"enable bridge settings"

[Corrado1 0]

Good morning.
First of all I apologize for my bad English.
I'm a beginner.
My printer is an elegoo Neptune 3max.
At the moment I use PLA from Elegoo but I would like to switch to PETG soon.
Attached is the printing profile that I mainly use. I laboriously built it by taking information from everywhere. It's certainly far from perfect but I don't mind the results.
unfortunately what I really don't understand how to set is the "enable bridge settings" section.
I can't even make bridges of a centimeter.
Is there anyone among you who would be kind enough to help me?
P.s. obviously I also accept suggestions on my press profile.
Best regards

profile settings.3mf

[Slashee_the_Cow 482]

• Minimum Bridge Wall Length: The minimum distance before a part will be considered for bridging and not an overhanging wall.
• Bridge Skin Support Threshold: Decides whether to bridge or not based on what percentage of that area is supported by the previous layer. Higher number = more small areas being detected as bridges (not necessarily a good thing, since bridges significantly interrupt the normally constant flow of material, and also won't be as strong as if an area could be joined by overhanging walls)
• Bridge Sparse Infill Max Density: This is only for the top of objects; if your infill percentage is low then the infill lines may be too far apart for regular lines to cross without sagging, this will make it bridge the top before doing the normal top/bottom layers.
• Bridge Wall Coasting: Because bridges are printed with thinner lines than regular layers, it requires less pressure in the nozzle. This setting makes the printer "coast" (moves without actively extruding material) to get anything built up in out. It will cause underextrusion in whatever part is printed before the model is printed before the bridge (most likely an outer wall, where it will be visible), and if it reduces the pressure in the nozzle too much (which at 100%, it will) then when it tries printing the bridge it may have to build up pressure before it actually starts extruding. This is very much a "trial and error" thing and will change depending on your printer, extruder and material.
• Bridge Wall Speed: Very much what it sounds like. With materials that print at cold temperatures (like PLA) you can get better results if you keep it low and keep the fan speed high then the material will solidify fairly quickly. With higher temperature materials this won't really work because it won't completely solidify the material, in which case you should print it at about the normal wall speed or it'll just sag as it trails slowly behind the print head.
  • PETG isn't really a high temperature material but it is still a bit moist when it comes out of the nozzle so won't dry as quickly. You should use a normal wall speed for it or it'll just droop behind the nozzle.
• Bridge Wall Flow: What percentage of the normal nozzle flow it will use when printing the bridge walls. Lower means lighter lines which will cool faster and won't sag as much. Just don't set it too low or the extruder may have trouble keeping up with the changes (especially if you have a Bowden extruder).
• Bridge Skin Speed: Same idea as the wall speed. You can set this a little faster (but not too much) because it might already have a wall to grab onto, but I always keep it the same speed as the walls.
• Bridge Skin Flow: Same idea as the walls. You set this a little bit (like 5-10%) higher because it'll give the next layers more to grab on to.
• Bridge Skin Density: At 100%, it will print lines immediately next to each to try and create a solid surface. If your bridge skin flow is less than 100%, the walls still won't touch because they're underextruded. Not a good idea to keep this at 100% if you put flow up to 100% because a solid surface will take a lot longer to cool than individual lines.
• Bridge Fan Speed: Unless you have a good reason, you want to keep this at 100% to help the walls solidify as quickly as possible.
• Bridge Has Multiple Layers: Exactly what it sounds like. Lets you change the options for the next level or two, the idea being you can build up to a higher flow instead of putting a regular surface right on top (which if it's too heavy and the bridge hasn't fully set, will cause it to sag).
  • From your settings:
    
    You want to keep the fan speed at 100% for all the layers. They're still not fully supported and need to set as quickly as possible.

Other notes on your profile:

• As a general rule, your line width (you have it set to 0.45) should be about the same as your nozzle width for the majority of the print. Exceptions are thicker lines for adhesion at the start and thinner lines where needed for finer details.
• You're printing a lot of walls. Fine if there's going to be lots of pressure placed on small areas, but a waste of time and filament otherwise. The "norm" (at least so far as there is one) is 2-3 for general purpose stuff, more if you're printing your lines thin, in which case you usually do enough to achieve a certain thickness, but for most stuff it shouldn't need to be any more than 1mm.
• This one's entirely up to choice, but concentric top/bottom pattern works best with round things. Lines is a bit stronger and usually gives you a better looking print, especially when you're using a monotonic order (since it can't control the direction all the lines are printed on a concentric fill, because they run two different directions).
• Ironing is awesome if you're printing stuff which needs to look great from directly above. Outside of that, it's mostly a waste of time, it doesn't increase strength or anything.
• Triangles isn't really a great infill pattern in a lot of cases. Flow rate gets interrupted significantly at intersections, resulting in a weaker result, and top lines have to bridge long gaps (at the density you're using, the lines are up to 9mm apart). Cubic is great because it adds strength equally in all directions and prevents pillows of air forming in columns which can be visible on the top surface. If you're doing something which has a big internal cavity, you can use Cubic Subdivision to save time and filament by printing the infill less densely in the areas which won't benefit from the strength of the full density.
• I'm assuming the flow rate is something you've got dialed in to get the best results. If you're getting overextrusion it's better to try and fix it at the source rather than adjusting it in slicing. Make sure your extruder steps/mm is calibrated properly.
  • You haven't turned down the flow rate for inner walls. This is going to be a minor problem when it switches from printing something else to inner wall (and vice versa) because it means the extruder has to adjust the flow rate to compensate.
• Be careful with your acceleration rates - just because your printer can accelerate fast (my Ender-3 V3 SE can go up to 4000mm/s²) doesn't mean you should. I've actually had it pull parts and stretch them as it zooms off on a travel move because the material hadn't fully set by the time it reached the end of the line. I usually limit mine to 500mm/s² out of an overabundance of caution, but for most things I do it doesn't affect the print time that much anyway.
• I'll just say this plainly - I think your jerk is too high, especially when you're using printing settings which will result in a lot of jerking, when you're doing concentric pattern in skin and triangles as infill. Jerk being too high be not just detrimental to the printing quality, if you're producing vibrations big enough it's possible for your bed to get a little out of alignment, would cause a layer shift (new layer isn't printed in exactly the same place as the previous one). I usually top out at 8mm.
• Your retraction settings seem a bit contradictory - 50mm/s speed probably means you have a direct drive extruder, but 3mm is far too much retraction unless you're using a very flexible filament like TPU. For PLA I retract 0.8mm at 40mm/s. If it's retracting too far that will unnecessarily damage the filament as it goes back through the extruder's gears. Also, retraction on layer change often isn't necessary, because it will start printing a new layer fairly close to where it finished the previous one most of the time.
• I'd change Build Plate Adhesion > Skirt Height to 1. I've never seen the advantage in more than one layer and it prevents some unnecessary travel and retraction.
• Your Maximum Resolution (under Mesh Fixes) is probably a bit too high - I'd say use your line width at most, but I have it set to 0.1mm regardless of the line width I'm printing. This will help details and things like curves look better.

 

Hope all that helps!

 

If you're having trouble with bridges, it's best to post some photos and the Cura project file (.3mf, in Cura get it ready to print then go to File > Save Project) so the boffins around here can better work on the diagnosis.

Edited January 31 by Slashee_the_Cow

[Corrado1 0]

 

A THOUSAND THANKS!! I can't wait to print with these new settings.
Next week I would like to try my first print with PETG because I have to mount a pair of arms on my bike!

[Slashee_the_Cow 482]

1 hour ago, Corrado1 said:

A THOUSAND THANKS!! I can't wait to print with these new settings.
Next week I would like to try my first print with PETG because I have to mount a pair of arms on my bike!

Just remember to print your PETG fairly strong (decent number of walls/top and bottom layers), maybe even completely solid if it's going to be bearing weight. It's a bit more flexible than PLA which in many cases is a good thing, especially if you want to exploit it (like I've made stuff that clips onto other things by bending to open it, you slide it on and then it closes) and it's also less brittle than PLA (PLA will just break, PETG will bend a little before it breaks) but it also means you need to make it strong enough for whatever you're going to do with it.

 

If you're mounting arms for your bike though it's definitely a better option than PLA if for no other reason than that PLA can got hot enough to start melting if you leave it out in the sun on a really hot day.

[Shadow2 0]

Hmm, there's no way to rotate how Cura wants to start the bridging, is there? I don't see any way. When I enable this for some long, thin models, Cura seems to start the bridging layer across the long axis instead of the short axis.

 

 

Cura would definitely be better off bridging across the shorter span, no?

Edited September 27 by Shadow2

[Slashee_the_Cow 482]

It 

1 hour ago, Shadow2 said:

Hmm, there's no way to rotate how Cura wants to start the bridging, is there? I don't see any way. When I enable this for some long, thin models, Cura seems to start the bridging layer across the long axis instead of the short axis.

 

Cura would definitely be better off bridging across the shorter span, no?

If you post a Cura project file (.3mf, get it set up then go to File > Save Project) I can play around with settings to see if I can figure out why it'd be doing that and/or fix it.

[Shadow2 0]

After I asked that question, I realized that I'm also trying to print some circles in mid-air, so I'm probably going to be using some supports anyway. I actually _want_ the 3D printed texture on the top, which is the only reason these things aren't face-down.

 

 

I attached the file anyway.

CE3E3V2_2020_Slot_covers_-_All_Types.3mf

Edited September 27 by Shadow2

[Slashee_the_Cow 482]

I have no idea how the hell Cura figures out what's the most stable support for bridges (it should run between the best supported edges) so I don't know why it would think ends which are bridges themselves would be the best support for them. If you want it to bridge the sensible way, your side walls need to be thicker. Here it is if I set Walls > Horizontal Expansion to 0.2mm:

If the exact dimensions are important, Horizontal Expansion isn't the right thing to use (going back to your source CAD or whatever file and resizing it is) since it's more designed for if your printer can't accurately print and makes everything a little too big/small.

 

If you want to bridge (instead of having to get supports off the bottom of everything) you could create a support blocker, use the Per Model Settings tool on the left to make it Print as Support, and then scaling it to fit a circle:

 

Also if I was you I'd seriously consider submitting a bug report for this. Make sure to include your project file and say that enabling horizontal expansion (to make your side walls thicker) results in the lines going in the expected direction.

[Shadow2 0]

The exterior dimensions matter, the dimensions on the "inside" do not matter as much as they will flex briefly when the parts are snapped into place.

[Slashee_the_Cow 482]

8 hours ago, Shadow2 said:

The exterior dimensions matter, the dimensions on the "inside" do not matter as much as they will flex briefly when the parts are snapped into place.

Then you'll need manually redo your model to make the walls a bit wider because Horizontal Expansion applies to every direction.