they are printed and what settings they take? I have noticed way worse quality when printed. I tried to keep bridge flow and internal bridge density the same but seems like I lack some fundamental understanding how these features are getting generated

[nocturne island]

You can experiment with the settings and use the various sliced preview types to see how they differ. Unsupported bridging is very rare in my prints, so there is little that I remember about them off the top of my head.

[desert valley]

I know my photo has been used before but this is with 10mm/s and 0.81 bridge flow with matte PLA. Can reproduce the same results across multiple filaments with the same settings as this was printed.

[desert valley]

The 3mf used

[quick sinew]

Hello

[tepid marsh]

I am going to try this out and report back about my results. Something I wanted to check anyways since I've seen some clips of bridges printed fast, hot and strung out which pulled themselves straight when cooling

[quick sinew]

for those who want to test this PR

https://github.com/SoftFever/OrcaSlicer/pull/11255

[desert valley]

My settings should be in the 3mf but it's 10mms external 65mms internal and 0.81 external bridge flow

[quick sinew]

the goal is to separate the bridge line width of solif infill

so setting it to 100% (nozzle size) and later increasing the flow make them print near the paralell line

[desert valley]

I suspect that different filaments will be slightly different but across the 7 matte pla's I've tried from different brands they all look like the above image

[quick sinew]

for what we are testing 100% bridge width and 1.5 flow it's relaly nice

[tepid marsh]

Which order are you printing? I'm printing infill first for improved outer layer (perimeter) quality (though now that I think about I'm not sure it does what I suspected it to - help with hull line artifacts)

also where are you changing bridge width? isn't it managed by using layer widths?

Edit: Gotta figure out how to use your PR for that 😀

I think 0.6mm outer wall width is messing with my free standing bridges that need bridge perimeters which are calculated as overhang walls

[warm scroll]

YouTuber is a strong term for someone who only has 3 videos and a few shorts 😆 . I'd also like to point out that I have no idea who created that enhancement request (as in, I don't know the guy beyond the handle that I saw on GitHub and have had 0 communication beyond what you've seen).
As mentioned on my YouTube and in the conversation, I do not think that we should be changing Orca. I presented a work-around that I created while working on another project. But, there is a much simpler way to get the same results that I am almost finished working on.

I have tried lowering flow similar to @desert valley . For some unknown reason, I do not get the same quality of results. Just saying, for my machine and filament, I am seeing a lot of waviness. I had a lot of success with increasing bridge flow, as have a few dozen others that you can see in the Maker World post.

[warm scroll]

Line Width is a variable that alters flow. This is what I am seeing when using the Bridge Width. These are 1cm cubes.

If line spacing were decreased, I would expect to see more lines created and the same flow. But, when the Bridge Line Width variable in increased, I see more flow and less lines.

When I finish compiling and testing, i will drop a link here. I always love to have respectful and kind collaborators!

[nocturne island]

As expected, because all line width settings inherently change the spacing of the lines.

[quick sinew]

yep, thats becouse it's calculating the path with a nozzle size of 0.8

the thing here is to use the real nozzle size for bridges

[warm scroll]

Nozzle diameter is set to 0.4. Would you like me to try %?

[quick sinew]

but layer width is 0.8

paint a wall with a thicket brush will need less lines

the same is here

and usually the walls are printed with 0.45 or even more to increase the amout of material used

squish it with other layers and walls

but that's what is breaking bridges

bridges cannot excede the nozzle diameter

[warm scroll]

So we agree, which is what I was saying over on the GitHub conversation.

[quick sinew]

here you have internal solid infill of 0.42 if your nozzle is 0.4 the brige will lose that 0.02mm

[nocturne island]

My main concern is that changing the Bridge flow ratio also changes the line width and spacing, so in effect changes to both bridge line width and bridge flow ratio are doing the same thing, and having both will create either a compounding or cancelling effect.

[quick sinew]

mmm

are you sure?

the flow ratio only changes the ammount of material extruded in a X path

[warm scroll]

That's what I am trying to articulate here. Respectfully, I disagree with the PR. I think that you (@IanAlexis) totally understand the principle, but Line Width does something different than you think

[quick sinew]

will not change the path (and spacing)

[nocturne island]

Yes, you can verify this by changing only the bridge flow and seeing in the preview how the line width of the bridge changes.
I do believe this should be considered a bug, because I agree that they should be entirely separate. The flow ratio/extrusion multiplier should never force a change to the line width/spacing.

[warm scroll]

Based on my research, I believe that Bridge Density is what should be changed. As I currently understand it, this dictates line spacing. Here is some evidence:

When my code finishes compiling, I'll push to GitHub and would love it if you guys took a look.

[quick sinew]

a density of 100% should cover it fully. Is not doing that becouse is calculated in a 0.42mm nozzle size

and bridges cannot excede nozzle size (0.4)

[warm scroll]

Density, based on what I am seeing, is the Number of Lines per unit Length, not the diameter.

So, it doesn't exceed nozzle size.

It prints with less space, and slight overlap.

Experimental evidence here. BD = Bridge Density. BF = Bridge Flow.

[quick sinew]

Na, density is used to calculate the path according to the fill pattern. In this case, the fill pattern is actually the bridge pattern.

thats why bridges should touch each other but it doesnt

[warm scroll]

I would claim that if you decrease spacing, without touching flow, you should see more lines in the same amount of space. Do you think that is true?

[quick sinew]

Yes, but that would cause over-extrusion.
The problem here is that the spacing is not calculated correctly because it is taking the size of the internal solid infill instead of the nozzle.

[warm scroll]

OrcaSlicer is a descendant of Slic3r, but distantly. OrcaSlicer was forked from Bambu Studio, which was forked from PrusaSlicer, which itself was forked from the original Slic3r.
But, it looks to me like the line width behavior descends from slic3r
https://manual.slic3r.org/advanced/flow-math

[warm scroll]

I agree that spacing calculation is incorrect. I do not think that it causes over-extrusion if it is tuned correctly, as seen in the photo I shared above. In many cases it does.

[quick sinew]

I don't disagree with the possibility of increasing the density in bridges to create a path that overlaps with the previous lines (although in a large overhang, overextrusion can cause falls).
I agree that the flow ratio should not change the spacing.
And the line width of the bridges should also be independent from the others.

[quick sinew]

i now, but what's doing now is not that

[warm scroll]

Based on everything you just wrote, I believe that we are in complete agreement. Ideally, line width and spacing would be separate. That seems like a big project, though, because that goes back to the files from slic3r (I could be totally wrong and am open to feedback)

[quick sinew]

nah

let me take a look

By the way, I'll check if it's really an error or a design change for some reason.

[warm scroll]

Ok, I can help look through these. Still waiting on compilation, unfortunately, but afterwards I can dive in

[quick sinew]

overlaped in photoshop

the flow is changing the ammount of material extruded

not the spacing

[nocturne island]

I'll get some screenshots of mine, because in v2.3.1 and a pre-H2D build of v2.3.2-dev, it is definitely changing the spacing and line width for me. Maybe something changed since those releases and wasn't noted.

I would like to jump this conversation to a different thread in https://discord.com/channels/1137181739773603922/1379961828276174938 since we seem to have hijacked this one from the OP.